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.

[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.

[Jim Neeley]

One aspect of the decision process is how much space you have and how much weight you want to add. If I had lots of space, I'd use water first, then sand, then concrete, since if I ever wanted to move the whole thing, water would be easiest to drain, then sand (scoop) and finally concrete (chip if poured or lift large blocks if modular).

If space is important, one cubic foot of:

Water = ~62#
Sand = ~100#
Concrete = ~140# to 150#
Iron = ~485#

So if you want the most weight possible in your space, concrete is far and away the best.

Jim

[jared herbert]

If you can find them, front end weights for tractors work real good. They are solid cast iron, and provide the most compact weight available. they are originally used to hang on a bracket on the front of tractors to hold the front ends down when the tractor is pulling a heavy load. google to find a tractor salvage yard and they should have a whole pile of them at a reasonable price. I have several of them on my powermatic lathe and it calmed it down a lot.

[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.

[David Winer]

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?This is the crux of your inquiry. Damping of sound and vibration is a technical subject that does not lend itself to one size fits all solutions. A lot depends on frequency (wavelength) of the vibrations and the material's ability to transmit or absorb vibratory energy. My GUESS in the case of your situation is that solid mass would be preferable to anything that moves (e.g., liquid or sand).

[Mike Cruz]

I'll file this one under "pixie dust"...both are as easily obtained...

[Mike Cruz]

Thanks, Jeff. This seems to answer my question directly. Sand is a dampener. While water, too, would probably work, the thought of a spill (yet another one) in my shop makes me hesitate.

[Mike Cruz]

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

[Mike Cruz]

David, thanks. Sounds like this is where I'm heading.

Jim, that kind of info is priceless. Thanks. I'm adding this weight mainly for dampening reasons. Also, I like things to be substantial and solid feeling. Sand seems like the perfect solution.

[Mike Cruz]

Heeeeey, cheap shot! The bearings in my shop are JUST fine. Now, there ARE some screws loose...

Dan, maybe I didn't create a good enough visual. I wouldn't be adding bags of anything. I would be filling the column with either sand or concrete. The base will be bolted down so it won't/can't travel.

[Steve Ryan]

Decide on a shape and make the whole stand out of concrete. Not too hard to make a cheap ply form and mounting bolts can be cast in place. Don't forget the fasteners for castors, and a few re bars for strength. I have used female threaded anchors bolted into the forms. The type that is usually epoxied into a drilled hole in concrete. I have done a lot with epoxy concrete too, a mixture of epoxy and ground quartz chunks. Quartz chunks are slightly less than pea size. Not cheap but it makes an incredably strong machine base. Strong and stable enough that many metal working machines are made from a similar product.

[David Hostetler]

The only machine I have that has a vibration issue is my lathe, and that is because it is a midi lathe on a fairly thin stand. I lay a couple of bags of concrete on the plywood I mounted across the spreaders... If I need more weight, I put my foot on it...

[Thomas Hotchkin]

Mike, I use lead shot in small areas or sand in larger. Used truck tire inter-tubes with hose clamps on each end (tube are free at tire centers), seems to tame the vibration better. Tom

[Mike Cruz]

Thanks for recognizing the specific question I am asking, David. Funny though, now I've had two people understand what I am asking, and two opposite answers. UGH. The one saving grace is that if I try sand and it seems unsettling, I could always empty it and fill it in with concrete!

[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.

[Jim Neeley]

Mike,

I just edit that post to add iron to the list. If you've got some junk iron and pack sand around it, it's waaaaay denser than even concrete. Hmm... time to watch CL for some junk barbell weights? You'd have your exercise equipment always in the shop that way!! <g>

[Larry Rasmussen]

Hi Mike,
A variation of this discussion goes on in audio enthusiast discussion groups regarding how to dampen loudspeaker stands. The stands made for smaller speakers are not dissimilar to pedistal tool bases. The most popular vibration dampener appears to be sand. There was a pretty strong lobby for lead shot (used for reloading shotgun shells) for a time. However given the higher cost and some alleged ringing when the shot the concensus appears to be for sand. I've used both and have not noticed a difference. I have not noted any arguments for solid material like cement, although I have seen arguments stating cement would be prone to vibration as well and be worse than nothing at all. Given my experience with sand filling I believe it would be great for a tool base.
Good luck,
Larry R
Seattle

[Rich Engelhardt]

I have a few fat lazy relatives I should lease out..
All they do is sit around all day.
Trust me - they don't vibrate at all. That implies movement, which in turn implies effort...
I better stop @ that point. I'm enjoying the idea of cramming a couple of them under a machine waaaaay too much. ;)

+1 on the cement bags.
Unlike the above - which just grows rounder - cement turns soild after a few months of sitting around.

[Mike Cruz]

Don't know why I didn't think of "fat lazy relatives" in the poll. Sorry...I'll be more thorough next time. :)

[David Winer]

Poll: What do you weigh a hollow machine stand with to dampen vibration?

Mike, the cheapest and most effective substance to dampen anything is water. You are trying to damp vibrations, not wet them. When I was in engineering school so many years ago we were threatened by a professor that if he ever heard of us using "dampen" for "damp" he would have our degrees canceled retroactively.

It turned out that my first job as an engineer found me joining an organization called the "Institute for Environmental Science." In those days (early sixties) the current usage of the word, "environment" was not in fashion. It referred to environments that men and machines could be subjected to. This varied from heat, cold, radiation, etc. but largely dealt with vibration. The vibration aspect was very technical, and thank goodness little of my work required me to get involved with the subject. I did learn a little though, and can assure you that an answer from a poll won't compare well with one based on physics.

I do remember some of the physics (not much) so that the first thing you need to know is the frequency of the vibration so that you can deal with that number and its overtones. And, that different materials transmit and absorb vibratory energy differently. Duuhhh. Well, at least you can see why I wouldn't have much faith in a bunch of woodworkers' answers!

Now I will go out on a limb and take a stab at your question. (With a little reasoning to back it up.) I think our big machines vibrate in the first place from something being out of round. So if you take the rpm of the motors for a start... no, wait, this is getting too technical. Starting with the mass of the machine and the energy needed to make it overcome the inertia of not moving... no, wait, this is also too technical. First you must consider the coupling between the the revolving parts... no, wait, I don't want to go down that path. Oh, heck, just fix the source of vibration or weigh the machine down with whatever is handy.

[Mike Cruz]

Thanks, David. Not only was that entertaining, at least your answer had some "why" behind it. Shy of knowing and even attempting to figure out the "technical" variables, maybe I'll just heed your advice about what to fill it with.

That said, solving the problem would likely be getting a new one. :) The unit isn't violently thrashing or anything. It is simply a Grizzly. What else do I need to say about it? It isn't a PM or Felder or some other high quality refined piece of machinery that will be handed down for generations. It was made for a purpose and will do that purpose. It is a benchtop (read doesn't include its own base, and has holes so that you can mount it to something) model. It has two spinny things that are not/can't imagine they are perfectly equally ballanced with one another or with themselves. Also, it relies (unless mounted to something) on its weight to keep it in place...at about 80-100 lbs, even if very well ballanced, I would imagine it would want to walk and vibrate to some degree. I was simple looking for what will likely be the best damping agent that also had a significant mass for making the base more "solid". You seemed to answer that quite well. Thanks.

Also, thanks for the English lessen. :) Funny how our use of the language, and common misuse destroys meaning and becomes "acceptable"...to the public at least.

[ray hampton]

I have a few fat lazy relatives I should lease out..
All they do is sit around all day.
Trust me - they don't vibrate at all. That implies movement, which in turn implies effort...
I better stop @ that point. I'm enjoying the idea of cramming a couple of them under a machine waaaaay too much. ;)

+1 on the cement bags.
Unlike the above - which just grows rounder - cement turns soild after a few months of sitting around.
cement bags will go solid in a day if they get wet, sometime the stock handler forget to take them in before the storm

[Jake Helmboldt]

Well, my answer is far from definitive, but Vega uses concrete in their lathes for damping, noting that its damping properties are x-times higher than cast iron (I don't recall the exact number). Given their use of concrete, as opposed to sand, I'd hazard a guess there is a reason for doing so given that it would be easier and cheaper to instruct the end user to fill the thing with sand. But that is supposition on my part. Either one would be more than adequate and you may not be able to discern a difference.

One other thing to note (and again, this is not definitive, so take it for what it is worth), a more rigid object vibrates less, so the concrete filled void would theoretically vibrate less than sand. Use of concrete within steel structures for damping has a long history, so again, my wager is on concrete.

And for English lesson #2, technically we are talking about concrete, not cement. Cement is to concrete, as flour is to cake (a lesson from a boss back when working construction).

[Russell Neyman]

Actually, the most efficient means of ballast is water, and you can find "bladder kits" down at the marine hardware store. The process is simply to construct a wood box that will hold the bladder, construct the bladder to fit into the box, and you're off and running. Not only does this put maximum weight into the space you have, but if you choose to move the darn lathe, it's a pretty simple process to empty the "tank" with a hose leading to the garden.

[Rich Aldrich]

Sand is the normal medium for damping vibration. It is what we used on our high speed paper machine in the hollow frames to dampen vibration. Concrete works great for extra weight and keeping the machine from dancing, but vibration needs something like sand that will absorb the motion (energy) without transmitting the motion (energy) to the next piece.

[Bart Leetch]

http://www.vegawoodworking.com/index.htm

Read (CONTROLLING VIBRATION AND OSCILLATION)

[Mike Cruz]

Bart, went to your link, but didn't see anything about controlling vibration and oscillation. Can you link the specific read? Thanks.

[Steve Kohn]

Under my lathe I laid 40 lb. bags of pea gravel from the local big box store. I didn't even take the stones out of the bag so they are easily removeable.

[Steve H Graham]

I would go to a machinists' forum and ask.

[Bart Leetch]

Bart, went to your link, but didn't see anything about controlling vibration and oscillation. Can you link the specific read? Thanks.

CONTROLLING VIBRATION AND OSCILLATION

Excessive vibration and oscillation become a problem when turning large and unbalanced shapes. While low RPM's are essential, having great mass properly placed and to use the best materials is equally critical. The most effective placement of mass is around the spindle center. Adding weight to the Lathe at any location helps, but as its distance from the center of the rotating turning increases, its effectiveness rapidly decreases. Adding weight to the base of a Lathe helps, but mainly to prevent walking or toppling. Materials to a lesser degree also affect vibration, mainly at higher frequencies. Cast Iron is somewhat better than steel in absorbing vibration, but concrete is 20 times better than cast iron. The Headstock on the 2600 is a 64-pound rectangular steel tube filled with 100 pounds of concrete. This combination has the very high strength of steel, and the unusually effective vibration absorbing capacity of concrete, with lots of mass surrounding the spindle.

[Steve Kohn]

I use 40 lb. bags of pea gravel. Cost about $2 at the local Borg, easy to sweep up if loose, and even easier to pick up if still in the bag. I have 5 of them added to the mobile stand for my lathe.

[Jim Foster]

What type of floor is the tool sitting on?


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.

[Brian Loucks]

I use a 30" long piece of railroad track that I found at the local transfer station. Very heavy, but "portable" Works great as an anvil also.

[Dan Hintz]

The most effective placement of mass is around the spindle center. Adding weight to the Lathe at any location helps, but as its distance from the center of the rotating turning increases, its effectiveness rapidly decreases.
Not sure I see where they're coming from with this statement. Assuming a sufficiently stuff machine, the farther you can get the weight away from the center of gravity, the better you should be (longer moment arm). Of course, if your moment arm is not stiff, it negates all of that.

[Harry Hill]

I used pea gravel to weigh down a lathe. No special reason, it was what was readily available at the time. It is easy cleanup and can be stored in 5 gal buckets. The pea gravel can be easily removed and reinstalled when movement of the lathe is required. I don't know what the weight is per 5 gal. It worked well for me.

[ray hampton]

getting a true weight of pea gravel [not so easy] because the gravel will settle if the bucket of gravel are bounced around

[Mike Cruz]

Thanks, Bart. Funny thing is, while this somewhat answers my question, the original question had nothing to do with a lathe. But I do appreciate your input.

[Jake Helmboldt]

Not sure I see where they're coming from with this statement. Assuming a sufficiently stuff machine, the farther you can get the weight away from the center of gravity, the better you should be (longer moment arm). Of course, if your moment arm is not stiff, it negates all of that.

Dan, your statement would be true if the aim was to provide ballast (to lower the center of gravity), but for damping vibration the mass should be centered close to the center of the rotating mass.

[Mike Cruz]

Sorry, Jim, for some reason I didn't get a notification of your question. My shop is built on 2 x 12s 1 foot on center with 3/4" interlocking plywood on top of them, then I installed 3/4" hickory flooring on top of that. So, it could easily be bolted down.

I have, since the begining of this thread, found a Baldor grinder stand that I found on CL for $30 to mount the flap/drum sander to. So, after all this, I won't be needing to build the stand.

[Rick Markham]

Well I know you have been patiently awaiting my reply Mike... :D

I'd use sand personally, 1. it's dense and heavy 2. it isn't going to eventually harden be hard to remove 3. large volumes of small particles dampen vibration much more efficiently than a solid. (think dead blow mallet). 4. It's cheap

Wow, and not even a wise crack! :p

Put your chainsaw down, your other toys are getting lonely!

[Mike Cruz]

'Bout time, Rick...

Actually, my chainsaw is the only thing I CAN run right now. Everything else requires dust collection, and I'm installing my ClearVue. I've stalled on the installation because I need help (an extra set of hands) repiping the shop. My one helper hurt his shoulder, then got sick. So, I've been stalled for about a week now. I have a neighbor coming over tonight to see if we can get it together.

My next biggest issue with it is figuring out how to power it up so that I have a remote switch for it. There are 3 ways I can do it for $200. All three are simple enough for me to do. I could do it cheaper with a relay and a 110 remote, but would need help with that. And when I say cheaper, it would be $75-100. Leaning towards the easy way...

[Rick Markham]

My "helper" that was helping install my dust collection, got me half the materials, and then moved to Texas:eek:... Could be worse:p... Mine has been stalled for about 9 months now... Certainly isn't my fault:rolleyes:

[Mike Cruz]

Boy, I hope that doesn't happen to me! I'm at the point, with my piping, that I "could" finish it by myself. But an extra set of hands would be really helpful. I just ordered my remote for the cyclone on Thursday, so that should be in sometime next week. I still have some minor things to do, then she'll be up and running! Woohoo!!!!!!!!