Material for weighing down equipment

[Mike Cruz]

When you want to weigh a machine down to minimize vibration, what do you use? I'm making a pedistal for a drum/flap sander, and am considering multiple mediums. Concrete would probably give it the most weight, but would require mixing and would be solid. Sand would be easy by simply pouring in, but would always stay fluid. Not sure if the pedistal being solid with concrete would reduce more vibration than a fluid (sand) filler, or would the opposite be true and would the sand's fluidity dampen the vibration?

I plan to bolt it down either way, so I'm not worried about being top heavy or anything like that. Little background (probably should have started with this), the pedistal will likely be something like 8"D x 10-12"W x 24"H. It will be made of 3/4" plywood. It will have a base made of 2 layers of 3/4" plywood, and a top of the same. The base, so I have something to bolt it down with, and the top so I can bolt the drum/flap sander down to it. Nothing fancy, just functional.

[glenn bradley]

I used to use 90# sacks of Ready-crete from the BORG for a few bucks. Dad found slabs of 1" steel at a surplus metal yard, they even cut them to size to fit in the bottom of his contractor saw for free. Less space, more weight, no dust.

[Peter Quinn]

I made two large concrete bricks to place on the base of my slot mortiser or vibration damping. This was not enough so I made a yoke for the machine from 3/8" angle iron and lagged this to the 12" thick foundation wall which has a house on it, so the whole thing weights in some where over 50,000 pounds, and that pretty much took care of the vibration problem.

[Josiah Bartlett]

I use old bags of readymix too- they eventually absorb enough moisture to harden up and be useless for anything but weighting things down. I have 4 90 lb bags holding down my lathe stand.

However, the bottom of my planer stand is full of old cast iron sash weights, which work just as well.

[Mike Cruz]

So, you guys find that any weight, regardless of composition, density, or whether or not it is solid, does the trick? I mean, I know that weight is weight as far as weighing down, but what about vibration transfer and dampening?

[Bruce Page]

I used concrete step stones in my disk/belt sander. It was quick & easy.

[Gary Curtis]

Felder and some other European saws and combo machines are filled with concrete in the chassis. Their sliding table saw/shaper/planer/joiner combo weighs about 1400 lbs, I believe.

[Ryan Mooney]

Felder and some other European saws and combo machines are filled with concrete in the chassis. Their sliding table saw/shaper/planer/joiner combo weighs about 1400 lbs, I believe.

Certainly not an expert here, but I was listening to some (experts that is) on the FOG the other day and word is that that isn't usually "concrete" in the redi-mix sense. More like a compressed aggregate with epoxy binder (akin to the quartz countertops). I've talked to/seen some machinists who are using epoxy + granite for infill and weight in heavy milling machines/lathes. In my opinion thats overkill for most ww machines, and isn't really what you call removable (although I suppose you could fit cast removable pieces it would remove some of the point because the bonded join actually helps dampen vibration as well).

The fluid fill idea is interesting, although I share others concerns about leaks.. I'll have to think about that more. I'm thinking some sort of dilatant ( http://en.wikipedia.org/wiki/Dilatant - not dilettante which is a whole nother ball game) would work really well in some cases.. like under a lathe. The silica and poly mix might be just what the doctor ordered, although I do know someone who has done the bulk silly putty order (http://bulkputty.org/ordering/dow.html) - the price is a little.. off putting... You could combine those ideas though... cast infill pieces and then seat them in silly putty to pass the vibration through.

[Larry Edgerton]

Liquid.

If you want to add weight and dampen vibration, that is what I would do. I spent a lot of money on racing engine in years past and put Fluidampers on most of them to dampen the harmonics. And as a bonus should you ever decide to move, just drain the liquid.

That will be two cents......

Larry

[Alan Lightstone]

Depleted Uranium. A little pricey, but I get glowing reviews on my workshop.

[Jeff Nicol]

Mike, Sand has been used for years as a dampening medium and since you are building the stand yourself and it sounds like it will be pretty large you should have no problems. Then if you ever decide to change the stand or need to move it you can take the sand out. If you look in most metal shops or industrial situatons the big grinders are mounted on a round tube with a base that is bolted to the floor and a plate on the top for the grinder/sander/buffer to be mounted. All the ones I used over the years were pretty substantial with little or no vibration.

Just my observations,

Jeff

[Peter Elliott]

Mad "elves" beer.. replace the bearings and you won't have vibration issue.. something is not round-d-round..

[david brum]

We made a grinder pedestal for work this last winter. We made a 8" tall plywood box, about 24 x 24" in size. We lined the box with a trash bag, then filled it with sand and screwed a lid on the top. Then we bolted a cheapo Harbor Freight grinder pedestal to the top. We plugged the bottom of the pedestal and filled it with sand also. The whole thing probably weighs 150 and does a nice job of absorbing vibration.

I also have a box of sand in the base of my Jet 1.5hp shaper. Definitely helps.

[Dan Hintz]

I think half of the bearings in Mike's shop are either shot or nearly so, Peter


Mike,

Unless the tool is placed on the sand, it's ability to dampen vibration will be only as good as any other weighted object held to the tool. If it's sitting in the bottom on the stand, it won't matter if it's 100 pounds of sand or 100 pounds of concrete bags (as long as the bags are solidly mounted to the stand and cannot vibrate independently). Metal (such as the large angle iron mentioned previously) is probably your best bet, if you can find it... its density means you have a smaller volume for the same weight, and if kept to reasonable sizes, it can be moved without trouble, when necessary. Strap it solidly to the table and be done with it.

[Mike Cruz]

I don't think the bearings are bad. It is a benchtop Grizzly drum/flap sander...enough said.