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Author Topic: Problems threading on the lathe  (Read 330222 times)

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Re: Problems threading on the lathe
« Reply #50 on: February 26, 2009, 07:40:29 PM »
I am pretty sure that Reiks and I are having very similar problems from reading his description.  I would be happy to try the suggestion for using a g32 as well as a g76  threading operation and report the results.  The only problem is even after reading a description of how to change the macro to output longhand code I still don't quite get it.  I know that there was something about changing something to false, but I need a little more direction.  If I can figure out how to change that setting then I will do a comparison test.

I think that I would try a 1/2-13 in 6061, maybe about 1 long at 350 or 400 rpm with everything the same except for the code.  I will use a brand new threading tool, and the same piece of bar, and report the results.  If someone can steer me in the right direction as to how to edit the macro, or even better just post a modified one that I can replace the existing macro with ;D

I would probably have time to do this tomorrow, and I might even be able to manage a photo of the results.

Again thanks to everyone for all of the great input!

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Re: Problems threading on the lathe
« Reply #51 on: February 26, 2009, 07:40:44 PM »
If you guys are using VFDs for speed control if at all possible try using a spindle speed which relates to the motors normal frequency (50Hz/60Hz depending on which side of the pond you are) Obviously it will depend on your axis speed as to whether you can physically do that.
 Like Rieks I am still intrigued why it does the x axis moves though, I will see if Art has any thoughts on this.
Hood

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Re: Problems threading on the lathe
« Reply #52 on: February 26, 2009, 07:53:15 PM »
Here's a thought for Hood.Try cutting a 4 tpi acme in some 4340.
set your gear change to the top speed and adjust the vfd down
so it is at about 15%.Motor should lug under these conditions.
I know it is alot of work or you could wedge a large timber up against the chuck
to simulate a spindle variation.I use a 2x4 but my Hardinge is just up from puny.

Afraid that wouldnt make any difference, I have a big  AC Servo on the spindle (see specs below), doing a 10mm DOC in 75mm Dia EN24 wouldnt slow the spindle for long enough for me to notice. The servo drive would compensate and if I pushed it even more then the drive would fault in milliseconds.
Hood

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Re: Problems threading on the lathe
« Reply #53 on: February 26, 2009, 08:00:36 PM »
I am pretty sure that Reiks and I are having very similar problems from reading his description.  I would be happy to try the suggestion for using a g32 as well as a g76  threading operation and report the results.  The only problem is even after reading a description of how to change the macro to output longhand code I still don't quite get it.  I know that there was something about changing something to false, but I need a little more direction.  If I can figure out how to change that setting then I will do a comparison test.

I think that I would try a 1/2-13 in 6061, maybe about 1 long at 350 or 400 rpm with everything the same except for the code.  I will use a brand new threading tool, and the same piece of bar, and report the results.  If someone can steer me in the right direction as to how to edit the macro, or even better just post a modified one that I can replace the existing macro with ;D

I would probably have time to do this tomorrow, and I might even be able to manage a photo of the results.

Again thanks to everyone for all of the great input!


Go to Operator menu then VB Script Editor. Browse to C:\Mach3 and open M1076.m1s. You will see a load of green text for a start then down a bit you will see in black   Test =false , change that to Test =True and then close and save.
 Next time you use the wizard your code will be written in G32, watch however that any preliminary moves are correct and make sure you change it back if you have any code that has a G76 in amongst other code as the M1076 will rewrite your file on loading.
Hood

Offline RICH

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Re: Problems threading on the lathe
« Reply #54 on: February 26, 2009, 08:09:20 PM »
Here is what you change to get G32 code.

MODIFIED: SORRY ABOUT THE PIC AND ALSO NOTE THAT THE FILE NAME IN THE PIC IS INCORRECT.
IT SHOULD SAY "M1076".
« Last Edit: February 26, 2009, 08:50:29 PM by RICH »
Re: Problems threading on the lathe
« Reply #55 on: February 26, 2009, 08:14:27 PM »
Didn't come through RICH.
Try again ?
Thanks,
RC
Re: Problems threading on the lathe
« Reply #56 on: February 26, 2009, 08:28:51 PM »
Thanks for the instructions on ow to change the threading macro.  I just tried it on the home computer and it was really easy, and it would generate nice long code for threading.  I will put it to use tomorrow, in the shop and report the results.  I think that i will try a 1/2-13 in delrin since I have some of it handy, and I have been able to get the result I have been describing while threading delrin before.  Thanks guys.

Offline Hood

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Re: Problems threading on the lathe
« Reply #57 on: February 26, 2009, 08:33:17 PM »
Talked to Art and he thinks it must be a VB error, some earlier versions had problems with VB but the latest ones should be fine. If it is a VB error then you will not see it with the G32.
Look forward to your results.
Hood

Offline RICH

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Re: Problems threading on the lathe
« Reply #58 on: February 26, 2009, 08:45:27 PM »
Well you get the written version and a picture also!
 -----------------------
I am scracthing my head on this one also. Back a week or so  i fooled around  and couldn't get the
x axis to do what is being described.  I harp on the mechanical stuff,  just want to be sure that
that is eliminated.
 
I have Art's postings on how threading works, but, hate to post something since if they changed threadng
or something in Mach versions it would only add to confusion.

If you loose a step with a stepper, and you usually know it, the x would take on a mind of it's owne calliing for a
hit of the estop. I have had them run away and also have had them skip but continue with the code,but if they skiip
a step usually it's for a time more than what these folks are experiencing.

If it's intermitant, finding the kremlin is tough.  Rf / noise can be a culprit here and that can be tough to converse
on.
RICH

Offline RICH

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Re: Problems threading on the lathe
« Reply #59 on: February 26, 2009, 09:30:48 PM »
Hood
May be all wet here, maybe someone can chime in,  but here's goes.
You have the following:
1-supplied voltage- say 60 hz
2-spindle sensor frequency to mach - 1 pulse per rev
3-VFD generated dominant freg- i can measure but most would not be able to do
4-the stepper pulses per unit- ???
Now you want to be away as far as you can go from any fundamenetal or harmonic....thus in terms
of suppled voltage  60,120,180, ...etc you want the spindle sensor being at 30, 90, etc.
So your input / output MACH pulses have less chance of having an intereference. Now if it's brute noise,
that's a diifferent story,. If that's the case then it would not be so intermitant and the grounding, shieldnig etc will have more effect.
A little far fetched but if the field builds up i can see where you can get some "goofy" pulse or interference
that could make the X axis not behave yet contnue. But like i said, a little farfetched.
Just some out of the box thinking,
RICH