Acrylic Nuts and Bolts

Published on 2015-09-01 in Hacking the MeArm.

One of the more important challenges in the design of MeArm is making it as light as possible, especially at the end of the arm, where there is the longest lever and the inertia is the worst. But if you look at the robot, it has 10 metal bolts in there, which are quite heavy. So what can be done without laser-cutting my own version of the gripper that would use fewer bolts?

When I was looking for bolts for the Talk Ranking Machine , I stumbled upon those acrylic bolts. They are like completely normal nuts and bolts, except they are made out of acrylic, instead of metal. And they are light. Sure, they are not as strong as metal bolts, but they are as strong as the rest of MeArm, so it doesn’t matter. They fit this project perfectly:

Now, there is a trick to using them. You will need one normal metal bolt, to thread the holes first. Preferably several times, and make sure you get all the way through, because if you don’t, you are going to break the acrylic bolts trying to force them in. After screwing the bolt in and out several times, you can screw in the acrylic bolt, and cut it to size with wire clippers. Easy.

You can see on the picture that I didn’t replace one bolt inside the robot, and the four bolts in the base. The bolts in the base are longer than the acrylic bolts I had, and they don’t matter for the weight of the arm itself anyways, and the bolt in the middle was just too hard to get to without disassembling the whole robot first, so I let it be. It’s close to the center of gravity anyways, so it shouldn’t matter that much.