Epoxy Granite and the Mini Mill

Thanks for the replies. A heavy/solid work stable was part of the plan to begin with. Unfortunately the walls are fairly thin here and it's a one room studio with limited space so I will likely work on building some kind of collapsible sound dampening enclosure.
 
I have a HF 44991 mini-mill. Added epoxy granite to the column, mainly to get some stiffness. Was not worried about sound damping at the time. My guess is that the column, being cast iron, is hard to improve on.
Here's the ingredients I used:
kHPIM2076.jpg
Bought a dog food dish from Goodwill to use as a mixing bowl, and here's what the mix looked like just before pouring:
kHPIM2071.jpg
Before pouring, I'd inserted a length of PVC pipe, to form a space in which to put the LMS hydraulic head "counterweight":
kHPIM2080.jpg

If you're concerned about conducted sound, I'd suggest something like mounting the mill on a chunk of ¾" plywood, atop a layer of foam (maybe like the 2' x 2' interlocking floor squares you can get at Harbor Freight, then a bottom of ¾" plywood. You could use Liquid Nails to keep the sandwich from shifting around sideways, maybe even adding a second layer of foam damping, etc.
www.harborfreight.com

Anti-Fatigue Foam Mat Set, 4 Pack

Amazing deals on this Anti-Fatigue Foam Mat Set 4Pc at Harbor Freight. Quality tools & low prices.
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For radiated sound, you might consider a surround of plywood faced with acoustic ceiling tiles.
 
hman said:
I have a HF 44991 mini-mill. Added epoxy granite to the column, mainly to get some stiffness. Was not worried about sound damping at the time. My guess is that the column, being cast iron, is hard to improve on.
Here's the ingredients I used:
View attachment 339326
Bought a dog food dish from Goodwill to use as a mixing bowl, and here's what the mix looked like just before pouring:
View attachment 339327
Before pouring, I'd inserted a length of PVC pipe, to form a space in which to put the LMS hydraulic head "counterweight":
View attachment 339328

If you're concerned about conducted sound, I'd suggest something like mounting the mill on a chunk of ¾" plywood, atop a layer of foam (maybe like the 2' x 2' interlocking floor squares you can get at Harbor Freight, then a bottom of ¾" plywood. You could use Liquid Nails to keep the sandwich from shifting around sideways, maybe even adding a second layer of foam damping, etc.
www.harborfreight.com

Anti-Fatigue Foam Mat Set, 4 Pack

Amazing deals on this Anti-Fatigue Foam Mat Set 4Pc at Harbor Freight. Quality tools & low prices.
www.harborfreight.com www.harborfreight.com
For radiated sound, you might consider a surround of plywood faced with acoustic ceiling tiles.
Click to expand...

May man! Yes this is what my game plan is. Thanks for the detailed response. I've been searching and re-searching youtube about epoxy granite but haven't seen anything with metal aggregate. Where did you get the idea to use drywall screws? This is interesting because years ago I was messing around with DIY UHPC and at the time there was a debate about glass vs steel fiber reinforcement.
 
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My goal was to include some "long range" stiffening to the aggregate. Gravel, sand, etc. are basically spheroidal. I wanted something akin to the rebar in concrete. Drywall screws were all I could think of. The challenge then became to find some that weren't oiled (rust protection?) by the manufacturer. The epoxy would stick a whole lot better to dry ones. The only visibly dry ones I had on hand were the ones I used. I think they were about an inch or 1 ¼" long. If you look carefully, you'll see that I also used a bunch of shorter #4-40 stainless steel screws - had an excess of this size, so I considered them to be "cheap filler."
 
Plain old clean concrete aggregate might do the job. Quarter minus or thereabouts. Or aquarium gravel? It probably is fairly clean. The chopped fiberglass used to control cracking in concrete might be useful, too.

I haven't used any of these materials for this sort of thing, just tossing in some oddball ideas.
 
Homebrew: Like I said above, years ago I was really interested in fiber reinforced concrete and got to try some strange stuff by just emailing industrial suppliers for samples. I THINK fiber is more important to exposed concrete but rock aggregate/steel screws are more effective in a casing (like a Z column).
 
These guys literally wrote the book(s) for all things composite.

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John
 
West Systems is great stuff! When making my witches' brew, I was really surprised at how well the epoxy wetted everything out. A friend of mine "introduced" me to West epoxy when he borrowed my garage to do a re-planking (doorskin applique) job on a Thistle sailboat hull with it. He'd bought the gallon size resin, quart size hardener and a set of their pumps, which give you the exact volume ratio. I couldn't justify the cost of the pumps, so I used disposable 60cc syringes.

PS - you'll see a vibro-graver in my photo. I attached a ~12" rod to the tip, to use as an agitator for the (3 or 4) pours deep inside the mill column. Probably not necessary, given how well the epoxy wetted out.
 
Do we think cured epoxy is a dense and stiff and vibration absorbing as concrete ?
 
I was milling some steel this afternoon, 3/4" cutter, mill makes little noise at all..
 
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