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Author Topic: Problems threading on the lathe  (Read 330184 times)

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Offline ART

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Re: Problems threading on the lathe
« Reply #600 on: October 22, 2009, 11:11:38 PM »
Rich:

 Great so far then.. Woth no correction required the threads now pass muster. And they should on anyone system then in theory.
Ill keep my fingers crossed for correction..

Art
 :)

Offline RICH

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Re: Problems threading on the lathe
« Reply #601 on: October 22, 2009, 11:24:31 PM »
Me t00! And the x axis is fixed. I'll do some threading tomorrow. Time for a nice glass of wine.  ;)
RICH

Offline RICH

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Re: Problems threading on the lathe
« Reply #602 on: October 23, 2009, 02:11:05 PM »
ART,
No joy with the correction on!

Attached are the two tests. The AL test errored on the 2 or 3rd pass and i stopped it. The CS ran like a champ for the first 8 passes and then 9 was bad along with 28 and again stopped the threading.

I don't know??????

RICH

Offline ART

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Re: Problems threading on the lathe
« Reply #603 on: October 23, 2009, 02:36:26 PM »
Hi Rich:

  Yes, I suspected as much. The correction code is still based on number of interrupts seen between index pulses, we now know that using PCI bus time is much more accurate, so the pitch is
correct, but I think Im going to have to swap the interrupt based correction code to time based as well, otherwise it may sense a correction when none needs to be done. Id go back to the non-corrected and see if AL threads are generally OK, or material that doesnt slow the spindle.

  Ill start work on the correction swap to time based, Im thinking that may solve the issue. Im wondering if the current non-corrected gives us any bad passes, that woudl be a clue thats valuable, if there are no screwups in soft material, then I suyspect the correction is now createing its own "whoops" passes..

Art

Offline RICH

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Re: Problems threading on the lathe
« Reply #604 on: October 23, 2009, 02:59:52 PM »
ART,
"Id go back to the non-corrected and see if AL threads are generally OK"

I did do that in the other post, but will retry just to confirm by doing more passes and a finer thread or something.

Will post something tommorrow.

RICH

Offline RICH

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Re: Problems threading on the lathe
« Reply #605 on: October 23, 2009, 10:30:12 PM »
ART,
The non-corrected seems to be fine. No crazy cuts, lead is fine here are some pictures of a few 1/4- 20 & 40
done at 402 RPM with 20 and 40 passes.
Look forward the time based correction.
RICH

Offline ART

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Re: Problems threading on the lathe
« Reply #606 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

Offline RICH

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Re: Problems threading on the lathe
« Reply #607 on: October 23, 2009, 11:05:17 PM »
"The end result should be much better than it ever was.."

I sure hope so since threading should be a fun kind of thing.
Of course i know your having fun!  ;D

Rich

Offline ART

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Re: Problems threading on the lathe
« Reply #608 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
,
« Last Edit: October 24, 2009, 10:40:07 AM by ART »

Offline Dan13

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Re: Problems threading on the lathe
« Reply #609 on: October 24, 2009, 01:06:53 PM »
Art,

Does it all have any effect on the Smooth Stepper? My threads with the Smooth Stepper seem all to be perfect, but then I have never run such long threads and never subjected them to the kind of tests Rich does.

Thanks,
Daniel