I’m trying to cut a 2.5inch circle from 1/4 ply wood. The end result is always oval shaped, measuring about 2.52 to 2.43.
Settings:
1/8 single flute
3mm doc rough pass at 400 mm/min climb milling leaving 0.3mm for finish pass
Finish pass at full depth 150 mm/min conventional
Milling.
Fusion 360 CAM
Things I’ve tried:
A various amount of setting changes with no real change
Examined gcode to confirm that it’s actually producing a 2.5 inch circle
Tightened up the core a little when noticing some minor slop. No change
Checked trucks for slop and tightened. No change.
Checked steps. 100mm command = 100.0125mm for x and y. Seems about dead on.
Checked belt tension. Seems ok.
Checked pulleys. Didn’t notice any slipping under load. Will have to disassemble enclosure to access them all and put a wrench on the screws to confirm tight.
What else am I missing? I have a hard time believing deflection is my issue here with a finishing pass. I would think any deflection during roughing would have been cleaned up with finishing. I’ve gotta be missing something. I haven’t checked squareness since I assembled the thing but it was square when I put it together. It’s also got dual end stops and the Rambo 1.4 board.
took apart my enclosure so i could get a closer look at everything. I loosened all of the belts and checked all the pulleys. no loose screws there. i took some time to sand the rails with 120 grit to get some of the scale of the EMT that i neglected to do from the beginning while i had it apart.
And while i was sanding the rails… one of my x axis rails started moving. DOH! The top clamps for my x rail never got tightened enough. i could rack the whole assembly a little bit with that rail loose. Tightened it up, re tightened the belts and ran a new part.
now im getting circles that are ± 0.01. I think i can live with that.
I did that with one of the feet it was loose, so when it went to cut, it would ride up on that corner and cause all kinds of weird things, mostly bad to happen