I made the crown test with a pen, but as you can see in the pictures, it’s is not completely symmetric. Is it because of the belt? Is the machine not level enough? Are the rails not square?
Any help is greatly appreciated
I can’t see your pen mount in any of those pictures, but it looks like something is moving with the pen tip as you go, and the pen tip is drifting in the X axis.
Either that, or you are skipping steps somewhere in the X axis. If so, it is happening in a somewhat uniform manner, since there don’t seem to be any stretches where there is simply missing X axis movement.
Does the CNC make noise while it draws? Some is normal, as the stepper motors cycle, but clunking or grinding noises are not. Mine sounds like synthetic notes being played as the motors describe arcs and circles.
Does the pen remain vertical?
What did you set motor current to? Too much or too little can result in skipped steps.
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Thanks for your reply, I’m not using Ryan’s pen mount as mine came broken in the box so I’m just using zip ties right now. Is that the reason? Or is it more likely something I did wrong mechanically?
Depends on what you’re zip tying the pen to, I suppose. If it’s remaining vertical, more likely skipping steps somewhere.
Of course, I should have mentioned… Check that your pulleys are tight. If the grub screws that hold it to the motors are loose, you’ll get some real weirdness. This looks more like that than skipped steps.
Thanks! I tried tightening the pulleys and it seems like it helped, but there are still some issues on the exact place as the tests I did before. The things that gives me a head ache is that it’s alway son the same spots thet the machine has trouble, even if I change the position of the tool/bed. Does that mean its intrinsic to the way I se tup the axis?
Your first test seemed to have the disconnects in primarily the X axis, with little discrepancy in the Y axis. This one clearly shows disconnect in both the X and Y axis.
There are 5 closed lines drawn in this test. The bottom arch, the small circle, the insides left and right, and the overall outline. Certainly when it finishes the outline it has drifted in both X and Y axes. This seems different (and worse) than your first image where the drift seems to be almost entirely in the X axis.
So the error is changing. It’s in the same places because that’s where the lines start and stop.
Pen mount is suprisingly important. If it can move in XY when it gets pushed in Z, then it won’t come out right. Good paper holding is also important.
There are a couple of mechanical things that can cause this but I would guess everything up to your motors is fine. The gears may be loose on the motor shafts. The belts may be loose (but they have have to be way loose). Or one of the motors might not be working.
Tried it on wood and it worked perfectly! Guessing I made a lousy paper holder as I didn’t have any tape laying around. Or maybe it was the belts as they were not tensioned equally. Either way thanks a lot!
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