PVC and other materials are not that expensive in tube form, but the problem
is how they are specified. PVC and HDPE are specified in the outside
diameter only but the inside diameter is the quoted "size". The thickness is
a minimum for each type. What happens is the wall thickness varies on the
inside. The outside is where the fittings go. The fittings also straighten
out the pipe, so they don't care about oval shapes.

I get mine specially made so it is uniform in thickness and is round. This
costs a lot more.

For chunks or rods of plastic, the price goes way up according to thickness
and pigmentation. I get that specially made so that there is no air in it
and it meets a certain flex rating while meeting a test of brittleness. This
costs more. In fact I have to get it made in Germany and shipped here.

To make a body out of HDPE requires a ridiculous thickness and large, thick
bulkheads , while the PVC tubes I use would stand 300 feet with no
bulkheads. I bulkhead them for an 800 foot calculation, way too much.

The nice think about PVC is that it has a chemical bonding material and it
can also be welded. The fake moron does not know that, so he confused the
two. I do both where necessary, and if there is a break of something I can
weld it back.

This asswipe also complains about "returns for repairs". I lifetime
guarantee the scooters and ask that the owners send me the motors and
anything else for all repairs which I do at cost of parts or for free, and I
have backed up every single one of these things for nine years. I can do
that, a nickel rocket roach can not.

-----Original Message-----
From: Matthias Voss [mailto:mat.voss@t-*.de*]
Sent: Friday, September 07, 2001 4:48 AM
To: terry michael
Cc: Trey; techdiver@aquanaut.com
Subject: Re: George has done it again!



Terry,
here in Germany prices for tubings are about
DM 100,-/m for 300mm diameter PVC , 16 bar
DM 64,-/m same, 12,5 bar;

DM 132,-/m for HDPE 315mm ID, 29mm walls, 12,5 bar.

Latter require some shielding as an upper laying when layed in the ditch
and buried.

The design criteria closely to be watched, among else, are the stiffness
of the geometrical shape, dependant on geometry and mechanical
properties.

Remember it is not so much the cost of the material, but the spent in
the manufacturing and development process which determine a products
price.
For simple stuff, as a rule of thumb approximation you may use the
formula " customer price = 4 x materials price.
But this only for stuff where there is  not that much artisans work
involved ( like rewinding coils)
Matthias


terry michael schrieb:
>
> I think the only real problem with PVC in some cases is purely political.
i.e. PVC is no good for canister lights but for canister scooters it's fine
etc. If you look at the chemical properties of each you'll see that each has
it's advantages and disadvantages depending on the application. Is it really
that much cheaper to use PVC?
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