Threading With the Compound vs. Crossfeed
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- Опубліковано 7 лис 2021
- Here's my take on the age old debate between threading with the compound or the crossfeed. I cut four threads in total, two each with the compound and crossfeed, with and without cutting oil, to see if there was any difference at all.
Cutting a Double Start Acme Thread - • Cutting a Double Start...
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/ stuartdeharo
If I could briefly say a few words about Disco Inferno, a fire 100 stories high is going to leave a mark on history. People would have died. We have solid historical records of fires that are much older. Rome in 64AD. London 1666. We know who owned the cow that burned down Chicago in 1871, yet there are no other contemporary accounts of this supposed musical conflagration that just happened in 1976. It just seems a little suspicious to me. Also, The Trammps seem a little too enthusiastic about fire. They keep saying”burn baby burn,” and “burn that mother down.” Are we sure they’re not arsonists?
As an apprentice, I was taught to use the half included angle via the top slide and we only had hand ground HSS tooling.
The Old Boy turner in the repair shop showed me how to put the cut on with the cross slide, but to advance the top slide (set parallel to the work) a couple of thousandths every cut, to mimic the angled infeed cut and reduce the load on the tool and that's how I've cut all my simple threads since the 70's.
I like your new energy, the quality of your videos has improved and the content is spot on.
A long time viewer appreciates the effort!
The cross slide method has the disadvantage that you have to remember exactly what your last pass was on every pass.
thats a game changer for an old dude like me I would never remember
Great videos. Thank you for sharing your knowledge with us.
I use the compound because that was the way I was taught.
Outstanding content and production value on the video, cheers from an old guy in Florida, Paul
Great vid!!! Beginning with a whiteboard / chalkboard explanation of the theory would have helped. Also you may consider a negative tool top rake? Thanks!!!!
Good video. I would make several suggestions that might help machinists doing threading for the first time. The first is don't start threading on nominal sized stock. Look in the threading section of your machinist reference book. You will notice that for a 1"-8tpi thread the stock major diameter is not 1" (same-same for mm threads). The major diameter is some thousands of an inch under the nominal size. Note in the video the threads have a sharp crest whereas a correctly cut 60 degree V thread will have a crest flat equal to 1/8th the thread pitch. If you thread nominal sized stock and are using thread go/no-go gauges to check your work in process by the time you get the go gauge to go on to the work the thread will be under size. As an aside if you are using a threading die the work is noticeably easier to thread if the work has the correct o.d. for that particular thread.
There is a trick to be able to cut threads at a much higher rpm on a manual lathe besides threading outwards. While threading outwards with the lathe in reverse is a viable method it won't work when no thread relief is allowed. This will require feeding from the compound. Run the threading tool in close to the work and stop the cross feed hand wheel so the handle is at about the 10-11 o'clock position and set the cross feed dial to zero. Bring the threading tool up to the work with the compound feed and set it to zero. Up to 1/2" (13mm) threads I run the lathe at about 220rpm. Engage the half-nut and when the tool reaches the point you wish the thread to end snap the cross feed out and open the half nut at the same time. Do it a few times and you'll get surprisingly good at it.
If you are cutting metric threads follow the directions above except that after pulling the threading tool back and opening the half nut cut the power and let the spindle stop. You will notice that the thread indicator dial hasn't moved very far from where it was opened. Put the lathe into reverse and when the thread dial mark you were using comes back up, re-engage the half nut and back the carriage up to the initial start position. Once in position set the compound feed for the next pass and turn the cross feed to it's "zero" and make the next pass.
Great video! I've always threaded with compound in feed, mostly because of speed in a production environment. When I began running NC lathes the programming had different in feed angles to control the flow of the shavings. I started using 10° with excellent results. I still do it that way. I usually had better tool life than the 29.5° in feed angle. Thanks for your time and sharing. 👍
Good as always! Remember us early adopters when this channel blows up!
Always
Thank you for sharing.
Well done, I find both methods to be comparable, even with an indexable tool. Enjoyed the discussion, cheers!
With using the compound you zero out the compound then just touch the tool to the work od and zero out the cross slide. When cutting you just need to take the cross slide to zero every time and move the cross side in a bit at a time. After the final pass write down the number on the cross slide for multiple parts and it is just as easy for production as using the cross slide only. Example, if the cross slide is set to .045 on the last pass you should be able to take your next part to .045 and get the same thread pitch diameter as the first part assuming the od's were the same as each other if not you have to compensate for that.
I should add, I always use the compound as it is easier to keep track of the feed in depth. No DRO on my lathe.
nice video, i like your aproach....
A positive rake on the HSS tool would help eliminate that.
Thanks Stu, I’ve always wondered what the difference would be to use the CF. As I learned the “correct” way, I have honestly never tried.
Thank you good content
I'll mark the cross-feed side with a C ... and the compound side with a ...ffff! That literally made me laugh out loud - not least because I've done stuff like that hahaha
Fun fact: I wrote that gag before anything else in the script.
Thank you.
Love this type of comparison content, would be neat to see fine thread (32) hard material (4140) with high speed and insert tooling. Now, as for the lazy factor.... hard to measure :)
As always, thanks for sharing
Cheers
You tube is reading my mind. I've been thinking about this recently. I don't have any preference because to me I've never ever noticed any difference in how the thread performs or looks.
UA-cam is good at that. I don't really have a preference either. It just depends on the circumstances of the job. Thanks for watching!
It'll be interesting to see the effect of RPMs (or surface feet per min) on surface finish when single point threading. Don't see much mentioned on this specific area.
When a machining video makes me LOL and detour into 1976 video...
I always put the tool post on the back side of the material and run the lathe backwards. The tool runs away from the chuck and no chance of a crash
my only problem using the compound, is keeping track of my depth of cut. and zero position. i have to write it down. with the crossfeed tech the crossfeed stays on zero and you keep track of your depth of cut with the compound. i was also taught to advance the compound a couple of thou in the end to clean up the back side of the cut.
thumbs up for the Pink Floyd shirt! 👍
Choosing 360 brass was not a very good test because almost anything can do a good job on brass. The chatter you were seeing may have been do to the gearing in the lathe. Run the test using some 1018, it would be more telling.
More threading info about the 29.5 degrees. ua-cam.com/video/8wxa7LB0FtE/v-deo.html
after I shovel out the snow im gonna go in my shop and try some crossed threading got some cheap Chinese inserts that are horrible and need to be pitched I'll break em instead gonna try some reverse threading higher speed too
In theory cutting with the compound would drive some of the force axially (compressing the stock towards the chuck) whereas cutting with the cross feed would be driving all of the force normal to the stock. However cos(29.5) is ~ 90% so the difference in normal force is about 10%, which means maybe on a smaller piece of stock you can get away with something on the compound that you couldn't with the cross feed but 90% of a big number is ... still a big number. Thanks for the visual confirmation!
So I have just machined a part this morning on what is a monster lathe to me.
I used an angle finder as I do at home, setting the compound at 29.5 degrees to the chuck face, which in turn gave me 60.5 degrees on the scale. I was thrown by this but have I set the angle correctly?
Yes you did. The angle depends on where zero is compared to the lathe axis. Some lathes have zero with the compound perpendicular to the spindle axis, some have it parallel.
Maybe you could try using Joe Pyzynski's reverse threading method where you cut away from the chuck which allows you to cut the threads faster. Thank you for the content.
Someone else brought that up and I would definitely do it, but the reverse contacter on my lathe doesn't work. It just sticks in and buzzes.
That is not HIS method regardless of what he claims. That was being used before he was even born.
@@billshiff2060
Show us that video!
@@tommelomme6761 🙄👆You see, back in ancient times before you were born, say the 1970's or so, there was this technology that we called "books" that looked like this🙄👉📖. These "books" were full of little symbols that were called "writing". People would write down all their discoveries in these "books" so that others could learn about them too. For thousands of years people learned from these "books" until video was invented so that people who can't read could learn some things too. Eventually people forgot how to decipher the symbols in these "books" and started to think ALL knowledge came from videos. Now only the high priests of knowledge still know how to "read" these "books". The common folk have only video. If you want that old knowledge you will have to know how to read a "book".
@@billshiff2060
I am sorry disappointing you but I was born before the 1970's.
My point was, without saying it, Joe P has showed it, he is alive an can still tell about it. I am no machinist but I do machining. My first contact with reverse threading method was... Joe P.
And your point is taken, Joe P was not the one discovering this, probably not even the guy you mention. Best regards Thomas
Stewart, I have the compound somewhere under a bench.
I have made a solid riser for my quick change tool post.
Having a taper turning attachment permanently set up most useful tapers are covered.
I love the rigidity this offers and 10hp Needs rigidity...
the compound method is 100% a hold over from HSS tooling, in a production atmosphere with manual machines, you will need to regrind your HSS bit several times a day, so rather then regring BOTH sides you mostly use one side, so then you just have to grind that one side, Also you can almost get away with grinding the trailing edge a litte steep and have only the one side to contend with, the "leaving a better finish" is likely one of them capt dummy explaining the who too's to the FNG, who then repeats its for 300+ years.
Tool stick-out looks most likely to me , at higher speeds the chatter resonance will be way below .
Loved the video. But.... looking at the angle of the tool at 5:56 leads me to believe it is not perpendicular to the work. The side of the HSS bit doesn't appear to be anywhere near the line of the cross slide travel. Is the angle of your point grind that far off, or did you not use your fishtail gauge to set it up against the work? Normally I would say it's probably due to the camera angle, but it sure likes like you were dead center over the top of the tool with the lens. Asking for a friend.... 😁
The angle was ground that far off. I'm not proud of it.
Stuart, I am trying to learn to thread on my 1236 , compound at 29.5 as better people suggest using carbide 60 deg. insert and using a DRO. No body ever showed the angle of the tool holder and insert so I set it at 90deg. to the material axis, starts great but as I cut a 1.75 met. pitch after about 3 passes then check with thread gauge it shows pitch is moving down towards 1.5 mm and less. I noticed your single point cutter is angled to towards the tail stock i.e not at 90deg. to the material axis line, would this be why I am failing to maintain 1.75 mm pitch even when using the compound , if so what is the correct approach angle to set the insert at. signed ( an
old fart who is running out of time)
The tool definitely needs to be perpendicular to the workpiece. The tool in the video is hand ground so the angle is not square to the bit, but it is perpendicular to the part. Regarding your issue, first check the gearing to make sure you've got it set correctly. If that looks good then tell me how the thread looks. Is it the correct angle on the headstock side of the thread but much shallower on the right? If that's the case then your compound is set incorrectly. There are a few other options. Why don't you email me pics of the threads and I'll try to troubleshoot them for you. My email is my channel name @gmail.com.
Hi is it possible to cut threads without a dial
And if yes how do you do it thank you
Absolutely. The safest way is to engage the half nuts and don't disengage them until the thread is complete. Just pull the tool out from the part, reverse the lathe to get back to the beginning, move in for the next cut, and run the lathe forward again. Lather, rinse, repeat until you get the thread finished.
@@StuartdeHaro
Thank you I will give it a shot and i Will let you know Eli
I conducted the same test cutting m12 in 303 stainless using a single pitch TC threading insert. Even under a microscope you couldn't tell the difference.
Despite my regular thread cutting I keep my top slide set parallel to the lathe bed, set true with a DTI, as it is so useful to take a small extra cut when the bed stop is reached. I shall however set it to 30/60 when i make a 16DP gear cutting hob as the load would or might be excessive to just plunge cut.
You called it a "Top slide" so I'm going to guess you are a brit. I've noticed the brits keep the compound set to parallel. Then again, you guys drive on the wrong side of the road! :-P
@@jagboy69 wrong side? Which side do you get on a horse? Think about it.🤔😂
Oh and yes a Brit, and was proud of it once, before the wokes took over.😭😭😭😭
There are many countries where it is standard practice to keep the top slide parallel, but it's a case of do what you are comfortable with. Some folks were taught to thread at an angle and don't have the wit to believe you don't have to, but it is always the result that matters not how you get there.
@@chrisstephens6673 You know I'm screwing with you right?😜
I've been watching doubleboost for years and when I got my lathe, my neighbor saw me with the top slide parallel and gave me a rash of shit. It's probably the smarter way actually.😉
@@jagboy69 of course, and I'm a big boy now and can take it.😉
I have not had to thread yet, but instead of threading forwards the chuck, why not thread away? Learned about this from a Joe Piezinski video. This eliminates the pucker factor.
Also, thanks for this. I have seen both compound and cross feed methods and did not understand the difference. I appreciate you going over both.
That would be a great option if the lathe ran in reverse, but I've got a wonky contacter and it doesn't do that.
@@StuartdeHaro ok, that makes sense!
I have an older South Bend Lathe and threading in reverse could potentially unthread my chuck.
Crossfeed should be "X"
But then my joke wouldn't have made sense.