# Single point threading



## jpfabricator (Mar 5, 2017)

A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.




I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.




Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544


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## Bob Korves (Mar 5, 2017)

A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.




I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.




Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544


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## jlsmithseven (Mar 5, 2017)

i like the cross slide a LOT better. but to each his own for sure. i completely agree with that. gotta do it the way it works.


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## stupoty (Mar 5, 2017)

I use a threading stop to allow quick retract and reset of  cross slide and use the compound to feed in.  Before using the cross slide stop it was always a much slower process and easier to accidentally wind back in a few to many thousandths and take a cut that was a bit deeper than i should have.

Sturt


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## higgite (Mar 5, 2017)

Congrats on your success. How about a pic of your setup when you use the compound to advance the tool? Just curious as to what your problem could have been.

BTW, I see a tapatalk red X instead of a pic in your OP, but the link to the photo worked fine.

Tom


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## Charles Spencer (Mar 5, 2017)

The picture:


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## darkzero (Mar 5, 2017)

Photo fixed in OP

*How to post Photos from Tap-A-Talk*


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## jpfabricator (Mar 6, 2017)

When I use the compound the threads look like they aren't timed correctly. It's set at 30*, the tool is sharp, and I'm engaging on the same # on the thread counter. It just looks "off".
When I get more time in the shop I will post some pictures of the fails.

Sent from my SM-S320VL using Tapatalk


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## Tozguy (Mar 6, 2017)

jp, to my mind it is worth getting both methods sorted so you can readily use either depending on the circumstances. Looking forward to seeing your pictures.


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## Bob Korves (Mar 6, 2017)

First, you want the angle to be less than 30 degrees, never more.  And that angle is measured from the cross slide direction, not from the spindle axis.  Sometimes the degree markings on lathes for the compound angle are laid out measuring from the spindle axis at zero to the cross slide at 90 degrees, which will give you a 60 degree angle to the cross slide if you set it at 30 degrees on the dial.  Get the compound pointed directly in line with the cross slide.  That should be 0 degrees, not 90.  Then swing the compound to the left as you count off the degrees until you get to less than 30 degrees.  Anywhere around 29 degrees is probably fine, it is not critical unless it is more than 30 degrees which will leave a stair step finish on the right flank of the thread.


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## Technical Ted (Mar 6, 2017)

I agree with those that suggest you try to figure out why you got poor results using the compound. I've done a fair amount of both internal and external single pointing and I don't ever remember using the cross-feed; I always use the compound set at ~29 degrees. Typically, you will get better chip control because you're cutting with the leading edge instead of both edges. But, whatever way you want to do it is fine as long as you get the results you're looking for.

Ted


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## jpfabricator (Mar 6, 2017)

This is what I was getting before, same tool, same everything, different advance.
It's like its not threading, but wiping the threads off a little more with each pass.

Sent from my SM-S320VL using Tapatalk


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## neilking (Mar 6, 2017)

I had some success with just using the cross slide, but after reading about using the compound I've had success  that way too.
	

		
			
		

		
	




Sent from my SM-G920P using Tapatalk


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## tweinke (Mar 6, 2017)

jpfabricator said:


> View attachment 228076
> 
> This is what I was getting before, same tool, same everything, different advance.
> It's like its not threading, but wiping the threads off a little more with each pass.
> ...



I have had the same result with the compound set at 30 or so but feeding in with the compound is ok. now I am wondering if I should measure the angle and be sure it is actualy between 29 and 30


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## mikey (Mar 6, 2017)

Have a look at this: http://www.mmsonline.com/articles/threading-on-a-lathe


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## willthedancer (Mar 7, 2017)

I have some thoughts, questions, and a suggestion.

Metric or USS?
I don't know zip about metric lathes.

If USS, how many threads per inch, and what is the pitch of your leadscrew?

What number(s) did you hit on your chasing dial?

My suggestion is to get a 1" - 8 nut from the hardware store. Set up and thread a 1 inch bar 8 threads. Set your compound to 29 and a half degrees off the face of the chuck. Be very diligent about getting the cross slide back to your zero every time.

Sent from my Moto G Play using Tapatalk


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## darkzero (Mar 7, 2017)

jpfabricator said:


> This is what I was getting before, same tool, same everything, different advance.
> It's like its not threading, but wiping the threads off a little more with each pass.
> 
> Sent from my SM-S320VL using Tapatalk



This sounds like you were not set to 29deg for threading which must be 29deg off the X axis when using the compound.

Do you have an Asian import lathe? Most hobby size Asian import lathes smaller than 14x do not have a full protractor scale for the compound slide. On lathes like this if you set it 29deg on the scale, it is 29deg off the Z axis and will cause the thread issues you described when trying to thread using the compound slide.

Take a look at the photos I posted in post # 4 here: http://www.hobby-machinist.com/threads/pm-1236-tool-post-issues.28428/#post-248506


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## Tozguy (Mar 7, 2017)

tweinke said:


> I have had the same result with the compound set at 30 or so but feeding in with the compound is ok. now I am wondering if I should measure the angle and be sure it is actualy between 29 and 30



The 29.5 deg setting is recommended to allow for some potential error in the protractor on the lathe, since it is OK to be under 30 deg but never over. I think that it is a good idea to check the accuracy of your protractor for your own edification. 

Also, if your protractor is set up like the one shown in the link that darkzero provided, I recommend that you establish a second index mark on the side of the cross slide. Set your compound at exactly 90 deg to the spindle axis and then scribe a mark on the cross slide opposite the 0 on the lathe's protractor. That way you will have a better time using the protractor for threading.


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## ddickey (Mar 7, 2017)

Arn't you supposed to feed in with the cross slide the final couple thou? This is what I learned on Tom's Techniques site.


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## Tozguy (Mar 7, 2017)

There are so many different threading jobs that I prefer to use the technique or combination of them that best suits the job and equipment as opposed to having the same hard and fast rules to follow for everything.


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## Bob Korves (Mar 7, 2017)

Tozguy said:


> The 29.5 deg setting is recommended to allow for some potential error in the protractor on the lathe, since it is OK to be under 30 deg but never over. I think that it is a good idea to check the accuracy of your protractor for your own edification.
> 
> Also, if your protractor is set up like the one shown in the link that darkzero provided, I recommend that you establish a second index mark on the side of the cross slide. Set your compound at exactly 90 deg to the spindle axis and then scribe a mark on the cross slide opposite the 0 on the lathe's protractor. That way you will have a better time using the protractor for threading.


On most lathes owned by mere mortal hobby machinists, the compound degree scale cannot be expected to be accurate to within 1/2 degree.  Either check that angle more accurately using a different method or simply choose a smaller number than the 29.5 degrees council of perfection, like 28 degrees or even less.  Make sure it is less than 30 degrees in reality.  Even zero degrees works...


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## ewkearns (Mar 8, 2017)

There is a LOT of tearing (rather than clean cutting) in creating these threads. Make sure of your cutter height setting and tool geometry. Consider your cutting oil. Feeding in with the compound is recommended only for threading hot rolled steel and then using a cutter specifically ground for the task. Feeding in with the compound is specifically NOT recommended for carbide threading tools....


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## darkzero (Mar 8, 2017)

ewkearns said:


> Feeding in with the compound is recommended only for threading hot rolled steel and then using a cutter specifically ground for the task...
> 
> Feeding in with the compound is specifically NOT recommended for carbide threading tools....



That's interesting, I never heard that before. I don't agree but could you elaborate, I'm curious as to why?


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## ewkearns (Mar 9, 2017)

When I was learning machine shop, I was taught, in part, by a bunch of guys that were making chips as early as just before the turn of the century. In their day, the material of choice was hot rolled steel and it WAS STRINGY. The technique was developed to grind the threading tool such that it cut on the leading edge only and sent the chip out of and away from the generated thread.... hence the use of the compound rest and the sainted and inviolable 29.5° setting. They were highly amused that the technique was applied to everything, rather than the task that it was specifically adapted to serve... They simply never used the compound to thread anything that would generate a non-destructive chip. (And, today, neither do I.)

When carbide tools came into wide acceptance, we found that the tips of those tools would fail using the compound rest. The carbide was simply not ground to accept a side load. So, abandoning the notion of the sanctity of the compound rest, threading was accomplished using the crossfeed, only, and the problem went away.

I realize that my position is anathema on this matter, but I was taught as much WHY as HOW and it has served me well. I believe that threading using the compound is so sacred, today, simply because it got a LOT more "press coverage."

My 2¢


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## Tozguy (Mar 9, 2017)

ewkearns said:


> When I was learning machine shop, I was taught, in part, by a bunch of guys that were making chips as early as just before the turn of the century.
> When carbide tools came into wide acceptance, we found that the tips of those tools would fail using the compound rest. The carbide was simply not ground to accept a side load. So, abandoning the notion of the sanctity of the compound rest, threading was accomplished using the crossfeed, only, and the problem went away.
> 
> 
> My 2¢



It seems to me that nowadays there is a carbide insert for just about any job imaginable.


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## Bob Korves (Mar 9, 2017)

ewkearns said:


> When I was learning machine shop, I was taught, in part, by a bunch of guys that were making chips as early as just before the turn of the century. In their day, the material of choice was hot rolled steel and it WAS STRINGY. The technique was developed to grind the threading tool such that it cut on the leading edge only and sent the chip out of and away from the generated thread.... hence the use of the compound rest and the sainted and inviolable 29.5° setting. They were highly amused that the technique was applied to everything, rather than the task that it was specifically adapted to serve... They simply never used the compound to thread anything that would generate a non-destructive chip. (And, today, neither do I.)
> 
> When carbide tools came into wide acceptance, we found that the tips of those tools would fail using the compound rest. The carbide was simply not ground to accept a side load. So, abandoning the notion of the sanctity of the compound rest, threading was accomplished using the crossfeed, only, and the problem went away.
> 
> ...


Another reason I prefer the cross slide method of threading most of the time is that the depth of cut dialed in is the depth of cut achieved, no calculating or trig involved, just read the dial and check the thread when you get close.


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## Dave Paine (Mar 9, 2017)

I know how I made my first mistake when trying to use the compound set to the 29.5 deg angle.  I read the scale on the compound and overlooked the axis which was the reference for the angle.  I expect I am not the only person falling for this mistake.  My Grizzly lathe made it easier to fall into this trap.

In this picture I have moved the compound to have the scribe mark at the 30 deg mark.  On my G9249 lathe, the only number shown is 0 (zero).  The marks go up to 55 deg either side of 0.




After making some bad threads I also changed to using the carriage.  I later realised my mistake was setting the angle to the wrong 30 deg, as in 30 deg from parallel to the lathe bed.   It needed to be 30 deg from perpendicular to the lathe bed, or the face of the chuck.  Easy mistake for a woodworker just starting out on a metal lathe.

I have a decent mitre gauge for the table saw so I cut a block of wood to 29.5 deg.



I glued a small magnet into the wood so it holds to the side of the compound.




I do not understand why Grizzly did not have the scale going to 60 deg.  My lathe needs an angle block in order to set angles less than 35 deg (or 55 deg) depending on how the angle is defined.




Interesting post earlier discussing the potential origin of 29.5 deg angle.  It is easier to use the carriage.


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## Bob Korves (Mar 9, 2017)

Dave Paine said:


> (snip)After making some bad threads I also changed to using the carriage. I later realised my mistake was setting the angle to the wrong 30 deg, as in 30 deg from parallel to the lathe bed. It needed to be 30 deg from perpendicular to the lathe bed, or the face of the chuck. Easy mistake for a woodworker just starting out on a metal lathe.(snip)


Bingo!  Thanks, Dave.  You and MANY others have made the same mistake, and a very easy to make mistake, I might add.  Thanks for putting up photos to help explain the problem and the solution.  Everyone, please do not trust those compound scale quadrants on lathes to be accurate or to show the quadrants in the orientation that you expect.  Stand back, get the big picture, and make sure that you are seeing something that looks like the angle of the block of wood Dave has posted.  If you are too lazy to measure the actual angle of the compound accurately, then set the angle to somewhat less than 29.5 degrees, to make damn sure that you are not at more than 30 degrees in reality.  25 degrees will give you no visible difference in your threads, in fact they will probably look better, and even zero degrees will work just fine...


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## Tozguy (Mar 9, 2017)

Dave, the Grizzly configuration is typical and my guess is that it's handier for setting to cut short tapers by feeding with the compound. Good idea to have made a gauge for setting the compound to 29.5 for threading.

My compound is usually accurately set at 29,5 deg. and left that way for any kind of turning unless the job requires otherwise. For most of my threading jobs I start by advancing with the cross slide and finish off by advancing the compound. I like being able to sneak up on final thread fit with the finer adjustments resulting from having the compound at that angle..

For really coarse threads like 8 or 10 tpi, cutting both flanks of the almost finished thread can get heavy in some materials. Personally I prefer to avoid such a wide cut so will likely do much of the coarse thread by advancing the compound.


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## willthedancer (Mar 9, 2017)

ewkearns said:


> When I was learning machine shop, I was taught, in part, by a bunch of guys that were making chips as early as just before the turn of the century. In their day, the material of choice was hot rolled steel and it WAS STRINGY. The technique was developed to grind the threading tool such that it cut on the leading edge only and sent the chip out of and away from the generated thread.... hence the use of the compound rest and the sainted and inviolable 29.5° setting. They were highly amused that the technique was applied to everything, rather than the task that it was specifically adapted to serve... They simply never used the compound to thread anything that would generate a non-destructive chip. (And, today, neither do I.)
> 
> When carbide tools came into wide acceptance, we found that the tips of those tools would fail using the compound rest. The carbide was simply not ground to accept a side load. So, abandoning the notion of the sanctity of the compound rest, threading was accomplished using the crossfeed, only, and the problem went away.
> 
> ...


I respectfully disagree here.

The issue with threading is certainly chip flow across the top of the tool.

When you plunge thread with the cross slide, there are conflicting vectors on each flank of the tool, resulting in a complex collision at the center line of the tool. This leads to stacking problems and resultant tearing for one and a difficult to predict curling of the chip. Swarf is subject to cold deformation and intense work hardening, so it will damage the workpiece on contact.

Using the compound allows the chip to flow freely across the tool. The little bit of back flank interference is just to keep the form true, and the tiny bit of swarf generated is easily swept along with the majority.

That said, the use of coated carbide makes for slick surface for the chip to flow across, and much higher surface speeds, allowing for a high finish that is more scratch and tear resistant when in contact with the curled chip. It's a cheat that buys some grace when plunge threading, and often good enough.

Sent from my Moto G Play using Tapatalk


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## Tozguy (Mar 9, 2017)

Dave Paine said:


> I know how I made my first mistake when trying to use the compound set to the 29.5 deg angle. I read the scale on the compound and overlooked the axis which was the reference for the angle. I expect I am not the only person falling for this mistake.



No you are not. I figure you haven't lived until you done this. My first threads gave me a feeling I'll never forget.


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## Tozguy (Mar 9, 2017)

Will in post No. 30 certainly made a good point about chip formation.
The following document mentions the same idea, and more, on pages 17 to 19.
http://www.sandvik.coromant.com/sitecollectiondocuments/downloads/global/technical guides/en-gb/c-2920-031.pdf


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## BGHansen (Mar 10, 2017)

Dave Paine said:


> I know how I made my first mistake when trying to use the compound set to the 29.5 deg angle.  I read the scale on the compound and overlooked the axis which was the reference for the angle.  I expect I am not the only person falling for this mistake.  My Grizzly lathe made it easier to fall into this trap.
> 
> In this picture I have moved the compound to have the scribe mark at the 30 deg mark.  On my G9249 lathe, the only number shown is 0 (zero).  The marks go up to 55 deg either side of 0.
> 
> ...


Another frustrating thing for me on this type of compound (similar to my G0709 14 x 40 lathe) is it's not graduated around the complete 360 (or at least 180).  I mounted an indicator on the head stock and indicated off the side of the compound to check 0 deg.  Basically verified the 0 deg. pointer on the compound.  Then blued and scribed with a square on the compound additional lines at 45 deg. increments all around the compound.

Bruce


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## rpmMan (Mar 10, 2017)

Some great info here...thanks to all on this site..

One of the things about threading and feeding in with the compound that seems non-intuitive is  that while we require that each pass be in perfect registration with the last, by feeding in with the compound set at an angle we are moving the tool in 2 directions (in relation to the work)... i.e. at 29 degrees feeding in  10 thousands results in the tool moving inward approx 8.746 thou and to the left 1.296 thou.
Which means our new starting point is not the same...


rich


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## ewkearns (Mar 10, 2017)

willthedancer said:


> That said, the use of coated carbide makes for slick surface for the chip to flow across, and much higher surface speeds, allowing for a high finish that is more scratch and tear resistant when in contact with the curled chip. It's a cheat that buys some grace when plunge threading, and often good enough.



Those of us tackling threads with a greater lead might not have your lightning reflexes, NC, or a hydraulic tracer........


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## willthedancer (Mar 10, 2017)

ewkearns said:


> Those of us tackling threads with a greater lead might not have your lightning reflexes, NC, or a hydraulic tracer........


That's what upside down and reverse is for  

Sent from my Moto G Play using Tapatalk


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## rpmMan (Mar 10, 2017)

rpmMan said:


> One of the things about threading and feeding in with the compound that seems non-intuitive is that while we require that each pass be in perfect registration with the last, by feeding in with the compound set at an angle we are moving the tool in 2 directions (in relation to the work)... i.e. at 29 degrees feeding in 10 thousands results in the tool moving inward approx 8.746 thou and to the left 1.296 thou.
> Which means our new starting point is not the same...



Alternatively...could we set the compound at 90 deg (parallel to the spindle) and then use the infeed and the compound feed to do this?... ie. for each thou in-feed move the tool to the left with the compound 1.296/8.746 or approx 0.148 thou?

rich


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## Bob Korves (Mar 10, 2017)

Go for it, Rich!  Report back with how it works for you.  I personally have trouble dialing in 'approximately' 0.00148" on my compound...


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## higgite (Mar 10, 2017)

I like the 29.5 degree compound method. I have enough trouble remembering to return the cross slide to zero for the next pass, let alone trying to remember a different number to return it to for each pass with the plunge method.

Tom


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## Technical Ted (Mar 10, 2017)

When I worked as a machinist and tool maker most of the lathes we had at work had built in thread stops which spoiled me. Now, at home with my 1930's vintage 15" South Bend lathe when doing just a quickie I'll either mark or zero the dial for threading, but for those jobs that really count I use a thread stop I made that attaches to the cross feed V ways to thread with. I like having the cross feed hand crank wheel knob right at 9:00 so I can get the tool out quickly if something isn't going right. Just push the hand wheel down quickly! Always having the hand wheel in the same position helps make it "automatic" as to how to react if something goes wrong. Works for me anyways; YMMV.

Ted


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## MattM (Mar 11, 2017)

Here is a threading method an old time machinist taught me:

1. Lock in the thread dial at the appropriate number and leave it locked in until the thread is complete.

2. Take a few cuts using the cross slide.

3. At the end of each cut stop the lathe and zero the DRO in X.

4. Bring the cross out a few thousands and put the lathe in reverse.

5. Run the carriage back to the start of the thread.

6. Bring the X back to zero and crank in about .005. 

7. Repeat for a few passes then switch to using the compound until the thread is complete.

The nice thing about this method is that it completely eliminates the tedious task of engaging and dis-engaging the lead screw.  I use my Monarch 10EE running a carbide threading insert and Viper's Venom for lube.  I am producing some excellent threads in the 20-30 TPI range.  Haven't tried it on coarse threads but it should work just as well.  Best thing about it is not having to deal with the thread dial on each pass.


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## Norseman C.B. (Mar 11, 2017)

I have used carbide tooling for threading for many years and have
found that proper grinding and setup of the tooling  is the key for success, no matter what cutting tool is used ........My  $ .02


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## Highsider (Mar 11, 2017)

From the before and after pictures of your threads, it looks like your problem is mostly that your compound is not truly set at anywhere near 30 Deg. from the cross slide.   As mentioned by others, many hobby lathes are not marked in reference to the cross feed angle and you may have to set your compound using an angle finder accurately set at 30 Deg. and then make a new reference mark lined up with 30 Deg.     Then always use a 29-1/2 Deg. setting for 60 Deg. threads

Your after pic, however reveals another problem with the finish you're getting.    If you set the tip of your tool (accurately) to the centerline of the work piece  and use a good cutting fluid/oil, on the work, your threads should come out shiny.    The very tops of the threads might be a bit rough, but that is easily rectified by a short filing job after the fit of the thread passes muster.

I have single pointed 60 degree screw threads in an industrial machine shop for 40 years, in materials from Bronzes through all grades of Machineable  steels to Aluminums and exotic alloys like the titanium's, using any cutting tool material from HHS through coated carbides and ceramics, to diamond faced tooling and .


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## Downunder Bob (Mar 11, 2017)

ewkearns said:


> When I was learning machine shop, I was taught, in part, by a bunch of guys that were making chips as early as just before the turn of the century. In their day, the material of choice was hot rolled steel and it WAS STRINGY. The technique was developed to grind the threading tool such that it cut on the leading edge only and sent the chip out of and away from the generated thread.... hence the use of the compound rest and the sainted and inviolable 29.5° setting. They were highly amused that the technique was applied to everything, rather than the task that it was specifically adapted to serve... They simply never used the compound to thread anything that would generate a non-destructive chip. (And, today, neither do I.)
> 
> When carbide tools came into wide acceptance, we found that the tips of those tools would fail using the compound rest. The carbide was simply not ground to accept a side load. So, abandoning the notion of the sanctity of the compound rest, threading was accomplished using the crossfeed, only, and the problem went away.
> 
> ...




I think what you are saying was quite valid in the early days of carbide tooling, but the new ones today that are specifically made for thread cutting don't seem to mind being used either way. BTW I find that using cross slide feed on small fine threads is ok , but much prefer compound set at correct angle for coarser deeper threads. Also don't forget 27deg for british threads.


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## jamby (Mar 11, 2017)

It's been a long time since I stood at a w/s 32 nc turret lathe and cut threads but I seem to remember that the thread cycle feed in a 29.5 and the finish pass was a tool offset that went in normal to the compound.  But the machine had no compound.   I just rotated the insert to a fresh edge before finishing and used that to rough the next thread after backing off the offset.   They usually repeated within .002 and were checked with a go/no-go snap thread gage.  Most were 4.00 + in dia.

Jim

edit: funny how it makes sense when you write it...  But the final cut was made straight in (nomal to the cross slide) cutting with both edges.


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## darkzero (Mar 12, 2017)

rpmMan said:


> Some great info here...thanks to all on this site..
> 
> One of the things about threading and feeding in with the compound that seems non-intuitive is  that while we require that each pass be in perfect registration with the last, by feeding in with the compound set at an angle we are moving the tool in 2 directions (in relation to the work)... i.e. at 29 degrees feeding in  10 thousands results in the tool moving inward approx 8.746 thou and to the left 1.296 thou.
> Which means our new starting point is not the same...
> ...



Yes the starting point of the cutting tip will not always be the same when feeding with the compound but the start of the thread would still be the same. Feeding at just under 30° is doing most of the cutting on the left side of the cutter (talking external threads here, feeding right to left). Now the end of the thread will advance more to the left as you cut the thread. Most guys machine in a thread relief & as long as it's wide enough it won't matter. The left shoulder of that thread relief is what you measure thread length to when critical.

But there's times where you don't need to machine a thread relief which I sometimes do. If you need the thread to be a specific length when feeding in with the compound, it's easy to do. Someone posted a video earlier by Joe Pie & the method he shows will take care of that. I do it a different way but the result is the same. One example is when I need to make a short thread in a blind hole like for a cap. I prefer to have as much thread as I can get since the threads are short but I need to know how close I am to the bottom of that hole. If you don't account for that when feeding with the compound you'll get into trouble.





higgite said:


> I like the 29.5 degree compound method. I have enough trouble remembering to return the cross slide to zero for the next pass, let alone trying to remember a different number to return it to for each pass with the plunge method.
> 
> Tom



Same here, kind of. When using the compound to feed, I don't have to bother remembering or writing down what to move the cross slide back to, just return to zero. I was also taught to set the cross slide handle at the 9:00 position for zero. This makes it really easy to not screw up when backing the tool out on the end of a pass, simply just push down on the handle to back the cross slide out, quick, easy, no thinking. Now the 9:00 position would be for external threads & 3:00 for internal threads. But since I thread internal threads with my tool upside down, I use the cross slide handle 9:00 & compound slide at 5:00 just like I would for external threads.

With modern tooling, as mentioned, you don't need to feed with the compound on fine threads, soft materials, or on a rigid lathe. But if you cut very coarse threads, thread hard materials, or don't have a rigid lathe, the compound is your friend. I rarely thread really coarse threads, but I still thread using the compound method for the reasons I mentioned earlier & because that's how I was taught. I have always done it that way, it's what I'm used to, so it's easier for me. It's also good practice for when you do need to use the compound for feeding.


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## pstemari (Mar 12, 2017)

That's all good advice.

I'm not certain which carbide tools have problems with loading. I've been using 16 ER full-profile laydown inserts and they make gorgeous threads using the compound at 29 degrees..  My biggest problem is hitting the half nut lever consistently.


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## MattM (Mar 12, 2017)

pstemari said:


> That's all good advice.
> 
> I'm not certain which carbide tools have problems with loading. I've been using 16 ER full-profile laydown inserts and they make gorgeous threads using the compound at 29 degrees..  My biggest problem is hitting the half nut lever consistently.
> 
> View attachment 228459



That's why I like leaving the half nuts engaged for the entire threading operation.  See my comments above.


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## Doubleeboy (Mar 12, 2017)

Matt,  If you leave the half nut engaged, you might benefit from Joe P threading videos on you tube.  He shows a way to take the drama out of engaging the half nut.  10EE has to be about the easiest lathe out there to engage half nut, check out Joes videos.


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## pstemari (Mar 12, 2017)

MattM said:


> That's why I like leaving the half nuts engaged for the entire threading operation.  See my comments above.


In my case, the issue arises when threading up to a shoulder. The upside-down trick doesn't work with that sort of tool—you'd need a left-hand tool with a reverse helix shim.

Stopping the entire lathe or cranking out the cross slide is much slower than hitting the half-nut lever. You'd have to crank the cross-slide out at least two or three turns to avoid crashing into the shoulder, and the various retraction mechanisms don't have enough travel. 

The one thing that does work reliably is the Hardinge-style single point dog clutch, but that's not something you can readily retrofit. You'd have to splice it into the gear train between the spindle and the threading gear box.

The Hardinge mechanism can be triggered by a carriage stop, and allows you to reverse the carriage and run it back without releasing the halfnuts or losing sync with the spindle.

Sent from my Nexus 6 using Tapatalk


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## Uglydog (Mar 12, 2017)

Note: I've not read this entire thread.
Check out:
http://www.hobby-machinist.com/threads/lathe-threading-several-techniques.52838/

Daryl
MN


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## MattM (Mar 12, 2017)

Watched the Joe P, video.  I was/am aware of that method, but still prefer to use the halfnut always in method.  Seems it just eliminates one step in the threading process.  I'm an amateur, amateur hobby machinist not interested in speed.

Today I cut a 3/4 x16.  Took me maybe 20 minutes and it came out near perfect with absolutely no sweat.   I know that's an eternity to the journeymen around here but for me that's probably a personal best.

Like has often been said, "There is more than one way to skin a coon.".


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## Catcam (Mar 13, 2017)

Bob Korves said:


> First, you want the angle to be less than 30 degrees, never more.  And that angle is measured from the cross slide direction, not from the spindle axis.  Sometimes the degree markings on lathes for the compound angle are laid out measuring from the spindle axis at zero to the cross slide at 90 degrees, which will give you a 60 degree angle to the cross slide if you set it at 30 degrees on the dial.  Get the compound pointed directly in line with the cross slide.  That should be 0 degrees, not 90.  Then swing the compound to the left as you count off the degrees until you get to less than 30 degrees.  Anywhere around 29 degrees is probably fine, it is not critical unless it is more than 30 degrees which will leave a stair step finish on the right flank of the thread.


Hi For clarity.  When setting up the compound to do single point threading you need to point the handle of the compound towards you, making this zero degrees. then swing the handle to the right away from the chuck,  approx 29 degrees up to 29.5 degrees and lock in the compound. The compound will be used for feeding into the cut as it progresses.

If it was set up at 30 degrees from the axis of the lathe then the threads will be over cut along the axis of the thread and appear to give multiple starts or a smeared thread..

in theory using the compound or the cross slide to cut threads make little difference other than possibly more chatter on the thread if there is a big thread being cut.


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## pstemari (Oct 7, 2018)

30° *exactly* would be ok, but anything over that will telegraph into the thread making the right side of the thread groove too flat.

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