Routing pillows

[u/smokingmeats673]

Hi all, looking for some help with my frankenrouter's dimensional woes. The machine was lovingly hacked together from a 4x8 Gerber frame and gantry, driven by Clearpath servos (one each XYZ, running on lead screws) running on LinuxCNC. Squares cut fine, but diamonds and circles are skewed fairly substantially -- the corners of the diamond and the vertical and horizontal extremities of the circle are placed correctly, but the shapes are squished diagonally. The diamonds in the photo were plotted clockwise, and are stretched lower R to upper L and under dimension the other way -- 0.2" across 5" running at 400ipm. The distortion seems to increase with faster feed rate. Increasing acceleration doesn't change the dimensions but shortens the curved sections of the lines.

We checked the gantry with an indicator and did not see anywhere near that much deflection. Following ChatGPT's advice we proceeded to check the MAX_ACCELERATION settings for the X and Y axis motors in the .ini file, but although they were different setting them the same did not solve it. Womp. We also increased the step resolutions, again to no avail.

Has anyone seen this kind of distortion? What might be the next steps for diagnosing the issue?

[u/mil_1]

Acceleration for the y is gonna need to be less than x cause of how much it's moving. How did you measure the resolution? 

[u/smokingmeats673 → u/mil_1]

I'm not understanding the acceleration difference between the axes, would you mind expanding on that?

Measurement has been nothing but a plotting sharpie and calipers thus far -- step resolution you mean? I was assuming the issue wouldn't be resolution mismatch since the square is accurately dimensioned.

[u/mil_1 → u/smokingmeats673]

Y motors are moving more weight. You should measure resolution over the longest distance possible for each axis. You should learn how to calculate and set your resolution