Epoxy Granite

I recently was given some beautiful, 30x30 Inch TIG welded projector boxes without baseplates. While my standard baseplate is a thick cast aluminum sheet with one inch by one inch stringers attached to add stiffness, I'm looking for some more damping. So working around machine tools and older optics labs, I'm well aware of the benefits of Granite, especially in surface plates. Adding custom ground and cut slabs of scrap rock from a maker of headstones is nuts, but there is an alternative that is used by both professional machine tool makers and dedicated hobbyists alike.

Here is a demo video:

https://youtu.be/4aBVAbfxLJw

If your thinking Jeezus, he's nuts, you've never projected graphics on a 150 foot diameter dome in the top of a packed 3500 seat theatre for one of the best Floyd tribute bands in the world. While I understand the desire of packing as many projectors into a compact car as possible, some times you need to have one really nice piece of precision gear that doesn't shake in front of a sound-stack. Especially when the Band's LD insists on OPSL or ION Pair or GO HOME*.

I'm thinking about adding EG in the base of Prometheus Three.. This way the now expensive, threaded plate only has to be thick enough to hold the threads of the 1/4-20 screws for the optics mounts, and just thick enough to shed the heat to the heatsinks around the laser modules. Then I can have a flipper mount to switch between external Ion and internal Diode as needed. I'll still put in the stringers, but I can reduce their length and thickness by adding a modest layer of EG in between them.

A recent check of the barn inventory shows 5 fiber fed remote heads for those days needing plenty of cheap and light little projectors. I can convert those to diode in the future. Thus life is good. Once Covid is over, I'll want to have some weekend Fun again. Besides, I really can use EG at the day job from time to time for those nano-materials projects.

* I once had a roadie climb on my scaff to reset an intelligent lighting fixture and stand on Prometheus II to get to his fixture. It was embarrassing having to crack the stage curtains and pop out about 50 mW of 488 to check the alignment of the bounce mirrors, after he did that. However, a slight rotation of the scaffold after opening the wheel locks put everything back on target. I'm not sure what the LD did to him later, but I did not see him on the other two days of the Christmas Floyd show. Now you know why I like well engineered gear....

PS...Thanks George for the old stuff :-)

Steve

Hello.
Yes epoxy granite is best for vibration damping but the resin is expensive so the best alternative is to use natural granite.
I have made cnc machine by using natural granite.

Natural granite especially some chinese granites are very cheap like 10usd / m^2 search for example white k granite
If the natutal granite has grain has better vibration absorbtion

The lathe that made hubble's lens was from 100tons granite

https://www.youtube.com/watch?v=d3f3vknWj-w

I have a 24x18 1” drilled and tapped alum optics plate. Come get it.

aluminium has bad vibration damping worse than cast iron and must worse than granite/epoxy granite

In a previous employment we manufactured imagesetter (internal) drums from cast epoxy granite; the properties of the material made it very good for image quality, with good vibration damping and stability over temperature. The only issue we had was static charge build up, but that was dealt with by adding conductive material to the surface layer.