Love your stuff man. Just got approved for my loan for a Tormach. 20 years of Mechanical design and I'm ready to do my own thing. Going to browse your vids for ideas of what I need to start up my home shop. Already have a few people needing quotes...lol. Love your stuff man.
why did I spend so much time stuck in production welding or working for the man in general then I hear something like this and I regret some of my life decisions. Where can a welder thrive in America nowadays? I'm in ATL GA it's home but I'll travel for money. should I put my hood down and rewind 9 years and work at machine shop instead of fan shop?
1st. The reason "you need to always go a little bit further" is because the ideal thread forms are not triangular pyramids but are triangular pyramids with the major and minor peaks/valleys lopped off. The Major and Minor diameters you read from the table are the diameters at those lopped off flats, now your tool path Diameter (the way you are programming it) is the diameter at the vertex of the triangular peak which is not the same thing. 2nd. Your statement "In Theory all 12 pitch threads should have the same difference between the minor and the major (diameter)" is fundamentally correct. Where you are going wrong is the Major & Minor Diameter for an Internal thread vs External thread are not the same. Minor Diameter for 1" External is 0.8978" but Minor Dia for Internal is 0.9098" 1"-0.8978"=0.1022" EXTERNAL Minor Dia which is what you wrongly calculated. 1" - 0.9098 = 0.0902 INTERNAL Minor DIA. Which is for intents-and-purposes is the same as the 0.0905 difference you calculated for the 1 3/16 x 12 tpi. Cheers
Graphically this is the Lopped off part you are overlooking. upload.wikimedia.org/wikipedia/commons/thumb/4/4b/ISO_and_UTS_Thread_Dimensions.svg/2000px-ISO_and_UTS_Thread_Dimensions.svg.png
At 2:35, why were you unhappy with the recipe? Because of the chatter? Or was it going the wrong direction? I'm no machinist but it sounded like relatively normal operation and it made the chips so, why were you unhappy?
The thread and the chamfers are for a SAE #14 O-Ring port. It will seal effectively at high pressures, something like 5000 psi. Nice video. Thanks, John 🎉🎉🎉 Woo hoo, new baby girl! Congrats again. 😊
Yep, Day Job we make tons of manifolds and machine tons of SAE Ports and Metric Ports. Part doesn't have a spot face must be using that flat he machined as the spot face
+Chief Machining Spotface would've taken up almost the whole face where the flat is and would've left a sharp edge to deal with. Machine it flat and done. Thanks, John
+Chief Machining For doing lots of them, you're right. This is a prototype. Most of the machining was done on manual lathes and mills. Special tooling was out of the question. Easier and faster to bring it to SMW. Thanks, John
John the reason that you need to take a lil more than the .905 is because that is at 100% thread engagement and the normal thread engagement is about 75% which is the lil bit more that needs taken.
Great job John. I think its really smart how you formatted this episode by doing a quick overview of the cam then getting right to making chips and following that up with a more in depth look at the cam then adding in a time laps at the end. That's great for ppl that don't care as much about the 360 stuff. I personally don't use Fusion much, but still enjoy watching it. Excellent editing and Machining, which both seem to get better with each and every post. Quick question, what didn't you like about the recipe on that thread bore adaptive operation? Didn't look or sound that bad to me.
I use a lathe internal indeable toolholder as thread milling tool. It's slowers since you only have one flute, but it you broke the tip, it's only a couple or bucks
I imagine it's the radius of the thread mill that dictates the amount of offset. When single point threading on a lathe there is always some difference when using a dedicated pitch insert verses a universal.
Is it possible your need to increase the cutting diameter might be due to tool deflection? Those long skinny threadmills don't seem super rigid. Ciao, Marco.
Funny way to hold on to a part it made everything slow. Thread mills with inserts are better for this cos it will only damage the insert if something goes wrong, you can also use some lathe tools that have round tails so that you can hold them.
Is tool deflection also a factor? I would think this is more likely than a tool radius. The tool radius should make for a looser fit unless the tool diameter is an effective diameter to a theoretical sharp point and not the caliper diameter of the tool. I'm just thinking out loud here, so I easily could be wrong.
All you guys have hit on aspects that affect the result. Sometime when you're looking for an interesting challenge, get a copy of the standard for Unified National Thread forms ASME/ANSI B1.1. Lots of equations and tables for thread tolerances and dimensions. The basic thread form is 60 degree with sharp points and the basic equations start there. However, the writers of the standard know that it is impossible to cut threads with sharp points so they add allowances for tool radius, truncated thread tops, etc.
Anyhow, the key dimension is the pitch diameter which is nearly impossible to measure directly. On internal threads, the minor diameter is a separate feature from the thread. That's how we machine it, too. We drill a hole to a certain size and tolerance so we get a good thread form that engages properly with good strength. The depth of cut is dependent on the thread pitch and pitch diameter and is almost independent of the minor diameter. What I mean by that is if the pitch diameter is oversized by .003 inch, the major diameter of the internal thread will follow but the minor diameter won't. The end result is that by the time you stack up all the allowances and tolerances of both the part and the cutting tool, even if you calculate the pitch diameter correctly, you will have to make adjustments. Cutting good threads becomes somewhat of an art form rather than just some good math. Don't get me wrong, we need the math to get us as close as possible but there will always be adjustments.
+Caveman's Mancave Yes. Threads are most certainly an art. Once you delve into all the class of fits H/D values on taps, tap tolerances, minor/major/pitch dia tolerances. You could spend literally weeks going through book after book, formula after formula and still barely scratch the surface. Threads and their accompaniments are probably hands down the simplest concept, but the most complex reality there is in machining.
Hey john; The difference could be that the minor diameter of the two different thread sizes you referenced could have different tolerances on them. As you looked at the acceptable sizes not the theoretical. It could also be the flat or radius on the tip of your threadmill is not the same as the theoretical used for the calculations. As a side note, the corner radius/ flat on each tool isn't the same. It has a tolerance just like everything else. This tolerance will effect the finished pitch diameter; given that the OD of the tool is the same. However the OD also has a tolerance. This radius/flat on the tip also applies to lathe threading inserts. This is typically only noticed when trying to achieve decent thread fit.
Hey, I do a lot of thread milling at the shop, I use Mastercam to program but the concept is the same. for me the best way and the easiest is to create geometry of the amejor dia. of the thread you want to create and pick that geometry instead of the minor Dia. like you did for this part. it always work for me...I hope it helps!!!
I'm sure it's been answered, but the simple answer is like this. The sharp point on the tool requires a deeper depth because thread form is based on a tip with a radius. The sharper tool requires you to go deeper because you're essentially farther away from the required PD. Think that makes sense, hope it helps.
When I thread mill in fusion I usually select "model thread" in the threading pop up box during design, once in cam, just select the modeled major diameter as the contour for the threading op and select your pitch. No need for calculations etc.
I believe that's a fitting called "oring boss". Those dimensions are pretty critical to that fitting not leaking over time. A washer and nut typically will be on the fitting and will force an oring into the small clearance on the fitting. Your customer has a straight fitting without a nut and washer. I've dealt with them on the fluid power side of things, never in a machine shop. Burrs cut the oring and the oring size is critical. Looks nice, you'll know if your size and finish are good if it works for them.
O-ring gland. And that's usually only on ports. Doesn't look like a port fitting to me. Could be a modified simple port. They make specific SAE-J#### porting tools to cut the specific spot faces and angles. The 2 chamfer angles seem reversed. Usually the 60deg is at the top of the threads and the 45 is at the hole opening. On a side note. A good practice to get nice clean tapped holes at the top is to spot to .005" - .010" over the tap major dia with a 120 deg spot. Using a 90deg spot leaves a funny transition between the chamfer and the start of the threads.
How did you do a multiple pass step over with the 2D chamfer or how did you make Fusion do what would be "tip offset" in the 2d contour you used for your first chamfer? I need to do a really broad chamfer and want to do multiple step overs.
He used a regular contour toolpath and not the 2D chamfer path. For the specific reason that the 2D chamfer path doesn't allow for multi-pass. Which is a really dumb oversight in Fusion of you ask me.
Thanks, what confused me was John must have renamed the 2d contour to "chamfer" in the tree on the left. Still wondering the best way to make the 2d contour chamfer the correct width with the desired tip offset, offset sketch maybe?
A question not necessarily related to video in particular: quotations (pricing). How do you provide a quotation for a customer, when you have to go through a number of times (which you do not know until the appointed time), to get it right? Say the "widget" spoils and you have to use fresh materials. Also, additional machine time.
You cant add time for your mistakes...well unless you are some shady shop. Would you pay for two oil changes if jiffy lube forgot to put plug in first time?
Hi John, awesome work ! One question... how versatile are the thread milling tools ? I mean, is there a limited range of pitches a certain tool will allow you to make ? If so, how many different thread milling tools you´d need to cover a usable range of thread pitches ? Thanks !
Very versatile. Pretty much an infinite number of thread pitches can be made. The only limit is the required thread depth. Which will require you to bump up to a large thread mill Multi-flute thread mills are limited to only one thread pitch, but are about 5X faster than single points. The best investment ever is NPT tapered multi flute thread mills, they are rather pricey, but honestly once you use them you'll never want to go back to the old style tapered reamer and NPT tap again.
Question for you John ( or anyone ) when cutting a thread on a lathe you set the cross slide to 30deg and adjust your depth of cut along this axis so you are cutting on 1 face , does thread milling do the same ?
You should actually be at 29.5 degrees. Gives you clearance to the of the cutting face of the threading tool. The thread mill does have clearance ground into it for the main cutting edges and the helical path by its nature gives clearance to the lower part of the tooth.
I think you have to cut a little more than the actual pitch diameter offset because of the nature of thread milling. Your threads are coiling at an angle, while the flutes on the thread mill are horizontal. Basically the flutes aren't cutting at the angle that your threads are coiling, therefor, there is always going to be some material that isn't getting removed that in reality needs to be removed. This effect would probably be exaggerated if you were using a larger diameter thread mill to thread a small hole. unlike a tap, where the flutes are actually angled, I imagine this is why this happens with the thread mill. Just spitballing, it makes sense in my head, but then again, I'm sort of special so there's that.
Hi, John. In this video you show a 1/2" hole being drilled in what looks like one pass at 650 RPM, 4 IPM Peck. I have an 1100 and tried this setup and the spindle stalls. Are the speeds and feeds shown in the video accurate? I'm asking this because I bought my 1100 used and I'm concerned that something is wrong with the spindle if it can't drill the same hole successfully. As always, thanks for the awesome content and inspiration!
A 1/2 dia. drilled at 650 RPM and 4 IPM is a gravy cut. That's only .006 in/rev. What material are you drilling? Are you cutting it dry? What is your peck depth? What is your drill depth? You may not be clearing the chips and the tool is galling and seizing.
The listed major diameter is to the sharp V of a thread. If the 2 parts had the same major thread diameter, there would be no clearance for the thread to go in. It would be an interference thread (kinda like a press fit dowel). For a part to thread in and it needs clearance on both the major Dia of the thread and inside the V. The amount of clearance is referred to the H-class of a thread (that's the H# on a tap) smaller the H# the tighter the thread is. Larger diameters require larger H#. At 1-1-/2" you're around an H4-H5 fit which is .002-.0025" over major thread dia. for clearance. So you'll to take an additional amount off. But it's not a 1:1 formula. Remember the thread mill is a 60deg included angle (120deg total), so the formula for the additional amount to take off follows similar to calculating a chamfer dia for a 120 deg spot drill. There's also an additional compensation due to the helical tool path with a tool whose flutes are perpendicular to the cut.
Also threads have a root flat dimension at the maj dia crests and the minor dia valleys so there's a small flat area at the major dia crests that the thread mill (most anyway) doesn't have. So you have to bump it out to compensate for that as well. Which means going beyond the maj dia of the thread. In short. Threads are actually am very vast and complex subject, they're no as simple and straight forward as they appear.
Annnnd one more helpful hint to thread classes. For general purpose (95% of threads) this is the H (D for metric) class you will want for taps. [standard] #0 - #2 H1 for UNF. H2 for UNC #3 - #8 H2 for UNF H3 for UNC #10 - 3/8" H3 for UNF/UNC 7/16" - 3/4" H3 for UNF H4 for UNC 7/8" - 1-1/2" H4 for UNF/UNC [Metric] 1.6 - 3 D3 3.5 - 5 D4 6 - 8 D5 10 - 12 D6 14 - 20 D7 24 - 36 D9
For a given pitch, you don't have to have the same delta between minor and major thread diameter. Some profiles have deeper or shallower threads. Definitely not the same for all within a given pitch.
Occams Sawzall I have a powered rotary table, with the right set of change gears I actually probably could do it by engaging the rotab feed and z feed at the same time. That is true stunt milling right there! Calculating the proper gears and feeds to get the right thread hurts my head just thinking about it. :-)
+bcbloc02 used to work with an old guy from Germany (still working on his 70's) who can do things on a simple Bridgeport that I'd find tricky even on a 5 axis. His said his apprentice project was to hand file and lap a 1-2-3 block to +\- .0002 in dimension, squareness and flatness....
Occams Sawzall Always as much the man as the tools. I would sure hate to spend all that time on those 123 blocks only to take .0001 too much off on that last stroke!
+bcbloc02 He made it in the 50's or 60's. Still had it in his box. Obviously a little dinged up and worn, but we threw it on the CMM for giggles.... Damn thing was still within .0004 all around.... You barely even buy a 1-2-3 block brand new that good! Yet 50 some years later his little block was still kicking ass
About your perplexity regarding the necessity to sneak up on the final fit for your milled thread: The thread milling cutter's helical interpolation cylinder diameter results in the sharp tool trace being larger than the nominal OD of the thread being cut by 2 X the thread crest truncation for internal thread (Unified system). My Machinery's Handbook (16th Ed) has illustrations on page 1120 and 1121: "Limits of Size Showing Tolerances, Allowances etc" I'm sure your 28th Ed has something similar. See how the internal thread major diameter is larger than the nominal diameter and how the truncations of internal and external threads are manipulated to prevent tip/root interferance.
Exactly this. The Major diameter will be smaller than a sharp toolpath diameter by sqrt(3)/8*P where P is the distance between threads (inverse of threads per inch) On the difference between same-pitch threads of different diameters: your thread profile depends on both, so the major diameter will make a difference as well--mostly in the crest truncation--which leads to the offset above. A good UTS thread profile diagram should make both of these statements very clear.
Put pins in the 2 holes opposite eachother and use blocks to make the centerlines of the holes parallel If there wasn't 2 holes directly opposite eachother you'd probably have to build a fixture plate to correctly orient the part.
Ah! I guess the only way that would get tricky is if you could not orient the part based on that. If you had to orient some angle relative to that if that makes sense. Good call.
So in the vid you mention a "thread spring pass" and say you will discuss at the end but I did not see that. Also I don't see a Thread Spring Pass option in Fusion 360 I'm using (9/1/16). What is this spring pass?
Very cool, as a tool maker from the 70,s this type of work is fantastic. Just wish you would use coolant as all you guys do the same because it spoils the filming....
Yes. They actually have down to 0-80 thread mills. (And maybe smaller now too) For practicality. A tap is always the fastest way to make a thread provided your machine has the capacity and HP to drive it. With single points you can do several different thread pitches and sizes with a single tool. Slower, but saves you a ton in tool changes and tool holders. Especially if you can helical bore the tap drill size with an endmill instead of a drill. You can also do either internal or external threads with the same tool. Anything 1/2"-13 and smaller, a tap is still the best way to go. The only exception being if you have to tap hard (50 HRC+) material. Then go with the thread mill. Even though a tap can do it, it'll wear out quick and probably break in a hole at the most in opportune time.
Incrementally reduce the depth of cut. Take the max # of passes you want to do. In this case 3 1st pass at whole depth 2nd pass at 1/2 the 1st 3rd pass at 1/4 the 1st so that would be 1X+.5X+.25X=1.75X Y= the single depth = 1.75X then X = Y/1.75 =SUM(D13/(1+0.5+0.25)) Paste in excel, D13 is the single depth
major diameter for internal thread is nominal. so its actually bigger. there should be tolerances too. if there no tolerances. peek pitch diameter and add half from it to nominal major diameter. you safe :P. i dont use CAM. i have build custom makros for everything. 1 line code will do same as 100000 lines cam :D
In milling you don't actually single point threads like you would do on a lathe. You generate the threads with a helical motion. Yes you can generate NPT threads.
John, more often than not, the tool tip radius is what forces us guys to have to monkey with the numbers. We need to remember we are touching off our cutting tools to the tip surface, with whatever radius it may have. That exact radius is often unknown. The published minor/major diameters make an assumption of tip radius and you can bet it's not the value that applies to the tool you're using. Lead angle is something else that I notice is not discussed in so many videos on single point threading. After all, most of us are cutting threads of 8 tpi to much finer pitches where the lead angle role diminishes in practical importance. If you like, I'll provide you an equation for cutting depth to take into account your tool tip radius. This will give you the numbers to make you shine first time, every time. Regards, Bill Phillips, Surrey, BC, Canada
John, here's a pic that easily explains your question. I know I usually find myself reading threading explanations 10 times before I grasp what the person is saying. If you are a visual learner like me, this should help. As you already know, UNC and UNF threads have flat roots and crests. Unless your cutting tool has the exact same radius on it's tip as what the thread calls for (it won't) then minor diameter is a poor measurement to use. Thats why we always measure from pitch diameter (in the case of external threads). You'll see in the picture that if you had a perfectly sharp tool and you cut to minor diameter, the thread will not be fully formed, you actually need to go past the minor diameter. However, the minor diameter gives you a relatively safe starting point when it comes to internal threads. s13.postimg.org/j4h0nvj6v/NYC.png
About the thread milling problem. Take a look at this picture en.wikipedia.org/wiki/ISO_metric_screw_thread#/media/File:ISO_and_UTS_Thread_Dimensions.svg Thread diameters are specified based on the truncated triangles formed by the threads, not to the theoretical sharp points of those triangles. However a single point thread mill does cut to a sharp point of a triangle. You need to do some math to find the diameter of where those theoretical points are for a given thread specification. I made a calculator to do this. You can copy and paste this code into a text file and save it as .html then open it in a browser to use it pastebin.com/KJqERU6H This doesn't take thread tolerances into account, it's exact, I program it as is, and use tool wear compensation in Linux CNC to fine tune the fit. Also the thread pitch is the pitch not TPI, so i.e. 0.08333 not 12 for 12TPI. If I put in the thread you were cutting, I get 1.2055" for the helix diameter you wanted to be cutting, or a 0.1085" pitch diameter offset from the modeled 1.097" minor diameter.
The handbook shows a min/max for the minor of the thread & you were going with the low of that tolerance. That might be why you needed to give it a tad more. Shoot for the middle of the tolerance.
Yeah...pitch diameter isn't what...oh wait. I just read the bellow comments and they say what I was about to say. I don't remember how just looking at the full thread tolerencing diagram is how I remember figuring out.
Man. You are just so far off on feeds and speeds. The RPM was in the ball park on the drill, but you're feeding half what you should (at least 7 IPM). That end mill should be running at 6000 RPM and 75-100 IPM. Kinda sketchy how you used the 3D taster to try to find the center of the part. I would have used a square or something touched up against the OD. I always start at the bottom of the hole and climb mill out with a thread mill. Takes a lot of time to sneak up on the pitch diameter.
He has limited HP on that machine don't forget. 1/2" drill is a pretty large power consumption on that machine. That's why a lot of his speeds and feeds on large diameter drilling or large dia turning are fairly far off from optimal. He hits the max HP on the spindle pretty quick.
OK. But if HP is limited, you need to reduce feed and speed to keep the chip load where it should be. He should cut the drill RPM in half to get the feed closer to .01/rev so it will properly break a chip. Same with the end mill. It's squealing like a pig because it's rubbing instead of cutting. It needs way more feed or even less RPM. Feed and speed are 100% interrelated. You cannot change one and not the other. I enjoy the videos, but he's supposed to be a teacher. Feeds and speeds are most of machining. It should be taught correctly.
+Wes Johnson Since it's a single phase motor, reducing the RPM brings him too far down on the motors torque curve, meaning again it will stall out. The drill for that machine was just about right to optimize the chip load and still be within the motors torque curve. The endmill was a bit off but he said in the little popup he wasn't happy with it. The tormachs are a much more finicky machine when it comes to trying to balance chipload with machine power. Even a Bridgeport has About twice the HP and a far better torque curve along with being 3 phase power vs single phase. Considering the machines specs, he's not that far off from optimal. His only other option would be to reduce the pilot drill size down to 1/4" and run a 3/16" endmill for the C-bore rather than the 1/2" drill and 3/8" endmill. Then he would be able to run the correct speeds and feeds. But that too has its on sacrifices that would have to be made. Though might have been the better option here.
+Wes Johnson a dewalt drill is also designed for high torque applications. It has a 30:1 gear reduction from the motor. It's highest torque setting also maxes out at a paltry 450 rpm. And I highly doubt a hand drill would go though that material even 1/2 as fast as the Tormach did it. Also the Tormach goes up to 10k rpm. Vastly different motor and gearing designs.
hey John, I'm about to make my 1er threads experiment with fusion. The problem I have is adding the tool to my library. www.maritool.com/Cutting-Tools-Keyseat-/-Milling-Cutters-Chamfer-Milling-Cutters-Double-Angle-HSS-Chamfer-Mills/c78_231_237_239_277/p2419/Double-Angle-Chamfer-Cutter-3/8-dia-X-60-degree/product_info.html in tool type which one did you pick. Counter sink, dovetail. can't find the way to have the doble angle option. thanks.
It's the WORLD'S LIGHTEST, SOFTEST AND FREE-EST MACHINING "1045 STEEL"! And remember folks. ALWAYS USE A "CUTTER" TO MILL OUT A "PILOT HOLE" TO THE FINAL SIZE BECAUSE DRILL BITS ARE FOR CHEATERS! Or is that "DRILL BITS ARE FOR REAL MACHINISTS WITH REAL MACHINE TOOLS AND REAL EXPERIENCE AND KNOWLEDGE DOING REAL WORK FOR REAL CUSTOMERS TO REAL "PRINTS"?
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Love your stuff man. Just got approved for my loan for a Tormach. 20 years of Mechanical design and I'm ready to do my own thing. Going to browse your vids for ideas of what I need to start up my home shop. Already have a few people needing quotes...lol. Love your stuff man.
I'm into mechanical design too, and this sounds great. I wish to do this aswell sometime.
I've had the 440 for a month now and I'm loving it. Still getting past the learning curve of Fusion 360, but I'm making parts!
Good luck to you in your venture.
I just started a shop, just came across this post and was wondering how you are doing one year on?
why did I spend so much time stuck in production welding or working for the man in general then I hear something like this and I regret some of my life decisions. Where can a welder thrive in America nowadays? I'm in ATL GA it's home but I'll travel for money. should I put my hood down and rewind 9 years and work at machine shop instead of fan shop?
1st.
The reason "you need to always go a little bit further" is because the ideal thread forms are not triangular pyramids but are triangular pyramids with the major and minor peaks/valleys lopped off. The Major and Minor diameters you read from the table are the diameters at those lopped off flats, now your tool path Diameter (the way you are programming it) is the diameter at the vertex of the triangular peak which is not the same thing.
2nd.
Your statement "In Theory all 12 pitch threads should have the same difference between the minor and the major (diameter)" is fundamentally correct. Where you are going wrong is the Major & Minor Diameter for an Internal thread vs External thread are not the same.
Minor Diameter for 1" External is 0.8978" but Minor Dia for Internal is 0.9098"
1"-0.8978"=0.1022" EXTERNAL Minor Dia which is what you wrongly calculated.
1" - 0.9098 = 0.0902 INTERNAL Minor DIA. Which is for intents-and-purposes is the same as the 0.0905 difference you calculated for the 1 3/16 x 12 tpi.
Cheers
Graphically this is the Lopped off part you are overlooking. upload.wikimedia.org/wikipedia/commons/thumb/4/4b/ISO_and_UTS_Thread_Dimensions.svg/2000px-ISO_and_UTS_Thread_Dimensions.svg.png
John...as a newby...this is a great video. I love how you went through every step...great detail. So much info for 16 minutes!!!
I really like this format - quick overview, and then more details for those who want it!
At 2:35, why were you unhappy with the recipe? Because of the chatter? Or was it going the wrong direction?
I'm no machinist but it sounded like relatively normal operation and it made the chips so, why were you unhappy?
The thread and the chamfers are for a SAE #14 O-Ring port. It will seal effectively at high pressures, something like 5000 psi.
Nice video.
Thanks,
John
🎉🎉🎉
Woo hoo, new baby girl! Congrats again. 😊
Yep, Day Job we make tons of manifolds and machine tons of SAE Ports and Metric Ports. Part doesn't have a spot face must be using that flat he machined as the spot face
+Chief Machining
Spotface would've taken up almost the whole face where the flat is and would've left a sharp edge to deal with.
Machine it flat and done.
Thanks,
John
Yea and cost way more instead hitting with a port tool and being done.
+Chief Machining
For doing lots of them, you're right.
This is a prototype. Most of the machining was done on manual lathes and mills.
Special tooling was out of the question. Easier and faster to bring it to SMW.
Thanks,
John
Most have been your part?
What's it for?
Interesting about the thread pitch calcs. I'm guessing metric is not that way since it's based on angle vs threads per inch.... I could be wrong.
Nice video on thread milling and great trick on using the bottom to get your other chamfer. also save you another tool change.
Thank-you for what you do! Having you channel to refer to is incredibly helpful.
John the reason that you need to take a lil more than the .905 is because that is at 100% thread engagement and the normal thread engagement is about 75% which is the lil bit more that needs taken.
Great job John. I think its really smart how you formatted this episode by doing a quick overview of the cam then getting right to making chips and following that up with a more in depth look at the cam then adding in a time laps at the end. That's great for ppl that don't care as much about the 360 stuff. I personally don't use Fusion much, but still enjoy watching it. Excellent editing and Machining, which both seem to get better with each and every post. Quick question, what didn't you like about the recipe on that thread bore adaptive operation? Didn't look or sound that bad to me.
I use a lathe internal indeable toolholder as thread milling tool. It's slowers since you only have one flute, but it you broke the tip, it's only a couple or bucks
very cool John. I would really like to see the set up with out the flat and a straight 1/2" NPT.
Really helpful John.
glad to hear the old theme song during time laps. great video.
Jody Olivent what’s the song called?
I imagine it's the radius of the thread mill that dictates the amount of offset. When single point threading on a lathe there is always some difference when using a dedicated pitch insert verses a universal.
Is it possible your need to increase the cutting diameter might be due to tool deflection? Those long skinny threadmills don't seem super rigid. Ciao, Marco.
compensate by 20% with those even threads but depends on what fit 1 or 2 or 3 and the oring factor hence the 60 percent chamfer also
Funny way to hold on to a part it made everything slow. Thread mills with inserts are better for this cos it will only damage the insert if something goes wrong, you can also use some lathe tools that have round tails so that you can hold them.
Great video John. Also congratulations on the new addition.
Looks to be an oring port, I did a lot of this at my last job. We mad hydraulic parts.
The Reason you have to cut deeper then the Book says is the Corner Radius of your threadnill. The Book Values are calculated with sharp Angles.
Is tool deflection also a factor? I would think this is more likely than a tool radius. The tool radius should make for a looser fit unless the tool diameter is an effective diameter to a theoretical sharp point and not the caliper diameter of the tool. I'm just thinking out loud here, so I easily could be wrong.
All you guys have hit on aspects that affect the result.
Sometime when you're looking for an interesting challenge, get a copy of the standard for Unified National Thread forms ASME/ANSI B1.1.
Lots of equations and tables for thread tolerances and dimensions. The basic thread form is 60 degree with sharp points and the basic equations start there. However, the writers of the standard know that it is impossible to cut threads with sharp points so they add allowances for tool radius, truncated thread tops, etc.
Anyhow, the key dimension is the pitch diameter which is nearly impossible to measure directly.
On internal threads, the minor diameter is a separate feature from the thread. That's how we machine it, too. We drill a hole to a certain size and tolerance so we get a good thread form that engages properly with good strength. The depth of cut is dependent on the thread pitch and pitch diameter and is almost independent of the minor diameter. What I mean by that is if the pitch diameter is oversized by .003 inch, the major diameter of the internal thread will follow but the minor diameter won't.
The end result is that by the time you stack up all the allowances and tolerances of both the part and the cutting tool, even if you calculate the pitch diameter correctly, you will have to make adjustments. Cutting good threads becomes somewhat of an art form rather than just some good math. Don't get me wrong, we need the math to get us as close as possible but there will always be adjustments.
+Caveman's Mancave
Yes. Threads are most certainly an art. Once you delve into all the class of fits H/D values on taps, tap tolerances, minor/major/pitch dia tolerances. You could spend literally weeks going through book after book, formula after formula and still barely scratch the surface.
Threads and their accompaniments are probably hands down the simplest concept, but the most complex reality there is in machining.
Very helpful, John! My 440 requires me to do thread milling so I need to get this process down cold...
Best wishes,
Tom Z
Hey john;
The difference could be that the minor diameter of the two different thread sizes you referenced could have different tolerances on them. As you looked at the acceptable sizes not the theoretical.
It could also be the flat or radius on the tip of your threadmill is not the same as the theoretical used for the calculations.
As a side note, the corner radius/ flat on each tool isn't the same. It has a tolerance just like everything else. This tolerance will effect the finished pitch diameter; given that the OD of the tool is the same. However the OD also has a tolerance.
This radius/flat on the tip also applies to lathe threading inserts.
This is typically only noticed when trying to achieve decent thread fit.
Hey, I do a lot of thread milling at the shop, I use Mastercam to program but the concept is the same. for me the best way and the easiest is to create geometry of the amejor dia. of the thread you want to create and pick that geometry instead of the minor Dia. like you did for this part. it always work for me...I hope it helps!!!
I'm sure it's been answered, but the simple answer is like this. The sharp point on the tool requires a deeper depth because thread form is based on a tip with a radius. The sharper tool requires you to go deeper because you're essentially farther away from the required PD. Think that makes sense, hope it helps.
When I thread mill in fusion I usually select "model thread" in the threading pop up box during design, once in cam, just select the modeled major diameter as the contour for the threading op and select your pitch. No need for calculations etc.
I believe that's a fitting called "oring boss". Those dimensions are pretty critical to that fitting not leaking over time. A washer and nut typically will be on the fitting and will force an oring into the small clearance on the fitting. Your customer has a straight fitting without a nut and washer. I've dealt with them on the fluid power side of things, never in a machine shop. Burrs cut the oring and the oring size is critical. Looks nice, you'll know if your size and finish are good if it works for them.
O-ring gland. And that's usually only on ports. Doesn't look like a port fitting to me. Could be a modified simple port.
They make specific SAE-J#### porting tools to cut the specific spot faces and angles.
The 2 chamfer angles seem reversed. Usually the 60deg is at the top of the threads and the 45 is at the hole opening.
On a side note. A good practice to get nice clean tapped holes at the top is to spot to .005" - .010" over the tap major dia with a 120 deg spot. Using a 90deg spot leaves a funny transition between the chamfer and the start of the threads.
I'm not sure what the Tormach's RPM maxes out at, but you should have been running that 3/8" carbide closer to 3000rpm to get a good cut on it.
These are the types of videos i like!!
Congratulations on your daughter
How did you do a multiple pass step over with the 2D chamfer or how did you make Fusion do what would be "tip offset" in the 2d contour you used for your first chamfer? I need to do a really broad chamfer and want to do multiple step overs.
He used a regular contour toolpath and not the 2D chamfer path. For the specific reason that the 2D chamfer path doesn't allow for multi-pass. Which is a really dumb oversight in Fusion of you ask me.
Thanks, what confused me was John must have renamed the 2d contour to "chamfer" in the tree on the left. Still wondering the best way to make the 2d contour chamfer the correct width with the desired tip offset, offset sketch maybe?
Which is more precise, thread milling with a spindle or tapping with a spindle?
A question not necessarily related to video in particular: quotations (pricing). How do you provide a quotation for a customer, when you have to go through a number of times (which you do not know until the appointed time), to get it right? Say the "widget" spoils and you have to use fresh materials. Also, additional machine time.
You cant add time for your mistakes...well unless you are some shady shop.
Would you pay for two oil changes if jiffy lube forgot to put plug in first time?
Hi John, awesome work ! One question... how versatile are the thread milling tools ? I mean, is there a limited range of pitches a certain tool will allow you to make ? If so, how many different thread milling tools you´d need to cover a usable range of thread pitches ?
Thanks !
Very versatile. Pretty much an infinite number of thread pitches can be made. The only limit is the required thread depth. Which will require you to bump up to a large thread mill
Multi-flute thread mills are limited to only one thread pitch, but are about 5X faster than single points.
The best investment ever is NPT tapered multi flute thread mills, they are rather pricey, but honestly once you use them you'll never want to go back to the old style tapered reamer and NPT tap again.
Very nice! You will be building space equipment soon!
Question for you John ( or anyone ) when cutting a thread on a lathe you set the cross slide to 30deg and adjust your depth of cut along this axis so you are cutting on 1 face , does thread milling do the same ?
You should actually be at 29.5 degrees. Gives you clearance to the of the cutting face of the threading tool.
The thread mill does have clearance ground into it for the main cutting edges and the helical path by its nature gives clearance to the lower part of the tooth.
I think you have to cut a little more than the actual pitch diameter offset because of the nature of thread milling. Your threads are coiling at an angle, while the flutes on the thread mill are horizontal. Basically the flutes aren't cutting at the angle that your threads are coiling, therefor, there is always going to be some material that isn't getting removed that in reality needs to be removed. This effect would probably be exaggerated if you were using a larger diameter thread mill to thread a small hole. unlike a tap, where the flutes are actually angled, I imagine this is why this happens with the thread mill. Just spitballing, it makes sense in my head, but then again, I'm sort of special so there's that.
i am curious if you found a solution to the fact that you always have to ad a little bit to the pitch diameter offset
Hi, John. In this video you show a 1/2" hole being drilled in what looks like one pass at 650 RPM, 4 IPM Peck. I have an 1100 and tried this setup and the spindle stalls. Are the speeds and feeds shown in the video accurate?
I'm asking this because I bought my 1100 used and I'm concerned that something is wrong with the spindle if it can't drill the same hole successfully.
As always, thanks for the awesome content and inspiration!
A 1/2 dia. drilled at 650 RPM and 4 IPM is a gravy cut. That's only .006 in/rev. What material are you drilling? Are you cutting it dry? What is your peck depth? What is your drill depth? You may not be clearing the chips and the tool is galling and seizing.
grad of tread quality .
Can we generate worm thread
Very nice job !
Beautiful! Great work! How long from start to finish, cad/cam?
very nice work
VERY cool!
The listed major diameter is to the sharp V of a thread. If the 2 parts had the same major thread diameter, there would be no clearance for the thread to go in. It would be an interference thread (kinda like a press fit dowel). For a part to thread in and it needs clearance on both the major Dia of the thread and inside the V. The amount of clearance is referred to the H-class of a thread (that's the H# on a tap) smaller the H# the tighter the thread is.
Larger diameters require larger H#. At 1-1-/2" you're around an H4-H5 fit which is .002-.0025" over major thread dia. for clearance. So you'll to take an additional amount off. But it's not a 1:1 formula. Remember the thread mill is a 60deg included angle (120deg total), so the formula for the additional amount to take off follows similar to calculating a chamfer dia for a 120 deg spot drill.
There's also an additional compensation due to the helical tool path with a tool whose flutes are perpendicular to the cut.
Also threads have a root flat dimension at the maj dia crests and the minor dia valleys so there's a small flat area at the major dia crests that the thread mill (most anyway) doesn't have. So you have to bump it out to compensate for that as well. Which means going beyond the maj dia of the thread.
In short. Threads are actually am very vast and complex subject, they're no as simple and straight forward as they appear.
Annnnd one more helpful hint to thread classes. For general purpose (95% of threads) this is the H (D for metric) class you will want for taps.
[standard]
#0 - #2 H1 for UNF. H2 for UNC
#3 - #8 H2 for UNF H3 for UNC
#10 - 3/8" H3 for UNF/UNC
7/16" - 3/4" H3 for UNF H4 for UNC
7/8" - 1-1/2" H4 for UNF/UNC
[Metric]
1.6 - 3 D3
3.5 - 5 D4
6 - 8 D5
10 - 12 D6
14 - 20 D7
24 - 36 D9
For a given pitch, you don't have to have the same delta between minor and major thread diameter. Some profiles have deeper or shallower threads. Definitely not the same for all within a given pitch.
Hi John, quick Q... if you could have only one thread milling tool, which size would it be ?
I can't do thread milling on my manual machines. :-( Someday soon though! Just 45ft more of shop wall and I will have a shop with 4 walls!
If you dial in your Z power feed speed and RPM just right you can do it with a boring head XD
Occams Sawzall
I have a powered rotary table, with the right set of change gears I actually probably could do it by engaging the rotab feed and z feed at the same time. That is true stunt milling right there! Calculating the proper gears and feeds to get the right thread hurts my head just thinking about it. :-)
+bcbloc02 used to work with an old guy from Germany (still working on his 70's) who can do things on a simple Bridgeport that I'd find tricky even on a 5 axis.
His said his apprentice project was to hand file and lap a 1-2-3 block to +\- .0002 in dimension, squareness and flatness....
Occams Sawzall
Always as much the man as the tools. I would sure hate to spend all that time on those 123 blocks only to take .0001 too much off on that last stroke!
+bcbloc02
He made it in the 50's or 60's. Still had it in his box. Obviously a little dinged up and worn, but we threw it on the CMM for giggles.... Damn thing was still within .0004 all around.... You barely even buy a 1-2-3 block brand new that good! Yet 50 some years later his little block was still kicking ass
Love the timelapse! You should show that first, then explain step-by-step... i.e. show us the "outline" then go into detail.
About your perplexity regarding the necessity to sneak up on the final fit for your milled thread:
The thread milling cutter's helical interpolation cylinder diameter results in the sharp tool trace being larger than the nominal OD of the thread being cut by 2 X the thread crest truncation for internal thread (Unified system). My Machinery's Handbook (16th Ed) has illustrations on page 1120 and 1121: "Limits of Size Showing Tolerances, Allowances etc" I'm sure your 28th Ed has something similar.
See how the internal thread major diameter is larger than the nominal diameter and how the truncations of internal and external threads are manipulated to prevent tip/root interferance.
Exactly this. The Major diameter will be smaller than a sharp toolpath diameter by sqrt(3)/8*P where P is the distance between threads (inverse of threads per inch)
On the difference between same-pitch threads of different diameters: your thread profile depends on both, so the major diameter will make a difference as well--mostly in the crest truncation--which leads to the offset above.
A good UTS thread profile diagram should make both of these statements very clear.
How would you have aligned the part if they would have (unfortunately) given you the part with the bolt pattern already drilled?
Put pins in the 2 holes opposite eachother and use blocks to make the centerlines of the holes parallel
If there wasn't 2 holes directly opposite eachother you'd probably have to build a fixture plate to correctly orient the part.
Ah! I guess the only way that would get tricky is if you could not orient the part based on that. If you had to orient some angle relative to that if that makes sense. Good call.
How to buy same tool,? I see ít verry good.
Hey John how's Keiths grill coming on
So in the vid you mention a "thread spring pass" and say you will discuss at the end but I did not see that. Also I don't see a Thread Spring Pass option in Fusion 360 I'm using (9/1/16). What is this spring pass?
It's a clean up pass if the tool flexed it can take the little bit of extra stock that didn't get removed from the roughing passes
THIS IS PRETTY NICE, THANK YOU SIR.
Very cool, as a tool maker from the 70,s this type of work is fantastic. Just wish you would use coolant as all you guys do the same because it spoils the filming....
can you thread mill 4-40 in aluminum? Steel? What is the practical limits if there is any?
Yes. They actually have down to 0-80 thread mills. (And maybe smaller now too)
For practicality. A tap is always the fastest way to make a thread provided your machine has the capacity and HP to drive it.
With single points you can do several different thread pitches and sizes with a single tool. Slower, but saves you a ton in tool changes and tool holders. Especially if you can helical bore the tap drill size with an endmill instead of a drill. You can also do either internal or external threads with the same tool.
Anything 1/2"-13 and smaller, a tap is still the best way to go. The only exception being if you have to tap hard (50 HRC+) material. Then go with the thread mill. Even though a tap can do it, it'll wear out quick and probably break in a hole at the most in opportune time.
You could try a helical interpolation to rough out the hole, like you did for the rough & ream story, maybe this is a better recipe
Nice work tho
Incrementally reduce the depth of cut.
Take the max # of passes you want to do.
In this case 3
1st pass at whole depth
2nd pass at 1/2 the 1st
3rd pass at 1/4 the 1st
so that would be 1X+.5X+.25X=1.75X
Y= the single depth = 1.75X
then X = Y/1.75
=SUM(D13/(1+0.5+0.25))
Paste in excel, D13 is the single depth
major diameter for internal thread is nominal. so its actually bigger. there should be tolerances too. if there no tolerances. peek pitch diameter and add half from it to nominal major diameter. you safe :P. i dont use CAM. i have build custom makros for everything. 1 line code will do same as 100000 lines cam :D
The thread angle is 60°, but because the tool is moving axially, the thread mill should be less than 60°.
You could have changed the angle for the face op to 90deg it would've did y axis instead of x
Can you single point npt threads.?
In milling you don't actually single point threads like you would do on a lathe. You generate the threads with a helical motion. Yes you can generate NPT threads.
first,
have you lost that pucker factor with single point threading, good vid
congratulations
good job and congrats :)
Do not stop feed at anytime
John, more often than not, the tool tip radius is what forces us guys to have to monkey with the numbers. We need to remember we are touching off our cutting tools to the tip surface, with whatever radius it may have. That exact radius is often unknown. The published minor/major diameters make an assumption of tip radius and you can bet it's not the value that applies to the tool you're using. Lead angle is something else that I notice is not discussed in so many videos on single point threading. After all, most of us are cutting threads of 8 tpi to much finer pitches where the lead angle role diminishes in practical importance. If you like, I'll provide you an equation for cutting depth to take into account your tool tip radius. This will give you the numbers to make you shine first time, every time.
Regards,
Bill Phillips, Surrey, BC, Canada
nice but try inserted threadmilling though. :-) Vargus or Carmex 16ER or IR.
John, here's a pic that easily explains your question. I know I usually find myself reading threading explanations 10 times before I grasp what the person is saying. If you are a visual learner like me, this should help.
As you already know, UNC and UNF threads have flat roots and crests. Unless your cutting tool has the exact same radius on it's tip as what the thread calls for (it won't) then minor diameter is a poor measurement to use. Thats why we always measure from pitch diameter (in the case of external threads). You'll see in the picture that if you had a perfectly sharp tool and you cut to minor diameter, the thread will not be fully formed, you actually need to go past the minor diameter. However, the minor diameter gives you a relatively safe starting point when it comes to internal threads.
s13.postimg.org/j4h0nvj6v/NYC.png
About the thread milling problem. Take a look at this picture en.wikipedia.org/wiki/ISO_metric_screw_thread#/media/File:ISO_and_UTS_Thread_Dimensions.svg Thread diameters are specified based on the truncated triangles formed by the threads, not to the theoretical sharp points of those triangles. However a single point thread mill does cut to a sharp point of a triangle. You need to do some math to find the diameter of where those theoretical points are for a given thread specification. I made a calculator to do this. You can copy and paste this code into a text file and save it as .html then open it in a browser to use it pastebin.com/KJqERU6H This doesn't take thread tolerances into account, it's exact, I program it as is, and use tool wear compensation in Linux CNC to fine tune the fit. Also the thread pitch is the pitch not TPI, so i.e. 0.08333 not 12 for 12TPI.
If I put in the thread you were cutting, I get 1.2055" for the helix diameter you wanted to be cutting, or a 0.1085" pitch diameter offset from the modeled 1.097" minor diameter.
This explanation and coded solution deserves many thanks!
Nice!
The handbook shows a min/max for the minor of the thread & you were going with the low of that tolerance. That might be why you needed to give it a tad more. Shoot for the middle of the tolerance.
Yeah...pitch diameter isn't what...oh wait. I just read the bellow comments and they say what I was about to say. I don't remember how just looking at the full thread tolerencing diagram is how I remember figuring out.
Man. You are just so far off on feeds and speeds. The RPM was in the ball park on the drill, but you're feeding half what you should (at least 7 IPM). That end mill should be running at 6000 RPM and 75-100 IPM.
Kinda sketchy how you used the 3D taster to try to find the center of the part. I would have used a square or something touched up against the OD.
I always start at the bottom of the hole and climb mill out with a thread mill. Takes a lot of time to sneak up on the pitch diameter.
He has limited HP on that machine don't forget. 1/2" drill is a pretty large power consumption on that machine.
That's why a lot of his speeds and feeds on large diameter drilling or large dia turning are fairly far off from optimal. He hits the max HP on the spindle pretty quick.
OK. But if HP is limited, you need to reduce feed and speed to keep the chip load where it should be. He should cut the drill RPM in half to get the feed closer to .01/rev so it will properly break a chip. Same with the end mill. It's squealing like a pig because it's rubbing instead of cutting. It needs way more feed or even less RPM.
Feed and speed are 100% interrelated. You cannot change one and not the other.
I enjoy the videos, but he's supposed to be a teacher. Feeds and speeds are most of machining. It should be taught correctly.
+Wes Johnson
Since it's a single phase motor, reducing the RPM brings him too far down on the motors torque curve, meaning again it will stall out.
The drill for that machine was just about right to optimize the chip load and still be within the motors torque curve.
The endmill was a bit off but he said in the little popup he wasn't happy with it.
The tormachs are a much more finicky machine when it comes to trying to balance chipload with machine power. Even a Bridgeport has About twice the HP and a far better torque curve along with being 3 phase power vs single phase.
Considering the machines specs, he's not that far off from optimal. His only other option would be to reduce the pilot drill size down to 1/4" and run a 3/16" endmill for the C-bore rather than the 1/2" drill and 3/8" endmill. Then he would be able to run the correct speeds and feeds. But that too has its on sacrifices that would have to be made. Though might have been the better option here.
I thought the Tormach had 2 belt ratios. It's pretty sad if it can't push a 1/2 drill. A Dewalt cordless can handle that...
+Wes Johnson a dewalt drill is also designed for high torque applications. It has a 30:1 gear reduction from the motor. It's highest torque setting also maxes out at a paltry 450 rpm. And I highly doubt a hand drill would go though that material even 1/2 as fast as the Tormach did it.
Also the Tormach goes up to 10k rpm. Vastly different motor and gearing designs.
Sorry I only have a poor mans Bob Cam.. I would not know how to to start.
But great video.. I will watch out for moor...
Robert Kent fusion is free for hobbyists
hey John, I'm about to make my 1er threads experiment with fusion. The problem I have is adding the tool to my library.
www.maritool.com/Cutting-Tools-Keyseat-/-Milling-Cutters-Chamfer-Milling-Cutters-Double-Angle-HSS-Chamfer-Mills/c78_231_237_239_277/p2419/Double-Angle-Chamfer-Cutter-3/8-dia-X-60-degree/product_info.html
in tool type which one did you pick. Counter sink, dovetail. can't find the way to have the doble angle option.
thanks.
Hi John take a look at : At-Man Unlimited on UA-cam he explains the math behind thread milling😊
Those tormachs seem to be a bit crap!
It's the WORLD'S LIGHTEST, SOFTEST AND FREE-EST MACHINING "1045 STEEL"! And remember folks. ALWAYS USE A "CUTTER" TO MILL OUT A "PILOT HOLE" TO THE FINAL SIZE BECAUSE DRILL BITS ARE FOR CHEATERS! Or is that "DRILL BITS ARE FOR REAL MACHINISTS WITH REAL MACHINE TOOLS AND REAL EXPERIENCE AND KNOWLEDGE DOING REAL WORK FOR REAL CUSTOMERS TO REAL "PRINTS"?
stop shouting
Stfu.
You need a DMG Mori Machine ;) Tormach is a juicer ;)
I love your videos - But you go way to fast to understand - please slow down in your videos.
heidenhain.. 2 minutes programming