My suggestions would be to first use a longer bar to give you space when threading so you wouldn't have to move the follow rest every time. Then I would recommend that before machining something I would anneal the entire piece to remove possible stresses and avoid deformations and finally as a knife maker whenever we say "we can straighten it in the press or in the vise" it breaks. Greetings from Argentina
Try and evenly heat up the part. I leaned this in knife making. I also learned that if you warp a blade don't put it into a vics and bend it back. Instead. Do a normalizing cycle[heat it up and let it cool down at room temperature]. Then carefully re shape it. Then retry the heat treating process.
Hi, heat treat metallurgist here. There are three constants in life: death, taxes, and distortion during heat treatment. There are a couple things you could do different on the next one... Stress relieving before machining will absolutely help. The material will move less as stresses are relieved while heating up in heat treat. Do not machine, stress relieve, and then heat treat... Every time the material is heated and cooled, stresses are relieved. When there is a change in stress, there is a change in strain, which equals movement. Only stress relieve if you're going to be doing subsequent machining operations. When heated before quenching, hang the part vertically. A lot of the bowing you saw after quenching is actually from the part bowing under its own weight since it was suspended horizontally. When quenching, only agitate the part up and down. Agitating side to side in the quench tank will cause preferential cooling on one side, which leads to bowing. If possible, you should heat your quench oil to 150-180F. The additional heat will reduce the quench severity and help with distortion. Even with all of these steps, you're still going to have to straighten after quenching. Your best bet will be to straighten and then heat to temper. This can be achieved by clamping and tempering, where you clamp the part between two flat surfaces so that it "takes" a flat, and then temper. You'll need to go above 500F to see any significant "taking" of the flatness. But, your lead screw does not need to be 60+ HRC, so that shouldn't be an issue. It can be difficult to clamp and temper round parts, though. Alternatively, you could also use your V anvils and the hydraulic press to press the shaft just past flat and use your torch to heat to a nice, deep blue. This will relieve the stresses put into the material by elastically deforming it, and it should "take" some flatness. Hope this helps!
Vertical positioning is a great suggestion. I knew a blade company that bulk produced rapier blades, and they actually had a consistent warp because even though they heated and quenched vertically, even the rapid movement between the oven and tank was enough to warp them slightly. The clamping and heating in position is also pure gold!
I've experienced the same issue with a part deforming under its own weight when heated. Surprisingly it doesn't take much. Totally agree with the above post though am thinking the straightening with heat is the best approach.
Hearing "easy for the hydraulic press" immediately after hardening I knew exactly what was coming... Might be worth it to straighten it after cutting everything and then anneal it to remove the stress from straightening and machining. After that anneal the hardening step shouldn't bend it and you'll end up with a straight, hardened, finished product.
We did a bit of straightening with a press like that in the last shop i worked. It's a tedious and difficult thing to do. Even on much softer stuff. Training new personnel to do it would inevitably cost a few 20.000$ parts...
Not an expert on this, but this is what I would try. Heat it up prior to turning to a cherry red, than cool it really slow (like in heated sand?) to anneal it completely. It would/should take all of the stress out of it. But as mentioned by KyleMc16, you already knew it was bent somewhat during turning. So straightening before heating, and a larger support when heating it might help as well. Anyway, failures is what we all learn from, right?
@@GerbenPolder456 I'd say as a complete non-machinist, a jig, something big with a lot of thermal mass to it, clamp it in the jig heat the whole thing up, let the whole thing cool very slowly, don't know if it needs to be something with a greater or lesser rate of thermal expansion than the piece or the same, though and having access to a forge would make it cheaper and quicker to heat, oh and the right sized ballend mill to mill the slot in the two halves of the jig.
@@robertrdell8898 That's kinda what I was thinking, too... but... what if the bend is introduced by the hardening process? A comment starting "Hi, heat treat metallurgist here" suggests that (a) is very much possible, and (b) is likely at least part of what happened here... so... alas, while I was very much thinking "de-banana before heat treating!", it may be that "Remove hardness before bending then re-harden it" won't actually fly. 😢
As a person who has nothing to do with machining I highly respect you for showing all your failures along the way to what is essentially a boss fight.All the episodes lead up to the restoration of the lead screw and I am hyped to see our protagonist come back from a temporary setback!!!!
Almost me. I sat on the toilet taking a shit when he started using the press. I was totally shocked, seeing him trying to bend a piece of hardened steel and I screamed in my head.
The relationship that you and your wife have brings a lot of joy to these videos. Keep it up man, as a welder turned software salesman, I am living vicariously through your projects.
More important than your heritage is your relationship with your wife. Like he said, it's awesome to see you two interact with love and excitement. (Glad you didn't die after the "c'mon girl" bit 🤣)
@@andymouse British people have emotions? Awesome I always figured they were just stuck on “jolly good”. You don’t make an empire with that attitude tho…
I used to work for a machine tool rebuilder. We would chase the worn screws in the lathe so the profile was even through the whole length of the screw. Then make a new nut with a matching profile to fit the screw. You end up with a screw with a non standard acme profile, but the lead is consistent which is the important part. It also saves a lot of time!
this sounds like a good out of the box idea from a non machinist. it not like it's a shop where the non-standard stuff is going to confuse some future person.
@@bmxerkrantz Ironically, this is exactly what a machinist would do if there is adequate backlash correction available. No one with experience will be confused. This is common in professional shops, and with rebuilders as stated. It doesn't change the thread count, and the backlash correction is designed to allow for exactly this within limits and can only be done so many times.
This channel is what inspired me to learn machining. Because if you, I'm going to a trade school as part of my high school curriculum to learn precision machining and get industry certified. Thank you for making these videos.
@@Lilac757 another vote of very cool and wishing you luck! (Which you'll hopefully increase your chances of with hard work, of course.) I kinda wish I'd explored machining in high school... don't think I knew it was a thing (maybe we didn't have a program for it, I dunno, but I could imagine there must have been something at a nearby community college or something, at least, kinda like the video production class I did take.)
Do it!! I took 3 semesters of community college for my CNC Operator certification and it's been life changing. I've been in the field for 3+ years now and I've not worked a day since - because I love my job. Listen to the greybeards in this field, they have very good knowledge that really helps. Creativity helps, too, but in the right dosage. Good luck!! 😁
Suggestion: Do not heat treat! Make from A-2 and use as machined. Any heat treat on a part this long and slender will warp. Industrial manufacture of hardened ball screws for example the stock is rough machined hardened, tempered, and genealogically treated. Then finished by cylindrical and thread grinding. The soft screw will last longer than you will live if not used for production on multiple shifts.
you can heat treat and either thread grind or... just, use carbide.... I don't know why everyone seems to think you need to grind hardened material. you don't, even okay quality carbide will cut, good quality carbide will laugh at it and good, name brand coated carbide will eat it for breakfast. there are coated acme thread inserts and he can also modify the insert if needed by using a diamond wheel. would be a lot easier than grinding and you get to keep the heat treatment!
@@ramentaryramblings I think this is a good suggestion for "Heritage". The idea he's putting forth in his videos is creating items and solving problems within his scope of capability. Seems like hiring someone to thread grind goes against the idea of his channel.
Heartbreaking, honestly surprised there wasn't a constant flow of bleeps after the snap. Chronova Engineering just recently did a video where they heat treated a lead screw for a much smaller machine by putting it in a drill press and spinning it constantly while heating and quenching. The results were impressive, it might be worth considering a way to rig up a similar setup that would work with your larger part if/when you decide to try again. check their most recent video at the 4 minute mark if you'd like to watch :)
also annealing the screw at least once before hardening it would also help, like I'm talking anneal, machine, anneal, machine to spec, straighten, anneal, harden, anneal, that should get rid of all of the stress in the material before the hardening step.
There are so many videos out there that show perfect outcomes, but they never show the failures. This video is so incredibly valuable. Showing what happens to materials when cutting or bending during certain states is worthwhile to document, and it is also quite exciting to view.
Just wanted to let you know you are part of the reason I became a machinist. Watching your videos over a decade ago made me super interested in the trade. So thank you.
You're right. Failure worth studying more than success. 80% of Textbooks talk about failures, but people only remember 5% of the whole text book that has 4% success and 1% theory.
I love the new format you introduced, with your wife being present, and more open style of communication/storytelling. It's unique and very easy to follow :)
I've been a machinist for 48 years. I agree with the heat treater's comment and the one that mentioned rotating the part while heating and quenching. Heating a part on one side and quenching is how you heat form parts. Another approach is to use 4340M. Plenty of strenth, hard enough to last your lifespan. And it is still machinable. If you're not satisfied with the hardness it can be hardened further. You can check specs on Carpenter steel's website.
A lead screw running in a bronze nut will last years with no issue at all, especially for a hobby shop application. I would cut off the geared section, drill and ream the gear. Make up a new threaded section with a smooth section to fit the gear. Press in, drill and pin. This way you salvage part of the job.
Raises the whole question of why the geared section must be monolithic with the rest of the screw? Are you concerned that heat on one part plus liquid N2 on the other won't result in an overall "permanent" bond?
@@blairlock Sort of with carbide tooling but it´s not fun and you definitely won´t cut an acme thread in a hardened tool steel rod. You would need to grind that with a special machine under coolant, which is what is done comercially on good machines.
Hope you're grateful to have such a cool wife. Seems like she is at your side, will stand by your side, and even laugh with you instead of at you to share good times that you will reminiscence years down the road. May God bless you and your family
Fulltime knifemaker here. Normalizing before machining helps prevent warps a lot. Also, some heat (less than temper temp) while bending is a must. You don't even need to see any color change for the part to be hot enough to bend, but if the part is north of 60 HRC, you've gotta give it some heat
I turned a lot of hardened steels in my career, including a few thin shafts like yours. You maybe should look into a different approach of doing things. Maybe start with a quenched and tempered raw stock as a base, rough out most of the features, even the threads and leave around 0.6mm of on all final dimensions, including the length of the shaft. Let it get hardened by a specialized company, this will ensure, that the shaft will come out as straight as possible, to make the final operations possible. I would harden it to around 48 HRC +3. The shaft has to take a lot of load during cutting, later when its in use, so it has to be flexible and not as brittle. To finalize it, I would grind a carbide thread tool. Around 50HRC is relatively easy to still turn with carbide tools, you just have to drop the cutting speed quite a bit. Only the spines could be a problem after hardening, as you would probably have to grind the splines, or use carbide spline cutters. Another thing I noticed, is that the thread pitch and its precision is also dependend on your lathes temperature. The pitch may change as your machine warms up. But I loved this video as always! I fell in love with you and your content on the first video and I watched every one since then! Greetings from Germany!
Best video I've seen in a long time sighed up just to leave this comment Finally someone showed things don't always go as planned You learn nothing from success and everything from failure Thanks for posting a real video the lesson is more than just about making parts but real world experience
One of the bits I have learnt from UA-cam blacksmiths is that a sword/knife (and thus leadscrew as well) is still slightly plastic coming out of the quench, and that it is possible to straighten out a banana as long as you dont wait more than a few minutes. You often see them pull out a sword, look down the edge to check, and then _immediately_ stick the end in a vise and start pulling to correct the warp.
Knifemaker here, and yes, that is true, though not sure how applicable is that here, since he has precision ground threads and sticking it into a vice will probably squish those threads a little bit, even if he can bend it straight. However, you can do a temper jig. Tempering is the part where you stick it into the oven to lose some hardness but gain toughness. While in the temper, you can put the object bent in the opposite way and while its tempering it will release some stress and so might come out straight after its done. Basically what he was doing with the hydraulic press, but gentler and doing it in the over.
He could also try to use cooling differentials to warp it back into shape, ( put the belly of the bow down on something conductive and big i.e. mill table) I have warped a couple pans doing similar things
@@FireZenix The bit about deforming the threads by sticking them in a vise is definitely valid. Though they weren't precision _ground_, they were just machined. The temper jig is a solid idea though.
@@thomasbecker9676 Funnily enough not Kyle Roger. I have seen something of his, but it's actually been others. A bit of Ilya (That Works), and Alec Steele, with odd others thrown in for good measure
I have an idea for your thread problem (when you crashed in to the tail stock) leave extra stock and turn it bellow the finale depth (just the excess) and after you done threading, you only have to cut of the excess.
Chronova engineering recently did a video on restoring a vintage lathe where they hardened a cross slide lead screw by rotating it in a drillpress while heating it and then quenching it while still rotating. Might be worth a shot!
So, one thing you can do is relieve the stresses in the material before you quench. Basically just heat it up like you were going to quench it, and then don't. Basically just let it slowly cool back down to room temperature. What this does is actually remove stresses by creating more uniform grain structure within the steel (pretty much like annealing but at a higher temperature because you aren't worried about ruining the heat treat). You can do it a few times (like twice) and then heat it up again and quench it. A post quench option is doing the annealing process with the screw set up in a jig to bend it back to straight. Or even. Right after quenching it’s still quite hot. So you can quickly put it in a jig to straighten it while it cools down to room temperature
And there was never any need to harden this shaft to the extend he did. It's way overkill for the purpose. He created his own problems by trying to over-spec the design.
To fix that follow rest problem you could leave a dummy end on. I do this a lot. Just leave whatever length you need on the end smaller than the minor diameter. When done part it off and face. We do 98 inch helical shafts and we always heat treat them vertically. It doesn’t stop the warpage all together but it greatly improved it. Another thing we do is stress relief before machining. Hope the next one works out!
As soon as I saw you heat treating the shaft without rotating it I saw the warping coming. I learned the same lesson about heating a rod from one side the hard way as well.
I saw Chronova Engineering recently make (machining/hardening) a thread as well actually. Just like you, he did it a bit unconventially by machining it first then heat treating and quenching, but he applied them evenly by having it rotate on a spindle. It worked out quite well for him. If you are interested, the video is called "Restoring a Vintage Watchmaker's Lathe", uploaded 4 days ago, and the timestamp of interest is around 3.20-5.00, though it might be easier to watch it from the start
Trying to bend tool steel after hardening it is crazy lol. Next go round, stress relieve it before machining, then maybe again after machining, if you're really set hardening it. If it were me, I wouldn't even harden it. It'll do what you need to do, and you can always make a fourth one later down the line if u need to. You're a braver man than I, though. This is the definition of a rabbit hole project and I commend you for your commitment to it 🫡
one thing I really appreciate is that you throw in your mistakes, its not a clean cut one and done process for every vid. Im building a cnc milling machine in my garage and it frustrates the hell out of me every time I mess something up. Its such a relief to know that the frustration and annoying setbacks that I experience is not just me, but a more universal experience for all makers, please keep up with this you have been such a huge inspiration for me
That heartbreak across your face in the final piece to camera, you were on the edge of tears, whereas I would have been submerged in an ocean of my own tears
I think the warp was induced during heating, not while quenching. Think about it. It becomes fairly elastic when cherry red, and laying on it's side, suspended between your hangers, I believe that is when it took the banana shape. You didn't notice while picking it up or quenching because you move relatively quickly. When you quench the next one, hold it vertically...dangle it, then quench like the guys that make swords and knives.
@@IslandHermitnope. Variable hours and too fricking tired to work it out means surprise on pay day. Since IM videos release the very evening after I get paid pay day is 'edging'...if ya know what I mean 😉
The image of you “literally” being dragged down a “literal rabbit hole” has made my day! Keep up the great work, love the videos and your honesty. Always remember, those who don’t make mistakes don’t make anything!
As a few have said before me, stress relieving the material after machining and hanging the material vertically while heating will help. Also, instead of relying on the press to straighten the shaft, additional spot heating can be used for straightening. Heat a small spot cherry red at the low side at the start (vertex?) of your bend and when that spot cools it will shrink and pull the shaft in that direction. "Fire the mountain, peen the valley" is what the old fellas say.
I was thinking along similar lines, but as he wants a hardened screw, any spot heat straightening may lead to inconsistent results in the hardening. That may not matter much if the bend was in part of the screw that doesn’t see much wear over time.
I don't have a lathe, I don't even work with metal, but, man, I was on the edge of my seat for the entire video. The suspense was killing me, especially witnessing the use of multiple tools to make one single lead screw, multiplying the risks of mishaps. And then the twist in the plot, right during the final scene... I shouted out loud at my monitor when it happened!
Oh man. I wanted to scream stop as soon as I saw the press in action 😂 Well, I really appreciate sharing mistakes and failures, that is life. Every time I do something like this my thoughts go to you and your box of shame. Best channel on youtube. Cheers.
Hi Brandon, I'm a professional knifemaker of very high end chefs, folding, and hunting knives so heat treating as well as removal of warps is an endless endeavour that I face. I'm from Australia so timing may be a bit hard, but I'm more than happy to have a chat and discuss some steps I take, tips, and observations I've made. These vary from working processes to selection of material thanks to literal thousands of hours of research I did procrastinating my engineering studies. Hopefully I can be of help! Regards, Mike - Orzel Knives
Charcoal forge. Propane weed burner forge. WAY Cheaper than Oxy Acety... When straightening in a press set up your dial indicator to measure the amount of negative bend you are putting in to counter the positive bend. Then keep track of negative versus positive improvement. Visually it appears you went very very far in the negative direction. Repeated small bends can add up in the desired direction. Slow and steady. Perhaps even a small amount of gentle heat. What about a borax? antioxidant protection. Would allow slower and more controlled heating.
Other comments already mentioned the most important ideas: excess material to prevent tool crashing, stress relieving by heating to non magnetic then slow cooling in pearlite, and Chronova Engineering’s method of hardening on a drill press. That leaves the order of operations. This is what I might try: 1) Stress relieve the stock before starting 2) Machine with coolant. Stop after each pass to allow temperature normalization (coolant cools, but not necessarily enough). 3) Straighten while metal is still soft. 4) Since I am a belt and suspender type, stress relieve again. 5) Repeat steps 3 and 4 as required until straight after stress relief. 6) Use Chronova’s method to harden. 7) Anneal using step tempering methods (at least 3 cycles). Building a three point straightening jig that fits in your oven would make a nice side project for this one. Yes, this is going far above and beyond reasonable requirements but, considering that the more perfect this part is, the more accurate any parts made using will be, it is worth being obsessive with it. Looking forward to seeing how you solve it. It does make you wonder how the first person to make one did it. I mean how was the first precision screw made? How precise was it? How did they maintain precision when they used it to make more precision screws. After all, we all know what happens when you make a copy of a copy of a copy. If anyone knows of a place to study the history of early development of machine tools, please point me to it.
Based on the random machining videos I've watched in the last few days, I'd suggest thread milling the replacement, and then roller burnishing the thread to work harden and improve it's finish. Also, when you cut the replacement on the lathe, just leave extra material on the end so you don't have to mess with the follower rest clearing the tailstock, then cut the extra off last.
Thread milling is a CNC operation. It can’t be done on a manual mill. Also, roller burnishing is a specialty operation. Not a machine that is common in shops.
@@narcoleptic8982 I was thinking he could use the lathe and the grinding figure to do the thread milling if he runs it slow enough. I ran a Lees-Brander thread milling lathe for a while, it's slow, but accurate.
@@ka9dgx I’d just leave it .050 oversized, harden it properly, like 45-50 Rockwell, not 65 holy shit. Put it back in the lathe and pick up the thread and turn it straight. Probably could even straighten it in the press if it wasn’t way harder than it should ever be. Honestly I think he should have just made it out of 4140 HTSR and just not worried about he hardening at all.. This is a failure due to over-engineering.
I actually just saw a video about this very same heat treatment issue. Their solution was chucking the lead screw in a drill press and spinning it at low speed while heating with the torch. Then with it still turning brought the quench tank up to the screw. Came out perfectly straight. It was a much smaller lathe but may be worth a shot. I believe the video was called “Restoring a vintage watchmakers lathe” on Chronova Engineering’s channel
@25:15 I would use 4140 instead of O1. You should be able to easily normalize it before machining which should prevent some of the bending, and you should be able to straighten it better afterwards (they used 4140 for gun barrels and had to straighten them after machining)
I can only say keep on keeping on. I have next to no knowledge of machining, but even just learning (from a couch) has been a wonderful experience. My little girl also loves watching the process, and I get to teach her words like pantograph, gear exchange ratio, and zeroing (which she'll actually understand when she's out of diapers).
Agree. You just want the bronze nut to wear before the lead screw because the nut is easier to bush and repair. Stressproof is hard enough, no? I flinched when I heard he was using O1 and planned to harden. Can also punt and buy a precision ground screw, and simply attach to the geared end.
Your attention to detail never fails to impress me. It appears that nothing less than perfection is acceptable to you. That is a rare quality these days. Kudos!
Typically that is done with forged blades. Essentially hitting the metal unevenly hundreds of times causes some local stresses to build. That's why it's annealed 1-5 times, depending on the metal and the amount of hammering and complexity of the shape.
@@ManiacallySmithing that's not from hitting with a hammer, that's from complete lack of concern regarding heating and cooling during the forging which causes grain growth
Had a similar challenge on a really long high tolerance thread, previously these had been machined, hardened and the straightened. Changed the method to harden then machine (different tips required), no more bending issues encountered
Hi there well I feel your pain. i did a cross lead screw a month back on a British Lathe with Whitworth threads. what i did was purchase an Acme thread rod from McMaster Carr. Cut the old lead screw so i could machine a slip boss 1" long on it. Took the new threaded rod cut it 1" longer than the old screw, machined a matching boss, pressed both together, pinned it, and perfect. Just what i did, and a low cost
Keep the humour.. keep the bloopers because they teach all of us what not to do, or least to be aware of. But most of all, keep the humour between you and the great lady you share your life with!! Thanks
Anneal at quench temp, put it in pearlite to slowly cool down. Do this at least twice. Then I'd take any bends or warps out. Then harden and anneal. Try aim for 55 HRC.
Amature blacksmith here. From my knowlage, normalizing a part is the best when deling with worps/crack after heattriting. Usually worked for me, for any kind of steel I used (rebar, tool stell, springleaf and so on). Usually I do with 3-4 normalization cycles before heattreating the part. For my and my needs (forging on coal furnice (makes A LOT of stresses and weird stuff with stell)) works like 95% of the times. Hope you don't give up and keep your, as always greate, work
I’ve never commented on a UA-cam video in my life, but I just want you to know I SCREAMED when it snapped. “Noooooooooo! My heart!!!” What a tough break. Watching that hurt me more than snapping 3 out of 4 exhaust bolts on a transmission job in my garage on my own daily😂
I don't know the English name for it but in Dutch we call it "spanningsloos gloeien". As the material heats up it's yield strength decreases. All the internal forces greater than the yield strength disappear. So when the material cools down the smaller (and less banana-inducing) forces remain and the larger ones go away. Hope this helps.
Stress-Relief annealing might be the correct word for it. It’s defined in EN 10052 but the process is pretty involved, if not even impossible for hobby shops as one has to hold the part at ~600C for several hours. Some materials can be bought in this state. Although I’m not interely sure if it would help with the bending while hardening
John over at Black Bear Forge heats the part to dull red and puts it in vermiculite to cool it over half a day to anneal. Might not get you to norm-level destressing, but it's certainly doable in a hobby shop.
@@jakobsasz8035 You can do full anealing in the hobby shop with a small electric heat treat oven You don't need to do a true anneal anyway though. As pr0crastinatr says, you can get amazing results from vermiculite or wood ash
@@skilletborneI don't think he can justify to his wife buying a "small" heat treat oven that is big enough to fit that shaft. Not even if she was the one to machine a screw for so many hours just to feed the hydraulic press a hefty meal.
I would suggest doing 2-3 normalising cycles before your quench in the heat treating cycle, bring the part up to non magnetic temperature and allow to cool to room temp it will help to relieve a lot of stresses in the steel, Godspeed good sir
Literally every time I see one of your videos I always think it is going to be boring. Then I go on a 3 day watching streak, where all I watch it you. It happens every time lol 😂😂
It doesn't need to be so hard to function. You did great. We live and learn. Like my favorite rich man once said. If your not breaking stuff your not learning from your mistakes.
well in blacksmithing if you want to stress releive you heat it above non magnetic then put it in a big bin of perlite to slowly cool down, keeping it as warm as possible for as long as possible, you can do that twice and then do the quench and tempering cycle I have to say your lady is super. edited to say heat above non magnetic
@@acy48 spot on ...above the Curie point most steels lose the crystalline structure that causes hardening, so taking them to that point allows the steel to relax and let go of all the machining or forging stresses, once it has cooled slowly the molecular structure is globular so it can be heated to the non magnetic crystallisation point (Curie point ) and quenched hopefully staying straight this time
There is a thing that knife and sword smiths do, which is tempering a knife that bends in the quench, in a jig that forces the blade to bend the other way, that you could probably leverage here. Its more gentle than a press is.
Let me give you my take on your situation: Every steel have inner clumps of different type of steel morphology when is fabricated (clumps of different states of steel martensite, austenite, perlite, bainite or ferrite), which causes inner stress. Every time you remove/heat treat material you relief/change these stresses which equal to bending of your part. What you should do for perfect result is: (1)normalize your rod material. Depends on steel but normalizing occurs in range 800-920°C. So you could build normalizing oven from soft oven bricks (cheaply on amazon, you can buy similar material in 25mm/1inch sheets) and kanthal wire with thermocopule probe and normalize your steel in high temperature. (2) Heat treat your part perfectly vertically, you heated your horizontally with two points and heat from one side which caused additional bending . You should stick with induction heater and give it more time, multiple passes and build temperature like you did with torch. Or if you had oven you could heat it in oven to precise temperature for quenching. (3) You could buy normalized steel bar - but good luck with it. (4) Choose different material and have it nitrited professionally. (excuse my english i´m foreigner and still learning)
A couple things, your threads only need to be harder than your brass nut. Warpage is inevitable when hardening a shaft of that size. When you temper, you could bring the hardness into the low 40s to avoid the spring back. Otherwise, if you’re deadset to have high hardness, you could attempt “hot” straightening, which is to straighten immediately after your 400F. Anyhoo, can’t wait for your follow up video. Great stuff!
This is so sad for real, I nearly cried when you showed broken halves. When you started to bend it, i remembered the thumbnail of the video and was "Oh no, oh no, oh no..." holding my head in suspense
@1:48 I like how you try to entice your wife to make a tap with a little dance that actually is a tap dance at the same time as it isn't a tap dance. Maybe I'm the only one who would call it a dance though...
@@JuryDutySummons That’s true, yeah - but still, taking some of it out before might have reduced the likelihood of brittle fracture and maybe even reduced the amount of bend that came in during the quench, I dunno. But possibly it was a DOA banana
Even if you bend it perfectly, all heat-treatments produce unpredictable deformations. I think he doesn't need to harden all the part, he needs to harden just the surface like every shaft.
You’re both totally right - I think that a process like… heat treat the stock before machining without a quench to relieve some of the stress and soften it up, machine it, take out as much bend as possible, harden the screw and gear, and then temper it a little further than he did and take the rest of the bend out then might work better. Still risky but less so. I also noticed him “swishing” the part a bit when quenching, which is a little dangerous. Better to “bob” straight up and down and reduce deflecting forces on the hot part, though with something this thick I’m not sure how much of a difference that would make. I also wonder whether an air-hardening steel might be a little safer. Slower cooling rate, less warping.
Bad Brandon! LOL I felt that too.. was saying "Noooooooo..", and then pop! I was going to suggest what others have here... you need to remove the stresses that are making it warp two ways. 1st) remove the stresses by GENTLY heating the screw to about 500°F, and use the press to add gentle force while it's hot. 2) Given the weight of the screw across the length, the heat treat should be started and finished in a vertical orientation Only(since you're using a torch for the process). This should be very conducive to achieving a very straight and reasonably hardened worm screw for the lathe. Best of luck!!! Can't wait to see the final product.... again!😵💫
Hey, I come from the birthplace of music boxes in Switzerland, the old timers used to straighten the hardened shafts going through the cylinder by hitting the tensioned side with a pointed tool and hammer so it "broke" the tensioned fibers in the shaft and straightened it. Hard to do on a thread but worth a thought. Option B: send it to a hardening place and ask for plasma nitriding or surface hardening. Not as sexy but gets the job done. Good work!
I kept trying to understand a company making a shaft with 10 thread per INCH acme on one end and a metric thread on the other. If they (Europeans) are making a lathe, can’t they make a suitable lead screw thread that is not measured in inches?
Knife makers often use a flattening jig out of heat treatment. Red Beard Ops is a good example. Maybe make one with machined jaws that match the profile of the lead screw? Just spitballing.
When you said press, I thought, "Oh, no!" Two things: Heat while the part is vertical and B: heat your oil to at least 150 - 200 degrees. This will still harden but do it slightly slower. When quenching you are shocking the material into a crystalline structure. If you take some of the temperature delta out, it shocks it at a less severe rate. Cheers!!
What we used to do in my engineering classes is “normalize” the steel after machining. High temp, followed by long slow cooling, to allow the grain structure to shift, then perform straightening, normalize again to relieve stress, then heat treat.
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Wow MyHeritage is so cool - gonna check it out right now!
@@RunBMC99 bot
My suggestions would be to first use a longer bar to give you space when threading so you wouldn't have to move the follow rest every time. Then I would recommend that before machining something I would anneal the entire piece to remove possible stresses and avoid deformations and finally as a knife maker whenever we say "we can straighten it in the press or in the vise" it breaks.
Greetings from Argentina
Try and evenly heat up the part. I leaned this in knife making. I also learned that if you warp a blade don't put it into a vics and bend it back. Instead. Do a normalizing cycle[heat it up and let it cool down at room temperature]. Then carefully re shape it. Then retry the heat treating process.
Couldn't give a half a crap about this site, but good for you for taking their money.
Hi, heat treat metallurgist here. There are three constants in life: death, taxes, and distortion during heat treatment. There are a couple things you could do different on the next one...
Stress relieving before machining will absolutely help. The material will move less as stresses are relieved while heating up in heat treat. Do not machine, stress relieve, and then heat treat... Every time the material is heated and cooled, stresses are relieved. When there is a change in stress, there is a change in strain, which equals movement. Only stress relieve if you're going to be doing subsequent machining operations.
When heated before quenching, hang the part vertically. A lot of the bowing you saw after quenching is actually from the part bowing under its own weight since it was suspended horizontally. When quenching, only agitate the part up and down. Agitating side to side in the quench tank will cause preferential cooling on one side, which leads to bowing. If possible, you should heat your quench oil to 150-180F. The additional heat will reduce the quench severity and help with distortion.
Even with all of these steps, you're still going to have to straighten after quenching. Your best bet will be to straighten and then heat to temper. This can be achieved by clamping and tempering, where you clamp the part between two flat surfaces so that it "takes" a flat, and then temper. You'll need to go above 500F to see any significant "taking" of the flatness. But, your lead screw does not need to be 60+ HRC, so that shouldn't be an issue. It can be difficult to clamp and temper round parts, though. Alternatively, you could also use your V anvils and the hydraulic press to press the shaft just past flat and use your torch to heat to a nice, deep blue. This will relieve the stresses put into the material by elastically deforming it, and it should "take" some flatness.
Hope this helps!
Vertical positioning is a great suggestion. I knew a blade company that bulk produced rapier blades, and they actually had a consistent warp because even though they heated and quenched vertically, even the rapid movement between the oven and tank was enough to warp them slightly. The clamping and heating in position is also pure gold!
Made a comment about it lying horizontally when he heated it up before I saw this.
I was looking at the sped up footage of the heating and looking at the screw flexing up and down under its own weight and said that can’t be right…
On the accelerated video of the heating, I think we can see it bow under its own weight. I'm no professional, but that seems coherent
I've experienced the same issue with a part deforming under its own weight when heated. Surprisingly it doesn't take much. Totally agree with the above post though am thinking the straightening with heat is the best approach.
On the bright side, two halves of this shaft fit into the box of shame easily.
Too soon man come on. ( i had the exact same thought)
Oh my god...
Hahaha 😆
You are terrible man.. lol
Forget the salt in the wound, that's like pouring acid into it lol
💀💀
Hearing "easy for the hydraulic press" immediately after hardening I knew exactly what was coming... Might be worth it to straighten it after cutting everything and then anneal it to remove the stress from straightening and machining. After that anneal the hardening step shouldn't bend it and you'll end up with a straight, hardened, finished product.
this is the move. annealing at least once in the process, even before machining. could use the induction heater.
We did a bit of straightening with a press like that in the last shop i worked. It's a tedious and difficult thing to do. Even on much softer stuff. Training new personnel to do it would inevitably cost a few 20.000$ parts...
I was thinking that'd how it end up, because everything loses against the hydraulic press ^_^
Not an expert on this, but this is what I would try. Heat it up prior to turning to a cherry red, than cool it really slow (like in heated sand?) to anneal it completely. It would/should take all of the stress out of it. But as mentioned by KyleMc16, you already knew it was bent somewhat during turning. So straightening before heating, and a larger support when heating it might help as well. Anyway, failures is what we all learn from, right?
@@GerbenPolder456 I'd say as a complete non-machinist, a jig, something big with a lot of thermal mass to it, clamp it in the jig heat the whole thing up, let the whole thing cool very slowly, don't know if it needs to be something with a greater or lesser rate of thermal expansion than the piece or the same, though and having access to a forge would make it cheaper and quicker to heat, oh and the right sized ballend mill to mill the slot in the two halves of the jig.
Sure I speak for everyone here, when it snapped we all felt that in our hearts
The relationship you have with your wife is truly wholesome
When it snapped, I expected it. Trying to bend hardened thing makes it snap. Remove hardness before bending then re-harden it
@@robertrdell8898 Jep, trying to bend hardened things isn´t a good idee. And then after he said that it have over 60 HRC, it is an even worse idee.
I love that she's genuinely interested in what he does! ☺
@@robertrdell8898 That's kinda what I was thinking, too... but... what if the bend is introduced by the hardening process? A comment starting "Hi, heat treat metallurgist here" suggests that (a) is very much possible, and (b) is likely at least part of what happened here... so... alas, while I was very much thinking "de-banana before heat treating!", it may be that "Remove hardness before bending then re-harden it" won't actually fly. 😢
@@robertrdell8898 yep, just as I thought: "isn't this going to break if he keeps going?"
it did.
As a person who has nothing to do with machining I highly respect you for showing all your failures along the way to what is essentially a boss fight.All the episodes lead up to the restoration of the lead screw and I am hyped to see our protagonist come back from a temporary setback!!!!
Anyone else sat on the toilet screaming “stop, it’s gonna shatter!!” at the screen?
Nah; most hydraulic press videos on UA-cam keep going until failure.
I wish I would have. The look my wife would have given me not knowing I was watching a video lol
Nah, in the livingroom ;-)
Almost me. I sat on the toilet taking a shit when he started using the press. I was totally shocked, seeing him trying to bend a piece of hardened steel and I screamed in my head.
Not screaming but i let out a audible whine…
The relationship that you and your wife have brings a lot of joy to these videos. Keep it up man, as a welder turned software salesman, I am living vicariously through your projects.
I miss when he did the drafting tho. Also my wife is way cooler and be sure to tell her I said that.
More important than your heritage is your relationship with your wife. Like he said, it's awesome to see you two interact with love and excitement.
(Glad you didn't die after the "c'mon girl" bit 🤣)
Personally I find it a touch too much as we Brits are not so open with our emotions and it's an engineering channel not a marriage guidance outlet !
@@andymouse Don't think he's trying to guide your marriage, no matter how much you clearly need it.
@@andymouse British people have emotions? Awesome I always figured they were just stuck on “jolly good”. You don’t make an empire with that attitude tho…
I used to work for a machine tool rebuilder. We would chase the worn screws in the lathe so the profile was even through the whole length of the screw. Then make a new nut with a matching profile to fit the screw. You end up with a screw with a non standard acme profile, but the lead is consistent which is the important part. It also saves a lot of time!
I'll either do this ^^^ or forgo the hardening. For a non-commercial lathe you'll still get years and years of perfect service.
I had the same thought. Depending on how much backlash correction is available, just chasing the original threads may do the job.
this sounds like a good out of the box idea from a non machinist. it not like it's a shop where the non-standard stuff is going to confuse some future person.
@@bmxerkrantz Ironically, this is exactly what a machinist would do if there is adequate backlash correction available. No one with experience will be confused. This is common in professional shops, and with rebuilders as stated. It doesn't change the thread count, and the backlash correction is designed to allow for exactly this within limits and can only be done so many times.
This channel is what inspired me to learn machining. Because if you, I'm going to a trade school as part of my high school curriculum to learn precision machining and get industry certified. Thank you for making these videos.
That is so cool.
Good luck with all your endeavors.
@@thosoz3431 Thank you very much.
@@Lilac757 another vote of very cool and wishing you luck! (Which you'll hopefully increase your chances of with hard work, of course.) I kinda wish I'd explored machining in high school... don't think I knew it was a thing (maybe we didn't have a program for it, I dunno, but I could imagine there must have been something at a nearby community college or something, at least, kinda like the video production class I did take.)
Do it!! I took 3 semesters of community college for my CNC Operator certification and it's been life changing. I've been in the field for 3+ years now and I've not worked a day since - because I love my job.
Listen to the greybeards in this field, they have very good knowledge that really helps. Creativity helps, too, but in the right dosage.
Good luck!! 😁
@@DavidLindes Thank you too.
Suggestion: Do not heat treat! Make from A-2 and use as machined. Any heat treat on a part this long and slender will warp. Industrial manufacture of hardened ball screws for example the stock is rough machined hardened, tempered, and genealogically treated. Then finished by cylindrical and thread grinding. The soft screw will last longer than you will live if not used for production on multiple shifts.
heck even just using a decent 4140 or 4340 prehardened (usually 40-45Rc) would wear out several bronze nuts before it needed to be replaced again.
drill rod maybe?
This!
you can heat treat and either thread grind or... just, use carbide.... I don't know why everyone seems to think you need to grind hardened material. you don't, even okay quality carbide will cut, good quality carbide will laugh at it and good, name brand coated carbide will eat it for breakfast. there are coated acme thread inserts and he can also modify the insert if needed by using a diamond wheel. would be a lot easier than grinding and you get to keep the heat treatment!
@@ramentaryramblings I think this is a good suggestion for "Heritage". The idea he's putting forth in his videos is creating items and solving problems within his scope of capability. Seems like hiring someone to thread grind goes against the idea of his channel.
Heartbreaking, honestly surprised there wasn't a constant flow of bleeps after the snap. Chronova Engineering just recently did a video where they heat treated a lead screw for a much smaller machine by putting it in a drill press and spinning it constantly while heating and quenching. The results were impressive, it might be worth considering a way to rig up a similar setup that would work with your larger part if/when you decide to try again.
check their most recent video at the 4 minute mark if you'd like to watch :)
too heart broken to even swear
Commented the same thing above, haven't seen your comment lol
Beat me to it, instantly thought of Chronova when it happened.
also annealing the screw at least once before hardening it would also help, like I'm talking anneal, machine, anneal, machine to spec, straighten, anneal, harden, anneal, that should get rid of all of the stress in the material before the hardening step.
I made this comment too! lol
"Should be no match for the hydraulic press"
Me: "Oh no."
To be fair, he was right.
Just in the wrongest way.
Hydraulic Press channel-fans sat forward and went, "Oh yes!"
same :D "didn't he JUST harden it??"
Me: OH CRAP
Well he wasn't wrong.
There are so many videos out there that show perfect outcomes, but they never show the failures. This video is so incredibly valuable. Showing what happens to materials when cutting or bending during certain states is worthwhile to document, and it is also quite exciting to view.
Just wanted to let you know you are part of the reason I became a machinist. Watching your videos over a decade ago made me super interested in the trade. So thank you.
The Box of Shame is the true celebrity here. You have to show it
You're right. Failure worth studying more than success. 80% of Textbooks talk about failures, but people only remember 5% of the whole text book that has 4% success and 1% theory.
@@TOXIXIFY Thanks!!
I love the new format you introduced, with your wife being present, and more open style of communication/storytelling. It's unique and very easy to follow :)
I've been a machinist for 48 years. I agree with the heat treater's comment and the one that mentioned rotating the part while heating and quenching. Heating a part on one side and quenching is how you heat form parts. Another approach is to use 4340M. Plenty of strenth, hard enough to last your lifespan. And it is still machinable. If you're not satisfied with the hardness it can be hardened further. You can check specs on Carpenter steel's website.
A lead screw running in a bronze nut will last years with no issue at all, especially for a hobby shop application. I would cut off the geared section, drill and ream the gear. Make up a new threaded section with a smooth section to fit the gear. Press in, drill and pin.
This way you salvage part of the job.
Came here to suggest the same thing. Might be able to salvage the gear section with this method.
Agreed! Great minds think alike!
Raises the whole question of why the geared section must be monolithic with the rest of the screw? Are you concerned that heat on one part plus liquid N2 on the other won't result in an overall "permanent" bond?
That would also work, he just doesn’t keep liquid Nitrogen around. It could be keyed in, or pinned. You just don’t want it to slip.
Yes, but the shaft is hardened to HRC 65, so it won't machine without annealing and re-heat-treating.
Me at 22:50 : wait didn't he just harden that shaft?
Me at 23:10 : he sure did! 😅😂
I came down here to make this exact same comment XD
22:50 was the moment where I remembered the video title 😅
Thankyou for your bravery and humility in posting videos of your failures.
"It's moving, not progressing " my new headstone!
Every contribution to the box of shame should ring a bell and dispense a shot of Cuervo
I was screaming at my TV when you said "this should be no problem for the hydraulic press". Man you had me on the edge of my seat.
"speaking of girth I have something to show you" sounds like a wild pickup line
"That's more metal and less flesh than I was expecting" haha
Kinda surprised wasn’t followed by “Excuse me while I whip this out”
You didn't hear me screaming at the screen "Follow Rest!!" on your first cuts.
I was helping and he still didn’t hear us!
I think all of his videos should be live streamed from now on. At least until he finishes his apprenticeship.
@@JetIgniter2k2 ha ha!
Can you machine steel that's already hardened?
@@blairlock Sort of with carbide tooling but it´s not fun and you definitely won´t cut an acme thread in a hardened tool steel rod. You would need to grind that with a special machine under coolant, which is what is done comercially on good machines.
Hope you're grateful to have such a cool wife. Seems like she is at your side, will stand by your side, and even laugh with you instead of at you to share good times that you will reminiscence years down the road. May God bless you and your family
Fulltime knifemaker here. Normalizing before machining helps prevent warps a lot. Also, some heat (less than temper temp) while bending is a must. You don't even need to see any color change for the part to be hot enough to bend, but if the part is north of 60 HRC, you've gotta give it some heat
I cannot express how much I flinched when I saw you go for the hydraulic press lol
i was thinking wow i cant believe you can flex a hardened rod that much without it snapping
The very first flex I'm like "WHAT ARE YOU DOING???"
I turned a lot of hardened steels in my career, including a few thin shafts like yours. You maybe should look into a different approach of doing things. Maybe start with a quenched and tempered raw stock as a base, rough out most of the features, even the threads and leave around 0.6mm of on all final dimensions, including the length of the shaft. Let it get hardened by a specialized company, this will ensure, that the shaft will come out as straight as possible, to make the final operations possible. I would harden it to around 48 HRC +3. The shaft has to take a lot of load during cutting, later when its in use, so it has to be flexible and not as brittle.
To finalize it, I would grind a carbide thread tool. Around 50HRC is relatively easy to still turn with carbide tools, you just have to drop the cutting speed quite a bit. Only the spines could be a problem after hardening, as you would probably have to grind the splines, or use carbide spline cutters.
Another thing I noticed, is that the thread pitch and its precision is also dependend on your lathes temperature. The pitch may change as your machine warms up.
But I loved this video as always! I fell in love with you and your content on the first video and I watched every one since then!
Greetings from Germany!
I had to comment seperately regarding the brilliant collaboration with the Mrs. I'm so glad she is so tolerant of all this sort of humor. 😊
Best video I've seen in a long time sighed up just to leave this comment
Finally someone showed things don't always go as planned
You learn nothing from success and everything from failure
Thanks for posting a real video the lesson is more than just about making parts but real world experience
One of the bits I have learnt from UA-cam blacksmiths is that a sword/knife (and thus leadscrew as well) is still slightly plastic coming out of the quench, and that it is possible to straighten out a banana as long as you dont wait more than a few minutes.
You often see them pull out a sword, look down the edge to check, and then _immediately_ stick the end in a vise and start pulling to correct the warp.
Knifemaker here, and yes, that is true, though not sure how applicable is that here, since he has precision ground threads and sticking it into a vice will probably squish those threads a little bit, even if he can bend it straight. However, you can do a temper jig. Tempering is the part where you stick it into the oven to lose some hardness but gain toughness. While in the temper, you can put the object bent in the opposite way and while its tempering it will release some stress and so might come out straight after its done. Basically what he was doing with the hydraulic press, but gentler and doing it in the over.
He could also try to use cooling differentials to warp it back into shape, ( put the belly of the bow down on something conductive and big i.e. mill table) I have warped a couple pans doing similar things
I, too, watch Kyle Royer.
@@FireZenix The bit about deforming the threads by sticking them in a vise is definitely valid. Though they weren't precision _ground_, they were just machined.
The temper jig is a solid idea though.
@@thomasbecker9676 Funnily enough not Kyle Roger. I have seen something of his, but it's actually been others. A bit of Ilya (That Works), and Alec Steele, with odd others thrown in for good measure
I have an idea for your thread problem (when you crashed in to the tail stock) leave extra stock and turn it bellow the finale depth (just the excess) and after you done threading, you only have to cut of the excess.
Great idea!
He's done that on several threading operations
@@tmdwu3110 right, i forgot
I love that this video ended failure and not only success. That's as real as you get in this trade.
Chronova engineering recently did a video on restoring a vintage lathe where they hardened a cross slide lead screw by rotating it in a drillpress while heating it and then quenching it while still rotating. Might be worth a shot!
I was gonna mention this, it's worth a try
Came here to say the same thing.
So, one thing you can do is relieve the stresses in the material before you quench. Basically just heat it up like you were going to quench it, and then don't. Basically just let it slowly cool back down to room temperature. What this does is actually remove stresses by creating more uniform grain structure within the steel (pretty much like annealing but at a higher temperature because you aren't worried about ruining the heat treat). You can do it a few times (like twice) and then heat it up again and quench it.
A post quench option is doing the annealing process with the screw set up in a jig to bend it back to straight. Or even. Right after quenching it’s still quite hot. So you can quickly put it in a jig to straighten it while it cools down to room temperature
And you can forcefully correct any unevenness with the press in the soft state.
And a little add: You can put the red hot shaft in some fire proof isolation. This will make the cooldown even slower.
And there was never any need to harden this shaft to the extend he did. It's way overkill for the purpose. He created his own problems by trying to over-spec the design.
To fix that follow rest problem you could leave a dummy end on. I do this a lot. Just leave whatever length you need on the end smaller than the minor diameter. When done part it off and face.
We do 98 inch helical shafts and we always heat treat them vertically. It doesn’t stop the warpage all together but it greatly improved it. Another thing we do is stress relief before machining.
Hope the next one works out!
to me it seems it was a choice between having just enough material for 2 attempts or just falling short on material for a second attempt.
That’s a great idea. Especially if you don’t have the right live center.
“That’s way more metal and way less flesh than I was expecting”😂😂😂
As soon as I saw you heat treating the shaft without rotating it I saw the warping coming. I learned the same lesson about heating a rod from one side the hard way as well.
"Hahaha, you have to make a whole nother tap?"
"I *get* to make a whole nother tap."
I saw Chronova Engineering recently make (machining/hardening) a thread as well actually. Just like you, he did it a bit unconventially by machining it first then heat treating and quenching, but he applied them evenly by having it rotate on a spindle. It worked out quite well for him.
If you are interested, the video is called "Restoring a Vintage Watchmaker's Lathe", uploaded 4 days ago, and the timestamp of interest is around 3.20-5.00, though it might be easier to watch it from the start
the end felt like a kick in the balls
Trying to bend tool steel after hardening it is crazy lol.
Next go round, stress relieve it before machining, then maybe again after machining, if you're really set hardening it. If it were me, I wouldn't even harden it. It'll do what you need to do, and you can always make a fourth one later down the line if u need to. You're a braver man than I, though. This is the definition of a rabbit hole project and I commend you for your commitment to it 🫡
Wife seems lovely. Conversation is a great addition.
one thing I really appreciate is that you throw in your mistakes, its not a clean cut one and done process for every vid. Im building a cnc milling machine in my garage and it frustrates the hell out of me every time I mess something up. Its such a relief to know that the frustration and annoying setbacks that I experience is not just me, but a more universal experience for all makers, please keep up with this you have been such a huge inspiration for me
"it may straighten out with the heat treat" prayed every blacksmith ever. 😅
That heartbreak across your face in the final piece to camera, you were on the edge of tears, whereas I would have been submerged in an ocean of my own tears
I think the warp was induced during heating, not while quenching. Think about it. It becomes fairly elastic when cherry red, and laying on it's side, suspended between your hangers, I believe that is when it took the banana shape. You didn't notice while picking it up or quenching because you move relatively quickly. When you quench the next one, hold it vertically...dangle it, then quench like the guys that make swords and knives.
What gives me dopamine every other Friday, payday and a New Inheritance Machining video!
Who are you trying to kid? You know what's going to be in your pay cheque. The IM vid is where all the excitement is!
@@IslandHermitnope. Variable hours and too fricking tired to work it out means surprise on pay day.
Since IM videos release the very evening after I get paid pay day is 'edging'...if ya know what I mean 😉
The only thing better would be if it was every Friday!
The image of you “literally” being dragged down a “literal rabbit hole” has made my day!
Keep up the great work, love the videos and your honesty.
Always remember, those who don’t make mistakes don’t make anything!
As a few have said before me, stress relieving the material after machining and hanging the material vertically while heating will help. Also, instead of relying on the press to straighten the shaft, additional spot heating can be used for straightening. Heat a small spot cherry red at the low side at the start (vertex?) of your bend and when that spot cools it will shrink and pull the shaft in that direction. "Fire the mountain, peen the valley" is what the old fellas say.
I agree that heat straightening is a good option however cherry red is hundreds of degrees too hot for doing it.
I was thinking along similar lines, but as he wants a hardened screw, any spot heat straightening may lead to inconsistent results in the hardening. That may not matter much if the bend was in part of the screw that doesn’t see much wear over time.
I've seen a few say to stress relieve _before_ machining.....
I don't have a lathe, I don't even work with metal, but, man, I was on the edge of my seat for the entire video. The suspense was killing me, especially witnessing the use of multiple tools to make one single lead screw, multiplying the risks of mishaps. And then the twist in the plot, right during the final scene... I shouted out loud at my monitor when it happened!
Oh man. I wanted to scream stop as soon as I saw the press in action 😂 Well, I really appreciate sharing mistakes and failures, that is life. Every time I do something like this my thoughts go to you and your box of shame. Best channel on youtube. Cheers.
Hi Brandon,
I'm a professional knifemaker of very high end chefs, folding, and hunting knives so heat treating as well as removal of warps is an endless endeavour that I face.
I'm from Australia so timing may be a bit hard, but I'm more than happy to have a chat and discuss some steps I take, tips, and observations I've made. These vary from working processes to selection of material thanks to literal thousands of hours of research I did procrastinating my engineering studies.
Hopefully I can be of help!
Regards,
Mike - Orzel Knives
Charcoal forge. Propane weed burner forge. WAY Cheaper than Oxy Acety... When straightening in a press set up your dial indicator to measure the amount of negative bend you are putting in to counter the positive bend. Then keep track of negative versus positive improvement. Visually it appears you went very very far in the negative direction. Repeated small bends can add up in the desired direction. Slow and steady. Perhaps even a small amount of gentle heat. What about a borax? antioxidant protection. Would allow slower and more controlled heating.
Induction coil, way faster and more even heat.
Other comments already mentioned the most important ideas: excess material to prevent tool crashing, stress relieving by heating to non magnetic then slow cooling in pearlite, and Chronova Engineering’s method of hardening on a drill press.
That leaves the order of operations. This is what I might try:
1) Stress relieve the stock before starting
2) Machine with coolant. Stop after each pass to allow temperature normalization (coolant cools, but not necessarily enough).
3) Straighten while metal is still soft.
4) Since I am a belt and suspender type, stress relieve again.
5) Repeat steps 3 and 4 as required until straight after stress relief.
6) Use Chronova’s method to harden.
7) Anneal using step tempering methods (at least 3 cycles). Building a three point straightening jig that fits in your oven would make a nice side project for this one.
Yes, this is going far above and beyond reasonable requirements but, considering that the more perfect this part is, the more accurate any parts made using will be, it is worth being obsessive with it.
Looking forward to seeing how you solve it.
It does make you wonder how the first person to make one did it. I mean how was the first precision screw made? How precise was it? How did they maintain precision when they used it to make more precision screws. After all, we all know what happens when you make a copy of a copy of a copy.
If anyone knows of a place to study the history of early development of machine tools, please point me to it.
Oh no!! The second you said “hydraulic press” i laughed and said “No way! You’ll shatter that thing!”
Oh dear
I know how you felt. Done the same with knives that I make. It's heart wrenching.
Based on the random machining videos I've watched in the last few days, I'd suggest thread milling the replacement, and then roller burnishing the thread to work harden and improve it's finish.
Also, when you cut the replacement on the lathe, just leave extra material on the end so you don't have to mess with the follower rest clearing the tailstock, then cut the extra off last.
Thread milling is a CNC operation. It can’t be done on a manual mill.
Also, roller burnishing is a specialty operation. Not a machine that is common in shops.
@@narcoleptic8982 I was thinking he could use the lathe and the grinding figure to do the thread milling if he runs it slow enough.
I ran a Lees-Brander thread milling lathe for a while, it's slow, but accurate.
@@ka9dgx I’d just leave it .050 oversized, harden it properly, like 45-50 Rockwell, not 65 holy shit. Put it back in the lathe and pick up the thread and turn it straight. Probably could even straighten it in the press if it wasn’t way harder than it should ever be.
Honestly I think he should have just made it out of 4140 HTSR and just not worried about he hardening at all.. This is a failure due to over-engineering.
I actually just saw a video about this very same heat treatment issue. Their solution was chucking the lead screw in a drill press and spinning it at low speed while heating with the torch. Then with it still turning brought the quench tank up to the screw. Came out perfectly straight. It was a much smaller lathe but may be worth a shot. I believe the video was called “Restoring a vintage watchmakers lathe” on Chronova Engineering’s channel
@25:15 I would use 4140 instead of O1. You should be able to easily normalize it before machining which should prevent some of the bending, and you should be able to straighten it better afterwards (they used 4140 for gun barrels and had to straighten them after machining)
I can only say keep on keeping on. I have next to no knowledge of machining, but even just learning (from a couch) has been a wonderful experience. My little girl also loves watching the process, and I get to teach her words like pantograph, gear exchange ratio, and zeroing (which she'll actually understand when she's out of diapers).
also learning from your mistakes you dont know how much it help on how to avoid some operations great job thanks for the videos and honesty
I was heartbroken for the both of us. Perhaps back to using 1144 stress proof and skip the heat treatment
Agree. You just want the bronze nut to wear before the lead screw because the nut is easier to bush and repair. Stressproof is hard enough, no? I flinched when I heard he was using O1 and planned to harden.
Can also punt and buy a precision ground screw, and simply attach to the geared end.
Your attention to detail never fails to impress me. It appears that nothing less than perfection is acceptable to you. That is a rare quality these days. Kudos!
Knife makers typically thermalcycle a blade prior to quenching.
Exactly my thoughts.
Typically that is done with forged blades. Essentially hitting the metal unevenly hundreds of times causes some local stresses to build. That's why it's annealed 1-5 times, depending on the metal and the amount of hammering and complexity of the shape.
I forgot about this. I haven't watched knife content in a while.
@@ManiacallySmithing that's not from hitting with a hammer, that's from complete lack of concern regarding heating and cooling during the forging which causes grain growth
Normalizing is only necessary with forged blades. Doing it to a machined rod is completely pointless
Had a similar challenge on a really long high tolerance thread, previously these had been machined, hardened and the straightened.
Changed the method to harden then machine (different tips required), no more bending issues encountered
Hi there well I feel your pain. i did a cross lead screw a month back on a British Lathe with Whitworth threads. what i did was purchase an Acme thread rod from McMaster Carr. Cut the old lead screw so i could machine a slip boss 1" long on it. Took the new threaded rod cut it 1" longer than the old screw, machined a matching boss, pressed both together, pinned it, and perfect. Just what i did, and a low cost
"Should be no match for the hydraulic press." OH how right you were buddy.😂😂😂
I was gonna ask how that would fit on the box of shame. But right at the end you figured it.
Oof
I winced the second you mentioned using the press to straighten it out.
Keep the humour.. keep the bloopers because they teach all of us what not to do, or least to be aware of. But most of all, keep the humour between you and the great lady you share your life with!! Thanks
Anneal at quench temp, put it in pearlite to slowly cool down. Do this at least twice. Then I'd take any bends or warps out. Then harden and anneal. Try aim for 55 HRC.
Amature blacksmith here.
From my knowlage, normalizing a part is the best when deling with worps/crack after heattriting. Usually worked for me, for any kind of steel I used (rebar, tool stell, springleaf and so on).
Usually I do with 3-4 normalization cycles before heattreating the part.
For my and my needs (forging on coal furnice (makes A LOT of stresses and weird stuff with stell)) works like 95% of the times.
Hope you don't give up and keep your, as always greate, work
I’ve never commented on a UA-cam video in my life, but I just want you to know I SCREAMED when it snapped. “Noooooooooo! My heart!!!” What a tough break. Watching that hurt me more than snapping 3 out of 4 exhaust bolts on a transmission job in my garage on my own daily😂
I don't know the English name for it but in Dutch we call it "spanningsloos gloeien".
As the material heats up it's yield strength decreases. All the internal forces greater than the yield strength disappear. So when the material cools down the smaller (and less banana-inducing) forces remain and the larger ones go away.
Hope this helps.
Stress-Relief annealing might be the correct word for it. It’s defined in EN 10052 but the process is pretty involved, if not even impossible for hobby shops as one has to hold the part at ~600C for several hours. Some materials can be bought in this state. Although I’m not interely sure if it would help with the bending while hardening
John over at Black Bear Forge heats the part to dull red and puts it in vermiculite to cool it over half a day to anneal. Might not get you to norm-level destressing, but it's certainly doable in a hobby shop.
@@jakobsasz8035 You can do full anealing in the hobby shop with a small electric heat treat oven
You don't need to do a true anneal anyway though. As pr0crastinatr says, you can get amazing results from vermiculite or wood ash
@@skilletborneI don't think he can justify to his wife buying a "small" heat treat oven that is big enough to fit that shaft. Not even if she was the one to machine a screw for so many hours just to feed the hydraulic press a hefty meal.
I would suggest doing 2-3 normalising cycles before your quench in the heat treating cycle, bring the part up to non magnetic temperature and allow to cool to room temp it will help to relieve a lot of stresses in the steel, Godspeed good sir
I would take this one further and normalize the stock before even starting, that will help reduce the warping during machining.
@@betterl8thannvr This right here ^
Literally every time I see one of your videos I always think it is going to be boring. Then I go on a 3 day watching streak, where all I watch it you. It happens every time lol 😂😂
It doesn't need to be so hard to function. You did great. We live and learn. Like my favorite rich man once said. If your not breaking stuff your not learning from your mistakes.
well in blacksmithing if you want to stress releive you heat it above non magnetic then put it in a big bin of perlite to slowly cool down, keeping it as warm as possible for as long as possible, you can do that twice and then do the quench and tempering cycle
I have to say your lady is super.
edited to say heat above non magnetic
FIY, the temperature at which ferromagnetic materials loose their magnetism is called the curie point.
@@acy48 spot on ...above the Curie point most steels lose the crystalline structure that causes hardening, so taking them to that point allows the steel to relax and let go of all the machining or forging stresses, once it has cooled slowly the molecular structure is globular so it can be heated to the non magnetic crystallisation point (Curie point ) and quenched hopefully staying straight this time
There is a thing that knife and sword smiths do, which is tempering a knife that bends in the quench, in a jig that forces the blade to bend the other way, that you could probably leverage here. Its more gentle than a press is.
Let me give you my take on your situation: Every steel have inner clumps of different type of steel morphology when is fabricated (clumps of different states of steel martensite, austenite, perlite, bainite or ferrite), which causes inner stress. Every time you remove/heat treat material you relief/change these stresses which equal to bending of your part. What you should do for perfect result is: (1)normalize your rod material. Depends on steel but normalizing occurs in range 800-920°C. So you could build normalizing oven from soft oven bricks (cheaply on amazon, you can buy similar material in 25mm/1inch sheets) and kanthal wire with thermocopule probe and normalize your steel in high temperature. (2) Heat treat your part perfectly vertically, you heated your horizontally with two points and heat from one side which caused additional bending . You should stick with induction heater and give it more time, multiple passes and build temperature like you did with torch. Or if you had oven you could heat it in oven to precise temperature for quenching. (3) You could buy normalized steel bar - but good luck with it. (4) Choose different material and have it nitrited professionally. (excuse my english i´m foreigner and still learning)
A couple things, your threads only need to be harder than your brass nut. Warpage is inevitable when hardening a shaft of that size. When you temper, you could bring the hardness into the low 40s to avoid the spring back. Otherwise, if you’re deadset to have high hardness, you could attempt “hot” straightening, which is to straighten immediately after your 400F. Anyhoo, can’t wait for your follow up video. Great stuff!
This is so sad for real, I nearly cried when you showed broken halves. When you started to bend it, i remembered the thumbnail of the video and was "Oh no, oh no, oh no..." holding my head in suspense
@1:48 I like how you try to entice your wife to make a tap with a little dance that actually is a tap dance at the same time as it isn't a tap dance. Maybe I'm the only one who would call it a dance though...
I was just thinking “hey Brandon, wouldn’t you want to unbend it before you heat treat it?”
It gained a lot of that bend in the quench
@@JuryDutySummons That’s true, yeah - but still, taking some of it out before might have reduced the likelihood of brittle fracture and maybe even reduced the amount of bend that came in during the quench, I dunno. But possibly it was a DOA banana
@@anihopkins6788 I wonder if going though a tempering previous to hardening would have helped? No idea.
Even if you bend it perfectly, all heat-treatments produce unpredictable deformations.
I think he doesn't need to harden all the part, he needs to harden just the surface like every shaft.
You’re both totally right - I think that a process like… heat treat the stock before machining without a quench to relieve some of the stress and soften it up, machine it, take out as much bend as possible, harden the screw and gear, and then temper it a little further than he did and take the rest of the bend out then might work better. Still risky but less so.
I also noticed him “swishing” the part a bit when quenching, which is a little dangerous. Better to “bob” straight up and down and reduce deflecting forces on the hot part, though with something this thick I’m not sure how much of a difference that would make.
I also wonder whether an air-hardening steel might be a little safer. Slower cooling rate, less warping.
Say screw you to the screw that screws you.
Hah, nice. 🪛 😉
Bad Brandon! LOL I felt that too.. was saying "Noooooooo..", and then pop!
I was going to suggest what others have here... you need to remove the stresses that are making it warp two ways. 1st) remove the stresses by GENTLY heating the screw to about 500°F, and use the press to add gentle force while it's hot. 2) Given the weight of the screw across the length, the heat treat should be started and finished in a vertical orientation Only(since you're using a torch for the process). This should be very conducive to achieving a very straight and reasonably hardened worm screw for the lathe. Best of luck!!! Can't wait to see the final product.... again!😵💫
Hey, I come from the birthplace of music boxes in Switzerland, the old timers used to straighten the hardened shafts going through the cylinder by hitting the tensioned side with a pointed tool and hammer so it "broke" the tensioned fibers in the shaft and straightened it. Hard to do on a thread but worth a thought.
Option B: send it to a hardening place and ask for plasma nitriding or surface hardening. Not as sexy but gets the job done.
Good work!
As a European I had an immediate visceral reaction to hearing the term "micro-inches per inch-degree Fahrenheit"
I kept trying to understand a company making a shaft with 10 thread per INCH acme on one end and a metric thread on the other. If they (Europeans) are making a lathe, can’t they make a suitable lead screw thread that is not measured in inches?
I thought I was having a stroke.
Knife makers often use a flattening jig out of heat treatment. Red Beard Ops is a good example. Maybe make one with machined jaws that match the profile of the lead screw? Just spitballing.
Side project in the intro? RUT RUT RORGE
I was literally screaming internally "DUD HE ANNEAL IT?" when you were bending it
And yes you did :(
When you said press, I thought, "Oh, no!" Two things: Heat while the part is vertical and B: heat your oil to at least 150 - 200 degrees. This will still harden but do it slightly slower. When quenching you are shocking the material into a crystalline structure. If you take some of the temperature delta out, it shocks it at a less severe rate. Cheers!!
BABE WAKE UP INHERITANCE MACHINING POSTED!
now that you can make gears, can you make one of those old timey pencil sharpeners for your next proj?
What we used to do in my engineering classes is “normalize” the steel after machining. High temp, followed by long slow cooling, to allow the grain structure to shift, then perform straightening, normalize again to relieve stress, then heat treat.
Brandon - what a major setback. My heart goes out to you, and I will be eager to see how you surmount this challenging job.
"come on girl lets go"
"So i guess im on my own"
🤣
that's rough buddy