Just wondering if anyone has had an offset problem when profiling an object. Most times this happens on the y axis and it is offsetting by a negative y factor each time. Is there a setting I need to change in GRBL?
Any thoughts and opinions would be appreciated.
GRBL v0.9g
Too high acceleration and/or speed? Too low or too high motor current?
I’ve had this happen when my depth was too great or speed too high/low making the spindle ‘shutter’ and lose its path
… and Belt tension
Stepper drive works open loop, if a stepper motor needs to provide more torque than it can, it will miss a step (or more), this will introduce an error into the toolpath that will not be recovered. You need to reduce the torque required by reducing the depth of cut and/or feedrate.
And double check all belt tensions. Something is making it slip or lose steps. If it happens again, take a video and post it.
It may sound annoying, but listen to your machine. The sound may tell you if something is wrong. Cutting too deep, belt tension being off, rubbing, a pulley being mounted a mm off of its optimal position…each of there could be your problem. A number of those have a distinct sound. I am not a pro at this, but I am pretty sure of that.
Thanks everyone, I will make those adjustments and retry my project. Nathaniel you are so right about the sound, these last few projects have sounded off.
My $8=15.00 (acceleration, mm/sec) is that something I should adjust?
I had d same problem: the cause on my machine was the the pulley slipped on the motor shaft. I solved to problem by grinding the shaft flat on one site.
Every so often some dust collects on the Y rails and if you get a chip in the right place, it can temporarily jam the V wheels. I usually brush the rails and wheels off with an old toothbrush and gently slide them back and forth to be sure there is little to no resistance when I do to. Just move it slowly though because the steppers will start to power the bourd if you go fast. It won’t hurt your machine but it will feel like your rails are skipping a few steps and you will see the lights turn on even if it’s not plugged in.
I tapped a piece of cardboard to the inside of each Y rail to keep some dust out while milling.
If you use a Polollu A 4988 to drive your stepper motor, look at the limit current, of the concerned axis (too low). Other option is that the axis works with to high efforts, so look at the free play of the axis, and how easy it works without stepper motor connected. Last, reduce the amount of material you take in one pass.
