"8" CIM drive?

[jman4747]

I believe the wheght would be about 25 or so pounds I can't say exactly at the moment.

[Pault]

Originally Posted by jman4747

I believe the wheght would be about 25 or so pounds I can't say exactly at the moment.

My first reaction was that there is no way each side weighs 25 pound. But then I remembered that all those motors will rack up ~13.5 pounds on each side, and also those side plates look pretty thick, so maybe its true. Well, thats another downside to so many motors.

[HumblePie]

My first reaction, from a strictly mechanical perspective, is that all this extra power could be wasted if the wheels break traction before maximum torque is reached. From a durability standpoint, I'm concerned that the vertical hex shaft may flex under load, causing stripping of the miter gears. Consider a mechanical support for the free end of the hex shaft, or use a worm/worm gear arrangement, like in the AM Raw Box.

BTW, we had great fun at Peachtree with you guys!

[KrazyCarl92]

Originally Posted by HumblePie

My first reaction, from a strictly mechanical perspective, is that all this extra power could be wasted if the wheels break traction before maximum torque is reached.

In many cases, the wheels slipping before maximum torque output of the motors is actually preferable. At first, I can see why it might seem counter-intuitive, but it is simply the best alternative.

Something is going to be the limiting factor in the drive train's ability to transmit force to the ground. It can be, among other things:
-Motor torque
-Mechanical strength
-Circuit breakers
-Electrical safety conditions
-Traction

I would rather have my wheels temporarily slip on the ground as opposed to my motors stalling, electronics frying, wheels breaking, shafts bending, gears shearing, chain snapping, belt skipping, circuit breakers tripping, battery dying, or wires catching on fire.

It is not a waste to have more torque available than needed to break traction, it is actually a very good practice in FRC.

[JamesCH95]

Originally Posted by KrazyCarl92

In many cases, the wheels slipping before maximum torque output of the motors is actually preferable. At first, I can see why it might seem counter-intuitive, but it is simply the best alternative.

Something is going to be the limiting factor in the drive train's ability to transmit force to the ground. It can be, among other things:
-Motor torque
-Mechanical strength
-Circuit breakers
-Electrical safety conditions
-Traction

I would rather have my wheels temporarily slip on the ground as opposed to my motors stalling, electronics frying, wheels breaking, shafts bending, gears shearing, chain snapping, belt skipping, circuit breakers tripping, battery dying, or wires catching on fire.

It is not a waste to have more torque available than needed to break traction, it is actually a very good practice in FRC.

This. All of this post, actually.

Also what AdamHerd said.

Model your drivetrain to see what motors you'll need to hit your target speeds and what gearing you'll need to help ensure that you can still slip the wheels.

As discussed in a few other threads a little bit of slip during acceleration can actually increase your effective traction. Yes, your HS physics teachers were not completely honest with you!

I do like the mitre gear design and the general construction and compactness of your design. It might need some revisions that others have pointed out, but it's got a good fundamental design and offers some distinct advantages over traditional designs. Good work.