Workshop finished, back to robots!

My workshop improvements are finished so I’ll be back to working on robots very soon. Have a look at the workshop page to see what it looks like now and what it was like when I started. I’m very happy with it!

The last thing I was working on with regards to my robot before starting the workshop was improved potentiometer mounts. The initial design was simple and involved 8mm air hose glued to the servo mount which the rotating end of the potentiometer pushed in to. This worked well for a while but if the servos moved too quickly, there would be some slippage. Also, gluing the air hose to the aluminium wasn’t the strongest method. I wasn’t happy with this so I felt a re-design was in order. A close up picture of the original design is shown below.

 

I needed to come up with a stronger, more secure method of holding the rotating end of the potentiometer. I found some threaded inserts that looked like they would be about the right size to hold the potentiometer. These inserts are the type that are inserted through thin sheet material and compressed to give a threaded hole to mount stuff to. They are also called rivnuts or nutserts. I found that I could drill the threads out of the insert to give a hole that the potentiometer will fit in to.  I could then drill the aluminium servo mount so that the insert will fit tightly into the hole. The type of inserts I found have a splined outer so pressing them into the tightly fitting hole gives a strong interference fit. A drop of glue also helped keep everything really solid. I also drilled and tapped a hole into the side of the insert to allow a bolt to be screwed in to hold the potentiometer shaft secure. I’ll put a picture below as I’m sure it will make it all a bit clearer.

 

This set-up is much better. The potentiometer shaft can’t go anywhere because of the bolt and I’ve tried my best to break the insert away from the servo mount and it can’t be done, not without the aid of a hammer! I’ve changed these on one of the arms and there are a few more to do. Have a look at the picture below to see what they look like on the robot.