Submitted by DanielLikesPlants t3_z4nd09 in DIY

I broke my coffee table glass top, its 24” x 48, and the table has a 24” horizontal support in the center of the glass for extra, well, support . its too expensive to replace it with glass, could i replace it with this polycarbonate sheet (link below), or would that be too weak? https://www.amazon.com/Polycarbonate-Resistant-Plexiglass-Robotics-Industrial/dp/B07VVFRFP5/ref=mp_s_a_1_3?crid=1U2IY326ROLXG&keywords=polycarbonate+sheet+24+x+48&qid=1669407973&sprefix=polycarbonate+sheet+24+x%2Caps%2C86&sr=8-3

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Tight-Conclusion-913 t1_ixrr33n wrote

If you’re going to use plexiglass I would shoot for at least 1/4 inch thick. Other than that you shouldn’t have a problem using plexiglass for this application. It isn’t as rigid and will scratch easier. I’m also assuming aside from the center support it will also be supported from all 4 sides

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DotAccomplished5484 t1_ixrrk4v wrote

Plexiglass is way too soft for a table top; everything will scratch it.

But if still want to go that route, I wouldn't consider anything thinner than 1/2".

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thblackdeth t1_ixrsvo2 wrote

Not really, films are also plastic and scratch easy.

But it isn't hard to polish scratched plastic (does require elbow grease). there are polishing kits.

If you wanted a harder surface, a two part epoxy may do the job, but epoxy is expensive and hard to work with.

I'd just use the plexiglass and if it scratches, who cares

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XOIIO t1_ixrwr2o wrote

There's stuff called marguard which is supposed to be a lot more scratch resistant than plexiglass, it's used for windows in construction equipment.

Never dealt with it myself but probabaly worth looking into.

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moldyjim t1_ixrz0di wrote

Polycarbonate isn't the same thing as "Plexiglass" that's actually a trademark for acrylic plastic. Similar but not the same thing.

Acrylic will shatter into bigger pieces but it's still safer than glass. It does scratch pretty easily.

Polycarbonate won't shatter, in fact it's used in "bulletproof glass ", face shields and motorcycle helmets. In fact if you wear glasses, the lenses are made from a special form of polycarbonate. Glass lenses have been banned in most countries.

It can be coated to be highly scratch resistant, UV blocking and comes in different shaded types.

I don't know how much more expensive the coated stuff is. If you have little children around I'd use it instead of glass for the safety part alone.

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BadmanBarista t1_ixs4inr wrote

While scratching is certainly something to keep in mind, if you're not too concerned about the table being transparent, then you could always get frosted polycarbonate. It'll show up scratches much less.

Or you could get clear polycarbonate and frost it yourself if/when the scratches become too obvious. Just takes some sandpaper and a bit of effort.

Edit: also imo fully transparent tables suck. I always bump into them and always end up slamming my cup into them or trying to place it in the air above it.

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Xychologist t1_ixsjfg0 wrote

Yes, but in a reassuringly self-restoring way. Polycarbonate the thickness you'd want for a table top is what they use in riot shields. It scratches a bit, it bends if you smack it or stand on it, but fundamentally it's going nowhere at the sort of forces a human in normal daily life will provide.

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Starrion t1_ixsnihi wrote

Or you could do multiple layers and sandwich a cool design in between.

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GloomyDeal1909 t1_ixsv0de wrote

So I replaced my glass with a full sheet of Acrylic. We had it for 3 years with no issue. Also mine was 1/4" thick. https://www.tapplastics.com/

I got mine from this site and ended up going with a frosted grey. It showe much less scratches than regular.

I recommend putting a tray on top to hold remotes etc. Then put felt bumpers on the tray.

Do not use an abrasive cleaners and use a soft lint free towel. Ours literally last us for 4 years before the scratches became pretty evident but even then it was fine just looked older.

New glass everywhere local was going to cost me more than I paid for the table so I went this route. Also you can get sample pieces from them for like $2.00 each and that way you can look at your color frost options

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zoinkability t1_ixsy11v wrote

I wonder if — ad long as the edges were covered — a thin piece of glass glued to (or just laid on top of) the polycarbonate would work. The glass could provide the scratch protection and the polycarbonate could provide the strength. Or is there something I’m missing?

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trowawaid t1_ixt3c28 wrote

You can't use traditional cleaners on plexi as they can etch it or make them cloudy. (Even things like Windex, etc).

I worked at a furniture store with lots of acrylic furniture (which granted is a different type of plastic, I know) and they got scratched up pretty badly.

Would it be possible to replace the glass with a contrasting piece of wood or paint a piece of plywood?

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thblackdeth t1_ixtb3t8 wrote

It could work for sure, but I see two tricky parts. Strength wise, since the plastic is less rigid, you have to be careful the glass doesn't crack. The polycarb top of the table will deflect more easily than the same thickness of glass. I think really thin glass helps with this, think screen protector for a phone.

The cosmetically difficult part is gluing them together. It's tricky to get a perfect bond over the whole surface of the glass with no air bubbles, voids, or dirt.

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alexgardin t1_ixtfkx1 wrote

Polycarbonate is plastic. As a table it will look like shit in no time. Just like a CD, same material. Plus it may not have uv protection so will also fade , get cloudy and look ugly. Plexiglass / acrylic plastic is better but I imagine same outcome eventually.

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porcelainvacation t1_ixtngdh wrote

Call a real glass shop, it’s not that expensive if you buy it from the right place.

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ithunk t1_ixtplwk wrote

I have a patio roof made of polycarbonate sheets. 1/4” from same tap plastic store in Berkeley. It bends when it is larger than 4 feet across. The sheet I got was a 4x8, so it bends and won’t stay up, so we had to put a wood bar in between and make them 4x4 squares, which are not bending. Why do you want poly for interior and not acrylic (which is more clearer, but is brittle)?

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DanielLikesPlants OP t1_ixus4p2 wrote

woa ty. I got 1/4”. its 24”x48” and itll rest on all 4 sides by the table edges and on a middle horizontal support like this/


| | | | |——| | | | | ——-

lmao that didnt work

like this

https://pixl.varagesale.com/http://s3.amazonaws.com/hopshop-image-store-production/42900653/3b29ca628869854f2860c1d69890d0ff.jpg?_ver=large_uploader_thumbnail&w=640&h=640&fit=crop&s=1d9e55e3dca309e6db14c4e3802a9bef

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BrewtusMaximus1 t1_ixuu33y wrote

If you’re looking at polycarbonate, make sure that your cleaning products of choice are compatible. Pick the wrong one and you’ll either end up softening it (which will lead to deformation) or spiderweb cracking it.

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drumsripdrummer t1_ixuuo7z wrote

You can place 52 lbs evenly spread along one half of the table, and the surface will deflect .25".


d=.142wa^4 /(E*t^3 (2.21(a/b)^3 +1))

w=1 psi

a=24 inches wide

E= 348,000 psi

t= .25 inches

b=24 inches to support


d=.142124^4 /(348000*.25^3 (2.21*1^3 +1))

d=47,112.192/17,454.375

d=2.7" @ 1 psi (or 576 lbs)

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drumsripdrummer t1_ixuwrf2 wrote

Good call on getting the thicker one! The 1/8" would deflect 8 times as much at the same weight. You'd be looking at about 6.5 lbs to deflect .25" with the 1/8" thickness. The polycarbonate alone is 3.1 lbs per side for 1/4" thick (and half that for half the thickness of course).

The calculation is based on 24"x24" since what's happening on one side of the table is nearly independent of the other side.

Gluing/adhering in some way will help for sure! Good luck

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Artisan_sailor t1_ixvd2k3 wrote

I replaced a small coffee table top with plexiglass. We've had it about a year, no scratches or yellowing. It's an inch thick, so no sagging either. 42"x28".

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Artisan_sailor t1_ixvenoi wrote

Temperature changes. The two materials will expand and contract at different rates, which may be fine or may not. The glass may "spontaneously" break at the slightest touch because it's stetched.

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ntyperteasy t1_ixxg1qx wrote

Polycarbonate is not the same as plexiglass. Two different polymers. Both bend more than glass, so you would need similar thickness, not thinner (the material you linked to is only 1/8 inch thick - about 3 mm.) Most glass tables I've seen are more like 3/8 inch (10 mm) or 1/2 inch (12 mm).

Have you looked on craigslist for glass you could repurpose? I've picked up glass shelves and glass table tops for free on there before for other projects.

Also, if the price you were concerned about is from a furniture store, try calling a local glass company - they can cut a piece of glass to size for you and its not very expensive. You don't want a sharp edge - for a small charge, they can grind or grind & polish it to make it safe.

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