Would love some help if anyone could shed insight into the problem.
I am using the Multi-axis manufacturing extension in Fusion 360 to run Spiral passes on a workpiece. The process is usually:
1: Adaptive Clear Front
2: Adaptive Clear Back
3: Roughing Spiral Pass
4: Finishing Spiral Pass 1 (1/4" bit)
5: Finishing Spiral Pass 2 (1/16" bit)
The problem is that when I finishing the 4th cut, usually a long process, the A-Axis no longer returns the correct 0 position. I have it marked on the machine and it appears to be off by about 2.5 degrees (not a lot but enough to absolutely ruin the project).
It also seems to have stopped at a point that sets off the position sensor.
I am wondering if there is:
- A reason for this happening
- A way to avoid it going forward
- A way to correct for it should it arise again.
Right now I am just nudging the A-Axis to just past the point of setting the sensor off. Would love any insight.
Have you checked the coupler between the motor and the gearbox to make sure it’s still tight?
Do you know how many total rotations you are taking during all the spiral moves? It could be a lot. If the calibration (turns ratio) is off just a little bit you could have cumulative error over the course of your run.
I don’t know which controller you are using (EX or Mach 4), but in CNC12 you could check accuracy as follows:
- Mark the headstock and chuck when they are aligned (zero position).
- In MDI type G0 A3600 and hit return. This will rotate the chuck ten revolutions.
- Are the marks still perfectly aligned or off even a little bit?
- If there is a little misalignment you could type G0 A36000 which will rotate 100 times.
I’ve taken some time to dial in my turns ratio, but if I rotate 100 times in one direction, I’m off. If I back it up 100 rotations it’s also off. For what I do, I don’t sweat it, but for what you are doing it might matter.
FWIW, I don’t have my position sensor hooked up to my A axis. For what I’m doing there is no benefit to home my chuck.