TOTW 02-01-05 Cutting plexiglass and glue

[Samper]

I have gotten ahold of a free rather large sheet of 1/4 inch thick plexiglass. I was going to use it as a canopy for my new light. What is the best way to cut this and build it into a custom canopy? I remember reading somewhere that thin plexiglass tends to warp over time so I was going to double it up to reduce the warping. Is there a glue out there that I can use that won't cut down on the light that will be shining through?

[Sueet]

I have gotten ahold of a free rather large sheet of 1/4 inch thick plexiglass. I was going to use it as a canopy for my new light. What is the best way to cut this and build it into a custom canopy? I remember reading somewhere that thin plexiglass tends to warp over time so I was going to double it up to reduce the warping. Is there a glue out there that I can use that won't cut down on the light that will be shining through?

I'm not sure I understand what you mean here... a canopy? Meaning that you intend to build an enclosure over the tank out of this, and then the light unit would go ... where? Or do you mean a cover for the tank for the light to sit on top of? I don't see how you could possibly work a 48" fixture into any kind of canopy built for a 20g tank... Could you further explain what you mean?

[Samper]

I'm just gonna use the plexi for a lid.....need to know how to cut it what to cut it with and what to use to fasten two pieces together. The light will stand on top of it.

[Sueet]

I'm just gonna use the plexi for a lid.....need to know how to cut it what to cut it with and what to use to fasten two pieces together. The light will stand on top of it.

You know that that light unit has a built in plexi cover right? You really don't need to put another cover between the tank and it, especially if you set it up on the legs. Or am I misunderstanding still?

[Reefland]

Besides, adding a cover of any kind over the surface of your water (between the light and water) will reduce the penetrating light as well as increase the temperature of the tank.

[Samper]

Ahhh ok thanks guys.

[Samper]

I have jumpers, so I need to utilize the plexiglass. If any of you have experience cutting it or building a custom hood using it please let me know.

[Sueet]

I have jumpers, so I need to utilize the plexiglass. If any of you have experience cutting it or building a custom hood using it please let me know.

Sorry, my only direct experience with plexiglas is having my 80gal acrylic burst on me, and I've been researching how to repair it so I can use it as a holding/qt tank... I won't be needing to cut tho, but I did find these links, maybe they might help you? : http://www.scrollsaws.com/Plexig.html and
http://www.thewoodbox.com/data/scrol...xglassinfo.htm

[Samper]

I'll check em out thanks


addicting board huh?

[dougc]

Your best bet is to make up some good drawings of how you want it cut, take it to a plastics shop, and let them cut it. I built a sump using donated plastic and the shop charged me $20 to cut all the pieces. I could not have done as good a job.

[Sueet]

Your best bet is to make up some good drawings of how you want it cut, take it to a plastics shop, and let them cut it. I built a sump using donated plastic and the shop charged me $20 to cut all the pieces. I could not have done as good a job.

dougc... That is a really good idea... I *should* have thought of that, since I just recently had to get storm windows and screens made up for my old cast-iron doors at a little glass/plexi/screen shop down the road.


Samper... Yes... lol.

[Samper]

Thanks for the tip but I've got tools and need to keep my expenses to a minimum.

[big t]

Thanks for the tip but I've got tools and need to keep my expenses to a minimum.

Well if you have the tools you should certainly do it your self! That is by far the best way in my opinion. I try to make everything possable for my reef. In fact the only thing that I didn't make is the tank itself because I couldn't build it for cheeper then the deal I found on a used tank.

Anyway the tools you need to work w/ acrylic are; table saw w/ 80t tcg grind blade; router table w/ adjustable fence and a spiral upcut bit or a straight cut bit, that is about the minimum. Now I cant really picture what a 'hood' made from acrylic would look like, can you draw a picture? Now if you want to bend acrylic that is pretty easy from what I understand, but I have not ever done it myself. You can buy heating strips from you local plastic supply house for about $40. Or you can build your own adjustable bending heater from mdf, nichrome wire and a adjustable power supply to controll the heat. Look around on the net and you should be able to find some plans.

If I had jumpers I would cover the top of my tank w/ plastic gutter guard mesh. It would allow good light penetration and heat dispersion, and keep those pesky fish in the tank.

[saltjunkie]

the grid on Flourescent lights is better for jumpers....


but cutting Plexi... basically anything you would use to cut wood is what will cut plexi..

heating and bending....
a heat gun works good.. but you will not get exact bends unless you build a jig.
also the clean edges are somewhat of a mystery to me.. you have to sand heat and polish them to get the clear clen edges...
the glue is fun.. if you drip it anywhere other than i the seams it kinda melts the plexi.. sop putting the 2 pieces together will not work..............

[AnemicOak]

If it's jumpers you're worried about just get a sheet of lighting grid (egg crate) and cut that to fit (it's about $5 at HD). That way you avoid light blocking & heat issues.

[Tribio]

Here are two pics of the cutter I was handed at Lowe's or HD? at the plexiglass cutting section. It supposed to cut thin tin also. It's a sharp 1" blade at the end but I seem to only use the edge of it. It's used as a score'er???? just like a glass cutter but your supposed to score a 1/4" or 1/2" way through the plexi. Only a couple of dollars. Then break off from the edge of a table like glass. I had trouble with it breaking too far, past my score from trying to cut boxes out of it to fit the filters and pipes in the back from the lid but straight lines were easy.


Sorry to wake the dead posting, but that's what they're there for, right?

[ick sucks]

your best bet is to get it cut by a professional. usually they will do it. the glue you can buy from a plastics place its called weldon. its clear glue almost like water. its runny like water so be carefull when glueing it,it tends to drip alot and can ruin the surface of it. also it requires a needle to be accurate when you glue it. the needles are about 1 dollar at the plastic shop they look just like the kind that take blood.

only thing i can say is take your time when glueing it because it does run and drip like water.

[the mad reefer]

to cut plexi-glass it is best to use a table saw or a circular saw with a guide. this will give you clean square and flush cuts. if you use the score and snap method then you will not have flush ends to glue.

to glue acrylic you must use a solvent cement!! any other glue will fail!! weld-on makes a great product. I use weld-on 16 with a syringe to apply it with.

hth and i have learned this from experiance. I have alot of dyi acrylic items.

[H20 Aquatic Solution]

By all means if anyone has any questions shoot.

To cut acrylic proffesionaly with a table saw you should use a blade with a high # of teeth with no offset. Blades designed for cutting aluminum or copper are the best. They have a similair appearance to a hacksaw type tooth arrangement.

It is absolutely imperative that you get a straight, even cut, or when you use the solvent you will not get a firm tight fit. If this happens you will have to use a thicker solvent made by Weld-On to make up the gaps. Sometimes you can use acrylic shavings mixed with the thinner weld-on solvent to make a thicker cement.

I would recommend against using a circular saw as it could bounce or jiggle and crack/chip the stock material

Once you have your pieces cut but them together and lossely apply a clamp. using a syringe flow the cement along the seam of the to pieces to be joined. Always flowing clue horizontaly and not vertically.

Then gently tighten the clamps... Let sit for an hour or 2 and you are good to go.. Final curing strength takes 2 weeks but will be manageable after 2 hours.


I hope this helps you out a bit.


Sincerely

[pavesi]

quote "To cut acrylic proffesionaly with a table saw you should use a blade with a high # of teeth with no offset. Blades designed for cutting aluminum or copper are the best. They have a similair appearance to a hacksaw type tooth arrangement.

It is absolutely imperative that you get a straight, even cut, or when you use the solvent you will not get a firm tight fit. If this happens you will have to use a thicker solvent made by Weld-On to make up the gaps. Sometimes you can use acrylic shavings mixed with the thinner weld-on solvent to make a thicker cement.

I would recommend against using a circular saw as it could bounce or jiggle and crack/chip the stock material

Once you have your pieces cut but them together and lossely apply a clamp. using a syringe flow the cement along the seam of the to pieces to be joined. Always flowing clue horizontaly and not vertically.
"

Perfect advice.. I have built a couple sumps/refugiums and skimmers using this same type of advice. Weldon 16 is actually MUCH easier to use then the 4 or 8 (lower numbers = less viscosity). The 16 is about right for most people as its a consistancy similar to epoxy, it doesn't just run all over the place. You will although have to be aware that drips/spill if not cleaned up instantly will result in 'burns' in the acrylic.