Hey guys. We tore down the robot today and thought about how the robot is too slow from what we’d like. We plan on having a gear ratio for speed. Possibly 3:1? My question is whether it would be better to use two 2 wire 393 motors at a speed ratio, or three 3 wire 269 motors at a speed ratio.
First off, there are no such things as 3 wire 269 motors. A 3:1 gear ratio is excessive and will just burnout your motors if you plan on having anything on the chassis. It all depends on your strategy(aggressive, passive, defensive, etc.) , planned weight, and also drive type (wheels, treads, holonomic, etc) Really you should only go to about 3:2 for safety (I had a 2:1 earlier on in the year with 4 393s total which burnt out in competition environment)
With more information it would be easier to help you.
EDIT: Tommy appears to have beaten me to it, albeit slightly rudely :P…
What do you mean by 3 wire 269 motors? I presume you mean you will be using 2-to-3 wire converters (Motor Controller 29s).
If you have the motors, go for 393s on the drivetrain. You will likely be going slow regardless of motor type if you are using on 2 or 3 motors on your chassis. Most robots will dedicate 4 or 6 motors to the chassis. With four motors, I would recommend going for regular high-torque 393 motors that are geared slightly for speed, to taste. With 6 motors, you should be able to go straight for 393s geared for speed. That does, of course, differ for robots depending on whether they are heavier or lighter.
Anywho, I try to stay away from the 269 motors whenever possible, except on mechanisms that need to be super lightweight or don’t need much power - like scoring intakes.
Haha not sure why I said 269. I meant regular 3 wire motors. And I just realized my wording was a bit wrong. I meant either 4 393s. Or 6 3 wires. And the robot won’t be super lightly but won’t be overly heavy. Probably around 13lbs. I think that’s normal? Haven’t weighed it yet.
I would personally use the full 10 motor limit. For our robot this year, we are using 6 motors internally geared for speed (1.6:1) on the drive, 2 motors geared 1:5 on the lift, and 2 motors on the intake (1:1). These are all 393 motors.
3:1 is a little to fast for this game. It is true you need speed to get around and score fast, but if you die in the first 30 seconds of the match because of motor overheating, that is not good. I would stick with 2:1 max. 1.6:1 is pretty close to a 2:1 ratio, so that might be a good option.
I would only use 393 motors on the drive, or lift. You don’t really need 393 motors on the intake. 269’s will work fine. Why would you only use 2-3 motors for your drive? That does not give you a lot of torque. I would at least stick 4 motors on the drive. That leaves you 6 more motors for your lift and intake.
We might end up having an 8 motor drive by the end of the year, but we will see what happens tomorrow
Depends on high strength chain vs regular chain. The old/regular chain has this nasty tendency to break under any reasonable stress. Also, if your gear/chain reduction only takes two gear/sprockets and you can fit them right next to each other, you might as well just use gears. If you need to use idler gears (gears that are not directly powered or attached to a wheel, or being used in your reduction), then you should be using high strength chain.
I’m a personal fan of this all-Hoosier thread… Don’t need no out-of-staters