Relief Valve and Reservoir Outlet

Continuing work on the reservoir box relief valve. I trimmed the base of the hinge and worked out a way to have it serve as the base of the spring as well. I attached the relief valve trigger arm to its base with a countersunk brass screw and some wood glue.

Then I stained everything with a mahogany stain, and made the valve seal out of a piece of chamois with a blackout cloth backing. My first two attempts at this backing failed. I first attempted using hot glue to try and seal the rubbery side of the cloth with the chamois, but the glue was too lumpy, and seemed like it wouldn't make a nice smooth sealing surface once assembled. So I then glued the cloth side to the chamois with wood glue, and then glued the rubbery surface to the bottom of the wooden pieces with the hot glue, but the bond did not hold. Finally, I found an old tube of contact cement, and that did the trick. I clamped everything for a few hours just to be safe.

Once the chamois/cloth facing was nice and secure, I worked on adding a piece to hold the spring in place. I used a small drill bit to carve grooves in the wood for the spring wires so I'd have a nice surface fit.

 While I was letting the glue continue to dry, I worked on getting a small piece of copper pipe cut. The 3/4" pipe was a slightly loose fit in the reservoir air outlet block that I had drilled with a 3/4" forstner bit, but over the past week or so, I've been applying layer upon layer of shellac in the hole hoping for a snug fit. I cleaned the copper pipe, cut about a 3" length of it and did a diagonal cut across the bottom of the pipe so I'd have decent airflow through the elbow of the block.

The repeated coats of shellac turned out to be beneficial, because I needed to use a hammer to pound the pipe into the block. It seemed like a nice tight fit, but just to be safe, I covered the joint with another coat of shellac, and shellacked the bare copper as well.

Returning to the relief valve... I knew there would be upward force on the hinge base caused by the spring, so I figured that a nut and bolt through the reservoir box lid would be most secure. I figured screws wouldn't be secure enough, especially since they'd only be grabbing the thin 1/4" plywood of the lid. Unfortunately, I didn't have any brass nut and bolt pairs, so I used a steel bolt, and figured out a way to completely hide it from view.

Here's the relief valve all put together, crazy curly-Q springs and all.

Looks like it will soon be time for a pressure test!