[Amps] : Silicone hose from Flex Technologies

[Jim Thomson]

Date: Sat, 21 Jul 2012 19:17:54 +0000
From: Manfred Mornhinweg <manfred at ludens.cl>
Subject: Re: [Amps] Silicone hose from Flex Technologies


When you need custom silicone parts, such as tube chimneys, they can 
often be made completely from RTV sealant. Just find or make a suitable 
form, smear sealant into it, let it set, then remove the form.

I have made many small silicone parts by making forms on a lathe and 
filling them with RTV sealant. Polyethylene is a perfect material for 
those forms: Inexpensive, easy to work with, and it doesn't adhere to 
silicone, so it's easy to remove the cured silicone piece from the form.

For those tube chimneys, you can use any suitably sized tubing or rod as 
form, wrapping it in polyethylene film (cheap from the hardware store) 
to avoid adhesion. Then you smear RTV sealant over it, using a spatula 
to get a roughly even thickness and trying to avoid air bubbles. Don't 
worry about the ends, just make your silicone hose long enough. When the 
sealant has set, you can trim off the excess length, obtaining a nice 
clean finish.

I have never tried these RTV silicone pieces in the microwave oven, but 
I have used them in radio equipment without observing any trouble.

Manfred

##  You would need one heck of a lot of silicone to make one sheet for a
chimney.   Just buy the silicone rubber sheets from mc master carr in the usa.
You roll  it into a cylinder.. then  use silicone rubber glue to glue the edges.
Silicone rubber glue looks  sorta like regular RTV glop.... but is high temp stuff,
made for gluing silicone rubber sheets.   The sheets are reddish colour.   They will
take a huge amount of heat.  the sheets are also used in exhaust systems on trucks etc.
You can also get  flexible silicone rubber hose... in large diam too.... used for  front brake cooling
on high performance cars.  ( see it up to 3”  so far).   Alpha uses rolled up sheets too. 

later..... Jim   VE7RF