MadSci Network: Chemistry

Re: how would I bend pvc to make musical instruments like the Blue Man Group

Date: Thu Oct 5 20:53:34 2000
Posted By: Narayan Variankaval, Grad student, Polymers/Textile and Fiber Engineering, Georgia Tech
Area of science: Chemistry
ID: 968548386.Ch

It seems to me (from reading about it) that it may not be that easy to bend PVC without flattening it. However, it shouldn’t be too difficult if you apply light heat to it. You can do this because PVC is a thermoplastic and it can be heated to some extent without undergoing any irreversible change like a thermoset would (eg. Epoxy). Typical molding temperatures used with PVC range from 300-400F. But it usually softens at much lower temperatures. There were some suggestions on the web as to how one might bend PVC and I list them below with due acknowledgment.

“build a wooden radius form to bend the pipe around. cut a piece of PVC about 3' longer than the distance around the bend. cap one end, pack it full with sand, shake it down good so it is solid. cap the other end. drill a 1/16 hole in each cap and then cover it with tape. fasten one end to the radius form. start heating near this end. heat about a foot or so of pipe at a time until it will bend around the form with just light finger pressure. Move down and heat another section.
You may have to repeat this with several pipe sections until you get the technique down.
You will end up with a $50 -$75 pipe fitting that only took 2 days to make. Depending on where this piece is to be used, consider pressure testing to double actual working pressure. Bending will reduce the burst pressure of the pipe, but it is impossible to estimate how much."

Acknowledgment: Dick Ross

This method will be more successful if the bend is of a low angle. For higher angles it is actually better to buy fittings and glue them. However, the more the number of fittings in the case of a musical instrument, the lower will be the quality of the sound I would guess! The smoothness of the inner surface of the pipe and the number of bends in it and the length between the opening in the pipe will all affect the music coming out of the PVC instrument.

I must say that I went to the URL that you has given as reference (Blue Man Group) and I could notice that the pipes had been bent through connectors or fittings. If you look closely at the picture you will notice that at each bend there are fittings. Of course the fittings are bent but these are small pieces and by the application so light heat I think you can mold them around say metal radii as indicated in the explanation of Dick.

Hope this helps!! Have fun creating music!

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