Rich:

  Hmm, sounds liek averaging should be on. The gradual tappering from pass to pass seems to indicate that its not locking in at all and its sensing a differing rpm as it goes.

We didnt see that before the averaging was turned off I dont think. The increase pitch seems proper, I added 1%, and it seems to lead by 1%. Can you restest just with averaging on,
do we then get a repeatable pitch of .01 over?  If so, Ill back off to 0 again.. I think I didnt help much on that one. I need to check the RPM gets properly locked, I think I may have screwed up..

Art

No problem. Will due a test in the next hour or so.
RICH

ART,
With averaging on  got a single line scribe and the increase in lead was 0.0033" / inch.
Made a big difference.
RICH

MODIFIED: All the other tests were done with averaging on.
                I will be out and about, returning on Tuesday. I may have some time early tomorrow to do some testing.
                Experiment as you wish. I am looking to the day when that lead goes to 0.000" / inch or exceeds my equipment.
                Then will try longer cuts, heck, still got 20 feet of copper tubing to play with!
BTW: For excitement all you have to do is forget to do a reset back to G94 after threading, dam a trueing cut
 can realy move fast. 
                 
                     

BTW: For excitement all you have to do is forget to do a reset back to G94 after threading, dam a trueing cut
 can realy move fast. 
                 
                     

Do all your lathe work in FPR and that wont happen

Not sure how much of a hassle it would be for you to hook up the SS and do a test, just it would be interesting to see how that works for you as it is perfect for me. I cant use the PP to test as my pico doesnt have a PP but when I had the previous mobo in I did tests with both PP and SS over a 150mm distance and all were accurate and all exactly the same.

Hood

ART,
BTW: For excitement all you have to do is forget to do a reset back to G94 after threading, dam a trueing cut
 can realy move fast.                       

Rich a line at the beginning of all your code to set the correct operation is the way to go check my toolchanging problem thread again for an example.

This is done in the post processor in my case.

Phil

Hood,
SS is still in the old pc and I'll get around to installing it in the new one. I am also curiuos.
Just been focused on trying to improve threading when using the PP with a single pointed tool. Comparitively, using the SS would be an apple and not an orange.The file I recently posted about lead error says it all.  I am also curiuos, if as shown by changing the feedrate, if it will hold true for long threading. That was like zero for a 2" length, which implies, 4"  of threading should work fine. The long thread would magnify any lead error.

On the practical side of things, in all these years , i have only needed to do very accurate threading to 6" or so and that was for replacing a screw and nut in crossslides. The screw was matched to the nut and was done with a manual lathe. I am hoping that we can refine PP threading to equal a manual lathe. For threading it would be per the
file i posted.

BTW, this testing is not about "Rich's" threading. It's in light of the typical hobbiest that will use Mach threading with
a low end CNC system ( if that is a way of saying it ). It will be nice to be say to a user, with confidence, that his problem is the lathe system.

Any suggestions appreciated, as more viewpoints are a lot better than one,
RICH

Hi Rich:

  Hmm.. .003 eh? Well, try this one, Im suspecting a 0.000 spread from expected. ( or close to it).

Art

btw,, Its Thanksgiving here in Canada, so Ill be hard to find most of the day. :-)

Happy Turkey-Day. ( for Canucks anyway..)

Art

Art,
 Enjoy the feast. Will do a quick test and post. If it's good, then will do more tests when I get back.
RICH

Rich,
 wasn't getting at you, what I was getting at is you are testing with the PP and if you can test with the SS then it would be interesting as it could show up where the error definitely is. Example if you didn't have these problems when using the SS then the issue has to be down to whatever threading is using with the PP, if however you still had the problems then it points to a computer issue and it may help Art home in on why some work and others not.

Hood