MicroArc, strange issue

This might take me a sec to explain, so bear with me. I’m new to 4th axis, so if this is normal, please let me know.

I have a part that I’m trying to machine on 5 sides. It’s a 2x3x1 block of aluminum with an extra 1/2" in X to hold onto in a self-centering vise. The operations are like this

  1. Face the 5 sides, starting with A0, then working around the part.
  2. spot drill 5 holes on the A0 face, 1 on A-90 and 1 on A90.
  3. drill operations, same holes, same faces
  4. Bore 3 of those holes on those 3 faces with a taper for an NPT thread
  5. Threadmill those bores
  6. chamfer/debur on all sides

Operation 1 & 2 go as expected but after the tool change to the drill for op 3 the part is in the A-90 position and Z begins to descend and drill then as it penetrates the surface of the part A begins to rotate towards A0. There is nothing in the G code that would seem to command this.

It has been suggested to me that adding G61 / G64 so the A-axis must finish and come to a complete stop before the next move would be a way to fix this, but it seems crazy that I would need to manually do this in G-code whenever using the Microarc. I’m also confused as to why the first 2 ops work fine but the 3rd does not.

I am using Fusion to create the CAM.

Scott,

Post the program.

Autodesk had a bug related to indexing with G92, I don’t know if they’ve fixed that or not. If you’re not on the latest version of the post, you should update to it incase they have fixed it.

Thank you,
Norman

Norman,

I think what it is, is with this drill op the tool T361 is longer than the other tools used so far in the job and when the G30Z is issued G30Z with this tool is not high enough. I was confused I think by the way it looked because I had the velocity and feedrate turned way down so it was in slow motion. Running it at speed made it look more like G30 is just too low.
Air Manifold OP1.nc (246.6 KB)