Various articles discussing formica products running on teflon discuss getting the PSI (pounds per square inch) correct. Is the PSI different for your two scopes? Maybe you need larger (or smaller?) teflon pads?
Once of the curious things about the friction formula is that area does not appear anywhere in it. This means that PSI does not matter because, assuming a constant force, increasing the contact area raises the friction resistance, but also lowers the pressure by the same rate. What matters more are the material properties related to softness. Teflon is a great non-stick surface for general use, but under higher temperatures it can soften, and (per Wikipedia) it can interact with aluminum. Most aluminum that we interact with on a daily basis is either anodized, or at least oxidized which gives it a very strong and hard surface. Polished aluminum is quite soft at the surface because the act of polishing removes that oxide layer exposing the soft, reactive aluminum. When used as a bearing surface (particularly under high loads) it has a tendency to gall. This is the likely source of the aluminum self-destruction that Pexdragon experienced.
A better bearing surface is likely to be Delrin (aka POM, or acetal). It is significantly stronger than teflon, does not interact with aluminum, and has nearly the same friction properties. It is also much easier to work with than Teflon. I use it all the time at work as a bushing material and it always out-performs teflon in practical applications.
At least with the laminates, a rough surface seems to be preferred -- not sure polishing the Aluminum is the way to go.
I do not know 100% why the slightly rougher surface texture works better on formica-teflon bushings, but here are my hypotheses. Firstly, I suspect that the rougher texture prevents fine particles of dirt, dust, and sand from getting embedded between the two plastics and creating a sand paper like surface over time. Secondly, I think that a perfectly smooth plastic-plastic interface will create a small region of vacuum (similar to gauge blocks sticking together) that increases the applied force and thus increases the resistance to motion. At some point in the (far) future I would love to do some of my own friction experiments inside a vacuum chamber to test this hypothesis.
I used Turtle Wax car wax on my Teflon / Aluminum altitude bearings and it helped, but needs to be re-applied often.
Applying the wax to the aluminum is likely the reason you have not experienced galling on the aluminum bushing surfaces because it provides a barrier between the two materials.
Edited by pjoyce, 03 May 2019 - 11:11 AM.