[atenman1]

I hope you guys keep working on this! We have been working on epoxy-granite mill bases for a small mill that we are developing (and will be releasing to market soon...we hope!). There are many tricky aspects to it, but the final results are worth it. Through many months of research and testing we have managed to create a small machine with the vibration damping and rigidity of a much larger machine. With knowledge, careful design and planning--a similar machine is within your reach. Don't be discouraged by the unknown.

I hope I can answer any questions about this process. I will try and write up a tutorial on making your own. For now, I will just leave you with some pictures of one of our prototypes that served as a development test bed. Sadly, it has been cannibalized for the benefit of newer prototypes, but it was a great machine and is a good goal for those up for a challenge.


Good Luck!
Matt

Hi Matt

Can you let us see your moulding box for the mill mentioned above? Did you use MDF, or alum for material? Did you use vibration table or something else?
BTW, how about let us take look at your latest model? Sorry for many question!(nuts)
Thanks
Calvin

[Eson]

Does anyone have any idea about how well graphite powder and epoxy is dampening vibrations? Graphite-epoxy is said to be very hard, they cast rockets in it: http://en.wikipedia.org/wiki/Graphite-Epoxy_Motor

[JerryFlyGuy]

NOT WORTH CRAP.. Both Epoxy and Graphite are rather brittle, the reason it works for rocket motors is because its not graphite powder but graphite cloth or twine. The wrap those suckers like crazy. The tension capability's of the graphite is where it really excels, which doesn't really apply to PC structures..

FWIW
Jerry

[greybeard]

IMHO the graphite in the rocket context is there for its thermal properties.
John

[JerryFlyGuy]

True John, graphite is great for thermal transfer as well as a NEGATIVE coef of thermal expansion [gets smaller w/ heat] however even that wiki site says 'due to the filimant wound casings having excellent strength w/ little weight and is stronger than steel" [ I paraphrazed a bit] basically you have a pressure vessel which can burst easily, having a graphite tank/casing which is wound properly is a fantasic weight savings. I'm curious to know what kind of liner or Epoxy they are using as most epoxy's will fail w/ just a slight elevation of tempurature [realitively speaking] a rocket motor is burning at over 2000F, must be quite the epoxy!

Jerry

[greybeard]

Sorry this is off topic, but one of those trivial bits of info.

I'm curious to know what kind of liner or Epoxy they are using as most epoxies will fail w/ just a slight elevation of temperature [relatively speaking] a rocket motor is burning at over 2000F, must be quite the epoxy!

Jerry

Yet another of my backlog of "curious things I have done in my past", I once made large internal turnings in blocks of wet(soaked) mahogany for a glass company, who made cut glass decanter by hand.
The technique involve spinning a blown bubble of glass(red hot) inside the wooden block which has just been taken out of a bucket of water !
The hot glass turns the water to steam and this produces a vapor cushion to spin the glass in.
However, inevitably the wood starts to burn, but once it has built up a layer of carbon on the surface, the mold hardly burns at all, and lasts a considerable length of time.
I suspect something similar happens in the rocket nozzle. The surface of the epoxy does char, but the carbon formed slows down further burning while the graphite already present helps conduct the heat away from the surface.

John