What's the best combination of weight, cost, size and availability?
June 2, 2018 11:00 AM   Subscribe

I want to make a small (8" x 8") piece of plywood very, very heavy by affixing something to the top of it. It could be a single solid object, or a container filled with a very heavy particle (sand, metal pellets, whatnot). The weight on top of the plywood can be up to 4" in height but no higher. I'd like to do this as cheaply as possible. What will give me the best combination of (a) weight, (b) cost to purchase, (c) availability and (d) size?
posted by Shepherd to Grab Bag (36 answers total)
A rock.
posted by the Real Dan at 11:12 AM on June 2

They make aluminum pellets for weighing down a pie crust when you pre-bake it - pie weights. Ball bearings would be similar, possibly heavier. Many people have jars of nails/ screws/ washers that would be free, or visit a hardware store. Smaller item pack together for more weight than larger.
posted by theora55 at 11:14 AM on June 2

I would say bulk lead/lead fishing sinkers. But you don’t want to use lead. Lead has, in this application, been replaced by bismuth.

So, a bunch of bulk fishing sinkers? They’ll have a good volume-to-weight ratio. Have also seen bulk bismuth ingots available on Amazon, etc.
posted by mandolin conspiracy at 11:19 AM on June 2 [1 favorite]

At the extreme, you could buy used lead tire weights, melt them into a block – 8” x 8” x 4” would weigh almost 440 lbs and cost about $600.
posted by nicwolff at 11:21 AM on June 2 [1 favorite]

You could buy 1700lbs of sand from Home Depot for about $150. It would cover a 4'by8' piece of plywood at a depth of about 4'', and you could just leave it in the bags so it stayed in place.
posted by deadweightloss at 11:29 AM on June 2 [2 favorites]

This is 8 INCHES square by 4” tall? This concrete calculator says it should weigh about 20lbs. You can get higher density concrete mix. It’s extremely cheap.
posted by Crystalinne at 11:39 AM on June 2 [1 favorite]

Pennies have a density of 7.8 g/ml. Pre-1982 they were 8.8 g/ml.
posted by rocket88 at 11:39 AM on June 2

On non-preview, I see you're in Canada. Pennies will be harder to find.
posted by rocket88 at 11:41 AM on June 2

His Herculean efforts to make me the best tofu press known to mankind have led us here.
posted by Kitteh at 11:42 AM on June 2 [22 favorites]

Concrete would be fairly easy (just make a little form and use part of a sack of premix) assuming you have a few tools and a place to work.

Even easier (but maybe a bit more expensive) would be having a metal fabrication or supply place cut you a square from the thickest piece of plate steel that they have. (If the single piece is still too light, you can always stack multiples, up to your 4" height.)
posted by Dip Flash at 11:52 AM on June 2 [3 favorites]

Wet sand. Sand is cheap and water is heavy and cheap. Frozen water would be keen if you could do that.
posted by mightshould at 12:05 PM on June 2

Without knowing how much weight is sufficient for your application, there's a weight vs. cost ratio in here that will be very much subjective based on your personal needs.

Here (Click the 7.5lb option) are some 8"x8"x1" iron weights for a weight set for $8 apiece from WalMart. Grab 4 of them for your 4" application and you have 30 lbs for $32. Add additional weight by creating a (sealable) container to place them in, where you can fill in the void space with sand and then water which should add several pounds.

(For reference, 8"x8"x4" worth of sand will weigh about 16 lbs.)

If you need heavier, it's easy but much more expensive. At the other extreme you can custom order an 8"x8"x4" steel plate - about 73 lbs - for around $400. Matches your 'heavy as possible' need but not your 'cheap' need.
posted by SquidLips at 12:10 PM on June 2 [2 favorites]

An 8”x8” square plate from a metal supply shop. You could buy up to 4 at 1” thickness each.
posted by MountainDaisy at 12:13 PM on June 2

8"x8"x4" of lead is ~47kg.
posted by rhizome at 12:28 PM on June 2 [1 favorite]

Checkout the weight calculator at Online Metals. Lets you specify the material and the length and width (I guess the thickness is specific to their material index.)

For instance, an 8" square of commercial bronze is 156 pounds and a bit. I didn't check the price.
posted by clew at 12:46 PM on June 2

... Having noodled around a bit with the weight calculator, I am dubious of it. Worse than dubious. Writing them a dubious letter! They're a really nice company, I would trust them to check my calculations in a email or phone call, cutting metal to shape is What they Do. But I don't think this webpage is right.
posted by clew at 12:52 PM on June 2

...No! I was misusing the calculator! So embarassing! Where is my face!

A *cube* of commercial bronze 8" on a side is 156 pounds. A 8" square cut out of a 0.5" thick sheet of commercial bronze is a bit under 10 pounds.
posted by clew at 12:57 PM on June 2

And part of the challenge is that this needs to be attached to the plywood? That narrows the options down...
posted by salvia at 1:14 PM on June 2 [1 favorite]

You could go down to a theater supply/rigging place and see if they'll sell you individual stage weights. They come in various sizes and exist primarily to be compact and heavy.
posted by Wulfhere at 1:16 PM on June 2 [1 favorite]

This tofu press uses a 4.5lb weight to make a 24 sq. inch block of tofu, which is 0.1875 lb / sq. in. To get an equivalent pressure on your 8x8 piece, you'll need a 12 lb weight. This is approximately the weight of a piece of steel 8" x 8" x 10/16" thick.
posted by pipeski at 1:22 PM on June 2 [1 favorite]

Just a thought... if you can get someone to cut you a little stack of 1/4" thick steel plates, you'd have the means to adjust the weight to achieve different grades of firmness.
posted by pipeski at 1:57 PM on June 2

If you do decide to use ball bearings, fishing sinkers, or other pieces of something in a container, you should also fill in the gaps between them with sand.
posted by kevinbelt at 2:01 PM on June 2 [1 favorite]

What do you mean by the "top" of your piece of plywood here? Is your plywood oriented vertically like a door, or horizontally like a floor?

If the former, the weight you add to the "top" will be 8" wide, up to 4" tall, and up to 1" deep (however thick your plywood is), or 32 cubic inches; whatever weight you attach to the "top" will make the top want to become the "bottom" very quickly, and has the possibility of just snapping or crushing your plywood depending on its strength.

If the latter, the weight you add to the "top" will be an 8x8 square, up to 4" tall, or 256 cubic inches, and there will be less of a chance of simply snapping your plywood that way because the strength will be reinforced by your weight rather than sabotaged.
posted by Pandora Kouti at 2:02 PM on June 2

Unless you consider something exotic (and EXPENSIVE) like gold or platinum, lead is the cost/mass winner.

Ebay always has some lead scrap, like these tire weights.
posted by Marky at 2:10 PM on June 2

It's not a weight, but the thing that will allow you to apply the most pressure to an 8x8 inch square is something more like this, which you could super easily DIY (or not).

Also, I always find my tofu getting pressed unevenly when weighted from the top, which this would remedy.

posted by supercres at 2:26 PM on June 2

Is there a way you could fashion an end-fulcrum lever (class 2) to amplify the force of a lighter weight at a further distance?
posted by rocket88 at 3:51 PM on June 2 [1 favorite]

A budget 1 ton press can be had for $60, yielding 33 1/3 lbs of pressure per dollar. Why rely on mere gravity alone to squeeze that tofu?
posted by mumkin at 5:09 PM on June 2 [5 favorites]

How about SCUBA dive weights? Solid weights of 5 lbs are about 4X4X2 inches. Divers lead shot bags are fabric shell with various mass weights. Gun shops generally stock lead or other dense shot for reloading shotgun ammunition in 25 lb. bags.
posted by X4ster at 5:12 PM on June 2 [1 favorite]

can be up to 4" in height but no higher

So you want to do a calculus between density and cost and workability. Depleted uranium would be excellent. Bulk bismuth can be bought on eBay or elsewhere online (both mineralogy and for shotgun pellets) and can be readily melted on a (well ventiliated) stovetop or propane burner outdoors. Cheap/ free bulk lead would be even better and can be melted over a propane burner outdoors.

Drill a few holes on yout 8x8 piece of plywood. Get some thin metal sheeting (either scrap, like ducting or siding) and cut a 8"x8"x8"x8"(plus a little) x plywoodthickness+4" sheet. Fold that around your plywood like a mould. Set this in a heat resistant container with a layer of water.Melt your Bi/ Pb and pour into mould - the water will help quickly solidify the liquid metal, forming a seal between the plywood and skirting.

If you have a bad leak, you can remelt all the metal and try again.

Tungsten is another candidate but is pricey (less so than DU).

Concrete is less dense but is cheaper - you could probably score an 8"x8"x4" volume of it free from someone's leftovers.
posted by porpoise at 6:24 PM on June 2

I'm working on a project now that needs a weighted base. I've chosen to chop up 20' re-bar & fill the gaps with play sand both from Home Depot. For you, cutting the re-bar will be a chore:

140 ft of 3/8" cut into 210 8" lengths = 52.6 lb
48 ft of 5/8" cut into 72 8" lengths = 50 lb
posted by tinker at 7:13 PM on June 2

Lead is available in several formats that would allow you maximum mass/volume/price. The two that come to mind are sheet lead (used for roofing, sound deadening and radiation shielding) and bar lead (used for leading cars). Solid lead can be simply screwed to your plywood.

Once you have your lead block you can coat the whole thing in plasti dip to make it food safe.

Be very careful melting reclaimed lead; The vapours are pretty toxic and it is often an alloy with other heavy metals; you want a very well ventilated area (IE: not just outside but also a stiff breeze). You can approach the density of a solid block with a lot of labour by cutting up things like wheel weights into small pieces with a pair of tin snips and avoid completely the risk of lead vapour.
posted by Mitheral at 9:51 PM on June 2

For aesthetical reasons if you can use lead/steel shot/ball-bearings or other small round things... I'd make them sculptable.

Probably some bondo (a 2-part epoxy used to fix dents in cars and things, found at any auto place).

Use some screw heads sticking up out of the board for the epoxy to latch around and hold it forever.

Mix the expoxy and round things and spread it out evenly and draw designs (maybe a zen rock garden).

Let it set and coat with lacquer or something to make it food safe.
posted by zengargoyle at 1:50 AM on June 3

Hunt down a scrap yard or metal fabricator/welding shop. A single piece of thick scrap metal will be heavy enough.
posted by sammyo at 5:56 AM on June 3

Lead is denser than steel (and is easy to work with) but just on general principle, I wouldn't want lead that close to my food. The actual risk is probably minor, but since you can get steel and other materials so easily and cheaply, I don't see the advantage unless you absolutely needed that additional weight.
posted by Dip Flash at 6:24 AM on June 3

Thank you, everybody! I'll investigate many of the above (avoiding lead).
posted by Shepherd at 8:53 AM on June 13

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