Replacing a Gear, Part III

With the other attempts failing, I decided to try making the gear using a milling machine. I already had the file with the gear drawn, so simply used that. I decided 3 milling operations would be best: A rough pass with a large (1/8") endmill for the outside of the gear, a rough pass with a smaller endmill (.6mm) to start the teeth, and a final pass with the smallest endmill (.009" or ~.2mm).

The first and second passes went great... well almost. I broke the .6 mm endmill and decided to use the .8mm in its place without updating the file. At this point, it was more important to see if the process would work than to get all the T's and I's crossed and dotted. No sense in wasting time if something else fails.

Something else failed. The .009" endmill had just a tiny bit of cutting length. Since they're so tiny it wouldn't take much more than looking at them wrong to break them. There was just no way that size endmill was capable of making the cut depth I needed.

After the second pass, I had something that resembled a gear. I'm certain if the third pass had been successful I would have had something that could be driven.

Time to explore other options. There's another approach to milling gears, involving some sort of spinning cutter and turning the gear blank a certain amount to generate each tooth. (Sherline makes one that's similar to a fly cutter, Ivan Law describes one that's a disc.)

As with last time, no idea when the next installment will be, or what the resolution will be.