My new MPCNC seems to have a problem jogging the correct distances. I’m using cncjs to manually jog a pen in each direction and although the machine is very precise, it is actually jogging 1in for every 1cm (when sending movement commands in mm). This seemed like a simple enough fix until I flipped cncjs into inches and saw that the machine only moves 1in for every 10in I tell it to move, in every direction.
I’m not sure if this is related or just a new wiring issue I’m having also but the Z axis motor refused to bring the gantry up as soon as I started having this scaling issue as well. Moves down no problem.
Has anyone seen anything like this? The test crown came out great, just a bit bigger than I’d hoped.
I’m using an arduino Mega with the ramps shield, I don’t think this is a pulley problem exactly since the problem negates itself depending on the units in cncjs. I just ran another couple jogs at longer distances and recorded everything in similar units this time for clarity. I placed a ruler down and jogged back and forth on the X a few times to line it up and then what I got was a 2" movement when I sent a 20" movement, and when I sent a 40mm movement I got a 100mm movement. I also tried a few different speeds ranging from crawling to sprinting and this didn’t seem to affect it.
You did just make me second guess myself and find out I accidentally purchased 20T instead of 16T pulleys though so thanks for that! Would’ve drove me mad otherwise. Still, I don’t this mismatch would cause the machine to move insufficiently in inches, but excessively in millimetres.
Marlin doesn’t do inches, so ignore those results.
Do you have drv8825 drivers, or something else? For 16T pulleys, and drv8825s, the steps for XYZ should be 200,200,800. For a4498s, they should be 100,100,400. For drv, and 20T pulleys, it should be 160,160,800. For 20T and a4498s, it should be 80,80,400.
The fact that there are 2.54cm in an inch is messing with you, I think. I don’t think this is a unit thing, it is a steps/mm thing. CNC.js and Marlin should always use mm. In your CAM, you can use inches, but by the time it spits out gcode, it needs to be in mm.
Dang that’s a bummer I didn’t realize I couldn’t use the inches mode on cncjs.
You’re an actual genius though, I feel like I just gave you a TV dinner of information and you returned a thanksgiving of answers. My only software problems were incorrect steps/mm and thinking inches were accurate, thank you!