Spindle encased in epoxy?

[lucenn]

I have a 2.2kw water cooled spindle. It is the standard 80mm round type. My cnc is of the homebrew variety, completely built in structural steel. I'm about to begin the process of filling the tubes with epoxy granite and/or sand. My question is this, if I were to put my spindle into a structural steel tube the length of the body of the spindle, and then fill the tube with epoxy, essentially making my round spindle square while also hopefully dampening vibration, would that cause any unforeseen problems to my spindle.
I have been tossing the idea around in my head for a couple days now, and basically the only thing i could see being a problem is possibly heat, but I dont think the spindle temperature would be enough to cause issues, unless the repeated heating and cooling of the epoxy could cause an issue I am unaware of. Thoughts? Good idea, bad idea?

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[joeavaerage]

Hi,
cured epoxy is has a Youngs modulus of about 3-5GPa, and a filled epoxy possibly 7GPa. I've meet stiffer noodles than that!

I think the idea is bad.

Craig

[mactec54]

I have a 2.2kw water cooled spindle. It is the standard 80mm round type. My cnc is of the homebrew variety, completely built in structural steel. I'm about to begin the process of filling the tubes with epoxy granite and/or sand. My question is this, if I were to put my spindle into a structural steel tube the length of the body of the spindle, and then fill the tube with epoxy, essentially making my round spindle square while also hopefully dampening vibration, would that cause any unforeseen problems to my spindle.
I have been tossing the idea around in my head for a couple days now, and basically the only thing i could see being a problem is possibly heat, but I dont think the spindle temperature would be enough to cause issues, unless the repeated heating and cooling of the epoxy could cause an issue I am unaware of. Thoughts? Good idea, bad idea?

Your spindle is water cooled so that part would not make any difference, the body of the spindle is where it is normally mounted this is accurately machined ground with the spindle, the tube would not give you the mounting accuracy needed, to align the spindle, so the mounting tube would have to be machined to support the spindle accurately, so unless you can do this mounting the spindle like this would not be a very good idea, filling the tubes with epoxy and sand mix can help a lot if you are just looking to dampen resonance in the steel