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Author Topic: More TURN Threading Questions  (Read 14661 times)

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Offline RICH

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Re: More TURN Threading Questions
« Reply #20 on: July 29, 2008, 10:09:34 PM »
FROM ART'S POST
"There is an LED on the diags, can you tell me if its staying on during the thread, I fear Mach3 may be killing it as soon
as it starts.. This may be a side effect of the pause removal we fixed earlier on in the year for the pause in drill cycles."

"If it goes out during the pass or rigth away when the pass starts, then we
have found the bug.. if not,  "

------------------------------------------------------------------------------------------------------------------------------------------------------------
I just checked this out / dry run some threading. The trigger will flash green, then threading flashs green , but as soon as the threading move starts the thread light indicator in diags on my machine goes out. This repeats for each cycle when the threading starts.
Using MACH 3 R3.041

Hmmm! Maybe what Taut taut he saw he only taut he saw during his other test!   ??? Tomorrows another day

MODIFIED 7/28/08 PLEASE SEE ANOTHER POST MADE BY ME TODAY  7/28/08.

 :)RICH
« Last Edit: July 30, 2008, 08:38:00 PM by RICH »

Offline Hood

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Re: More TURN Threading Questions
« Reply #21 on: July 30, 2008, 02:31:33 AM »
If it looks like steps down the back edge of the thread then maybe you have too much of an infeed angle.
Hood

Offline RICH

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Re: More TURN Threading Questions
« Reply #22 on: July 30, 2008, 06:51:43 AM »
It steps down the front side / tail stock side of the thread. Infeed angle used is 29.5 degrees for a sharp 60 deg pointed thread tool. This may sound dumb, but i assumed that the infeed of the x was  perpendicular to the od of the
piece and not an x-z move . I know some programs do a progrssive cut to the front side of the thread.
Can you clarify?

PS: One of the tests i did was to set depth to .0001" and let it run thru a lot of passes, maybe 60 or more then stop
      the threading, reposition back to original start point, then redo the threading. ( piece not removed from chuck
      and motor left running ). Want to play around with this some and inspect the cutting marks. But I know what will
     be seen can be influenced by a number of things, so need to think more about it.

RICH
     


Offline Hood

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Re: More TURN Threading Questions
« Reply #23 on: July 30, 2008, 06:58:35 AM »
If you are using the wizard then its a G76 which I think is a flank infeed thread, try setting the infeed to 15 dgerees and see how that goes.
Hood
Re: More TURN Threading Questions
« Reply #24 on: July 30, 2008, 07:02:14 AM »
Hey Rich,
If you get a chance to, maybe try this test also as I did. Set up a thread, say 32 tpi, cut it in 6 or so passes and set 10 or 20 spring passes. The spring cuts, after 1 or 2 should stop cutting..but here it varies. Cutting the front, the flank, none...very sporatic.
RC

Offline RICH

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Re: More TURN Threading Questions
« Reply #25 on: July 30, 2008, 08:43:27 PM »
Hi all,
This may be of interest to you or someone in the future. It sums up some testing i did on the lathe today using the diag screen.
RICH

MODIFIED 8/3/08 - ADDED THE FOLLOWING:

The attachment will be modified in the future. If you have been following the Yahoo threads you know that there are discussions on threading
going on. Art informed me that the threading LED should always be on. In my attachment that is not the case, so comment #1 in the attachment is probably wrong, but then, that is what was found during my test. So....just a heads up until additional info is recieved.
RICH

« Last Edit: August 03, 2008, 10:12:25 PM by RICH »

Offline RICH

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Re: More TURN Threading Questions
« Reply #26 on: August 04, 2008, 11:29:46 PM »
Better than info are results. Attachment at 12 to 15X shows 20-40-80 threads which I just cut.
Will fool around some more and do some measuring.
RICH
 
« Last Edit: August 04, 2008, 11:31:39 PM by RICH »

Offline RICH

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Re: More TURN Threading Questions
« Reply #27 on: August 07, 2008, 11:41:46 PM »
Hi All,
Still fooling around cutting threads. Dimensional results are good; Pitch diameters are .001 to .003 over the length of the
thread, the pitch cut for all practical purposes is right on ( hard to measure at the bottom of the v but stays witin .001),
using a sharp 60 deg tool and the v as cut is about 62 deg when done radialy. Will try flank cutting some and see how things turn out. Will be interesting to see how the electronic gearing compensates when the spindle speed really drops.
So far with minor drops, a few rpm, things seem good at the practical level.
Now if the fix comes out along with the SS also providing threading and backlash compensation life will be really good.
RICH

Offline Hood

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Re: More TURN Threading Questions
« Reply #28 on: August 08, 2008, 02:52:20 AM »
What are you using as the thread cycle, G32 or G76? I use G76 with an infeed of 15 degrees and dont have any problems at all, just finished a load of 30 pullstuds the last day and all threads were perfect, then again the spindle motor doesnt slow down so Mach doesnt have to do much in the way of calcs :)

Hood

Offline RICH

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Re: More TURN Threading Questions
« Reply #29 on: August 08, 2008, 07:33:29 AM »
Using the G76. Art was kind enough to send me a Mach test file which he recently did. I assume the next release of Mach will include the fixes. When monitoring in diag screen, the threading box should turn green and STAY ON for every thread cycle. Mine was not doing that as shown by the test. So the comments I made are actualy incorrect and that's the reason the post was modified adding a clarification.
I needed to confirm that my lathe backlash setting was correct, etc, as it dosn't take much for a thread to get screwed up. With the machine mechanics confirmed, a working program, and the knowledge that threads can made to tolerance
on my punny lathe, I can now play and see effects of the program.
Will deliberately do things like heavy cuts, radial & flanked cutting, testing the limits of a small machine. The electronic 
gearing will allow for around a  50% rpm reduction from started rpm. Dry running showed it's working but don't know
the quality the threading that will be produced. This may sound like a waste of time to some but it's darn good practical
experience on my part using a CNC punny lathe. 
RICH