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PVC molding?

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PVC molding?

Unread postAuthor: PVC Arsenal 17 » Mon Jun 29, 2009 5:03 pm

Is it possible to melt down PVC and mold it around existing dry PVC? Will it adhere properly and retain reasonable strength?

The picture should explain what I'm trying to accomplish.

The darker circle is a length of pipe, the black square is the mold. The lighter gray is liquid PVC.

(Step 5 is irrelevant, it's just what I plan to do with a section of the square stock after I make it)
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Unread postAuthor: theBOOM » Mon Jun 29, 2009 5:18 pm

I have tried it before with other things... Doing this would be a close to impossible task. For starters you would need to apply even amount of cointious heat to the pvc for it to melt... When it melts it is nearly a liquid and it hardens REALLY fast (im talking seconds here)... It would be preatty cool but extremely difficult to achieve... if yuor gonna do this you might just wanna get a pvc rod and drill a hole of your disered diameter...

If you do get it which I'm predicting you wont... you will have a Solid SEAL ... I think this is called thermobonding and it's as if you got a whole new piece of pipe... So if you do try it good luck and try not to get it on your body beacause it BURNS.

hope this helped

BOOM :twisted:


EDIT: I think there was a thread about melting pvc you might wanna try the advanced search tool so you might get different adivce,help or opiniones
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Unread postAuthor: PVC Arsenal 17 » Mon Jun 29, 2009 5:31 pm

Ah, I wasn't aware of that topic. I guess I'm better off doing this with epoxy or even bondo. I just thought PVC would be more convenient since I have a ton of it. Thanks for the tips.
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Unread postAuthor: theBOOM » Mon Jun 29, 2009 7:16 pm

Sure... yes I would read up on jack's epoxy casting so you can make a nice chamber.... plus I think it has a pressure rated of 1600 for marine epoxy and 3.5k (I think) for jb weld :D ... anyway good luck :lol:

Boom :twisted:
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Unread postAuthor: THUNDERLORD » Mon Jun 29, 2009 7:50 pm

Off topic slightly, but if you have that much epoxy,
it's fun to take epoxy and glue the key locks of an office you don't like.
If you have enough you can glue the whole door frame shut!!!
It's fun to glue your teacher's stapler and accessories on thier desk to thier desk...
Or put it on a toilet seat in a busy bathroom may7be...
Glue cardoors shut etc. etc. etc.
Maybe you can pick up a stiff road kill and set it up and glue it's feet in a road
IDK but now I gotz 1000 posts and 5 more spudz bucksez bux too!!!
:P :P :P 8) 8) 8)
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Unread postAuthor: btrettel » Mon Jun 29, 2009 8:51 pm

PVC is a thermoplastic so yes, this is possible. But generally you can't form it well in that state without the proper molding equipment.

The "pressure rating" theBOOM mentioned is maximum shear stress mentioned on the package (as far as I know) which is not the same as maximum pressure differential. Generally the maximum stress in the material is far higher than the maximum pressure differential. Also, shear stress is only one type of stress, and safety factors are essential.

I'd suggest either working with something like epoxy or starting with square PVC rods and using a lathe and/or mill to get what you want.
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All spud gun related projects are currently on hold.

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Unread postAuthor: Technician1002 » Tue Jun 30, 2009 1:12 am

btrettel wrote:PVC is a thermoplastic so yes, this is possible. But generally you can't form it well in that state without the proper molding equipment.

The "pressure rating" theBOOM mentioned is maximum shear stress mentioned on the package (as far as I know) which is not the same as maximum pressure differential. Generally the maximum stress in the material is far higher than the maximum pressure differential. Also, shear stress is only one type of stress, and safety factors are essential.

I'd suggest either working with something like epoxy or starting with square PVC rods and using a lathe and/or mill to get what you want.


It has a very narrow temp band between viscous and carbonizes.

Softening Starts, (approx.) 250°F

Material Becomes Viscous 350°F

Material Carbonizes 425°F
From here..

http://www.sd-w.com/civil/pipe_data.htm

All my work bending and and forming PVC pipe and conduit, I have never seen the "viscous" state. It goes from being pliable like a garden hose to toasted with no liquid or flow state in between.

There are many formulations of PVC. It is all the way from soft children's toys, garden hose, bags, to hard pipe.
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Unread postAuthor: mark.f » Tue Jun 30, 2009 4:08 am

If you're looking to make a bracket, why not make up some sheet PVC, and then make a jig to bend it at a 90-degree angle?
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Unread postAuthor: Technician1002 » Tue Jun 30, 2009 4:29 am

mark.f wrote:If you're looking to make a bracket, why not make up some sheet PVC, and then make a jig to bend it at a 90-degree angle?


I doubt he is making a bracelet for the competition. The hole is bent 90 degrees. The finished material is a solid block with an elbow section inside it.

I've never gotten PVC pipe to flow as a gel or liquid ever. I can't see any way to make a mold and pour it in. Not going to happen. It softens and becomes pliable like a garden hose, and if over heated, toasts, or scorches like a marshmallow. Examples of bent PVC below.
http://www.spudfiles.com/forums/reformi ... 18417.html
http://www.spudfiles.com/forums/general ... 18336.html
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Unread postAuthor: mark.f » Tue Jun 30, 2009 1:51 pm

I was wondering what that little block floating in the middle of nowhere was.
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Unread postAuthor: psycix » Tue Jun 30, 2009 3:07 pm

(Step 5 is irrelevant, it's just what I plan to do with a section of the square stock after I make it)


Lets get onto this topic (once again). PVC may burn before melting, and that will cause the need for an inert or vacuum atmosphere.
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Unread postAuthor: THUNDERLORD » Tue Jun 30, 2009 7:14 pm

It's probably not too much different from polycarbonate or other clear acrylic, which can be heated to mold temperatures using a plywood box with some standard light bulbs inside, a dimmer switch and an oven thermometer to manually work the dimmer as a thermostat.
OR boiling water (been done on SF's before)...( the m-16 styled BBMG from PVC) (link now...(???))

It would be cool to create polycarbonate body armor...

BTW, one time I was thinking (mesh) steel window screen could be folded together to make bullet resistant body armor...
I discussed the idea with a friend who disagreed until he got so urked, he removed a screen from his window folded it until about 64 layers... shot it with a 2.5" barrel .22 LR, which penetrated that and 1.5 phone books behind it...."Back to the drawing board"...would've been cool to add fiberglass bondo and create hard armor... :oops: :lol: :x 8)
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