Slave motor lag during default program run

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ramurph1
Posts: 6
Joined: Thu Mar 18, 2021 1:51 pm

Slave motor lag during default program run

Post by ramurph1 » Fri Apr 09, 2021 6:57 pm

I have an issue with the slave motor lagging during the Buildbotics logo program during testing. The program generates some rapid movements of the Y axis which appear to go beyond my max velocity based on the joystick speed.
It only seems to lag a few times during that simulation and only when the extreme rapid movement of the Y axis happens. Both motors and the gantry seem to be tracking equally throughout the rest of the program.
I don’t have any mechanical binding with my machine. I don’t have coupling slippage. I haven’t scoped/triggered anything but I don’t feel it’s an issue with missing pulses (speculating).
When I manually move the axis via joystick, it doesn’t happen. I move it many times back and forth and several 100 mm, and it doesn’t have a problem. It only happens during the logo program.

Any suggestions?? I don’t want to stress the bearings any further before trying a solution. Thanks.

I really like this controller and I’m excited about getting things off and running!

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Doug
Posts: 233
Joined: Fri Feb 02, 2018 4:56 pm

Re: Slave motor lag during default program run

Post by Doug » Fri Apr 09, 2021 7:55 pm

How are you determining the actual velocity of the rapid moves on the Y axis?

Keep in mind that the velocity that is displayed on the Control page is the vector sum of the velocity in all directions, so if you are moving in two directions, the velocity displayed will be greater than the maximum velocity for either axis during rapid moves.

What is the maximum velocity set to for your x and y axes, and what is the maximum velocity that you are witnessing?

ramurph1
Posts: 6
Joined: Thu Mar 18, 2021 1:51 pm

Re: Slave motor lag during default program run

Post by ramurph1 » Sat Apr 10, 2021 6:16 am

My velocity max was set to 5 m/min
Before running the program again, I set the max velocity to 3m/min. (didn’t want to stress bearings, etc. with the issue)

It’s ran through the program 3X now with no issues at 3m/min.


The joystick only moves it at .75 m/min, so initially I was just visually noticing the program speed moving much faster than manual. Is it possible the 5m/min was just way too fast? I’ve only done manual routing, so I haven’t tried relating speeds to the CNC world. I would consider my machine small and low weight on the gantry. Ball screw and linear bearing machine. Nema 23’s.

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Doug
Posts: 233
Joined: Fri Feb 02, 2018 4:56 pm

Re: Slave motor lag during default program run

Post by Doug » Sat Apr 10, 2021 9:02 am

If you press the yellow 'Y' button on the gamepad, then gamepad moves will travel at the 'max-velocity' that is set for the axis.

In most cases, 5 meters/minute is easily achievable. You have to configure each axis on the respective motor pages. Have you done that? If so, can you report the settings that you have on the axis. Also, have you confirmed that the travel distances are correct?

ramurph1
Posts: 6
Joined: Thu Mar 18, 2021 1:51 pm

Re: Slave motor lag during default program run

Post by ramurph1 » Sat Apr 10, 2021 10:47 am

I haven’t done any cuts yet, although I do have the VFD configured and working properly. All home switches and hard limits are working on each end. The controller is very versatile and accommodating. I understand that test cuts may go a long way in getting things tuned. I’m just waiting on some T track to get the waste board installed.

I’ve attached a few pics of motor config. Thanks for the help!
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E2EC0DF6-6D64-4E86-AABF-00BF02812239.jpeg

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