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Topic: Bending PVC Pipe
Message: Posted by: pastorclyde (Feb 13, 2007 10:09AM)

I'm working on a prop that needs 3/4" pvc pipe bent to odd shapes. Upon heating it I find it very workable but bending it then creates creases. Filling it with sand isn't convenient since it runs about while heating/shaping. Any other ideas as to how I can bend "snake-like" bends in it without creating creases is greatly appreciated!

Thanks in advance for your help.
Message: Posted by: Mick Hanzlik (Feb 13, 2007 11:43AM)
Hi Clyde, long time no hear! Can you use one of those spring type pipe bending units that plumbers use to bend copper pipe without it collapsing? I assume you have them in the States. If it works on copper piping, it must be able to work on pvc pipe.

Just a thought.....

Message: Posted by: freefallillusion1 (Feb 13, 2007 12:22PM)
I made a simple levitation hoop this way- here's what you need to do. I used 1/2 inch and 3/4 inch successfully, but I've heard the larger sizes will tend to collapse when bending. Also, use "schedule 40" pipe as it has thicker walls. If you look at the hardware store, you'll notice the difference. Now, get some 3/4 inch plywood and make a form to bend it around. In my case, it was a big circle since I was simply making a hoop. Make sure your form is as perfect as you can get it- the pipe seems to pick up any little bumps in the finished product. Heat your pipe with a hand held propane torch. There's a knack to this- you want to get it really hot, but slowly, so that it doesn't scorch and catch fire. Also, do this outside because you will produce bad fumes. For me, I heated and bent about 12 inches at a time, and contined around the form. Let the pipe cool and you're there! Don't be discouraged if you don't get this on your first try. I made three hoops before I was happy. Patience is the key- get the pipe really soft and you can make perfect bends. Good luck!

Message: Posted by: pastorclyde (Feb 14, 2007 08:10AM)
Thanks for the help and for the greeting Mick! :)

The bends I need to make are sharper than a bending tool (for copper pipe, etc.) is able to make. Mine is in the shape of a dollar sign. The two rounded sections are fairly easy to do- its the sharper beginning and end of the bend that tougher to do without it crushing. I'm going to buy a spring for the inside of the pipe and see if it will prevent it from crushing in that area. If that doesn't work I'll seal it full of sand prior to shaping it.

Message: Posted by: gsidhe (Feb 14, 2007 08:16AM)
I have never used a propane torch to bend PVC...Too hard to control. For the heating I always used boiling oil on a hot plate. It heats the pipe very uniformly, and that seems to help with collapsing.
Just my imput.
Message: Posted by: kaytracy (Feb 14, 2007 08:43AM)
When using the sand inside, I just push end caps onto the pipe and add a tiny bit of duct tape to insure they stay put. Though I admit to not having done such sharp curves.
Message: Posted by: VisualRiddles (Feb 14, 2007 07:56PM)
Would pex pipe work? It's not as sturdy as schedule 40 but it bends nicely with a little heat. Oh and I'd use a heat gun instead of a torch.
Message: Posted by: CardConjurer (Feb 15, 2007 02:02PM)
Yeah, I'm pretty sure theres no way a copper pipe bending tool will work on PVC... I worked in a hardware store for a few years, and we had some small sections of pvc that had been pre bent and shaped. I know they have sections like this available in like 1/2" and 3/4", but any bigger than that I am not sure. Never really tried to heat up a pipe, but I bet that's your best option.
Message: Posted by: leapinglizards (Feb 17, 2007 10:34AM)
I often melt PVC to make artificial bamboo. If you have to keep it "puffed up" you could fill it with sand, and cap the ends, or preassurize it with air from a scuba tank, and cap it off. Also, rather than make a bending form that is just a flat shape, make it the thickness of whatever pipe you are trying to bend, and give it a top and bottom surface that overlaps by the same thickness as well.

This way you are bending it in side a groove. If the edges can't pop OUT, there is less chance of it caving in on sharper bents.

Heat it by boiling (Water works, though I never thought of oil!) or with a constant heat gun is less risky than a torch. If you DO use the torch, PLEASE have fire extingusiher on hand, and use a torch meant for weeding or pipe defrosting, rather than for welding, and PLEASE have welder's gloves.

Once the pipe is melted and bent to shape, you have to let it cool 100% before you remove it from the form, or it will spring back.

Any reason not to just cut this out of a solid substance? or if it has to be hollow, cut it fron lawers of wood or acrylic, and then laminate them together? Might be less effort if you only need ONE.... if you want to make more, then a bending form would be easier.

Let us see pictures when you're done!
Message: Posted by: pastorclyde (Feb 17, 2007 09:05PM)
Thanks for your input everyone. I heat mine over the gas stove. if done slowly it doesn't brown. I place it in water to set it and that too works well. I'll try the sand with caps and then a mold if the sand/caps don't work well. I'll let you know how I make out.
Message: Posted by: Dave Lewis (Mar 1, 2007 01:11AM)
Please be careful not to breathe any fumes or smoke that may come off PVC if it should ignite. The fumes are toxic and could kill you, according to those in the aquarium business, where forming PVC is done extensively.
Message: Posted by: pastorclyde (Mar 2, 2007 07:18AM)
Thank you Dave! I will be working on it this upcoming week hopefully so I'll let everyone know how it went.

Message: Posted by: Magic Tad (Mar 3, 2007 12:18AM)
Another way I have bent pvc pipe is with a spring around it (a soft flexable spring like one from a screen door but larger, Maybe a garage door spring) Some pumbers use these to bend copper cold. If you can get a spring that fits your pipe snugly enough you can heat it gingerly so as not to damage your spring and bend away. The spring will keep the round shape and can be slid off or if you make tight turns you can uncoil the spring carefully. Good luck Magic Tad
Message: Posted by: Charlie the Tuna (Mar 7, 2007 03:31PM)
Clyde, What type of prop are you building? There may be other material which may be easier to work with.
Message: Posted by: Zazz (Mar 8, 2007 10:45PM)
I am an electrician and there are several ways you can bend PVC pipe.
A propane torch is one way if you are very careful not to scorch the pipe.
Electricians have, in a pinch, heated up PVC by holding it up to the exhaust pipe of a truck or tractor. Not the best way.
The two most common methods of bending PVC pipe is with the use of a heat blanket or heater box.
These items are a little pricey but they can be rented.
When heating the PVC it should feel like a wet noodle before you start shaping it. If done correctly you shouldn't have to put anything inside the pipe like sand or springs.
The ideas made above are good for making a jig and I would suggest having a bucket of water handy and when you have the shape you are happy with lay a soaked towel on top of the hot pipe to speed up the hardening process.

Message: Posted by: Dave Lewis (Dec 31, 2007 01:26AM)
I've always been extremely careful not to catch PVC on fire because I was told the smoke/fumes are essentially cyanide gas. Not keen on expiring in order to bend up some plastic pipe!
Message: Posted by: owln_1 (Jan 8, 2008 11:03AM)
Might try a heat gun. owln_1