Re: [PSUBS-MAILIST] Pod Seals

["James Frankland" <james@guernseysubmarine.com>]

Hi Brent/Jon.

Thanks for the replies, I'll reply to all 3 messages here in 1.

>I think a better idea would be to drill pilot holes first, and then
>expand them to the desired size after welding is complete.
>Jon

Yes, i think that would have been better.  The holes need to line up with both rings obviosly, so they have to be drilled while clamped together before welding.  The only trouble with drilling after welding is that it would be awkward to drill the endcap.  You'd have to make some sort of jig to hold it flat.  Not impossible mind.  Pilot holes to ensure its lined up, weld and then complete drilling and finally machine.  Yes, that would have been best.  Too late now.

Brent Hartwig wrote:
>
>
> Hi James,
>
> If some one were to use the configuration you have for pods cap
> attachment, would you think it would work best to drill the holes with
> the two ring mating surfaces clamped together, and after you welded on
> the rings and finished machining them?
> **

Unless you had a very long drill of some sort, this wouldnt work.  You'd never be able to get to the drilling point with the caps and pods assembled.

>James,

>My take on this is that smaller bolts will do fine with washers on each
>side.  The compression from tightening the bolts should be more than
>enough to keep the cap end in position.  Just make sure that there isn't
>enough play such that the cap can shift and expose the o-ring.  I like
>the design.  One question I have, did you use full penetration weld for
>the ring, or fillet on both sides, or fillet one side?

>Jon

I think i agree that the smaller bolts will be ok as well.  They will only be a fraction smaller, like 1mm.  There is no way the O ring will become exposed.

The weld is full penetration, welded only from one side like you would do for a pipe weld.  I did it single bevel (could not bevel the ring) and set up a really large root gap (about 3mm) so i could get the bead all the way through to the other side.  Once id completed all the filling and capping runs, i took part of the plastic handle off the gun and was just able to squeeze the gun round to the inside, so i did just manage to get a fillet on the inside as well, even though i had not intended to do so.

Regards
James




James Frankland wrote:
> Hi Everyone.
>
> Quick question.
>
> Ive been machining the alternative sealing arrangement for my battery pods.  I had problems with the cladding system shown on the K350 plans so after messing about for ages trying to get that right, i gave up and have opted for a straight forward flat rings and O ring seal.  I know its not as streamlined, but it will be easier to get the pods open.  (thats my excuse, the real reason is that they are easier to make!)
>
> http://www.guernseysubmarine.com/index_files/Page17899.htm
>
> I have nearly completed the machining work on the endcaps as well now (not shown).  BUT, there is another problem.
>
> Due to distortion from welding, the nice straight holes i drilled that all line up, are no longer straight.  I drilled them all 9mm.
>
> The question is,
>
> 1, Leave them and just use a smaller bolt?  Does this tollerance matter?  As long as the bolts pull the 2 faces shut.
>
> 2, Do i drill them straight again?  Maybe 10mm.  I dont like this idea as i dont want to damage the machined surface and it will be awkward to hold the caps vertical somehow.
>
> Option 1 surely?
>
> Any ideas?
>
> Thanks as always.
> James
>
>
>




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