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Author Topic: Problems threading on the lathe  (Read 330279 times)

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Offline Chip

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Re: Problems threading on the lathe
« Reply #170 on: March 22, 2009, 08:34:12 PM »
Hi, Art

Thank you for letting us know, Just another wasted day in a string of many lately, Your dedication hear is Appreciated by ALL.

Thanks, Chip

Offline RICH

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Re: Problems threading on the lathe
« Reply #171 on: March 22, 2009, 09:02:02 PM »
Art,
Thanks, for the heads up.
Ya know, before playing around all day, i took a look at the revisions in the change log, and it said:

March 17/2009
Release 3.042.023
-- Threading bug found and fixed in Driver...   ???

I am still laughing. Must admit that the my index slot is a whole lot bigger now!   ;)

Heck, you can use it to cover the half moon hole on the outhouse.   ::)

Should make a nice holiday gift for Brian!  :) :) :) :) :) :) :) :) :)
 
RICH





Offline ART

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Re: Problems threading on the lathe
« Reply #172 on: March 22, 2009, 10:31:00 PM »
Hi Rich:

 YEah, sorry about that, that was from when I was pretty sure the driver was bugged. On the bright side it did fix a nasty driver bug, just not in threading is all. :)

 That version I just linked to should have the required fixes in it. But it may still bug out, who knows, its an iterative process, but at least we know my code base works, so we shoudl be able to fix it up pretty quick IF it is bugged.

Thx
Art

Offline Chip

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Re: Problems threading on the lathe
« Reply #173 on: March 22, 2009, 10:34:12 PM »
Hi, Art & ALL

Version 3.042.024 seems to work much better, I'm using a 555 timer circuit to simulate the index pulses at the moment so no actual thread report.

Edit: Hope it can be used in the new release Brian's working on.  :D

Thanks, Chip
« Last Edit: March 22, 2009, 10:48:59 PM by Chip »

Offline RICH

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Re: Problems threading on the lathe
« Reply #174 on: March 22, 2009, 11:15:31 PM »
Hi All,
Dry ran 3.042.024 a number of times and from what  i can see and hear looks like a winner
for both SS and PP.

You can't do the looped G32 file that i posted you'll get an error. Will post something different
tomorrow.

The amount of rpm allowance and readout seems back to normal and movements seem well behaved.
By well behaved i mean, the Z tracks the spindle slow down and speed up and reacts rather quickly to
the rpm changes  and dosen't trip the threading cycle so easily.

Will cut some threads tomorrow and see how things go.

Thanks for sticking in there Art, it's appreciated.

RICh

Offline RICH

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Re: Problems threading on the lathe
« Reply #175 on: March 23, 2009, 09:42:11 PM »
Hi Art & everyone else,
These are just a few  of the threads done using Mach ver 3.042.24, the SS, and G32 code generated by the wizard. They represent a good range of threading for Punny lathes.

#   THREAD  RPM         IN-FEED ANGLE         MATERIAL
--   ------------   -------         -------------------------         ---------------
1    0-80        600          30                               WELDING ROD             
2   1/4-20      400          29                                6061 AL
3   1/4-20     100           20                                AL ( THE SOFT STUFF )
4   3/8-16      400          29                                1018 CR
5   1/4-40-2 LEAD 200   29                                1018 CR
     ( G32 code not generated from the wizard )
6   1/2-13      400          15    ( TOP PART )        TOOL STEEL
"    1/2-13      300          15    ( BOTT PART )      TOOL STEEL

I coudn't find any pitch problems with 1,2,3,4,6  and the threads look good. The top part of 6 is was not finished as the thread tool holder
moved and the tool jammed the thread, so yes there was a slowdown and the thread cycle recovered from it! The bottom of 6 created numerous slow downs but the thread still came out.

The two lead thread has some pitch problems in the last 1/8" of it but not sure why.

I didn't get around yet to using another computer to try the PP as it is limited by axis speed. The SS will do at least 4x in axis speed as compared to the PP.

So looking good so far.

RICH

Offline Chaoticone

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Re: Problems threading on the lathe
« Reply #176 on: March 23, 2009, 10:04:04 PM »
Thanks RICH, you have hung in this one like an old rusty nail.  I really need to thank everybody for all of the work you guys have put into this.

Thanks,
Brett
« Last Edit: March 23, 2009, 10:05:49 PM by Chaoticone »
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline ART

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Re: Problems threading on the lathe
« Reply #177 on: March 23, 2009, 10:55:22 PM »
Rich:

 Excellent. Thanks for the photo's ..nuthin says "thread" like a nice photo. :)

Art

Offline RICH

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Re: Problems threading on the lathe
« Reply #178 on: March 23, 2009, 11:42:18 PM »
ART,
Maybe you can shed some on this question.
How or what inpact does the debounce input values affect the thread cutting RPM?
I notice if set to "0" that i can get the displayed rpm value to increase but it fluctuates
by say 5 rpm. What kind of stability on the rpm do you need?

Modified to add some clarity:
No problem here with the SS, so the question only relates to the  PP.
The manual states: "The index pulse and the other inputs have independant settings".

Now my understanding on the index debounce / debounce interval  has always been relative to
homing switches. But if the slot index for threading happens to provided limited rpm, like say 300 rpm ,
and then you go and change the index debounce to a low value you can the get full rprm , like say 1400 rpm,
but it is not stable ( may constantly vary by 10 rpm ). Will threading lock into an average or something?

Rich
« Last Edit: March 24, 2009, 12:31:15 AM by RICH »

Offline CNCwt

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Re: Problems threading on the lathe
« Reply #179 on: March 24, 2009, 05:48:12 AM »
I am following this thread with much interest as I am encountering the exact same kind of threading problems as narrated by others here.

I am using the index pulse of a differential encoder as a feedback to the spindle and it was pointed out to me that the index pulse width may not be enough for Mach3.

Can someone tell me what is the minimum pulse width or better pulse time (milliseconds?) needed by Mach3? I may use a 555 to stretch the pulse width or time. I know that this may depends on the kernel speed and I am running at 60 KHz kernel speed.

I have tried the Mach3 3.042.24 with PP and it is much better already. However, this is the first time that I encounter my spindle (1 Kw - for a Sieg C6 mini lathe) slowing down to also zero RPM even under no load when threading at a set speed of 300 RPM. Did anyone else encounter this same situation?

Weedy