Evil Con Carne
This is my first robot for the national BattleBots
competition. I have been collecting parts for quite a while now. The concept
was dreamed up as a powerful base onto which I could mount some suitable weapon.
I started with a Rhino3D design of the bot based on the dimensions of known
components such as the motors, pillow blocks, and gears. This led me to a
frame dimension of 16 1/4 x 27 inches. Because I plan on using the 12V 4.5
AH batteries that I already have, and the angle stock I chose to use is 2
inches, I made the height of the frame an even 4 inches. This will leave plenty
of space inside for batteries, controls, and probably some other goodies.
I chose to make the frame out of 2 x 2 x .125 inch aluminum angle and .125
inch aluminum plate. I priced around and found that I simply could not afford
to use a quality alloy such as 6063. Since I won't be welding the frame, and
would likely not pay to have it properly heat treated, 6063 would probably
be a waste anyway. So, against my better judgement, I opted for the cheap
Home Depot stuff. The bottom pan of the frame is .125 inch aluminum cut from
a partial sheet I already had lying around. I have no idea of the alloy, but
it was free. The angle was cut on my ancient Craftsman band saw.
My parents bought this for me when I was in junior high school, but it still works great. The plate for the pan was cut with a jig-saw which is older than the band saw. This is a shot of the bottom pan.
This is the first layout of the POP (pile o` parts). These are the parts I have assembled to date: 6 Jensen motors, 6 large gears, 6 small gears,6 Colson Caster wheels, 3 foot of keyed shaft, 6 Team Delta pillow blocks. See the parts grid for information on these parts.
And this is the parts laid out in the pan.
Here's a pic of the guts of one of the Jensen motors. I was curious as to the composition, so I disassembled one.
I was able to turn down the 5/16 inch helical gear shaft on the Jensen motors to a usable 1/4 inch by powering the motors and using a grinder and file on them. Not exactly the most precise metod, but in the absence of a lathe, it worked adequately well. I then brazed a small gear onto the shaft which will mate with the larger gear on the axle.
This procedure was where I experienced the first casualty of this project. I hadn't turned down the shaft quite enough on the first motor and was trying to press fit (with a mallet) the small gear on the shaft. Unfortunately, the poor little gear wasn't up to the stress and split in half.
This is a picture of the layout of one of the axles. I still have to come up with a hub for the wheel and get my gears broached, but it should look about like this.
The next step will be to layout the position of the axles and motors in the pan. Then I'll be adding reinforcements and fastening everything together. I hope to have a drivable frame within 2 weeks. In the meantime, here's the obligatory shot of my incredibly messy shop.