Body - The Making of Blaster Shark (Sumo)
June 14, 2010
After settling on a layout for how I wanted the robot to look I set about making the body.
I use the software provided by eMachine Shop since it is free and simple to use. There is also a tutorial on this website about how to CAD up a part. So with all the dimensions together, I decided to make the motor mounts support both the base and a top plate to mount the PCB. And I came up with something like this:
Insert Picture Here
Since there are bends in the mount I decided to go with aluminum. It's lightweight and easy to work with. I haven't milled any metal on the CNC machine yet, and I didn't want to break any bits at that time. So I printed out my design to scale, made some marks to cut and started hacking away with the hacksaw.
Once I got the shape I wanted I proceeded with the dremel to drill the mounting holes and straighten out the edges.
I then put the work piece into my metal break and bent the piece to the proper shape. For those of you who are wondering, I got the metal break for cheap at Princess Auto here in Canada. If you don't have one or can't find one a vice works fine too. And voila, I have a motor mount.
Back again with the CAD software, I started out with 10cm x 10cm square. I the pushed the sides in, and pulled the front back to account fot the scoop. This will ensure the footprint of the robot is less than 10cm x 10cm. Cut aways were made for the wheels and then the design is complete.
I printed it out and set about to cut the base out of metal. The original plan was to use the metal casing from an old floppy disk drive. Which at the time seemed pretty rigid. After cutting it out however, it was pretty floppy and wouldn't be suitable for the base.
Out of the corner of my eye I spotted a large PCB in my scrap pile.
This would be perfect. But I was feeling lazy and didn't want to desolder all the parts that were on there. So I did the next best thing, I went to Fingertech Robotics and bought a sheet of Garolite. Garolite is a trade name, it is made of fiberglass or as I like to call it the poor man's carbon fiber. It is the exact same stuff used for PCBs. I got blue :D.
Garolite is very easy to work with, so I threw my CAD drawing into some CAM software and made some Gcode for the CNC mill. About 20 minutes later I have a good looking base plate.
I was considereing different designs for the scoop and settled on a straight front, since I think the motors are strong enough to push anyone. Rummaging through my scrap plastic I found a chunk of UHMW plastic. It was black which was nice, but let me tell you UHMW is not a very nice plastic to machine. For me it only really machined well when I tried to fly cut it and drill it, other than that it was a bitch to work with. So basically I use the fly cutter to make all the sides flat and cut a channel in one side to fit onto the front of the base plate.
The last piece is the top plate which I just ripped a square of lexan big enough to mount the PCB on my scroll saw. Well thats all for now folks. The rest of the build will be completed in the actual robot page. See you there.