Machine moves in very tiny steps

I have an openbuilds ox machine with a laser diode on it. I have a grbl controller on it that runs on USB. I can run something like CNCjs and cut stuff out using the milling bit so I know the hardware is ok. however in Lightburn, when I tell it to go it makes a thumping sound and looks to be moving in fractions of a millimeter at a time. over the course of a minute it might move a mm. I also tried lasergrbl and it does the same thing. I have grbl 1.1f on the controller board. What could be causing this? Some setting in GRBL? A serialport issue? Any help will be greatly appreciated.

To start, please post your grbl settings. You can type $$ into the LightBurn console, then copy and paste here. Also, post screen capture (no phone pix please) of the LightBurn screen showing your ‘Settings’ window and ‘Device Settings’ window. To do this, select the gears icon to show the ‘Settings’ window. Select the wrench/spanner icon to expose the ‘Device Settings’ window. image

We can go from there. :slight_smile:




“When I tell it to go” - Can you be a bit more specific? Do you mean when you’re doing something as simple as jogging, or when you try to cut something?

Your max speeds are 7500mm/min, which is about 125mm/sec - can your machine move that fast? If not, and you haven’t changed LightBurn to mm/min, you might be trying to move it faster than your machine will go.

First, you have not enabled laser mode ($32=1). For the speed, check that you’re not exceeding the maximum speed you allow in the controller itself. LightBurn defaults to mm/sec as units, so the speeds may be scaled 60x faster than you’re used to (you can change this in the settings). The maximum rate settings in grbl are $110 and $111.

I also notice that you have you Max spindle speed ($30) set to 12000. The default is usually set to 1000. The $30 value can be set either in your firmware to match LightBurn, or in the LightBurn device settings (S Max) to match your GRBL setting.

I changed the $32 now as well as selected mm/minute.
the speed of 7500 mm/min was what was set up as default. the grbl board was setup for this machine when I purchased it. But I lowered that setting to 4000 on both axis.
Max spindle speed of 12000 is set that way as that is the max rpm. of my spindle.
Jogging has been fine, just cutting is the problem. However with these changes I just made it looks to be working. I have the laser switched off but it is moving back and forth now like it should be. Not sure which one of the above was the issue, but I think it is working.

Glad to hear you are getting some better results.

If you are going to leave you Max spindle speed set to 12000 in grbl, you will need to change in LightBurn to match it.

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