[PSUBS-MAILIST] Clearances

[Jon Wallace via Personal_Submersibles]

 Hi Rick,
Hopefully Alec Smyth will see your post and comment.  Also, Dave Colombo just went through using caulking to re-mount his K-250 dome in the field at Block Island and can be another good resource.
How round is your viewport thru-hull?  If it's close to perfect why not reduce the viewport diameter just enough to get a tight clearance and stick with a gasket seal?
If you decide to use sikaflex, a loose clearance (1/8 to 3/16) should work I suspect.  You don't want too large of a gap because geometrically it will negatively affect the required seat width for the acrylic.
Jon


    On Monday, December 9, 2024 at 08:24:23 PM EST, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
 
Sent from my iPhone
I got a real surprise yesterday, I went to fit my large viewport in front on my K-350 and it wouldn’t slide inside the receiver that I had machined for it. They made it about 1/4” too small!
I should have double checked it before welding it into the front head but didn’t. 
I had the viewports cut in California and is to speck, 15”.  Kitteredge called out using gasket but a lot of you I believe used Silaflex that comes out of a tube.
I found someone who can chuck up something that is 16” in diameter so will have him turn it down 1/4” or so, so it will fit in the receptacle but I need enough of a gap on the edges for the Sikaflex to ooze out. 
Your thoughts? 
Rick
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