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Author Topic: Threading problem, strange motion, Please help!  (Read 1352 times)

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Threading problem, strange motion, Please help!
« Reply #10 on: June 11, 2018, 01:20:34 PM »
I assume it's OK to use this BOB for threading. I have read other posts where people successfully used it on lathes with threading.  When I exchanged emails with Arturo at CNC4PC he didn't say it was a problem.

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Offline RICH

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Re: Threading problem, strange motion, Please help!
« Reply #11 on: June 11, 2018, 03:49:27 PM »
Quote
Manualy turn on and manualy set rpm of the  VFD.
I did this too. I had the spindle manually controlled at the VFD set to 400 RPM. The stepper drives and PS were disconnected. The C3 board was disconnected. The C6 board was disconnected.

So you keep it basic. Just use the VFD manually for a test. The hall effect index is used to provide input to Mach for the RPM.
So.....load Mach3 , turn on and set the vfd ( you should not see any rpm indication until the you click spindle button, then you should see rpm via the input from the index ),load the threading program and do an air test of the threading. better yet would be to just do a scribe test of the threading for a test.

I personally also prefer to have the wizard provide g32 threading code since every axis move is delineated in the code.
So maybe change the macro ( how to change the macro is in the Threading On the lathe Writeup).

RICH
Re: Threading problem, strange motion, Please help!
« Reply #12 on: June 11, 2018, 07:54:36 PM »
Thanks Rich. What you described is exactly what I did. The video I linked to shows the weird movement Mach is calling. Those strange ZigZag moves.
I will have to try the G32 setting.
Another weird thing it does sometimes is slowing the feed to a crawl.  In threading it has to move fast in the Z to match the pitch, but sometimes maybe even mid-pass, it slows to a snail's pace.

Arturo sent me a video that shows how to check for continuity between the power supply negative terminals and the chassis and ground.  My machine passed that test.

Sigh...

Offline RICH

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Re: Threading problem, strange motion, Please help!
« Reply #13 on: June 12, 2018, 05:21:29 PM »
Quote
Another weird thing it does sometimes is slowing the feed to a crawl.  In threading it has to move fast in the Z to match the pitch, but sometimes maybe even mid-pass, it slows to a snail's pace.

That is a motor power problem as it relates to the depth of cut you are taking. Note that the VFD has no feedback to maintain the rpm
under motor load.

I strongly suggest you read Threading on The Lathe writeup I did as it makes no sense to repeat what has already been noted in the writeup.

RICH
Threading problem, strange motion, Please help!
« Reply #14 on: June 12, 2018, 05:32:55 PM »
There's no cut being made. The stepper drives are not powered. Mach only thinks they are moving.  The motor rpm is steady within 2 rpm.

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Threading problem, strange motion, Please help!
« Reply #15 on: June 12, 2018, 05:33:26 PM »
I did read the file you suggested.

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Re: Threading problem, strange motion, Please help!
« Reply #16 on: June 22, 2018, 09:07:20 AM »
Update!
After removing everything in the system except the index pulse and the breakout board, I was still having this problem.
I decided to reinstall all the system components back to my original setup.  I still had the same problem.
I then reformatted the computer drive and installed XP, the drivers, and Mach3.  Then threading worked perfectly.  I have no idea what was causing the issue, but it's gone now.  WOOT!!!!

Offline RICH

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Re: Threading problem, strange motion, Please help!
« Reply #17 on: June 23, 2018, 07:09:40 AM »
Fusion,
Glad it's working.
I didn't forget this thread just dealing with so many things and didn't have the time to get into a detailed look.

I did find that, when simulating, that there were additional moves shown in the graphic screen and didn't matter if G76 or G32 was used for threading.
Additionally , depending on how one selects a the start point of the threading the graphics would change, and BTW that was using you XML file.
To get a "cleaner" graphics display of the gcode produced you select a start, referenced / tool change location, with a  3x the lead away from physical
location of the material and I didn't get goofy display. Note that it's a screen issue and you should not actually have an actual axis move as shown on the screen. I know the above is not clear but, again, just don't  have time to write it all up / explain  in detail.

That's why I said to actually do a thread!

Anyway, it's working for you and life is good......

RICH