How to Bevel Gears

How’s it going? I am planning a transmission for my robot, and I wanted to ask a question about the gears. When I see really good transmissions on YouTube, the gears are normally rounded off at the edges. How would one be able to accomplish this rounding off? Should I just carefully dremel each gear, or is there a better way? Thank you!

VEX sells these gears themselves so you don’t have to shave the sides off yourself. I will post the link if I can find it.

Those are actually beveled gear. I believe what he is talking about is beveling the edge of the gears to enable easy shifting. (Example attached)

The best way to bevel the gears is to spin them (drill press, lathe, or hand drill) and use a file to grind the edge. What I usually do is:

  1. Put a small shaft through the gear
  2. Put axle locks on both sides to hold gear in place
  3. To attach to “spinner” put extra axle locks on one side of the shaft. This gives a nice, round, even stock for the jaws to grab onto.
  4. Attach and grind away.

Check out the Advanced Gear Kit [276-2184] on this page:

Or the Advanced Mechanics and Motion Kit here:

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Oh sorry. I misunderstood the question. I have never built a transmission, so I have no idea how to make those little curves on the gear. What I would do is just use a file, but that is probably the most crude method.

We made a small rig with a motor to act as a makeshift lathe, then held a dremel with a sanding bit at an angle to the gear teeth.

I’ve made a couple of transmission robots, and I’ve never beveled any gears. Seems to work fine without it.

@idenzer I tried filing with a drill and file. I have attached a picture of a gear that I did. Do I need to continue filing it from here?

Nope! That looks just about right

That looks great! As a final step, use a razor blade to shave off the “leftovers”. If you’re looking to make it even a bit better, continue to use the razor blade to shave off a little bit off the sides of each triangle on each tooth. A bit painstaking, but the double bevel can really make shifting a breeze.

Cool! Thanks for the suggestions everyone!

If you have a belt sander put a shaft with collars through the gear and stick it in a drill. Run the drill at an angle to the sander and you can get a nice rounded edge really cleanly and quickly.