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  • PCW
  • PCW's Avatar
17 Nov 2024 00:29 - 17 Nov 2024 00:57

Strange motion offsets in one direction on one axis

Category: General LinuxCNC Questions

Without a differential probe it's pretty hard so see,
but position recovery really seems like a drive or mechanical stall issue.

Can you set the drive following error limits tighter?

If it's possibly a drive strength issue, you could try single ended wiring.
(Since the drives have optoccoupler inputs this should have little effect on noise immunity)

 
  • PCW
  • PCW's Avatar
17 Nov 2024 00:12

Fanuc Serial Pulse Coders - Red cap servos, mesa 7i76e, how to?

Category: Driver Boards

In addition to the two polarities that need to be right
(TX to REQ and RX to data) The DPLL needs to be setup to
start the transfer _before_ LinuxCNC reads the data

I'll try and dig up a sample FANUC hal file Monday
 
  • Lcvette
  • Lcvette's Avatar
17 Nov 2024 00:06
Replied by Lcvette on topic probe basic tool direction

probe basic tool direction

Category: QtPyVCP

It's fixed for all now
  • dbtayl
  • dbtayl
16 Nov 2024 23:07

Strange motion offsets in one direction on one axis

Category: General LinuxCNC Questions

Some debugging. Per update above, mechanically things seem fine- I can shove the Y axis around and it's definitely not moving as much as the undercuts previously mentioned. I measured those, and the deepest is maybe ~0.01"/10 mil/0.25mm. Not as bad as I thought, still entirely unacceptable.

See attached pictures for some scope traces of one of the Y axis quadrature phases. Note that the measurement setup wasn't great for this, so there might be more noise represented here than is present in normal use- scope leads were dangling from jumper wires wedged into the cable ends, so... yeah.

With nothing moving, the signal idles at 5V +/- ~1.2V. Moving the X axis doesn't seem to influence this at all. Enabling the spindle adds some noise, dropping the signal as low as 2.3V. That's quite possibly enough to create false motion- minimum input to the servo is listed at 4V, but it also says it has digital filtering against noise, so... who knows. I should look at both A and B phases at once, but ran out of time. The fourth picture shows the Y axis moving- it's pseudo-differential, which in this case I don't think is actually buying anything, since the motor inputs are opto-isolated.

All of the above seems suboptimal, but I'm not seeing how it would somehow create extra steps in -Y, then somehow seemingly exactly recover them when going to +Y. Unless I want to level-shift, I'm not aware of a way to get the 7i76E to output > 5V on the motor control pins.

Anything else I should check? I'll plan on getting traces of both A and B phases simultaneously. Is a 3D model of  the issue still helpful, or is the cross-section sketch sufficient?
  • bnet
  • bnet's Avatar
16 Nov 2024 23:04

Fanuc Serial Pulse Coders - Red cap servos, mesa 7i76e, how to?

Category: Driver Boards

I have created a basic .hal and declared the Fanuc channel, see attached .hal.

I am getting an error on startup of linux cnc:
 

When I watch the corresponding hal pins and turn the encoder I am not seeing any activity.

Any tips on what to check or adjust next will be greatly appreciated.
  • tommylight
  • tommylight's Avatar
  • swanie2000
  • swanie2000
16 Nov 2024 22:09

Are there no increase/decrease spindle speed buttons in Gmoccapy?

Category: Gmoccapy

Hi All,
  I have been reading this forum for weeks now, and have managed to solve most of my problems without needing to ask a stupid question, But the time has come. Be gentle, this is my first post.   I will attach my files to this to help.
Current Setup:
Dedicated computer running Linux Mint Debian Edition 6 "FAYE"
LinuxCNC 3.4.1
Gmoccapy gui
3040 Chinese CNC controller.
XYZ motion, although it also had the forth Axis, I am not including that in my setup.
7i76E motion controller card
0-10V AVI
24000 RPM
800W water cooled Chinese spindle.

My files have been created with the PNCCONFIG wizard.
I have now reached a point where every time I run the wizard, it breaks something, and I have to roll back changes.
(Even when I change NOTHING, just click through the wizard, it still breaks my setup, and will not start.)

I have been carefully trying to edit my files manually, baby steps, and backups!


PROBLEM:
I am having trouble getting the spindle to correctly work in the Gmoccapy display.
I can turn on the spindle, and turn off the spindle
I have the spindle start at 5000 RPM, and this works.
The bar graph on the bottom shows  "5000                  0                  24000"
It starts at 5000, as that is my (min) setting, and the "0" in the middle would display a percentage if I could only increase it.
I cannot adjust the speed of the spindle in the Gmoccapy GUI as there are no speed controls.

I want to add speed controls. and I have tried to understand what is written here in this post,
but I just cannot get my head around what I am doing wrong.

May I ask a member here to please look over my files? Perhaps it is something easy?

Thanks in advance!
Swanie

 
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