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Posted by lostfrom68jay@googlemail.com on April 8, 2008, 6:54 pm
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I want to make an oval shape from a 28" length of 2.1" OD, .050" wall,
grey PVC drainpipe, flattening it to about half it's original
diameter. It's too big for the oven, and I don't know anyone in the
pizza business (let alone someone cool enough to let me contaminate
their pizzas with dioxin!) so I'm wondering if I could do this with a
heat gun and weighted boards. Any tips, or means I haven't thought of?
Robobass
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Posted by Ecnerwal on April 8, 2008, 7:24 pm
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In article
> Any tips, or means I haven't thought of?
Hot water. Plug the bottom "well enough", pour in hot/boiling water,
wait a few minutes, dump the water, pull the plug, shape before it cools.
--
Cats, coffee, chocolate...vices to live by
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Posted by RoyJ on April 8, 2008, 7:29 pm
Please log in for more thread options A heat gun will work fine. For that size tube, just aim the heat gun
through the tube, maybe swapping ends every couple of minutes to get
even heating. The typical 1500 watt heat gun will warm the tube up to
the proper temp in a few minutes.
I might use something a bit fancier than a flat board. It seems that for
any tube, once you get past a certain point it will start inverting in
the center, forms a figure 8 rather than an oval. The exact point it
does that depends on the wall thickness to diameter ratio and the material.
lostfrom68jay@googlemail.com wrote:
> I want to make an oval shape from a 28" length of 2.1" OD, .050" wall,
> grey PVC drainpipe, flattening it to about half it's original
> diameter. It's too big for the oven, and I don't know anyone in the
> pizza business (let alone someone cool enough to let me contaminate
> their pizzas with dioxin!) so I'm wondering if I could do this with a
> heat gun and weighted boards. Any tips, or means I haven't thought of?
> Robobass
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Posted by Al Patrick on April 8, 2008, 8:05 pm
Please log in for more thread options I *think* that melts not much above 122 degrees F. Once it starts
softening it will "melt" pretty quickly and get very floppy. You'll
need gloves and it wouldn't hurt to have a "form" approximately like the
shape you want it to finish in. Once it start getting hot you may want
to heat it very gently and start pressing it into the shape you want.
Not sure on melting point of PVC but the 2008 NEC won't allow it to be
used in ambient air above 122 F and the wire which may be rated above
that temp has to be derated (load wise) to 122F.
Let us know how it works.
========
RoyJ wrote:
> A heat gun will work fine. For that size tube, just aim the heat gun
> through the tube, maybe swapping ends every couple of minutes to get
> even heating. The typical 1500 watt heat gun will warm the tube up to
> the proper temp in a few minutes.
>
> I might use something a bit fancier than a flat board. It seems that for
> any tube, once you get past a certain point it will start inverting in
> the center, forms a figure 8 rather than an oval. The exact point it
> does that depends on the wall thickness to diameter ratio and the material.
>
> lostfrom68jay@googlemail.com wrote:
>> I want to make an oval shape from a 28" length of 2.1" OD, .050" wall,
>> grey PVC drainpipe, flattening it to about half it's original
>> diameter. It's too big for the oven, and I don't know anyone in the
>> pizza business (let alone someone cool enough to let me contaminate
>> their pizzas with dioxin!) so I'm wondering if I could do this with a
>> heat gun and weighted boards. Any tips, or means I haven't thought of?
>> Robobass
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Posted by RoyJ on April 8, 2008, 10:17 pm
Please log in for more thread options The 122F temp is where the PVC starts to soften or deflect ie lose it's
structural strength. Fully melted processing temp is 310F to 390F
depending on exact composition. The temp the OP needs to soften the
tube enough to form the tube and take a set is in the 200 to 250 degree
range. Much hotter than you can handle with bare hands or even thin gloves.
I'd agree that a good form and slow heating once you get close it a good
idea. You can set the final shape by plunging into cold water but it
will have a good deal of memory and spring back.
Al Patrick wrote:
> I *think* that melts not much above 122 degrees F. Once it starts
> softening it will "melt" pretty quickly and get very floppy. You'll
> need gloves and it wouldn't hurt to have a "form" approximately like the
> shape you want it to finish in. Once it start getting hot you may want
> to heat it very gently and start pressing it into the shape you want.
>
> Not sure on melting point of PVC but the 2008 NEC won't allow it to be
> used in ambient air above 122 F and the wire which may be rated above
> that temp has to be derated (load wise) to 122F.
>
> Let us know how it works.
>
> ========
>
> RoyJ wrote:
>> A heat gun will work fine. For that size tube, just aim the heat gun
>> through the tube, maybe swapping ends every couple of minutes to get
>> even heating. The typical 1500 watt heat gun will warm the tube up to
>> the proper temp in a few minutes.
>>
>> I might use something a bit fancier than a flat board. It seems that
>> for any tube, once you get past a certain point it will start
>> inverting in the center, forms a figure 8 rather than an oval. The
>> exact point it does that depends on the wall thickness to diameter
>> ratio and the material.
>>
>> lostfrom68jay@googlemail.com wrote:
>>> I want to make an oval shape from a 28" length of 2.1" OD, .050" wall,
>>> grey PVC drainpipe, flattening it to about half it's original
>>> diameter. It's too big for the oven, and I don't know anyone in the
>>> pizza business (let alone someone cool enough to let me contaminate
>>> their pizzas with dioxin!) so I'm wondering if I could do this with a
>>> heat gun and weighted boards. Any tips, or means I haven't thought of?
>>> Robobass
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