# Epoxy Granite and the Mini Mill



## StudioMachinist (Oct 2, 2020)

First post here so I apologize if there are already multiple threads on the discussion.

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. The ultimate goal is to machine aluminum 80% and steel 20% of the time.


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## silence dogood (Oct 2, 2020)

I'm not sure if I understand the question, but I'll give it my best shot.  I have a LMS 3960 that has been modified using a counter weight instead of the spring, otherwise it's the same machine. These machines are pretty quiet since they are belt driven instead of gears. The motor is a brushless DC which makes it a little quieter than  a brush DC.   I never needed ear protection if that what you are concern about.   Just mount it on a good solid bench and you should be okay.  I suppose one could mount the mill on rubber pads but I never heard of any one doing that.


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## StudioMachinist (Oct 2, 2020)

silence dogood said:


> I'm not sure if I understand the question, but I'll give it my best shot.  I have a LMS 3960 that has been modified using a counter weight instead of the spring, otherwise it's the same machine. These machines are pretty quiet since they are belt driven instead of gears. The motor is a brushless DC which makes it a little quieter than  a brush DC.   I never needed ear protection if that what you are concern about.   Just mount it on a good solid bench and you should be okay.  I suppose one could mount the mill on rubber pads but I never heard of any one doing that.



Mostly curious about the effective sound dampening EG might have considering I live in a multi story apartment complex or any other tips to deal with that problem. Already figuring out dimensions of travel to build an enclosure that would still allow me to manually operate.


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## Ken from ontario (Oct 2, 2020)

These mills, 3990.3960 are fairly quiet machines even running at higher RPMs,  I would build a small enclosure or barrier around the machine and make that sound proof before doing anything else, there are a few tips on soundproofing compressors, google "soundproofing a noisy compressor" and see what materials are available ,it might be the same type of procedure for your mini mill.
Here's one I just found:









						Soundproofing Small, Loud Machines
					

When it comes to soundproofing small, loud machines, we have no magic product to sell. However, we can tell you how to make a solution for yourself.




					acousticalsolutions.com


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## silence dogood (Oct 3, 2020)

Can you hear the neighbors when they play music or use  the vacuum cleaner? .  The mill it self does not make a lot of noise. It is just when is cutting some thing and it's not bad.   Maybe placing the bench on a rubber pad will help.


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## matthewsx (Oct 3, 2020)

Hi and welcome 

I'd suggest talking with your immediate neighbors to see what they think. There may be times when they aren't home or wouldn't be bothered, or you might have someone who would be annoyed with a sewing machine. 

Most places have quiet hours and if you're working outside of those you should be fine but if you live next to a whiner you might not be able to do anything that will make them happy.

You might also want to clear it with the landlord and make sure you won't be violating your lease, it would stink to buy a new machine only to find out you can't use it.

I've done some research on epoxy granite and I don't think it will do that much for sound.


John


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## tghsmith (Oct 3, 2020)

my small shop vac makes more noise than my 3990, for an apartment a very solid stand or bench so nothing vibrates.. if its backed up to an adjoining wall some sound absorbing material mounted there might be in order..


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## Flyinfool (Oct 3, 2020)

Some thoughts.

Can you set it up on an outside wall so there is no neighbor sitting 2 feet away form it on the other side of the wall? Next choice would be against a wall where the other ssside is still in your appartment. Worst place is any wall that can have people on the other side of it.

Make sure the machine has no solid connection to the structure of the building. You need rubber or some other dampening material either between the machine and the bench, or between the bench and the floor, do not have either touching the wall. This will prevent vibrations from being transmitted into the structure of the building which can let them travel a long ways. 

Use the ideas above for a sound box around the machine.


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## pontiac428 (Oct 3, 2020)

Adding mass in the form of epoxy granite will change the frequencies transmitted through the machine.  This will change the hum transmitted to the floor, as will adding isolation.  The thing is, this particular noise is not likely to bother your neighbors, and if it does, it won't have the sound power to reach 85 dB at your neighbor's property line.  The noise that will exceed that sound level is the high frequency noise from the cutting tool doing its work.  The best way to stop high frequency noise is with heavy insulation in the walls and thick sheeting.  You could set up your shop like a band practice room and nail carpet remnants all over the walls... if it came down to it.

You could use a smartphone based sound level meter set for data logging, and set it on your fence line.  Do some of your noisy work, and see if you actually reach a statutory noise limit.  My money's on no.  At least when the cops come you'll be able to confuse and baffle them with empirical data.  If they come in hot, have some coffee and donuts on standby to remind them that they're not in Kenosha.


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## Flyinfool (Oct 3, 2020)

pontiac428 said:


> Adding mass in the form of epoxy granite will change the frequencies transmitted through the machine.  This will change the hum transmitted to the floor, as will adding isolation.  The thing is, this particular noise is not likely to bother your neighbors, and if it does, it won't have the sound power to reach 85 dB at your neighbor's property line.  The noise that will exceed that sound level is the high frequency noise from the cutting tool doing its work.  The best way to stop high frequency noise is with heavy insulation in the walls and thick sheeting.  You could set up your shop like a band practice room and nail carpet remnants all over the walls... if it came down to it.
> 
> You could use a smartphone based sound level meter set for data logging, and set it on your fence line.  Do some of your noisy work, and see if you actually reach a statutory noise limit.  My money's on no.  At least when the cops come you'll be able to confuse and baffle them with empirical data.  If they come in hot, have some coffee and donuts on standby to remind them that they're not in Kenosha.



Except this is in an apartment on the 3rd floor of an apartment building The neighbors are just one wall, ceiling and floor thickness away. I agree that in a house this would not be an issue. As is it may or may not be an issue, a lot depends on how the walls, floors and ceilings between the units are built, and that is hard to tell even if you are living there. The only clue is, how much do you hear of what your neighbors are doing. If you cant hear them then odds are they can't hear you.


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## StudioMachinist (Oct 3, 2020)

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.


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## hman (Oct 4, 2020)

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:


Bought a dog food dish from Goodwill to use as a mixing bowl, and here's what the mix looked like just before pouring:


Before pouring, I'd inserted a length of PVC pipe, to form a space in which to put the LMS hydraulic head "counterweight":



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.








						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
				



For radiated sound, you might consider a surround of plywood faced with acoustic ceiling tiles.


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## StudioMachinist (Oct 4, 2020)

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
> 
> ...



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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## hman (Oct 5, 2020)

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."


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## homebrewed (Oct 5, 2020)

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.


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## StudioMachinist (Oct 5, 2020)

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).


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## matthewsx (Oct 5, 2020)

These guys literally wrote the book(s) for all things composite. 









						Home
					

WEST SYSTEM marine grade epoxy resins and hardeners for boat building, boat repair, home repair, and restoration. By Gougeon Brothers, Inc. since 1969.




					www.westsystem.com
				











						Instruction Manuals
					

Free, downloadable epoxy instruction manuals for boat building, fiberglass boat repair, wooden boat restoration, vacuum bagging, gelcoat blisters, and more.




					www.westsystem.com
				




John


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## hman (Oct 5, 2020)

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.


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## Mitch Alsup (Oct 5, 2020)

Do we think cured epoxy is a dense and stiff  and vibration absorbing as concrete ?


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## tghsmith (Oct 5, 2020)

I was milling some steel this afternoon, 3/4" cutter, mill makes little noise at all..


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## hman (Oct 5, 2020)

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.


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## pontiac428 (Oct 5, 2020)

Mitch Alsup said:


> Do we think cured epoxy is a dense and stiff  and vibration absorbing as concrete ?





hman said:


> Probably not quite as good at vibration damping as "real" concrete.  But pretty good nevertheless.



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.


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## StudioMachinist (Oct 5, 2020)

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.


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## homebrewed (Oct 5, 2020)

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.


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## matthewsx (Oct 6, 2020)

Most of the modern machine bases are epoxy granite, when I was researching I came across this article









						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


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## silence dogood (Oct 7, 2020)

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.


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## whitmore (Oct 8, 2020)

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.



[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.


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## hman (Oct 9, 2020)

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!


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## silence dogood (Oct 9, 2020)

Would perlite or vermiculite help in sound deadening?


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## whitmore (Oct 9, 2020)

silence dogood said:


> Would perlite or vermiculite help in sound deadening?



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.


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## homebrewed (Oct 10, 2020)

silence dogood said:


> Would perlite or vermiculite help in sound deadening?


Both of those probably would want to float on the epoxy, and also would be impossible to de-air (if that even makes a difference in this kind of application).  Before trying that, I'd do a test run on something I don't care about, like a length of ABS tubing.  To reduce the amount of epoxy needed, use a smaller-diameter and shorter piece of tubing.  A test run to figure out how to mix it all up wouldn't be a bad thing, regardless of what kind of composite you decide to make.


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## silence dogood (Oct 10, 2020)

homebrewed said:


> Both of those probably would want to float on the epoxy, and also would be impossible to de-air (if that even makes a difference in this kind of application).  Before trying that, I'd do a test run on something I don't care about, like a length of ABS tubing.  To reduce the amount of epoxy needed, use a smaller-diameter and shorter piece of tubing.  A test run to figure out how to mix it all up wouldn't be a bad thing, regardless of what kind of composite you decide to make.


You may be right.  It was just an idea, one would have to test it and see if it will work.  I know that perlite or vermiculite is added to concrete to make it lighter.  Epoxy, being of a different consistency may not work, I just don't know.


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## homebrewed (Oct 11, 2020)

silence dogood said:


> You may be right.  It was just an idea, one would have to test it and see if it will work.  I know that perlite or vermiculite is added to concrete to make it lighter.  Epoxy, being of a different consistency may not work, I just don't know.


I'd forgotten that they're used as a concrete additive.  It's even denser than epoxy so perlite/vermiculite might be OK for a composite.  Still, an experiment or two would be advisable.


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