Debugging the pendulum

Still working on debugging the pendulum. Thanks to Hugh for figuring this little quirk out. The bearing that I was using previously was not up to cutting the mustard so, I culled one from a hard drive. The hard drive bearing worked great but, it didn’t fit properly in the Thorlabs holder. Hugh came in this morning and started playing around with the items and figured out that the new bearing I was using could be put in the right angle optical post holder with no problem. Unfortunately, doing so would cause a redesign that wasn’t the quickest thing to do. It did, however, fix a lot of issues and so, it won in the end because I’d rather have something working that can take data than redesigning it to make it keep original aspects. In life, business, and the lab, never get emotionally attached to a design because it’s either what your customer wants, or what makes you get the data that will win.

So, Sarah and I removed epoxy and re-epoxied things back together to incorporate this design shift. See Figure 1 for the new look.

Third design of the pendulum.
Figure 1: Pendulum V3.0. This is the third design of the pendulum. It fixes some issues about stability with the bearing.

It is much more compact and the most important thing, works nicely. The other issue with the pendulum was that the protractor was wonky. Meaning that it did not display angles correctly because of poor mounting. In order to mount the protractor read head properly, Sarah came up with the idea of using a grommet. I had a couple extra grommets lying around at home and brought one in. Thankfully it was a 1/4″ ID grommet that accepted the 6mm shaft properly. We decided to epoxy the grommet into place to prevent any movement of the read head from causing problems with measurements. See Figure 2.

Pendulum grommet.
Figure 2: Pendulum V3.0 grommet. This is a side by side comparison of the read head for the protractor. In the left image, the grommet is installed and the read head is very stable. The right image shows it without the grommet.

So far, this is robust. The next step is to figure out the whole magnet thing and a better method for placing the pendulum at some height and letting it go. I think better magnets and the coolant hose idea will work.


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