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Re: Blown Rolled "Hull" Capacitor Discussion

Bert and coilers, 

>One of the problems that you can run into with PVC pipe and PVC end caps is 
>that if you try to use a good vacuum pump, you can suck air THROUGH the PVC 
>end caps!  I put a vacuum pump on one of my caps after filling with oil to 
>see if I might be able to coax some additional air out from between the 
>layers of plastic and aluminum.  I was pleased to see a lot of bubbles 
>rising up thru the oil.... only they never stopped.  I became suspicious and 
>poured some oil into a capacitor housing that had no cap in it and connected 
>the pump.  Sure enough, the vacuum pump could pull air right thru the pvc 
>plastic end cap.  Although a vacuum can pull air through the plastic, oil 
>will not leak out.  The result of trying to use a vacuum pump was that I 
>ended up sucking millions of air bubbles INTO my capacitor, not what I was 
>trying for.
>Anyone else tried this with better luck?

If you can get access to a vacum chamber  youlle be in business. Equal vacum 
over the entire capacitor will insure that air is not sucked through the
capacitor casing and you can do away with making the cap vacum tight. Sealing 
of the top can be done after the cap has been evacuated. Ime having a local 
transformer manufacturer complete this part of the proscess in exchange for
a carton of beer. 1 carton of beer=6 hard vacumed polycaps. Its good to make 
a freind at your local transformer/power supply manufacturer! :) A real handy
contact indeed. If this isnt an option, I might suggest even building a vacum 
chamber of an improvised design. Ime sure many other uses could be found for it
once you had it. Any suggestions out there on how to improvise a decent chamber.
The ideal scenario is to be able to introduce the oil into the capacitor after 
a vacum has been pulled on it. This way your not removing bubbles from oil, but
completley removing bubbles from the proscess!....well except for bubbles
allready present in the oil. With this method you wont have to worry about
stress fractures in end caps or leaks caused by distortion of the capacitor
casing. In addition only the bottom cap need be initially sealed. A lighter
'dust cap' can be used at the top, which can be sealed after the evacuation.
Making each cap into a self contained vacum chamber will allso add extra 
construction time.......unless you only plan to build one. 

Suggestions on inexpensive vacum chamber designs or improvisations??
Ime thinking along the lines of an epoxy sealed 8" PVC pipe the overall 
design much the same as a Hull caps' case. Any ideas for constructing 
a vacum gasketed removable top plate/observation window?

Marcus