I’m having problems cutting holes that are about 1/4in in diameter or smaller. I thought that I read a post here or maybe the Cambam forums about it. Some seem to cut almost round with a flat area… Some just plunge the bit in. Some make some weird movements… And with different settings for step over and such, the same holes seem to mess up the same consistently. I’m half thinking it is the tinyg. The bit I’m using is a 3mm bit. Also bigger holes or circles work fine. Does anyone else have this problem?
Check arc tolerance and if there’s backlash
In CamBam, go to post processors, find the default and set Arc Output to Convert To Lines. That fixed it for me.
I vote for check backlash; wheels and belts. That was the magic on my 3D printer (after having run for years without adjustment…).
I don’t know how to check for backlash. And that sounds somewhat random… This is not. A run of the same code will produce the same results. I’ll try the arc settings.
Backlash in CNC systems doesn’t act random at all. It is normally totally repeatable. As an example, on my 3D printer, backlash in the wheels made holes oval because one direction had slop in it and the other didn’t. All the holes were oval, every print, and exactly the same way each time. I thought my steps per mm had gotten messed up on ONE axis!
As for checking it, try turning your wheels by hand. If they have some drag due to pressing on the extrusions, you’re good to go. If one or more spin freely, you need to tighten your eccentrics. Another quick check is to see if the X carriage or Z rail can move around (other than in the direction its supposed to move. If you can feel motion, that’s bad…
On the belt, feel if the belt is tight. If its loose, fix it.
If you want to get fancy you can use a dial indicator to check either that your motions don’t move when you push on them (with the stepper drivers on!), OR you can check that + and - motions produce the same stroke.
Ah OK. Pretty sure everything is fairly tight, but I will check it again. It just seems weird to only apply to smaller holes.
Changing the settings in Cambam worked. Thanks.