After seeing Matthias Wandel’s video about making wood pseudo bevel gears that will will run at right angles, I decided to attempt making a true bevel gear or at least a closer approximation. My idea was to cut a 45 degree angle on the edge of the wood disc and then cut the teeth on the band saw with the disc tilted at a 45 degree angle.
Here are the steps I used to cut it on my band saw and the results. This was just a prototype but I think that I might try using this to make a router lift mechanism or possibly even an oscillating spindle sander.
1) I started by using the woodgears.ca gear generator to print templates and glued them to 1/2” plywood.
2) To cut a bevel on the disk, I used a quickly made band saw circle cutting jig but angled the table at 45 degrees.
3) I drilled a hole in the middle of the disk and attached it to a wedge block with the bevel down to tilt it at 45 degrees so that the bevel sticks out over the block towards the saw blade. The block was made from some triangular scraps I had laying around from my octagonal storage bins (yeah, I have a hard time throwing away scraps but it paid off this time) that I simply screwed together to form a wedge.
4) With band saw table back at 90 degrees, I positioned the disk so that the center, blade and center of the gap between 2 teeth lined up and cut straight in to the bottom of the gap on the template and backed the piece away from the blade
5) Keeping the disk in the same position on the block, I pivoted the block so that I could cut along the teeth lines of the template being careful not to make too tight of a curve especially since there was so much unsupported blade between the disk and the table.
6) I nibbled away to remove all of the wood between the teeth and only sanded where wood removal was incomplete or the template line was still showing near the tips of the teeth.
The result is gears that mesh and turn pretty smoothly and are very quiet even when run at high speed with my drill. Most of the noise is caused by the face of the gears rubbing against the block I mounted them to. There seems to be very little backlash or play. With some tuning, they would really run quietly.
My band saw skills are still pretty basic since I’ve only had my band saw for a short time so the gears are kind of ugly but even without much fine tuning this method seems to show some promise for me. It didn’t seem any harder really than cutting regular spur gears and though I haven’t tried Matthias’ method for cutting angled teeth, this looks easier to me. I assumed that the gear profile generated by the woodgears.ca program would need some tweaking but just using the standard spur gear profile worked pretty well. This shows the gears with no other cutting:
I eventually sanded off the ends of the teeth that protruded through the opposing gear. You can see a video of a couple of gears here:
-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.