PVC bending

[elementcollector1]

I have 2 pieces of 4" I.D. PVC. They are about 5'6" long each, and partially cut open to make a 'U' sort of shape. Now, my question is, is there any way to make a curve across the length of the PVC, to make a sort of hemisphere shape?

[Moontanman]

Heat would have to be applied, i do have some experience with PVC, bending it without distorting it greatly will be a problem... Then again if the length is long enough you can bend it into a arc or even a circle but your pieces are too short to do that without heat. with heat you should be able to lay them out flat and then you can bend them into an arc but you would no longer have pipe...

[Schrödinger's hat]

bending it without distorting it greatly will be a problem..

 

I've never had any experience with PVC+heat, but I know of a metal pipe-bending technique that is used to get around this problem.

You cap one or both ends, fill the pipe with sand, sit it vertical, (this is for thinner steel pipe, so maybe something coarser might work?) and heat it with a blowtorch

Then when you bend it, the sand prevents the pipe from collapsing.

You still need a reasonably large radius for the bends, but it stops some of the distortion.

[Moontanman]

I've never had any experience with PVC+heat, but I know of a metal pipe-bending technique that is used to get around this problem.

You cap one or both ends, fill the pipe with sand, sit it vertical, (this is for thinner steel pipe, so maybe something coarser might work?) and heat it with a blowtorch

Then when you bend it, the sand prevents the pipe from collapsing.

You still need a reasonably large radius for the bends, but it stops some of the distortion.

 

 

He said the pipe was already cut into a U shape so the sand trick would not work.

[elementcollector1]

So, I was thinking: If I laid the pieces between two posts, put a heavy spherical object inside the area I want to bend, and heat on the outside, would that cause a bend?

[Pantaz]

Numerous pages on forming PVC -- http://www.google.com/search?q=heat+forming+pvc+pipe

[matty]

Cool. Did you remove material creating the semicircle profile in order to accommodate or house something later; some rerod for a makeshift tent or something?lol Or would it be better to have left it whole, I do see advice that without the sand you get collapse but, anyway, checkout this fixture looking badboy...

http://compare.ebay.com/like/160652823790

 

And the PVC 'Bendit' gadget is neato, checkout the gallery They brag, whoa.

http://pvcbendit.cgom/gallery

 

I had no idea you could bend like this, you always see so many pvc elbows--but then same with a standard pipe, but when I think bend, I'm thinking strictly metals...cool thread.

 

Craigslist, eBay are good places to keep in mind and there's some kinda heat gun fresh on the market you might wanna take a look at, since the bendit was for applications where you'll be needing it a lot. There was an affordable version though, not all instances were upwards of $300.

 

P.S. I think the idea behind the end product you're trying to achieve is everything; for instance, if you put too heavy pressure too fast in the way of that spherical object you'd like to rest in it while two posts support it at either end, you may thin area toward center of the arc you're trying to create and compromise strength or Function; whatchya' tryin' to fashion???

Edited October 16, 2011 by matty

[elementcollector1]

Cool. Did you remove material creating the semicircle profile in order to accommodate or house something later; some rerod for a makeshift tent or something?lol Or would it be better to have left it whole, I do see advice that without the sand you get collapse but, anyway, checkout this fixture looking badboy...

http://compare.ebay....ke/160652823790

 

And the PVC 'Bendit' gadget is neato, checkout the gallery They brag, whoa.

http://pvcbendit.cgom/gallery

 

I had no idea you could bend like this, you always see so many pvc elbows--but then same with a standard pipe, but when I think bend, I'm thinking strictly metals...cool thread.

 

Craigslist, eBay are good places to keep in mind and there's some kinda heat gun fresh on the market you might wanna take a look at, since the bendit was for applications where you'll be needing it a lot. There was an affordable version though, not all instances were upwards of $300.

 

P.S. I think the idea behind the end product you're trying to achieve is everything; for instance, if you put too heavy pressure too fast in the way of that spherical object you'd like to rest in it while two posts support it at either end, you may thin area toward center of the arc you're trying to create and compromise strength or Function; whatchya' tryin' to fashion???

I'm making the Aperture Science Handheld Dual Portal Device from the game Portal. The two white parts on the outside need a curve, as you can see if you look up the in-game worldmodel. And I don't really mind thinning out the PVC a bit, but will that be brittle when I'm done?

Edited October 16, 2011 by elementcollector1

[Externet]

I would restart from the beginning again, bend a complete pipe and later rework/cut its shape to needs.

 

Now; how to bend ? ----> Fit the PVC pipe to a metal hose, like those for a clothes dryer vent; connect it to an automobile exhaust. Shortly the PVC pipe will be like a noodle to form at will.

You will need oven gloves and have the forming jig ready right there.

 

It will not be brittle when cooled.

Edited October 17, 2011 by Externet

[elementcollector1]

Er... that's somewhat beyond my capabilities... I'm only 15.

What about applying a blowtorch a few inches away from the pipe?

[Externet]

Hi.

Am pleased you are not into Nintendos but excercising your knowledge and skills instead.

 

A blow torch will not work from the outside of the pipe. It will create a melting spot area with deformation and possible burning spots. PVC does not transmit heat easily and the rest of the pipe will stay rigid. A heat gun would be too wimpy for the task.

 

The blow torch hot gases -no flame- directed inside the pipe can work. That is why I suggest a length of dryer duct as buffer.

 

Another way could be a kerosene 'garage heater' at a low heat setting but after a good length of pipe so high temperature flames will not be near at all. It is about amount of heat fed, not so much about temperature.

 

The difference between temperature and amount of heat :

A match burns at say 1000 degrees F. A house on fire burns at say 1000 degrees F. Same temperature.

But they put a huge difference in the amount of heat produced.

 

Do some testing with smaller PVC leftovers, say a hair dryer into a 1 inch pipe, evaluate the results and come back.

 

-Get some assistance from a nearby old fart with lots of experiences-

Edited October 17, 2011 by Externet

[matty]

Won't really matter so much on whether it's brittle if it isn't supposed to support any weight and just sits there; what is it's Function, a stationary model?

 

I'm sorry, it's just a link is super helpful. I did try to google it but hm, I'd rather not guess with what I'm coming up with myself in the search, the Game Portal is a website, yes?

[elementcollector1]

Um, not really... It's a game on Steam.

So, where can I get some dryer insulation?

[Externet]

Not dryer insulation.

Clothes dryer vent duct. At any hardware store.

 

Did you try the hair dryer into a small PVC pipe first ?

[elementcollector1]

First test; open-ended PVC: I was able to compress it ever so slightly between my fingers after several minutes of heating.

Second test; closed PVC filled with tissues: Same thing.

The hairdryer was set to Low, as High made a sputtering noise and I was not about to find out what it was.

Your advice?

[Externet]

Hi.

Sorry for responding late, my compfuser died on a power surge and been fixing it a few days.

 

Do all internal heating flow with open end pipe to exhaust the warm gases, no tissue please. What is the tissue meant for ?

If your hair dryer sputters at high speed, it may be something wrong with it, or flow is not flowing.

 

- hair dryer hot air into pipe ----->===============-------> warm air venting

 

- after a while the entire pipe will get hot enough to bend it. Give it enough time, give it enough heat... It will work.

[Erb]

Put a spring the same size as the internal diameter of the pipe. Heat it slightly with a heat gun and you will be able to bend PVC to any angle or distortion you would like. For a complete circle or very large bends you must gradually bend along the pipe so the outside walls don't get too thin. I used to bend PVC conduit up to 150mm in diameter all the time. Take it slow and don't burn it or it'll become too brittle and lose it's strength.

[elementcollector1]

Alright, I'll try again with the hairdryer.

Heat the spring or the pipe?

 

The problem with the spring is that the pipe has been cut open. Would this still work?

[Erb]

You should bend the pipe before you cut it, or the cut will deform. Heat the pipe not the spring..

[elementcollector1]

A bit late for that (no offense), and I could just re-cut it afterwards.

I think I'll get some dryer vent duct, and try that. If that doesn't work, then I'll just buy some new PVC.

[elementcollector1]

Used a blowtorch spray add-on, and the result was great. My pieces bent near perfectly.

[adam_withrow]

the trick for making a bend like that really is the pvc bendit tool that is mentioned lower down on this page. if you were to use a b series bender with a 4" sleeve, you could completely and evenly heat the pipe from end to end, and if you used a second 4" sleeve, you could make the bend without having to worry about the pipe wall collapsing.

 

that is definitely the best way to evenly heat pvc pipe for bending. i noticed that there is a link to the site down below, but it's got the url wrong, so it doesn't work. the url is http://www.pvcbendit.com and the page he was sending you to was the PVC Bendit Gallery

 

It really is a cool tool, and it works great.