# of motors on DR4B

Our team is working on a stackbot using DR4B. Currently, we use two V5 motors which is plenty powerful. We tried using only 1 motor (to conserve motor and reduce weight). The lift does go up, but always tilt towards the side where motor is attached. We do have axles connecting gears on both sides, as well as framing elements like cross bars. How does other teams solve this problem? There are quite a few successful DR4B stackbot on YT using only one V5 motor! Amazing engineering!

We use 100RPM with 1:7 gear ratio

rubber bands are your best friend
this should help

Rubber band serves as counter weight. How does that help with imbalance issue? Put more rubber bands on the side with no motor attached? Now, that’s the art we haven’t grasped.

You could try a big axle going across to mechanical connect them more

thats what i was referring to sorry i wasn’t more descriptive

Yes many teams do that, but the best method for balance, is probably by putting the motor in the middle.

On our lift, our claw only uses 1 motor and puts more weight on one side. we put a gyro on it to determine which direction it is tilting, and TONS of rubber bands as the claw is really heavy. I’d say around 60 bands total. Like some other people said, rubber bands act like a counterweight with more weight on one side. I’d also say we are using 100rpm 7:1, two motors, and we can’t lift our cage without an absurd amount of rubber bands. I would jsut put two motors on there if you intend to put a good intake mecanism.

7 :1? I’m no expert on gear ratios but that seems too fast.

Even with 2 motors, we still have tilting issue as lift goes up and down, because some small differences between the 2 motors(one being slight more powerful or less internal friction). We will try heavy duty axle idea. That means big change to our current design.

gear ratio = driven/driving gear tooth count
driven gear is 84 tooth driving gear is 12 tooth. learn some gear ratios
84/12 = 7/1 => 7:1

This is a petty thing but I think you mean 1:7 as 7:1 refers to 7 times faster. However, we understood what you meant and pointing it out wasn’t helpful or necessary.



7 :1? I’m no expert on gear ratios but that seems too fast.

@Glaciace please don’t encourage it. This is not a dispute worth anybody’s time

i’m litterally just providing context.

We’ve got a db4 tray that lifts 5 cubes with about 30 bands, so if your using 60 something isn’t right. There might be excess friction in your gearbox or cross bracing that pushes your sides apart, or if your using screw joints maybe the nylocks are too tight.

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we’re using 60 total to hover in place. we can lift 5 cubes as well. without powering motors, we can just let it go at any given form and it will stay like that reguardless of gravity.

Your using bands to counteract the weight of the lift and gravity, so that the motors are only lifting the weight of the cubes correct? My observation is that with half the rubber bands, we have the same system. That being said, if 60 is what works for you, then I’m sure everything is perfectly good the way you have it.

it might be that we are using rubber bands branded for “reliability”. so there are different colors, and with the tighter ones, 40 appears to work fine, but after lifting one time, at least 2 rubber bands break.

That makes sense. Yea we want to use surgical instead of bands but can’t figure out how to tie the surgical uniformly.

i’ve tried surgical bands, and they actually break really fast. they are not that strong in terms of elasticity, and as you said, tying knots effectively is a problem. might just be the case for me