I am new to this. Does the angle affect how you would time your half nut engagement when cutting threads? Or would you simply come back to where you started in your Z direction and go in another unit on compound and time it as before?
Hi Dan! The engagement of the split nut is not affected by the compound rest's angle. The normal sequence for cutting most materials would be : Take a cut by engaging the split nut on the appropriate division, at the end of the cut disengage the split nut. Retract your tool using the Z (cross slide) axis and then return to your start point (past the start end of the part) and return the Z axis to zero (don't forget to set your Z zero during setup). Now you can set your next depth of cut by advancing the tool toward the part using the compound rest (normally set between 29 and 30 degrees). You can now engage the split nut for the next cut and so on ... Using this method reduces the cutting force required and helps with not getting lost (forgetting at what depth the last cut was) since your cross slide always comes back to zero and the compound rest only advances. I you haven't already done so, check out my threading on the lathe video ua-cam.com/video/ObdqJKGZnGQ/v-deo.html and for more threading examples check out the screw jack project ua-cam.com/video/tgyELiYk9Wg/v-deo.html Thanks for watching and for taking the time to write, Marc
You would not believe how incredibly difficult it is to find the information presented here! Every machining forum and website you go to will tell you to either use 29, 29.5, or 30 degrees on the compound for cutting threads and swear up and down that THEIR answer is the ONLY correct one, but NONE, and I mean ABSOLUTELY NONE of them ever say WHY. I'd be willing to bet dollars to donuts that these armchair machinists don't even know why, they just parrot what they were taught or read on another site. Thank you very much for such a complete explanation! I look forward to many more of your videos!
Marc, thanks for making this excellent video. It's great to finally know the reason why many sources suggest setting the compound to 29 or 29 1/2 degrees. It's wonderful to be able to make educated decisions with an understanding of the theory rather than just following a procedure blindly. You are an excellent professor.
An excellent presentation. Way better than most textbooks on the subject. Nothing like practical workshop experience to cut through the fluff. Thank you very much.
Thank you Professor Marc! A fantastic explanation of how the compound interacts in treading. The have been argument over 30 degs or 29 degs. Your explanation made it clear to me. Thanks for sharing!
Dear Marc, this was a wonderful explanation of angles, and thread cutting.... I especially like the part about why 29 degrees, I have always wondered about that....best wishes from Florida, Paul
Holly cow! That was the best explanation I've heard on threading angle. Fantastic Marc. I become a huge fan of your videos. Thanks for taking the time to do them. Everything I watch one it's like a light bulb comes on.
This is the first video I've watched of yours. I immediately subbed. Very clear and concise. It seems most people tell you how to do something but not why you are doing it that particular way. I found, at least for me, that knowing "the why" makes it stick in my head. It also allows me to know what adjustments can be made, if necessary, without compromising the operation. Thank you for this channel!
Brilliant explanation. Clear as can be. I'm trying to recall a teacher from my past experience as a student that explained so clearly the underlying concepts of how and why things work and don't work. Sadly, I recall only a very few. I enjoy your presentations and will be eagerly following your work in the future. Thanks also to Des Mes for asking and eliciting such a useful response. Have a great new year.
With a 29-30 degree cutting angle, we’re cutting on both sides of the bit. But most of the cut is on the leading edge. But the trailing cut does cut the part of the tip of the thread on the rear, and knocks off the small jag flies that would have otherwise occurred. This is well known as has been stated here in another video, that I believe was made later than this one.
Hi Marc. I enjoyed your presentation. Good job. I am working on a video I will post within the next 24 hours to address some of this exact same material. Specifically, the 30 ( and 29 1/2) degree compound settings. You are still cutting on the right side of the tool in each circumstance. Take a look at my channel for the video that demonstrates it. Good job with the 3 colors. It really highlighted what is happening.
BRAVO SIR! Gonna learn threading if it wounds me! You just saved on waste/swearing/sulking/whining/ foot stomping, wrench throwing, and tears ! Thxs! Although some of the above will just be reduced I suspect!
Good explanation. It should be pointed out that some of the lathes from Taiwan and China have the scale on the compound that is 90 degrees rotated, so to achieve the 29 to 30 degree proper angle of the compound you really need to indicate 60-61 degrees on the scale. The 3.5 part of the tip was most useful since I never thought about being able to change accuracy based on the sine of the screws, totally makes sense, just never thought about it (at least in terms of I turn the screw X and it advances at a ratio of X based on the angle).
Excellent video. Spent days searching for an in depth explanation of the influence the angle of the compound rest has when cutting a thread. There´s one thing though that is still a mystery. When cutting internal threads the 29 degree method will not only advance my cutting tool into the material but also move it inwards a bit, in the direction of the chuck holding my piece. Since there is no way for me to see where the half nuts must be disengaged, i zero my apron dials and stop just there. If this inside thread is not cut using the plunge method, my cutting tool will move not only into the material, but also closer to my chuck. If the cut goes all the way through this represents no problem. If my bore has a defined depth, the cutting tool will have to be stopped before reaching my 0 on the apron. With every cut taken i would have to move further away from the 0 position. This makes it tough to cut as close as possible to the end of my bore without wrecking the cutting tool. Do you have any videos that could help me out here?
Thank you for another informative video. Machining is my second career and I'm new to the machining world. I refer to only a couple different channels for help and instruction. Yours is one that I am always referring to. I did find one thing in this video that needs a little clarification. On the 30 degree threading angle, you mention that the cutting tool only cuts on one side. Even though the tool cuts on the entire left side, because the tool is plunging into the part, it appears to also be cutting on the right side of the tool, but only slightly. Is this correct or am I seeing it differently. Thank you do much for sharing your knowledge with new machinist like myself.
Well, I am only 4 years behind, exactly to the day, but catching up. This was an extra super vid with the justification of why to use 29 degrees. That also means you are slightly bighting into the right side of an external thread each pass. I get it now. So glad you are so generous with your time and info. Happy 2018, much health and happiness to you...
Hi Cross Thread! You were 4 years behind and I am 3 months late answering you comment! Thank you for taking the time to write and to let me know that you enjoyed the video. I produce the videos for fun but I must admit that it is nice to know that my rainy day retirement project is helping others. Marc THATLAZYMACHINIST.COM
Hello there Teach, Sir, from down across the pond, South Africa to be more precise. Been watching Your most informative Videos which we will have to now study a bit more in detail. Much appreciate the "SHARING" like we tell all the other YT Creators However, 'tis just a pity U Guys are still working in Imperial denominations whilst we have long-since followed Europe into Decimalisation. Like going into the past - except that we have to do some quickie double Calculations to keep abreast with U. But then again that's not Your fault Keep 'em rolling and keep up the tremendous work. U are a ...... * !!!! aRM
Marc thank you kindly perfect quickie just what i needed, after dinner i think i will go down into my basement and thread something on my lathe at 29 degrees just for the fun of it!
11:14 Hi Marc, I'm italian so I'm not too much able to understand and speak english. So here the question: the 30° compound position for threading is the left one, or the right one? Make difference? Both right positioning? Becouse once I saw a machinist spoking about a mistake and set up the leathe with the "right 30 degrees compound position". I really never understood what he meant. Thanks.
related question, why do some people swing compound around to 30 degree the other side of perpendicular for internal threads? I think it doesn't matter which side of the tool cuts on, does it? front side if turn compound around so the handle is near the chuck or back side if the compound is swung with handle away from the chuck. Can you explain your preference and why?
Hi Teun, you are on my list for the scale on the drill point. I haven't forgotten you, some videos require more preparation and time, as soon as I can find a suitable part and tools for an example. Marc L'Ecuyer
Hi, I thought that setting the compound at 45 degrees would give you a .5 thousand advance into the work for every 1 thousand mark you moved on the compound dial. Isn't that right? Tony
Regarding earlier post, I mean that if the compound is set at 45 degrees, then for every mark you turn the dial on the compound your tool will advance into the work one half a mark. So in turning down the diameter of a bar, advancing the compound by a one thousand mark will reduce the diameter by .005". Isn't that right?
+ATINKERER Hi Atinkerer! Sorry for the late response. Sinus of 45° is 0.7071". That means that if you advance your 45° compound rest by .001" your tool will advance by 0.0007" in the longitudinal axis and if you are surfacing that means that the part will be 0.0007" shorter. However since the diameter cuts are made on both sides of the part simultaneously, if you advance the compound by .001" the tool will advance by 0.0007" in the transverse direction but the part will be .0014" smaller on its diameter. I hope this helps, If not let me know I will try again. Marc
+THATLAZYMACHINIST Hi Marc, Thank you very much for the response. I've been mistaken about this 45 compound thing for many many years! I'm going to review your video and set my compound accordingly to advance the tool .0005" for every .001 mark on the dial. I think I should also dust off my micrometer and use it to make sure I'm getting the cut I think I'm getting. Maybe this is why I've always found it hard to turn things to the exact diameter I wanted, and almost always found that I've taken off a little more than I intended. Great videos! I've never seen someone so knowledgeable about high precision machining. When I get the chance, if I ever have the time, I'd like to watch all your videos. Sincerely, Tony
+THATLAZYMACHINIST Got it! I set the compound at 30 and I was surprised to be able to turn down the diameter of a bar by .001" at a time, accurately. Thank you very much!
Hi Kanoee64, the name sounds Canadian and I am guessing you are fifty years old? I have turned on the heating, but even with that it gets pretty cold up in the shop! Marc L'Ecuyer
Hello Mark .Can you please explain how set up top slide for imperial threads .For metric threads 60deg . is half 30 dag.(29) ,but what about UNF,UNC ,BSF, BSPP, BSPT,BA?. All are 55 deg.? so top slide must be 27.5 deg.? Thank you V.D.
Hi! Most (almost all ) imperial threads are 60°. However should you come across a 55° thread you would cut it the same way but, as you mentioned, you would position the compound rest at half of the threads angle (27.5°) minus 1° to ensure that your thread will be 55°. So 26.5° will work fine,. For small Acme threads (22°) the compound should be set at 10°, and so on. Large Acme threads are cut differently. I hope this answers you question? If not get back to me, Marc
Hi Irrops, if no one watches, all my videos are for not, so thank you for watching. it make me feel useful and that makes me feel good. Marc L'Ecuyer THATLAZYMACHINIST.COM
Hi, I thought that setting the compound at 45 degrees would give you a .5 thousand advance into the work for every 1 thousand mark you moved on the compound dial. Isn't that right? Tony
I am new to this. Does the angle affect how you would time your half nut engagement when cutting threads? Or would you simply come back to where you started in your Z direction and go in another unit on compound and time it as before?
Hi Dan! The engagement of the split nut is not affected by the compound rest's angle. The normal sequence for cutting most materials would be : Take a cut by engaging the split nut on the appropriate division, at the end of the cut disengage the split nut. Retract your tool using the Z (cross slide) axis and then return to your start point (past the start end of the part) and return the Z axis to zero (don't forget to set your Z zero during setup). Now you can set your next depth of cut by advancing the tool toward the part using the compound rest (normally set between 29 and 30 degrees). You can now engage the split nut for the next cut and so on ... Using this method reduces the cutting force required and helps with not getting lost (forgetting at what depth the last cut was) since your cross slide always comes back to zero and the compound rest only advances. I you haven't already done so, check out my threading on the lathe video ua-cam.com/video/ObdqJKGZnGQ/v-deo.html and for more threading examples check out the screw jack project ua-cam.com/video/tgyELiYk9Wg/v-deo.html Thanks for watching and for taking the time to write, Marc
You would not believe how incredibly difficult it is to find the information presented here! Every machining forum and website you go to will tell you to either use 29, 29.5, or 30 degrees on the compound for cutting threads and swear up and down that THEIR answer is the ONLY correct one, but NONE, and I mean ABSOLUTELY NONE of them ever say WHY. I'd be willing to bet dollars to donuts that these armchair machinists don't even know why, they just parrot what they were taught or read on another site. Thank you very much for such a complete explanation! I look forward to many more of your videos!
Most understandable instructor on YT, thanks for sharing your videos.
By far the best explanation I've ever heard on this. The stepped visuals, the wording. Great great great!!
Marc, thanks for making this excellent video. It's great to finally know the reason why many sources suggest setting the compound to 29 or 29 1/2 degrees. It's wonderful to be able to make educated decisions with an understanding of the theory rather than just following a procedure blindly. You are an excellent professor.
This is the best, the most sensible, the most efficient explanation I heard of thread cutting in the last 79 years. Congratulation Marc.
Bob
wow , after all these years some 65 ,you have explained the mystery of the compound slide. many thanks,Chris Adams
An excellent presentation. Way better than most textbooks on the subject. Nothing like practical workshop experience to cut through the fluff. Thank you very much.
Thank you Professor Marc! A fantastic explanation of how the compound interacts in treading. The have been argument over 30 degs or 29 degs. Your explanation made it clear to me. Thanks for sharing!
You are a great teacher. I'm enjoying learning the basics.
Dear Marc, this was a wonderful explanation of angles, and thread cutting....
I especially like the part about why 29 degrees, I have always wondered about that....best wishes from Florida, Paul
Clear explanation for hobbyists like me. Thanks!
Holly cow! That was the best explanation I've heard on threading angle. Fantastic Marc. I become a huge fan of your videos. Thanks for taking the time to do them. Everything I watch one it's like a light bulb comes on.
This is what I have been asking other machinist and all of them answer the same “I don’t know” thanks for the video
best explanation i could find on youtube. excellent teacher
This is the first video I've watched of yours. I immediately subbed. Very clear and concise. It seems most people tell you how to do something but not why you are doing it that particular way. I found, at least for me, that knowing "the why" makes it stick in my head. It also allows me to know what adjustments can be made, if necessary, without compromising the operation. Thank you for this channel!
Thank you for the most informative video I have ever seen about treating on a lathe. You are a wonderful teacher.
The 29* mark on my compound is 61* from the cross axis. I learned that by making wonky threads. One can never forget the sanity check.
Brilliant explanation. Clear as can be. I'm trying to recall a teacher from my past experience as a student that explained so clearly the underlying concepts of how and why things work and don't work. Sadly, I recall only a very few. I enjoy your presentations and will be eagerly following your work in the future. Thanks also to Des Mes for asking and eliciting such a useful response. Have a great new year.
thanks for your videos, they are very well done and very informative
With a 29-30 degree cutting angle, we’re cutting on both sides of the bit. But most of the cut is on the leading edge. But the trailing cut does cut the part of the tip of the thread on the rear, and knocks off the small jag flies that would have otherwise occurred. This is well known as has been stated here in another video, that I believe was made later than this one.
Hi Marc. I enjoyed your presentation. Good job. I am working on a video I will post within the next 24 hours to address some of this exact same material. Specifically, the 30 ( and 29 1/2) degree compound settings. You are still cutting on the right side of the tool in each circumstance. Take a look at my channel for the video that demonstrates it. Good job with the 3 colors. It really highlighted what is happening.
Excellent. I'm good at threading. But this helps me REALLY understand why I should set the compound the way I do.
Excellent explanation. Thank you for taking the time to put this video together.
BRAVO SIR! Gonna learn threading if it wounds me! You just saved on waste/swearing/sulking/whining/ foot stomping, wrench throwing, and tears ! Thxs! Although some of the above will just be reduced I suspect!
Good explanation. It should be pointed out that some of the lathes from Taiwan and China have the scale on the compound that is 90 degrees rotated, so to achieve the 29 to 30 degree proper angle of the compound you really need to indicate 60-61 degrees on the scale. The 3.5 part of the tip was most useful since I never thought about being able to change accuracy based on the sine of the screws, totally makes sense, just never thought about it (at least in terms of I turn the screw X and it advances at a ratio of X based on the angle).
Excellent video. Spent days searching for an in depth explanation of the influence the angle of the compound rest has when cutting a thread. There´s one thing though that is still a mystery. When cutting internal threads the 29 degree method will not only advance my cutting tool into the material but also move it inwards a bit, in the direction of the chuck holding my piece. Since there is no way for me to see where the half nuts must be disengaged, i zero my apron dials and stop just there. If this inside thread is not cut using the plunge method, my cutting tool will move not only into the material, but also closer to my chuck. If the cut goes all the way through this represents no problem. If my bore has a defined depth, the cutting tool will have to be stopped before reaching my 0 on the apron. With every cut taken i would have to move further away from the 0 position. This makes it tough to cut as close as possible to the end of my bore without wrecking the cutting tool. Do you have any videos that could help me out here?
as usual your explanation makes it seem so simple....
thanks again!
I've often wonder about this myself. Thanks for the explanation. Great job!
Je la visionne également en anglais, juste pour le plaisir.
Merci encore Maitre
Thank you for another informative video. Machining is my second career and I'm new to the machining world. I refer to only a couple different channels for help and instruction. Yours is one that I am always referring to. I did find one thing in this video that needs a little clarification. On the 30 degree threading angle, you mention that the cutting tool only cuts on one side. Even though the tool cuts on the entire left side, because the tool is plunging into the part, it appears to also be cutting on the right side of the tool, but only slightly. Is this correct or am I seeing it differently. Thank you do much for sharing your knowledge with new machinist like myself.
Very good explanation! Yet another great educational video! Thank you for sharing...
Well, I am only 4 years behind, exactly to the day, but catching up. This was an extra super vid with the justification of why to use 29 degrees. That also means you are slightly bighting into the right side of an external thread each pass. I get it now. So glad you are so generous with your time and info. Happy 2018, much health and happiness to you...
Hi Cross Thread! You were 4 years behind and I am 3 months late answering you comment! Thank you for taking the time to write and to let me know that you enjoyed the video. I produce the videos for fun but I must admit that it is nice to know that my rainy day retirement project is helping others. Marc THATLAZYMACHINIST.COM
Thank you so much. Explained as I've never seen it before.
Another great video. Thanks for the information.
Yet another very instructional video. Gordon, AUS
very well explained sir
Thank you Marc, that answered the question for me as well.
AWESOME!! So there is a reason for those 29!! Thanks for teaching me.
best explanation on youtube, thank you!
Marc, excellent explanation!
Very good explanations, Thanks
Hello there Teach, Sir, from down across the pond, South Africa to be more precise.
Been watching Your most informative Videos which we will have to now study a bit more in detail.
Much appreciate the "SHARING" like we tell all the other YT Creators
However, 'tis just a pity U Guys are still working in Imperial denominations whilst we have long-since followed Europe into Decimalisation. Like going into the past - except that we have to do some quickie double Calculations to keep abreast with U.
But then again that's not Your fault
Keep 'em rolling and keep up the tremendous work. U are a ...... * !!!!
aRM
Marc thank you kindly perfect quickie just what i needed, after dinner i think i will go down into my basement and thread something on my lathe at 29 degrees just for the fun of it!
THANK YOU MARK FOR THE GREAT VIDEO.
Thanks for this Video. Really helpful explanation.
Excellent explanation, thank you!
thanks for making this excellent video.
5 STARS on the video! Thanks
Now I know why and that is simply too kool!
John
Thanks Mark ,wish i had found your video before i started cutting. Oh well, can't win em all.
Thank you so very much!! :) Answered some questions I had.
Thanks for explanation.
11:14 Hi Marc, I'm italian so I'm not too much able to understand and speak english. So here the question: the 30° compound position for threading is the left one, or the right one? Make difference? Both right positioning? Becouse once I saw a machinist spoking about a mistake and set up the leathe with the "right 30 degrees compound position". I really never understood what he meant. Thanks.
Another good video thanks
related question, why do some people swing compound around to 30 degree the other side of perpendicular for internal threads? I think it doesn't matter which side of the tool cuts on, does it? front side if turn compound around so the handle is near the chuck or back side if the compound is swung with handle away from the chuck.
Can you explain your preference and why?
Nice information
I plung straight in but at 30 or 50 deg you cut on one side witch takes the slop out of the gear train.
I am still looking forward to a quick explanation how one would draw a scale on a DRILL POINT GAUGE...
Hi Teun, you are on my list for the scale on the drill point. I haven't forgotten you, some videos require more preparation and time, as soon as I can find a suitable part and tools for an example. Marc L'Ecuyer
Awesome teacher.....glad I subbed !!
Thanks pdoggy! Marc
For the flats at the bottom of UN threads according to asme b1.1 is the range .25p to 1/8? I'm trying to understand the drawing.
Hi,
I thought that setting the compound at 45 degrees would give you a .5 thousand advance into the work for every 1 thousand mark you moved on the compound dial. Isn't that right?
Tony
Regarding earlier post, I mean that if the compound is set at 45 degrees, then for every mark you turn the dial on the compound your tool will advance into the work one half a mark. So in turning down the diameter of a bar, advancing the compound by a one thousand mark will reduce the diameter by .005". Isn't that right?
+ATINKERER Hi Atinkerer! Sorry for the late response. Sinus of 45° is 0.7071". That means that if you advance your 45° compound rest by .001" your tool will advance by 0.0007" in the longitudinal axis and if you are surfacing that means that the part will be 0.0007" shorter. However since the diameter cuts are made on both sides of the part simultaneously, if you advance the compound by .001" the tool will advance by 0.0007" in the transverse direction but the part will be .0014" smaller on its diameter. I hope this helps, If not let me know I will try again. Marc
+THATLAZYMACHINIST
Hi Marc,
Thank you very much for the response.
I've been mistaken about this 45 compound thing for many many years! I'm going to review your video and set my compound accordingly to advance the tool .0005" for every .001 mark on the dial. I think I should also dust off my micrometer and use it to make sure I'm getting the cut I think I'm getting. Maybe this is why I've always found it hard to turn things to the exact diameter I wanted, and almost always found that I've taken off a little more than I intended.
Great videos! I've never seen someone so knowledgeable about high precision machining.
When I get the chance, if I ever have the time, I'd like to watch all your videos.
Sincerely,
Tony
+THATLAZYMACHINIST Got it! I set the compound at 30 and I was surprised to be able to turn down the diameter of a bar by .001" at a time, accurately. Thank you very much!
Very nice explanation Marc. Just trolling the archives.
_Dan_
well explain sir love from india
thanks
Man Marc I wish I could come spend a year with you ,I'll sleep in the garage.
Hi Kanoee64, the name sounds Canadian and I am guessing you are fifty years old? I have turned on the heating, but even with that it gets pretty cold up in the shop! Marc L'Ecuyer
lol Thanks for the consideration.
Hello Mark .Can you please explain how set up top slide for imperial threads .For metric threads 60deg . is half 30 dag.(29) ,but what about UNF,UNC ,BSF, BSPP, BSPT,BA?. All are 55 deg.? so top slide must be 27.5 deg.? Thank you V.D.
Hi! Most (almost all ) imperial threads are 60°. However should you come across a 55° thread you would cut it the same way but, as you mentioned, you would position the compound rest at half of the threads angle (27.5°) minus 1° to ensure that your thread will be 55°. So 26.5° will work fine,. For small Acme threads (22°) the compound should be set at 10°, and so on. Large Acme threads are cut differently. I hope this answers you question? If not get back to me, Marc
Great
what if use -30 degree and tool cut that another edge. becouse CNC cut with that 30 degree angle and its not that great lol
Marc,
Thank you for the excellent presentation.
Peter, Victoria B.C.
Hi Irrops, if no one watches, all my videos are for not, so thank you for watching. it make me feel useful and that makes me feel good. Marc L'Ecuyer THATLAZYMACHINIST.COM
Recycle good, but who stealing the Cash from it? The devil in the opening about cycle huge biohazard! Great show though!
Hi,
I thought that setting the compound at 45 degrees would give you a .5 thousand advance into the work for every 1 thousand mark you moved on the compound dial. Isn't that right?
Tony