Messages

821

General Mach Discussion / Re: Problems threading on the lathe

« on: October 30, 2009, 11:36:22 AM »

Rich:

   You just keep stacking up the beer I owe you! :-)

Art

822

General Mach Discussion / Re: Problems threading on the lathe

« on: October 30, 2009, 01:49:18 AM »

Rich:

  Sorry about that. This one should fix that, if not turn off or delete the advanced threading plugin, it may affect the reading by zeroing one of my var's..

Art

823

General Mach Discussion / Re: Problems threading on the lathe

« on: October 29, 2009, 09:21:24 PM »

Hi Rich:

  Well, I noted serious flaws in my correction logic as it WAS applied, and this test version is new code based on the time of plannng. I cant test this at the moment as I have too much going
on to fix up my rotation tester, so please try this in the air first to ensure I havent screwed up something basic. Its a lot of new code. It should plan a thread at a set rotation and then use that rotation
speed as the correction algorithms reference speed. It also keeps track of higher speeds to subtract from any correction done in slow speed situations.

 Let me know how it tests in the air if you can. You need the enclosed driver and exectuable to try this one.

Thx
Art

824

General Mach Discussion / Re: Problems threading on the lathe

« on: October 28, 2009, 03:00:01 PM »

Hi Rich:

  Didnt want to let you think I had forgotten you. I think Ive figured where the weird passes come from. The pitch is planned before motion, and it uses the speed at time of motion
to correct to.. Im making the application lock the planned pitch speed so that is what is used instead. Be a couple more days while I spit and glue the pieces together. I think this will
help greatly. It should in theory stop the weird passes which I think are occuring due to a slight RPM difference between the planner and whet the locked speed it set to.

Art

825

General Mach Discussion / Re: Problems threading on the lathe

« on: October 26, 2009, 09:23:39 AM »

Rich:

  Yup, sounds as if correction badly affects things then. From .003 to .040 is quite a jump. Ill see what I can do this week..

Art

826

General Mach Discussion / Re: Problems threading on the lathe

« on: October 24, 2009, 10:02:59 PM »

Rich:

  Before I rewrite all this, I found some troubleing code in there. Can you confirm this driver does the same bad corrected thread as the last correction driver?
Turns out the driver was clippign the value used.. Im wondering if that clipping was causing the crazy passes when correction was on.

Thx
Art

827

General Mach Discussion / Re: Problems threading on the lathe

« on: October 24, 2009, 03:34:44 PM »

Rich:

 When it comes to averaging.. Mach3 can keep a running average of the last 8 revolutions. At the start of any pass it either uses the averave OR the last measured time.

So in theory, hitting any hard spot has no effect on the actual planned pitch for the thread, the idea is simply to be as accurate as possible as to what the unloaded speed is, and since
every thread starts with an unloaded spindle, the 8 rev average is typically unloaded average. ( unless your turnign very slowly on the spindle.. no-one is I think less than 8 turns in the air
prior to a thread pass.

  SO the correction code is all that controls speed during the cut to take into account the slowdown caused by hitting a hard spot or an average slowdown due to harder material.
The averaging is discounted for correction, it cares only abou tthe real last index to index time, and it compares that to the locked in average or locked in last rev just prior to the
thread pass starting.


 Since your threads, as well as Johns seem to be nuts-on with no correction.... we're good till the last step in the chain..correction.


  More of a job than I thought.. be a little whlie yet..

Thx
Art

828

General Mach Discussion / Re: Problems threading on the lathe

« on: October 24, 2009, 01:49:54 PM »

Daniel:

   If averaging is on, then the SS is affected, if off, no effect.

Art

829

General Mach Discussion / Re: Problems threading on the lathe

« on: October 24, 2009, 10:38:26 AM »

Hi Rich:

 Report from John Stevenson on the test he did today..

>>>Ran a 1.5mm pitch thread for 50 mm, after 3 passes it was way off so
bailed out.
Did what Rich said and switch averaging off and re ran the thread.

All passes looked to be dead nuts on, bit of double thread at the end
from the first 3 passes spoilt it a bit, quick clean up with
scotchbrite and checked against a 1.5mm tap and it's the best thread I
have done to present. Very slight pitch error over the 50mm, probably
1/4 pitch out at the end.

This is the most promising long thread that I have done to present,
aim to tune in to read 600 better but not certain how critical this
is.

>>>

      As you can see he had to switch off averagiung, where you need it on. Ntot sure what that means yet, but it seems both of you are getting better threads than
ever before.
 Im thinking if averaging kills the thread, then the RPM must be wavering more than normal OR that the new code has changed it so that averaging doesnt help,
and non-averaging may be better.. Not sure yet..


Anyway, couple days for new code I think..

Thx
Art
,

830

General Mach Discussion / Re: Problems threading on the lathe

« on: October 23, 2009, 10:54:58 PM »

Rich:

 Wow..Nice threads really.

  OK, itll take a coupel days to recode this.. its a slightly complex code in the driver that does corrections, so Ill have to crunch more numbers as I go.

Your tests seem to have proven the weakness of both sides, the correction and the rpm reading. The end result should be much better than it ever was..

Thx
Art