Thanks for the reply ART,
You do see what I mean.
It would be best if the actual thread pitch never changed while X pulls back. That would eliminate any grooving at the end of the thread.
Just like when cutting by hand...X out first, then disengage the half nut. Perfect pitch.
If this could be done, rpm could be increased too.
RC

Graham,
In Brian's response to you, he said your macro would be in the next rev.
Did he give you a timeframe of when it might be released ?
Being it's approved, can you send it to me in advance ?
I submitted parts to a customer for approval and they were rejected but told them of the changes in progress.
We are anxious to satisfy our customer who is otherwise pleased with the part.
Thanks,
RC

Hi:

  The macro will be in the next release. But heres an advance copy of th emacro involved..

Art

Thank You ART,
I saved it in the Turn Macro folder replacing the orig. 1076 file, is that right ?
I will try it later today .
Thanks again,
RC
BTW....NICE CAT ! Did you train it ?

Hi:

  Id put it in the C:\mach3 folder. As I recall, thats a special macro which is the same for all profiles,
and resides in the Mach3 folder, not the macros folder..

Art
 

Hello all,
The new macro works quite a bit better. I experimented with L90 through L1440 and it does very well. Results are as expected.
There is only a very slight pause that causes a very slight change in the pitch at the point where the tool begins to pull back.
The Z slows also but not as much as before.
Not perfect.. but much MUCH better.
I don't want to appear picky but this is a delicate part and my customer is the picky one.
Thanks for your help folks,
RC
1 Question: Which is commonly used for thread cutting, Constant Velocity or Exact Stop ? Please explain.
I searched the manual and found no reference to this.
Thanks again.

Well at least its better than before. 

when cutting threads you should always use exact stop mode if cutting into a groove. if you use cv then the thread can become tapered towards the end of the cut due to cv blending corners.

The slight pitch error is probably the reaction time of your machine and the signal processing time of your system.

To get the best results from threading you must allow time for the machine to react, even on fast industrial machines you have to allow acceleration and deceleration times.

Allow 5mm (.200")  in front of the thread for acceleration and 2.5 (.100") if possible at the back for deceleration. Also keep the speed down, if the exit looks ragged halve your speed.  It is impossible to say what speed to use as every machine is different but start low e.g. 100 rpm and work up.

Using the new macro you could issue a L720 and allow the thread to feed out over 2 pitches thus giving a very smooth and neat exit.

Graham.

Thanks for making all of this clear. EXCELLENT explanation. This will go in my notebook, supplement to the M3Turn Manual.
L720 IS where I actually ended up with the best final results.
The customer is more satisfied as well.
Grateful,
RC