Picture of PVC VISE ADAPTER -- for holding pipe
My vise has jaws that were designed for holding flat material, not round pipe. The adapters I made hold the pipe more securely and without damaging the pipe. I made adapters for different sizes of pipe.

The adapters are easy to put on the vise and to take off. They just slide over the jaws.
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Step 1: Safety while heating PVC

Picture of Safety while heating PVC
We love plastics for what they do for us, but plastic manufacture and decay tend to pollute the environment and negatively affect our health.

Vinyl Chloride, one of the components of PVC, is carcinogenic. When it is locked up in the polymer, however, it is much safer to be around. In my years of experience working with PVC, I have not noticed any adverse effects on my health from being around it.

Always work in areas with good ventilation. If you do get caught in a cloud of smoke, hold your breath and move to clean air.

When heating PVC with a gas stove or propane torch, try not to let it burn. Smoke from burning PVC is bad. With experience one burns it less and less. Don't panic the first time you do burn some. It scorches, but doesn't immediately burst into flame. Move the material away from the flame and try again. Don't breathe the smoke. Smoke avoidance comes naturally for most people.

While heating PVC over a gas flame, keep the plastic an appropriate distance from the flame to avoid scorching the surface before the inside can warm up. It takes time for heat to travel to the center of the material being heated.

Keep the plastic moving, and keep an eye on the state of the plastic. When heated, the PVC material is flexible, like leather. Beyond this stage, you risk scorching it.

A word from James, the plastic engineer -- "Just a word of warning, PVC can handle some high heats but if it catches fire, you wont be able to put it out, it does not need oxygen to burn so don't do this inside".

I do work inside, but my house is made of cement and has good ventilation. MAKE SURE THAT YOU HAVE GOOD VENTILATION. PLAY WITH FIRE -- CAREFULLY.
cw876 months ago

Why not use a thick piece of leather?

Thinkenstein (author)  cw876 months ago

I'm sure that might be useful at times. The rigid plastic is better in this case, because if the pipe wants to travel upward, the plastic stops the upward movement. Leather might flex and let the pipe pass.

DoxxRoxx6 months ago

Great idea for shaped vise jaws!

I have used boiling water to soften PVC to a bendable state on many occasions. PVC gets soft at 100C (boiling water). It's melting point is 100 - 260C. If you need more heat than 100C, use some type of heated oil as the bath.

This project is a perfect size for boiling water immersion. Plus, no bad fumes from PVC decomposition to worry about. If you don't get the right shape the fist go, just put the piece back in the bath to re-soften

It goes without saying, but please make sure you use gloves when handling hot plastic.

You will have to experiment as to the time needed to fully soften the material for your purpose; dependent on the size and thickness of the work piece. Sand filled tubing is a bonus, as it should hold the heat to allow for a longer working time provided the sand also gets +100C.

I will admit though, it takes a bit of ingenuity to use this process on a 20' stick of PVC.

I've thought about steam, but have yet to try it.

Thinkenstein (author)  DoxxRoxx6 months ago

Note that there is very little burned plastic from heating it over a flame, if you keep the work at an appropriate distance from the flame and in constant motion.

Heating it indirectly by using hot water seems like you would be wasting fuel heating the water first. Still, if it works for you, go for it.

lemonie5 years ago
Neat. Have you got any devices for PVC pipe bending?

Thinkenstein (author)  lemonie5 years ago
Not a device, but a technique. Fill the pipe with sand, ends capped with masking tape. Heat the pipe, bend it, let it cool, empty out the sand.
That's a good one. Do you think it would work with copper? L
lime3D lemonie1 year ago
For copper, fill the pipe with soapy water, and freeze it. It can be bent without heat, and the ice will melt when you are done. This is how brass trumpets and trombones are made.
Thinkenstein (author)  lime3D1 year ago
Nice bit of info. Thanks.
Thinkenstein (author)  lemonie5 years ago
I never tried it. It seems like the general idea would be the same. The sand keeps the pipe from pinching shut when bent. Bending it inside a channel, like a pulley wheel might help, too. Also, maybe heating one side more than the other, perhaps to favor stretching over compression.
I might try it - no need for pipe-benders! L
I just found a great new fast easy technique for bending pvc pipe.

I have used this with 1/2 inch internal diameter schedule 40 pipe, but I have heard it can work with larger pipe as well. The one tool you need is a long spring (like the springs on old time screen doors) that is close to the inside diameter of the pipe you want to bend.

After attaching a string to one end of the spring, you insert the spring so it is centered on the area the bend will be in. Grasp the pipe on either side of where you want the bend to be and smoothly pull it against your bent knee (or any other sturdy rounded form) until you have bent it to the curve you want. Magically the spring will prevent the pipe from collapsing or kinking on the bend. You may have to slightly unbend it to remove the spring, but you can rebend it after the spring is removed.

For larger diameters (up to 4 inches) you might need a pipe bender (like they use for metal pipe bending) in addition to an appropriate sized spring to give you enough leverage to bend the pipe.

Here is a video of how it works with a fancy purpose made ($30) spring, but at least for the 1/2" pipe I find the $2.95 spring from the hardware store works just fine.

For the larger diameters it is hard to find the right diameter spring, so you might just have to bite the bullet and get the "Pipeviper" pipe bending spring:

Make an instructable on that one? It sounds useful.

A heat gun would be safer than a touch.
Phil B5 years ago
My brothers gave me a gift certificate to a home improvement store on the occasion of my birthday. After a lot of thinking about a practical way to use it, I bought a heavy duty heat gun. I can already tell it will be very handy for any project in which I want to bend and form PVC. This Instructable is a good idea. A person could make simple covers for vise jaws so soft materials can be held without marring them. I may make a set for myself tonight. Thanks.
Thinkenstein (author)  Phil B5 years ago
You're welcome. Good luck with your soft jaw project.
rimar20005 years ago
Very well done. For that task I use some sheets of newspaper folded repeatedly.

But that is because I do not usually press delicate things in the vise.

I liked the step 7, it is a detail that often is overlooked (see step 5)