Hi all I’m looking for a little help as my CNC has started doing some weird stuff. While trying to cut some 9mm ply like I have done many times before I’m getting juddering and cuts in the wrong places, I’ve checked belts and wheels and tried another but but I keep getting the below where the X axis does not seems to be going the right amount while under load.
Any ideas as this is driving me crazy, also reduced the cut depth to 3mm so half the normal too.
Cheers
I had a similar issue but I think it was due to the ply used, as there was unseen not layers under the top layer making it harder and causing the belt to slip
Im not convinced that would be the same with this as I used 4 separate bits (but good call). I can try a cut in MDF to see I guess.
@Rich_Walton Check the setscrews on the X axis pully. If they have come loose, the belt can still be tight but you will have play in the X axis causing it to lose position every time it changes directions.
MG
Ironically all replaced the other day with new ones and threadlock, also tensioned the belt with the same issue. I’m wondering if it could be the bits but one is a decent carbide one the other is a Hong Kong special
@Rich_Walton I can’t see bits causing this issue. If it was a bit problem, it would affect both axes equally. You are obviously losing steps on the X axis. The Y axis seems to be good, since it cuts in that direction properly. As soon as you try to go left or right, it loses position .
Try cutting a circle, just a light cut, and measure top to bottom and side to side on the circle. They should be exactly the same. If they are not, you are losing steps on the X axis. Check the motor wires to make sure one has not come loose or something.
It is possible it’s one of your stepper drivers, but not likely. They usually either work or they don’t. More likely a loose or broken motor wire. Could possibly be the motor itself as well. Also, take off the belt drive for that axis and see that it moves freely and smoothly from side to side.
Also, check the axis by twisting it against its normal movement axis to see if there is any play, but the sheer size of the errors you are seeing make it unlikely that its a play issue. Play in the wheels typically shows up as very small errors, not big ones like you have.
MG
Thanks all, somehow it seems that the depth of cut was taking too much on a pass so the straight cuts were ok but the curves went to pot.
I ran it again on some MDF after reducing the pass depth and that works ok so I can only assume that I had made an error when I generated the code or with my depths in vcarve.
But thank you all for the help
