Motorstop = coast to release catapult

[Paradox-E]

We are planning on building a catapult this season. However, I don’t want to make slip gears yet. Would setting motor stop to coast work in place of a slipgear? To clarify, I would set the motor stop to coast when I wanted to launch the discs, and .5 seconds later, I would set it to brake and move the catapult back again. Would this damage the motor in anyway? (The catapult would have a few rubber bands for tension and a 1:7, motor:driven gear ratio on a green motor.)

[dodgedoodle]

This would work but it would damage your motor and ports if you do it too much
I would just make the slip gears to avoid motor sacrifice

[Foster]

Let me repeat back what you said with different words:

I want make a rubber band powered catapult. I’ll use a motor with brake set to ON and pull the catapult back putting tension on the rubber bands.

Then I’ll set the motor to coast to let the rubber bands launch.

If I have it right it won’t work because the motor won’t unspool fast enough.

But as a general question moving from brake to coast to brake won’t damage the motor. But a reminder that if the motor is in a “stalled state” for a period of time it will generate heat and trip the overload protection.

[Sylvie]

@dodgedoodle

This would work

No, it wouldn’t. A gear ratio large enough to allow the motor to spin the arm in the first place would provide far too much resistance for the catapult to snap back.

“Coast” mode on the motor makes the motor freespin like it does when it’s unplugged entirely. It doesn’t free the motor up any more than that.

[asdf]

you could try making a cho-cho mechanism. This worked well last year in viqc catapults and should work for vrc. Search online to find out how the linkage works. However, I do recommend making slip gears they aren’t that hard.

[Paradox-E]

Thanks everyone! I will most likely use slip gears now. I did not consider that the large gear ratio would affect the motor that much, but I see what you mean now.