Average number of shaven teeth?

Just out of curiosity, how many teeth have you guys shaved off of the gears on your catapults/punchers?

we have 1/2 to 2/3 of the teeth shaven off on a 36-tooth gear. We use the slip gear for our catapult.

catapults can be quite needy with the shaving of the teeth.

+1. My pullback only takes about 7 teeth left in a 36 tooth gear.

My double catapult used to have only 6 teeth left, but that wasn’t enough when we changed some stuff so we now have 8 teeth left. This is all driving a 60t gear.

so just to be clear, your 36T gear has 7 teeth left?

Wow that’s a lot of teeth shaved off. On our puncher I’d say we have about 60% teeth left

Yes. Well… technically no. But for these intensive purposes, it has about 7 teeth left. It might be 6-9. I didn’t count. I have a catapult.

As Xenon said, catapults get greedy on shaven teeth. Punchers require more teeth intact.

Can you explain how you have your catapult gearbox setup, we just started prototyping a catapult and we don’t have nearly that many gears shaved Off and I’m kinda confused.

Yeah, sure. My actual arm in attatched to a 60 tooth gear. My slip gear is 36 tooth. It only pulls back about 70-95 degrees. (Never actually measured) once again, it may be more than 7. I don’t have my robot or any good pictures to look at.
So, those few teeth are enough to get the desired pullback. I load it with about 3 rubber bands per side, and it fires pretty well.

In case I’m misunderstanding the question, I have a 1:5 overall gear ratio with two torque 393 motors. If you’re still confused, I may be able to dig up some older cleaner pictures if the system, but they were from before I tuned my slip gear.

@callen what size chisel do you use?

@Xenon asked a similar question in the other thread.

I prefer a 1/4" chisel. Even with that width I clip a second tooth when I take the first one off. Maybe also with the second. But you can’t make a slip gear without taking at least three or four teeth off anyway. I find 1/4" is plenty wide enough to take a whole tooth, but once I’ve gotten started it’s also trivial to do one tooth at a time without worrying about the next tooth.

That being said, you can really use any size you want. You’ll clip a few extra teeth when you take the first ones, so getting those first few will be a bit of a pain. But that extra pain is pretty minuscule as compared to the pain of using a file or sanding. Once you’ve gotten a few teeth off, even a 1" chisel can take one tooth at a time by using one end of it. It does mean the mallet won’t strike right above the tooth, but that doesn’t matter too much with a sharp chisel. As always with a chisel, the most most important thing is for it to be very sharp.

oof my chisel is about as sharp as a wooden stake. and is probably 2 inches wide lololol
rip my hopes and dreams.

2" wide and dull doesn’t sound like something you should be using on anything small, or maybe using at all. To work properly a chisel should always be extremely sharp. Meanwhile, if it’s 2", using only one end will mean you’re applying the force to the top of the chisel well over horizontally from when the bottom of the chisel applies its force, which means a noticeable amount of torque on the chisel, which isn’t great for good control.

yes it doesn’t work…

Makes sense thank you!

We have shaved just over half left on a 36t gear for about 3 inch of puncher pull back.

It depends on the loading position and the firing position of your specific catapult or puncher.

Try to have two rotations per gear, this would be however many teeth you need to pull it back on both sides with shaved teeth in between them. You generally want 1.5 time more shaven teeth than teeth