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Lexan/Polycarbonate Joining question

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N

NovaShine

Member
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Joined
Nov 20, 2003
Location
Sydney Australia
Well, im going to be making a reservoir using Lexan. It's been planned out, and cut, but since this is my first time working with Lexan, im not too sure what to use to join the peices together. First, my friend suggested chloroform to weld, later on, we found out that that dosnt work on Lexan, then we thought Sillicone rubber stuff. That joined our scrap pieces, but after 12hrs of drying, a low force wiggle caused the two pieces to come apart.

This reservoir is going to be rather complicated so there are alot of joins, but mainly, the joints will be butt joints.

The Lexan is 6mm thick, so i guess that's going to be the thick stuff. What could i use to hold the lexan together? Will Sillicone + thin screws work? Anything to look out for?
 
Dosnt anyone know? I really need the answer to this soon or i'll never get this reservoir made up and no reservoir means i cant get this watercooling setup :(
 
Angle irons will hold, but you probably need some kind of sealant aswell.
 
silicone sealant works well, which is what we used to use on our fishtank. You can get it at home depot for about $3 - $5. If you've got a caulk gun, that really helps too :)
 
I tried sillicone sealant on some scrap pieces, it really didnt hold very well, snapped off easily even after 12hrs of drying. It was some GE stuff.

Im not quite sure what u mean by Angle Irons. Any pics?
 
You need Polycarbonate Adhesive

I buy it in small tins from my nearest plastics shop (where I also buy scrap at really low prices). It's rather liquidy, clear, and dries in minutes with a permanent bond. It's easiest to brush it onto the area you want to join with a cheap watercolor brush of some kind so you can make sure to get an even application. There are two different formulas. One tries faster and is not as runny, the other is very liquid and dries rather fast.
Works with acrylic as well.
 
I searched all the plastic shops in my area and none of them have that Lexan joining solvent. They say, nobody in HK has that kind of stuff and even if they did, it would be prohibitably expensive. I showed them all the pieces i cut and they said, with the current techniques in HK to put that stuff together, it would fall apart and pour water all over my com in 1 - 2 months time, being optimistic...

Anyway, they suggested using Acrylic. They got some pretty high quality 1cm thick acrylic they could cut for me, i was thinking, well, if i could get it professionally done, might as well since im gonna have no way of cutting that kind of plastic again since school's out and i cant use their facilities no more.

So what do u guys say about Acrylic? Will it work as a reservoir?
 
NovaShine said:
So what do u guys say about Acrylic? Will it work as a reservoir?
Click to expand...
Yep. but while theyr cutting it for you you may also want to have them drill and tap the holes for the barbs. Acrylic is a rather fussy material when it comes to drilling.
 
I knew I should have clarified ;). I meant after you bind it, use silicone sealant to be sure there arn't any leaks. I used Plastic Fusion epoxy to bind my lexan for my CPU fan duct, and it seems to be holding quite well. I would drop it on the floor to see how durable it is, but I'm afraid that it isn't as strong as I hope and I'll have to re-glue everything :(.
 
thanks guys, much appreciated...

about that plastic fusion thing, i've never seen it, the guys at the plastic shop claim it dosnt exist in HK and this res is meant to hold water... Needs to be tuff. Well, back to the drawing board. If it's gonna be professionally made, might as well make it more complicated.
 
Yeah. I found the plastic fusion at home depot with all the adhisives, in the "glue" section. It was with all the differant types of epoxies, it's yellowish color. It was $2 - $3 for it here (Idaho)
 
Im not sure if it's just with plexiglass, but take a few scrap pieces, put it on a rag and fold it in half, smash it a few times until only small chips remain, dump these into a jar and add some acetone, enough to turn it into a paste. smear a decent ammount on your joints and press them together. As the acetone melts into the two main pieces of plexi, the plexi joins with the other.

When the acetone evaporates, you should have two glued together pieces of plexiglass :-D

I robbed this from a bit-tech article I think, it's been a while.


(edit)

Heres the article from the bit-tech archive.

Q: How do I glue acrylic pieces together?

A: IPS Weld-on #3 or #4 are suitable adhesives available from your plastics supplier. You can use other products, but these are specially formulated. Use #3 if you're working with Lexan. Use #4 if you're working with Acrylic. #3 may make your seams appear cloudy if applied in humid conditions. The adhesive is the consistency of water. Use a needle applicator available from your supplier to apply the adhesive. Edges to be glued should not be polished. Use corner clamps to hold the joint together under mild pressure. Apply the cement to the inside of the joint, keeping the joint horizontal. The adhesive will flow into the joint by capillary action. The bond will set in about an hour, but allow eight hours or more for the adhesive to fully cure before removing the clamps.


(/edit)
 
Last edited:
Pro*Banshee said:
Im not sure if it's just with plexiglass, but take a few scrap pieces, put it on a rag and fold it in half, smash it a few times until only small chips remain, dump these into a jar and add some acetone, enough to turn it into a paste. smear a decent ammount on your joints and press them together. As the acetone melts into the two main pieces of plexi, the plexi joins with the other.

When the acetone evaporates, you should have two glued together pieces of plexiglass :-D

I robbed this from a bit-tech article I think, it's been a while.


(edit)

Heres the article from the bit-tech archive.

Q: How do I glue acrylic pieces together?

A: IPS Weld-on #3 or #4 are suitable adhesives available from your plastics supplier. You can use other products, but these are specially formulated. Use #3 if you're working with Lexan. Use #4 if you're working with Acrylic. #3 may make your seams appear cloudy if applied in humid conditions. The adhesive is the consistency of water. Use a needle applicator available from your supplier to apply the adhesive. Edges to be glued should not be polished. Use corner clamps to hold the joint together under mild pressure. Apply the cement to the inside of the joint, keeping the joint horizontal. The adhesive will flow into the joint by capillary action. The bond will set in about an hour, but allow eight hours or more for the adhesive to fully cure before removing the clamps.


(/edit)
Click to expand...
 
You can also use methlyene chloride to bond acrylic (apparently works with lexan as well). It's a solvent that melts the two parts together (work in a well ventilated space). It looks like you can buy bottles on Amazon, so it shouldn't be too hard to find.
For longer working time and to get a more perfect finish, you can add some acetic acid to it (if you apply this mixture to a bond using a syringe you can get a bubble-free joint that is quite strong; this is how most acrylic cases are bonded).
Tape your parts tightly with masking tape into the shape required and use a paintbrush (or syringe), lightly loaded, to touch the edge of the joint. You'll see the methylene chloride get sucked into the joint; this bond will take several minutes to gain full strength, though is pretty tough at about 30 seconds (for a waterproof application, you'd want to ensure perfectly sanded edges and full solvent penetration of the bond. thicker plastic is more forgiving for a tight seal)
You can also just use a paintbrush and It is advisable to sand the bonding edge first for a smooth finish.
 
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