pic: Monocoque Treads

[AndyB]

loading photo ...

[sgreco]

Wow, very nice render.

Excuse my ignorance, but how do you get power to the tread itself?

Good stuff though, I like it.

[Akash Rastogi]

That looks amazing Andy.

I'll definitely have to take a crack at replicating that next week. RC's thinking the same thing right now probably.

[R.C.]

Originally Posted by Akash Rastogi

That looks amazing Andy.

I'll definitely have to take a crack at replicating that next week. RC's thinking the same thing right now probably.

WOW Akash, you read my mind But Andy, that looks SICK. ME LIKEEEE.

-RC

[sdcantrell56]

That is an absolutely beautiful render. I too am curious about how the tread is driven though.

[EricH]

It looks like the drive system is in the middle, where what seems to be an axle pokes out from a bearing. I'd say right above that is where the drive goes. Am I correct?

[AndyB]

Yes Eric, you are correct. If you look closely, a bit of shaft is sticking out of the middle into the bay of the frame. I think my original intentions were to use a Gen 2 AM shifter but the shaft is standard 1/2" keyed, so direct drive would be possible as well.

[Akash Rastogi]

What's the wall thickness of the various rails and the electronics pan?

[AndyB]

I'm not 100% sure on that. I found the cad file of the design and noticed that the wall thickness was .1in, but that's hardly accurate. In a design like this, I'd probably use .08-.09" for 6061 aluminum or .03-.05" for some sort of galvanized steel. I'd probably use sheet steel just because it's readily available to us.

I've never actually worked with sheet steel within FIRST robotics. I tried doing some research on it but couldn't find much in terms of second hand experience. I've used chromoly steel back when I was with 269 but the properties of chromoly extrusion and galvanized sheet steel are probably pretty different as well. I've heard the number 3x the weight/strength when compared to aluminum but I have no clue if that's correct or not. It was with chromoly extrusion compared to aluminum extrusion which is why we could use .035" wall thickness extrusion.

So to answer your question Akash, .08-.09" Aluminum or .03-.05" Steel.

Something interesting to point out now that I'm looking at the design more up close is how the rollers are set up. There are no crossbars inside the tread modules to add support. At least not any supports designed solely as crossbars... the axles for each roller are dead and the UHMW or UDPE rollers spin freely on them. This way, the roller acts as a crossbar support as well.

[Nick Lawrence]

That kind of reminds me of the 2006 robots that NiagaraFIRST built.

-Nick

[Akash Rastogi]

Its also pretty similar to the frame 25 uses on their beautiful drivetrains.

[artdutra04]

Originally Posted by AndyB

I'm not 100% sure on that. I found the cad file of the design and noticed that the wall thickness was .1in, but that's hardly accurate. In a design like this, I'd probably use .08-.09" for 6061 aluminum or .03-.05" for some sort of galvanized steel. I'd probably use sheet steel just because it's readily available to us.

I've never actually worked with sheet steel within FIRST robotics. I tried doing some research on it but couldn't find much in terms of second hand experience. I've used chromoly steel back when I was with 269 but the properties of chromoly extrusion and galvanized sheet steel are probably pretty different as well. I've heard the number 3x the weight/strength when compared to aluminum but I have no clue if that's correct or not. It was with chromoly extrusion compared to aluminum extrusion which is why we could use .035" wall thickness extrusion.

So to answer your question Akash, .08-.09" Aluminum or .03-.05" Steel.

...

One of the general rules of thumb when working with sheet metal is that aluminum sheets need to be 40% thicker to achieve similar structural properties. Since .080 to .090 wall thickness aluminum sounds about right for a well designed FRC frame, the equivalent steel thickness would be a little higher than your estimates, in the .060 to .063 range.

Depending on the actual alloy used however, these figures will vary.