Serious VIBRATION noise when moving

mtb_rider86 · May 30, 2022, 5:50pm

Happy Memorial Day, everyone!

Hoping to see if anyone can help point us in the right direction with an issue we starting experiencing this morning with our OMTech CO2 machine. After running some tumblers on the rotary recently we unplugged and removed the rotary axis this morning and plugged our Y-axis back in its place. When we jog the machine to a position via Lightburn we get a horrible grinding noise, erratic movement, and the machine loses it’s relative position (i.e. 0,0 is no longer the upper right corner but somewhere else). I’ve read about stepper motor issues with similar symptoms on here before but am struggling to nail this one down.

What works without issue:

Jogging X via the controller
Jogging Y via the controller
Jogging X&Y simultaneously via the controller
Jogging X via the Move window of Lightburn
Jogging Y via the Move window of Lightburn
Running an existing program that’s already loaded onto the controller
Opening an existing Lightburn file in Lightburn, Saving RD File to thumb drive, plugging thumb drive into machine and loading it onto the controller

I can consistently get the machine to “grind” by doing any of the following:

Using Set laser position by clicking (Alt+L) via Lightburn
Drawing geometries in Lightburn to cut, selecting them, selecting Cut Selected Geometries, and then clicking Start
Sending a basic program to the machine from Lightburn and then loading the file and starting it from the controller
Making a basic program (several circles at various locations across the work area), saving it to a USB, loading it onto the machine from a USB

This one cut (without laser turned on) a couple shapes and then started grinding when jogging from one cut position to another.

Any input would be greatly appreciated. Thanks, all!

jkwilborn · May 30, 2022, 8:32pm

‘Grinding’ could be many things.

If you are ‘cut selected graphics’ you need to ensure how ‘use selection origin’ is set along with ‘start from’ selection. Although with a Ruida, you don’t seem to be able to run things out of bounds and physically strike a part of the machine. It will only generate code for the selected objects.

You state it works when

“Running an existing program that’s already loaded onto the controller”

Then "consistently get the machine to “grind” section

You state

“3. Sending a basic program to the machine from Lightburn and then loading the file and starting it from the controller”

What’s the difference?

How did you get the “existing program” in the controller in the first place?

If there are gears, pulleys or other mechanically moving parts, they can give you a grinding noise.

When you move the field faster than the motor can respond, some people call that a grinding sound.

From my experience and understanding, if you ‘start’ or ‘send’ a file, it will write the same file. ‘Start’ will cause the machine to execute it when it’s completed loading. These dsp controllers must have the complete file before they can execute.

Good luck

Stillwater · May 30, 2022, 9:01pm

Jack,

Thanks for the input. Regarding your first question, I simply ran a program that was already copied onto the controller and had successfully ran in weeks past to see if that old program ran without issue or if it was something different. The existing program was sent to the controller via Lightburn back when it was first made.

I’ve surveyed all mechanical items and am not seeing anything there that would give the impression of resistance leading to grinding.

Can you elaborate a little for me on what you mean by, “Move the field faster than the motor can respond?”

mtb_rider86 · May 30, 2022, 9:51pm

Here are a couple short videos to show what I’m talking about.

1st Video: You can see that I can jog the machine around from the controller without issue

2nd Video: You can see that it begins running a program without issue and then when traversing from right to left towards the top of the bed it has the failure in discussion. Sorry now for the lawnmower noise.

mtb_rider86 · May 30, 2022, 10:18pm

Some more updates. The noise is better described as a howling than a grinding. Also, it’s isolated to the x-axis stepper motor. It does not have any trouble if being manually jogged along the X axis. The trouble only comes when running a program and rapiding along the X axis.

jkwilborn · May 30, 2022, 10:34pm

Does it do it randomly, positional wise or is it always at the rear?

When things like this occur, with the machine off move the head around slowly and feel for some kind of resistance.

Kind of looped it around and I can see the head changing speed in the X direction.

If you manually run it to it’s back limit and drive it left does it work?

You can also check and ensure the controller isn’t issuing an error (light on controller, doubt it) but check.
That is LED13, sorry the pwm wire sort of covers it…

There is also the motor drivers. Ensure they all have ‘green’ lights…

It does sound mechanical, I’d try to locate a source there as the configuration data isn’t going to change as the machine runs…

The acceleration of an axes is set in the controller and is usually related to mass of the head/associated parts, size of the power supply, motors… etc… You can set the acceleration faster than the motor can physically move, resulting in a chatter or other strange noises…

If you ‘hung on’ to the head of your machine and prevented it from moving you’d hear it. Don’t worry about it, just try and clarify sounds as beast as you can, the video is great…

Good luck

mtb_rider86 · May 31, 2022, 2:48am

GREAT input! Thanks so much for the time to help troubleshoot. After a couple more hours this afternoon I can better describe the noise and what I believe the cause is.

I disconnect the X-axis timing belt to isolate it from the movements. With the X-axis stepper motor free spinning I cycled the X position to in the controller. The stepper motor sounded as one would expect.

I then jogged the gantry forward and back along the Y-axis. Still no issue. I decreased the speed from 400mm/sec to 5mm/sec in steps to see if the slower travel speed would induce the noise when moving along the Y-axis. It did not.

I then commanded the nozzle to the upper right corner of the table. The nozzle did not move along the X-axis as the timing belt was still removed, but the gantry did move to the upper end of the table. Once there I selected a location in lightburn at the left side of the table and about 2” down the Y-axis. This type of motion made the noise consistently appear. And it was clearer now what it is. I was wrong. It wasn’t a stepper motor. It’s a vibration that appears to be coming from a bind of the linear bearings on the Y-axis linear rails. As best as I can tell it appears that the gantry is binding on these long and slow y-axis movements.

My first inclination was to check squareness of gantry to rails. There was a +2mm variation from left to right. I adjusted this slightly to no appreciable gains on the problem.

I then disconnected the y-axis timing belt, reconnected the x-axis belt, and repeated the steps above. The noise was present in this configuration as well.

The noise only presents itself when the move called for is a combination X&Y movement, regardless of whether both axis are physically engaged or not. Straight line movements alone either axis are noise free. Small movements along both axis also seem to escape this (example: circles).

I’m at a loss right now to be honest.

jkwilborn · May 31, 2022, 10:43am

My machine has a single stepper for the Y axes with two shafts to either side to drive the gantry belts.

Could those ‘shafts’ be torquing up, causing a ‘twist’ on the gantry from uneven pressure.?

Check the Y gantry belts… correct adjustment with tension, feel both of the belts to ensure they have the same tension. One side of the drive couplings/pulleys could loosen and cause different tension on each side belt.

Since this is a new problem, I doubt any controller changes would help.

Good luck

mtb_rider86 · May 31, 2022, 1:40pm

Thanks, Jack. I’ll give that a look this evening. Thanks again for weighing in here and helping out. I appreciate it very much.

jkwilborn · May 31, 2022, 1:42pm

No perspiration…

Take care

mtb_rider86 · May 31, 2022, 5:14pm

Here’s a third video of the noise while viewing the X-axis stepper motor
https://youtu.be/c6JBvueiSR8

mtb_rider86 · June 4, 2022, 9:38pm

Does it do it randomly, positional wise or is it always at the rear?
Randomly

When things like this occur, with the machine off move the head around slowly and feel for some kind of resistance.
Everything takes force to move. I don’t have a good gut check for what an “appropriate” amount of force is, but I can saw that the moving the head along the top of the gantry, in the X-Axis, the movement is consistent across the range. The Y-Axis motion feels less consistent, like the teeth of the belts have a pronounced step at each groove on the timing gears/pulleys. That said, I don’t feel any binding, just the effort and the steps on the Y-Axis.

Kind of looped it around and I can see the head changing speed in the X direction.

If you manually run it to it’s back limit and drive it left does it work?
It does. Whether jogging from the controller on the machine or from Lightburn, it moves from right to left without issue when moving along the X-Axis. The only time it’s doing this is when a program is running or if I use “set laser position by clicking on the screen” feature within Lightburn.

You can also check and ensure the controller isn’t issuing an error (light on controller, doubt it) but check.
That is LED13, sorry the pwm wire sort of covers it…
Confirmed. I ran the attached program again and after cutting the circle in the upper right corner it begins to jog to the left for the next cut always fails at this time. I watched the controller and there were no changes observed with the LEDs when it started to act up.

There is also the motor drivers. Ensure they all have ‘green’ lights…

Confirmed. They stay green during the program running and do not change when the noise starts either.

It does sound mechanical, I’d try to locate a source there as the configuration data isn’t going to change as the machine runs…

The acceleration of an axes is set in the controller and is usually related to mass of the head/associated parts, size of the power supply, motors… etc… You can set the acceleration faster than the motor can physically move, resulting in a chatter or other strange noises…
Copy. Thank you.

If you ‘hung on’ to the head of your machine and prevented it from moving you’d hear it. Don’t worry about it, just try and clarify sounds as beast as you can, the video is great…

Good luck

mtb_rider86 · June 4, 2022, 10:58pm

SOLVED!

Machine cut parameters were way off from where they should have been.
What they were when all this was going on:

What I changed them to:

Works like a dream again.

jkwilborn · June 5, 2022, 12:41am

How did those change?

Glad you’re up…

Take care, have fun

mtb_rider86 · June 5, 2022, 1:03am

Good question. Not totally sure to be honest. Just glad we got it sorted out

system · July 5, 2022, 1:03am

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