Today Swen and I started cutting the gear. Here is the setup.
I started the mill conservatively at 200 rpm and a 0.5mm deep cut, but gradually increased the RPM to 450, and the depth of cut to 2mm. Later adjusted to 300rpm, 1mm cut.
The CNC table performed flawlessly, with rapid advances between the 360/77º degree cuts (about 4.6º each tooth). The feed rate was controlled by manually winding the X axis feed on the mill.
We initially used water soluble cutting fluid, but changed later to raw Tap Magic, which seemed to work better.
As you can hear in the following short video, the cutter teeth are slightly off centre, but working well. Didn’t quite finish the gear teeth in this session. Some sparks later on, indicated that a cutter sharpening was required before the finishing run. That will happen tomorrow.
The smoke is evaporation of cutting oil.
The setup will be left undisturbed by removing the gear cutter for sharpening.
I changed my mind about sharpening the cutter in the middle of the job, and continued cutting.
Instead, I lowered the spindle rpm, and the feed-rate. The sparks stopped. Maybe I was just pushing too hard, or maybe there was a hard spot in the metal. Anyway, I finished the cuts.
I made a video of the gear being rotated through 360mm, perfectly, but for some reason it will not upload. (did upload eventually.. see below). It looks perfect, with a tiny amount of backlash. Full installation in a day or two. I was quite surprised that making the gear to the specifications worked so well.
Me, testing the backlash.
And afterwards, sharpening the cutter on the Quorn T&C cutter grinder which I made a few years ago. An amazingly versatile tool.
Just in case I need to make another.
The lathe headstock will be properly reassembled in a couple of days. But I am finally feeling a bit confident about this job.