Question Aluminum Edge Offeset Problem

I'm milling out a heatsink out of 1060 and I'm having an issue with the Y-axis. There doesn't seem to be any alignment issues on the left edge of each fin, but for some reason the right edge is being offset slowly to the right after each layer. I attached a picture showing the part.

The cut was made to be a 90 degree Y axis raster so the gap cuts were small left to right movements on the Y axis with a 1/16" bit. The pocket cut that was done with a 1/8" bit before this did not have any issues. Anyone know what might be causing this?

Hi!
It looks like that at each pass, you are skipping some steps and get shifted.
Have you already investigated in this direction?

Gaël

Ivan,

have you checked if all set nuts on the axis are tight, at mine machine these started to loosen after 50/60 hr of milling.
This resulted in oval circles instead of nice round ones, looks similar to your problem.

good luck

Hi guys, thanks for your responses. I don't believe it is an alignment issue because it is not a symmetrical issue. If the step got shifted then both edges of the fin should be cut wrong.

I'm starting to think it is a software issue. After I let the machining continue, the ramping stopped and milled straight down at the right dimension for the last 4mm. For some reason the gap between the fins were doubled for the first couple layers and then slowly ramped to the correct dimension for the last 4mm.

My Vectric software and UCCNC modeling shows the fins are cut at vertical walls, but that clearly did not happen in reality. I'm really at a loss on why this could be happening.

What type of investigating should I be doing?

I don't believe it is a hardware issue since the mill eventually gets to the right place. (As I explain in the post above)

Why not describe your problem to Vectric - software bugs are not that rare!!

Hi Peter,

On the image you sent, the fins on the left row and on the front row look shifted on both sides.
Did your CAM software defined a tool path that would make the problem visible only on some specific rows of fins?

Gaël