Out of round cutting

CNC Machines Shapeoko
1

material: Baltic Birch 1/4"
The design was drawn in TurboCad platinum. Exported as a DXF file. Imported into Carbide Motion.
The design is a circle and the cut is on the inside of the circle.
Bit is 1/8" end mill.
The belts were tightened to remove all slack. Now like a guitar string.
The cut is distorted in the x axis. More like a lop sided ellipse.
This is a recent phenomena.
Any suggestions to true the cut?

Thanks

2

Can you post a picture, as well as the G-code file used for that cut ?
How distorted is it ? (X versus Y dimension difference ?)
Suggestions:

  • check whether all your W-wheels are nice and tight against the rails, no slop (and no excessive friction either)
  • tell us the values of your $100 and $101 GRBL parameters (open Log window, go to MDI, type “$$”, read them there)
3

I had that issue, the two things I did that you didn’t mention were.

The first was square the X and Y rails to each other. I had to shim the X-rail as one end was not cut square.

The second was to calibrate the X & Y movement variables so it’ll move exactly 12" when I tell it to move 12". I did Z too.

It cut circles after that to within 0.005" instead of elipses

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If I could click the like button z dozen times or so…I would :slight_smile:

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5

I followed the suggestion regarding squaring the machine. Removed the factory wasteboard and squared the machine. Re installed the wasteboard. Did a 0.010" shim on the x axis. Re tightened all the belts, installed longer 10/32 screws to aid in tightening the belts.

Will tram the z axis.

Cut a series of shapes and the out of roundness has decreased to 0.00

Thanks to all that offered suggestions and a fix. Much appreciated.

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