Arduino/GRBL CNC from printer and scanner. Need Help.
Wondering if anyone can help me out with configuring GRBL to get a crappy little ‘CNC’ working properly. I have cobbled one together out of parts from old printers, a scanner, and a cd-rom drive, and last night was able to get some motion out of all 3 axis. While that was immensely satisfying, I now would like to be able to get somewhat accurate (i use that term loosely) movement out of it.
The setup is an Arduino Uno, a Protoneer stepper shield with A4988 drivers.
Using Universal GCode Sender to send manual commands.
I have tried messing the the GRBL steps/mm setting, but changing the value from 250 to 10 only results in the motor moving slower and more ‘individual steppy’ but still travelling the same distance.
If anyone has any suggestions I appreciate it. I am hoping to use this machine as my learning curve before investing in bigger, better, faster, stronger equipment.
Yes I am sure we can help. Can you bring it over to the makerspace on a hack night? (Any Wednesday from 5pm). On top of my head I know @toxuin @Ron_Ron @Chris @fullmetalbuddha would be able to help. Bring your project, I am sure someone will be interested.
Bring it over! We’ll figure something out. At least two our machines run GRBL. Would be glad to help!
be able to help. Bring your project, I am sure some
I would love to bring the project in but I am in Sicamous. My best hope to actually make it to the space would be on a weekend. :-/
In between house and yard chores I have made a little progress today. I changed the step/mm values for the axis and am getting closer. I tried changing $0=10 in setting prior to posting initially, and the only result was a slower travel, but same distance traveled. Today I tried messing with the steps per mm setting again, and it actually changed the distance traveled.I think there were some funny things going on with Universal GCode Sender. Quite a few times after changing values I would issue a command like G0 x1 and it would run right to the end of its travel and pin itself there for a second before stopping… Also, in UGS sometimes during the typing of the command I was about to send a seemingly random axis would move just slightly as soon as I pressed a numeric key. I have discovered that I don’t seem to have these issues using the arduino serial monitor.
Tonight, time permitting I will attempt to export an inkscape drawing to GCode and see how that turns out.
Happy to report that I was able to get things working well. It may not be 100% accurate, but I am well within ‘close enough’. Changing the step/mm setting for each axis was indeed what needed to be done in the end. Which is exactly what I tried originally. I think the issue was with Universal Gcode sender being a bit glitchy and not applying the changes appropriately immediately. I suppose I should have done a reboot on the arduino immediately after making the changes?
Anyways, tonight I was able to use Gcode Tools and Inkscape to export a .ngc file and used Universal Gcode Sender to open the file and sent to grbl. Big smiles.
One thing I’ll mention in case anyone else ends up building a CNC from salvaged printer and scanner steppers. I ended up setting the step/mm for my x axis to 2 (in grbl 0.9 the setting is $100=2) I thought this value was ridiculously low, but actually appears to be pretty accurate when I test it out by drawing a 20mm x 20mm square.