Last modified: 2023-10-20 14:52:48
Positive angles turn the axis anti-clockwise as you view towards the chuck. (Is that how it should be?).
2023-09-08: I cut gear teeth using the 4th axis, it was 0.25mm out of concentric. I wrote a Perl script to correct for the concentricity error, it works pretty well.
2023-09-03: I re-cut the register for the chuck to try to improve concentricity.
2023-10-17: Concentricity error in cutting pivots was about 0.27mm. So this is no better than before! OK some of the error is from the collet, but I did notice that the high spot was always in the same place relative to the chuck register, so the chuck register is definitely the major source of error.
2023-10-20: I discovered that the source of the concentricity error is that the chuck is registering on the bolts rather than on the register. I widened the bolt holes and now it is possible to centre it, but there is a bit of play in the register. Better than before though.
Potential improvements to the 4th axis
See https://github.com/jes/concentric-gear-cutting for the script to counteract the eccentricity.
There's a script in https://github.com/jes/concentric-gear-cutting for cutting pivots on shafts.
Also instructions in 20231017.md for an efficient workflow.