Small smooth very hard plate material?

[Illinoyance]

Would something like this work? https://flexpivots.com/flexural-pivot-products/

 

[zondar]

I think that a hss lathe parting tool would fit the bill. And, it can easily be cut with a rotary cutoff tool.

That would be good, except most have a bevel or even a step along its length. If one is available that is actually just flat and parallel, then yes, that would be a good solution.

A lot of parallels are hardened, isn't that right? They can be had with an uncoated bright finish, too. I'll look into that.

Or maybe just a large square tool blank. Hardened 3/4 or 1" square blanks are probably easy to come by. Using the full length is probably OK. Deburr the edges and polish one side a little, and It could work. Nice and stiff, too, which is good for this application - it has to be mounted rock solid.

 

[zondar]

Would something like this work? https://flexpivots.com/flexural-pivot-products/

Interesting! However, those are not frictionless as is claimed. Bend them back and forth fast and they will get warm from the friction amongst molecules and grains of the metal.

But these are inappropriate for a pendulum. They have a built-in resistance and spring back, which would completely distort the pendulum's motion.

I've wondered how an air bearing might perform. That would be interesting to try.

Anyway, the knife blade approach has been king in the world of high-precision pendulums for 200 years.

 

[Winegrower]

1-2-3 blocks without the holes are hard, flat and cheap.

 

[zondar]

1-2-3 blocks without the holes are hard, flat and cheap.

Yes, that's a very good idea. Probably not as hard as the knives and other options, but they are cheap enough to be sacrificial to some degree. And there are one-hole models that could offer convenient mounting. I was thinking of rigging a test stand for trials, and that could make things easier.

 

[francist]

High speed steel in simple flat form could also be had from replacement knives for woodworking planers. Here’s an obviously large large one but a typical pair of blades on a Dewalt say are about 5/8” x 12” x 3/32” thick or in that general area. I cut sections off this large one with a cutoff blade in an angle grinder — the smaller knives could likely be cut with your Dremel though. Not sure how they’d stack up price wise against other options, but you might be able to find spent ones from somebody too. The ones for the smaller home shop machines are meant to be disposable so don’t get resharpened.

 

[Cadillac]

McMaster sells individual gauge blocks pretty cheap to. They also have ceramic Ones.

 

[whitmore]

I've used RNG shapes, in tungsten carbide, for this kind of thing. They come already ground flat both sides, kinda
thick coin shape, and can be shrink-mounted in a steel socket, to keep the edges from being a bother.
RNG at Kennametal

 

[zondar]

I've used RNG shapes, in tungsten carbide, for this kind of thing. They come already ground flat both sides, kinda
thick coin shape, and can be shrink-mounted in a steel socket, to keep the edges from being a bother.
RNG at Kennametal

That looks very promising! Thanks!

 

[Asm109]

You want sapphire. https://www.swissjewel.com/