My wife gave me a six-wheel Wild Thumper Robot / RC chassis a couple of years ago for my birthday. I wanted it to use as a platform for a robot project. Sharp-eyed readers may recognize it as the underlying platform for my “ARDI” robot. After I got the batteries and cpu board and whatnot figured out, I decided that I wanted to add shaft encoders to the two center wheel motors and that’s where my troubles began…
I obtained a pair of motors of about the same housing diameter and gear ratio with the shaft encoders already attached. So that part was good. But the overall length of the motor with the encoders was longer than the total depth of the motor bracket assembly. So I took a dremel tool to the back side and totally butchered it up pretty good. And having done the first, in for a penny, in for a pound and all that– I proceeded to butcher the other bracket. You can look at the photos in the build album to see how badly I botched it up. It was definitely not my finest work.
So fast-forward a year or so. I did what I could to continue on with the robot project, adding sensors, writing code, etc., everything but make it move. The wheel motors worked well enough, as did the encoders, but the motor brackets were weakened past the point of being serviceable. I contacted the company I purchased it from and they told me they wanted a lot of money to replace the motor brackets and I politely refused. And then I was breezing the GrabCad.com catalog one day and saw a very nice CAD model of the Wild Thumper, complete with motor brackets and everything.
So naturally the first thing I did was pull it up in CAD, punch a hole through the back wall and then printed it out on the 3D-printer to see how well it would work. And as you can see in the pictures, it came out beautifully. Then I went to add the motor and assembly it onto the robot frame but it was just slightly too tight for everything to fit right. So okay, some slight tweaking needed, but basically I had a winner– it was gonna work.
On the second attempt, I made the motor hole just a tiny bit bigger and added some nice chamfering to beef up the shoulders just a little. And then figuring it would probably work I pressed my luck and printed two of them. And it did work this time. The motor was a perfect fit. I also added a bit of easement so the wires would have a better way to exit the motor bracket housing. After a little tapping and screwing it was all back together and working fine.
3D Printing to the rescue!
You can look at the photos in the build log to see how it all came together. This one was really a neat and useful project.
Here are the original CAD files on GrabCAD made by user Pamir.