Epoxy Granite and the Mini Mill

Probably not quite as good at vibration damping as "real" concrete. But pretty good nevertheless. Definitely more resistant to cracking - it's plastic, not stone. Plus you're not messing with water-based materials around cast iron. And it bonds very well to whatever substrate you're adding it to. I recall a post on one of the Yahoo forums, where the owner of a round column mill filled his base with epoxy concrete. Though somewhat rough, I doubt the casting would have held on to concrete as well as it did to the epoxy.
 
Mitch Alsup said:
Do we think cured epoxy is a dense and stiff and vibration absorbing as concrete ?
Click to expand...
hman said:
Probably not quite as good at vibration damping as "real" concrete. But pretty good nevertheless.
Click to expand...

If you look at epoxy-hybrid stuff like countertops, it's notable how "dead" they feel. They don't transmit vibration like cast iron, which will ring for a long time when struck, and transmits sound over great distances (ever heard a railroad track sing a mile ahead of the train?). It is definitely a step in the right direction.
 
My money is on epoxy granite because it wont crack unless something catastrophic happens. Concrete will eventually crack every time with the right forces, especially push/pull twisting forces not matter how much rebar/fiber. The micro cracks may not be evident for a while but they will turn into macro cracks.
 
Your mill is very similar to mine. The inside of my mini-mill's column is a rough casting surface, so I'd expect epoxy to really lock onto it. From there, it seems it's up to you to decide on the aggregate material(s) you go with.
 
Most of the modern machine bases are epoxy granite, when I was researching I came across this article

gearsolutions.com

Polymer Composite Bases for Machine Foundations | Gear Solutions Magazine Your Resource to the Gear Industry

gearsolutions.com

featuring a company in our town that builds tool cutter/grinders for the auto industry.

When I finally get my CNC mill/drill dialed in I plan on casting epoxy granite around the fabricated base I built, or maybe I'll end up just building a new base with the precision ground pieces I have bolted to my existing base.

JOhn
 
I just ran my LMS 3960 to cut cast iron. Had to shorten a boss on a lathe compound so I can add a QCTP. 1/2 end mill at 250+ rpm, max cut at .010. AT the time the radio was going at normal volume. Heard every word clearly. Cutting the excess of the boss with a hacksaw before using the mill was actually louder. You might be just fine with only a little sound dampening.
 
StudioMachinist said:
I'm specifically interested in the LMS 3990. Does anyone here have experience with this specific application or something similar with advice? Sound dampening is actually a priority over rigidity so any tips on that would be very helpful.
Click to expand...

[about a hollow column part of a mill]

If you want damping, you want lossy materials (not solid concrete, it can ring like a bell); you also want lots of scattering
to prevent resonances. Steel and epoxy are expensive, I'd think ceramic (tumbling stones, for instance) with
higher speed-of-sound than steel, mixed with plaster of paris (soft, low speed of sound) would work well.

Strength is NOT an issue, the column won't flex beyond the elastic limits of its fill. One wants the
fill to be a sound scatterer and not have a single bell-like ring mode.
 
Hmmmm ... Tumbling stones .... maybe those extra-pointy triangles would be a good choice ... they'd offer "longer distance" stiffness than relatively spherical gravel, and have a surface texture that epoxy would love to grab on to. Just need to add a smaller filler (sand and/or very small gravel) to fill the spaces between the triangles. I'll definitely want to keep this idea in mind if/when I do another fill. Thank you!
63673_I.jpg
 
silence dogood said:
Would perlite or vermiculite help in sound deadening?
Click to expand...

Interesting idea; the use of puffball inclusions will make lots of scattering. You can't get much acoustic energy
coupled into a particle like vermiculite- which is expanded mica, about as airy as popped popcorn.
It's likely, though, to get crushed under the other fill. Maybe consider the clay-type kitty litter, though,
if it doesn't blot up the liquid element that completes the mix.
 
You must log in or register to reply here.
Back
Top