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Author Topic: Mach3 turn threading problem with Z feedrate  (Read 466 times)

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Offline Graham Waterworth

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Re: Mach3 turn threading problem with Z feedrate
« Reply #10 on: February 12, 2020, 06:14:46 PM »
What size of thread are you trying to produce and can you post up the code you are using to do it.
Without engineers the world stops
Re: Mach3 turn threading problem with Z feedrate
« Reply #11 on: February 13, 2020, 07:45:06 AM »
It's the same whatever size I use, in G76 or G32.
In this particular case I was trying to do a 28mm pitch round profile thread in a piece of plastic.

Offline RICH

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Re: Mach3 turn threading problem with Z feedrate
« Reply #12 on: February 13, 2020, 07:51:18 AM »
Christian,
- Are you using current reduction on the drives?
  1. I would suggest that you make sure that the current setting is correct for the steppers that you are using.
  2. Set drive SW4 to ON.
  3. Test axis  motion with steps per resolution seting of 2000 .(ie; need to set SW5,6,7,8)

Mach configuration:
  1. Tune the the steppers for velocity and acceleration and make sure the steps per unit are correct.
  2. Notice you are using Backlash for the Z axis. That SUCKS for threading! Test the axis motion with it
      off. ( .15 mm = .006" backlash )
      You have no backlash in the x axis?
  3. Can you set your set the spindle speed manualy?
      Mach3 and spindle control may be "fighting each other" for control of the feedrate during thread   
      cycle.

RICH
Re: Mach3 turn threading problem with Z feedrate
« Reply #13 on: February 13, 2020, 08:32:33 AM »
Rich, I actually don't have any current reduction in the drives. The current settings are correct for my size motors.
SW4 is already ON.
I have now set the steps per revolution at 1000, why have to try at 2000?
I already have correct steps per unit settings, I use the lathe frequently with no issues.
I have the backlash enabled yes, and in the pdf Threading on the lathe it says that works fine...however, I already tested it without it and the result is the same. The X axis is ok for backlash on my lathe.
I can't set the speed manually, I only set it via Mach3.
Thank you,
Christian

Offline RICH

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Re: Mach3 turn threading problem with Z feedrate
« Reply #14 on: February 13, 2020, 10:49:31 AM »
I have now set the steps per revolution at 1000, why have to try at 2000?

Using 2000 you would be micro stepping at 10x. Above 10x there is nothing to be gained.

I can't set the speed manually, I only set it via Mach3.

The threading PDF talks about what happens when both Mach3 threading and the spindle control are both
trying to influence feedrate in threading. Some folks have no problem but others do and I think that may be your problem.
Until you try threading with setting spindle speed manually you will never know for sure!

RICH


Re: Mach3 turn threading problem with Z feedrate
« Reply #15 on: February 17, 2020, 03:20:59 PM »
Why are you wanting to cut a pitch of 28mm?  Maybe that is well outside the design envelope of the wizard and it generates errors.  Has anyone ever tried to cut a 28mm pitch using Mach3?

What happens if you try a more normal thread pitch, like 1 or 2 mm?  That may help to sort out whether it's a configuration problem or a controller bug.  I can imagine that there could easily be a bug with such large pitches because it may never have been tested.  If there is a bug in M3 it ain't going to get fixed now!

Offline RICH

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Re: Mach3 turn threading problem with Z feedrate
« Reply #16 on: February 18, 2020, 10:42:52 AM »
Christian,

How was the gcode that was used in the video created? Did you code it?
Watching the video I notice your actually clicking buttons to change something........doesn't make sense!
Why the G04 P100 dwell part of the code.........doesn't make sense!
Noticed that the spindle RPM in the video was stable ie; 170 to 171

Do the following:
- Create the threading gcode using the "Simple Threading ( Lathe ) wizard.
   The inputs should represent a common metric thread. ie; M8-1.00

NOTE: The m1076 macro should set for G32 ( that's the output code that "I" want to see)
           as shown on page 47 in the threading manual. If you fooled with that macro in any
           other way AND  or OR  using a modified one done by someone else, replace  with
           the original m1076.mis provided with the original turn screen!

- After completing the inputs required, click the ( Calc number of passes ) button to make
  sure your NOT exceeding your max feedrate.

- take a screen shot of the Wizard screen.

- Click the Post Code and run it.

Please post both the screen shot and the generated code when you reply.

RICH


« Last Edit: February 18, 2020, 10:47:23 AM by RICH »
Re: Mach3 turn threading problem with Z feedrate
« Reply #17 on: February 18, 2020, 03:12:41 PM »
Rich, I was clicking to slow down the feedrate to see what's happening, without clicking it's the same, just don't consider that.

The G04 P100 dwell is there because I put it there, because between every change of direction the motor stalls, don't ask me why, because in normal turning also in G0 rapid doesn't stalls. Maybe it's for the accelerations, but they are the same with a little stop before moving, and with that doesn't stall anymore...I think is for the too fast change in direction.

If I create a standard threading code with the wizard, like M8x1.0, I think I can't see the problem, if it's there, because in proportion the movement is a lot smaller...but I will try.

The macro is the original one, I tried with G76 and with G32 from that macro.

I will try your suggestions as soon as I have some time, now I'm really busy and can't try them.

Thank you for your time for now.

Christian