For all Acrylic Experts

snakeblitz33

snakeblitz33

Well-Known Member
Hi,
I am trying to get into building sumps, refugiums, aquariums and terrariums out of acrylic. I know how to do straight edges, which are really easy.
What I can't "wrap" my head around is how to put a bend in acrylic. I have read and read online about bending acrylic, but I want to bend a sheet into a perfect circle.
I know in order to do this that I need a mold, so I was considering creating a half circle and laying a sheet of 1/2" acrylic int he center of the mold and using a heat gun to mold it into shape. Then, using a second sheet of acrylic and repeating the process and just welding them together to form a perfect circle. Would this be the best way to go about doing it?
HOWEVER, I have seen large acrylic companies use something like heating blankets over their molds and then laying the acrylic on top of it to mold it in place. What kind of blanket is this and where can I find one?
By the way, the diameter of this tube would be 2 feet and the length would be 5ft. I am making a custom built protein skimmer for a client, I guess I am a little out of my league.
 
acrylic51

acrylic51

Active Member
Shoot a PM to Acrylic (James) he might be able to give you some info.....Doing it on a heater strip you'll get tons of distortion in your panel....I have a 4' heater for acrylic, and you actually need a oven to bend the pieces correctly....This is how the major "acrylic" players usually do it.....
 
snakeblitz33

snakeblitz33

Well-Known Member
ah, so using a nice large oven to heat the acrylic up first and then laying it down on a mold would probably be the best way to go about doing it...
 
snakeblitz33

snakeblitz33

Well-Known Member
how hot would the oven have to get? I know a friend who has a powder coating oven that I can use... it gets to about 300 to 400 degrees F.
 
snakeblitz33

snakeblitz33

Well-Known Member
not necessarily, I was talking about a cylander that is 2 foot in diameter and two foot tall.
that means that I would have to have either two sheets of acrylic
OR the other mathmatical schmatical way of doing it... I would need some help. lol. I guess I should have paid attention in Geometry.
 
snakeblitz33

snakeblitz33

Well-Known Member
How do you think acrylic manufacturing companies bend those very large sheets?!
I am trying to take the simple approach without having to buy a large oven.
Is there some other kind of material that can be used, that is already cylindrical and about 1 1/2 foot in diameter?
 
acrylics

acrylics

Member
You can buy pre-made acrylic tubes up to 96" diameter. Theses cylinders are spun-cast so no bending required. To make your own in an oven is an altogether different issue. You will need an oven to do this, heat strips and heat guns *can* work but not in radii this large as a generality. And forget the straight numbers from geometry; you will need to account for material shrinkage and when you form acrylic - the radius always runs smaller than anticipated. Ie, if you make a 24" radius mold, the material will actually come out at say 21-22" radius. The actual outcome is only learned from experience and practice. The radius will change with longer heat times and different heat ranges. BTW 300F is a good average temperature to start with.
HTH,
James
 
snakeblitz33

snakeblitz33

Well-Known Member
Wow, thanks for the information. Where can I find these acrylic tubes online? I keep looking but I have yet to find a supplier!
 
acrylics

acrylics

Member
Originally Posted by SnakeBlitz33
http:///forum/post/2509571
Wow, thanks for the information. Where can I find these acrylic tubes online? I keep looking but I have yet to find a supplier!
Look for companies such as Laird Plastics (www.lairdplastics.com) or GE Polymershapes (www.gepolymershapes.com), there are others as well. But, I would strongly advise you to look in the yellow pages in the nearest large city (not sure where in LA you are located). Look in the yellow pages under plastics; distributors, sheet, rod, film or something to this effect. The 24" diameter tube is made by 2 companies, one is Spartech (mfrs of Polycast sheet) who bought Townsend and Glasflex (old tube mfrs) several yrs ago. The other is Reynolds Polymers, who make good stuff but not the easiest folks to work with for smaller orders. I say order locally as probably 30% of all acrylic tube of this size is damaged in shipment so let the local distributor handle the mess. Ie., do not let them ship in to your place, go pick the good material up at theirs.
HTH,
James
 
geoj

geoj

Active Member
circumference = pi multiplied by diameter
24 inches is diameter
pi is 3.1416
75.398 inches
half is 37.699 inches
account for material shrinkage and your good
 
snakeblitz33

snakeblitz33

Well-Known Member
the thing is that I am not experienced enough with an oven to account for shrinkage. It would be much much easier to just order it from a plastics company in Shreveport, LA.
Thanks for all your help. ...
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