At the last Motorama, Scott came to Harrisburg to hang out, and brought with him his wife and step-son. Turns out that Kyle was interested in the whole thing, and so a short while after the event, Scott asked me to design a simple 'bot he could work on with Kyle. Oh, and he had gotten his hands on a chunk of aluminium, and found someone who would be able to mill it out, so could I make a unibody-design 'bot? It took a while, but here's what I came up with. Hit Back after viewing an image.
The raw material: a 16" x 16" x 4" billet of aluminium. He'd better snag one for me too! This is a huge chunk of metal, and weighs almost one hundred pounds!
The first thing to do will be to cut it down to size. The block has been cut down to 12" x 12". Then sliced up to yield a 1/2" thick top plate, and 2.5" inch thick body. This is still 42 pounds of aluminium, so we'd better start hogging it out.
Here's the body after it's been milled out. I have no idea how long this would take to do. I just created a number of curves in Rhino3D, extruded them to solids, and BooleanDifference'd them out of the main block, assuming the radii of the cutting tool to be 1/4". There are a few virtual bolt holes in there too, but significantly less than usual!
Here's the top plate too. The two sets of nine holes are cooling holes for the drive ESCs, along with a hole to get at the power switch, and a hole for a power LED. Ten 1/4"-20 bolts hold the lid on.
The drive train is very simple, and very powerful! Two 18V DeWalt motors with Team Delta mounts and strengthening kits, 4"x1.5" Colson wheels, and some chain to hook them up. Because of the unibody construction, I had to cheat, and make polycarbonate bearings for the wheels and motors, otherwise we wouldn't be able to physically install the drive axles!
The electronics are very simple too. Two 3S 3Ah LiPo battery packs, that will be connected in series to give 22.2V to the DeWalts. Two Victor 883 drive ESCs to control the drive, a 40V Battery Eliminator, Receiver, and MS05 Power Switch.
Here are all the components inside the unibody. I'm quite proud of myself for remember to cut channels in the block for wiring - usually the wires are an after-thought when I'm designing a 'bot, but I had to make sure there was a way of routing everything for this 'bot.
Here we are all buttoned up. 28-ish pounds of 20mph indestructability! In theory, any way ...
Using the Tentacle Drive calculator, this should be a seriously fast, pushy 'bot, so the sooner Scott and Kyle get it built, the longer they'll have to LTFD it :-)
Without the weight of bolts, wire, chain, or sprockets, they still have almost two pounds available, so no worries there.