Finally got around to knocking up my parrot: more on that in a sec - first I thought I'd put up some pics of how I got my ball valve onto the bottom of the parrot using just soft solder and a couple of fittings... I'm sure this has been done before but figured I'd put it up anyway.
Firstly, got a couple of capillary to threaded connections from Bunnings. To get around the brass contact issue, I put them in the lathe and drilled out the internal lip using a 13mm drill bit (you can see the lip inside the one I'm holding).
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Then, because the threaded end bells out to a slightly larger ID, I cut a small section of 1/2" copper, cut down the side and opened up. Then cut another small piece to fill the gap left from opening up the first.
These are to fill out the internal gap in the brass fitting. (the piece inside the brass fitting in the photo is the main piece of pipe, passing all the way through the drilled-out fitting)
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Then gently tapped into the brass fitting. Doesn't matter if it's not perfect, Its going to fill up with solder. The inner-most copper is the actual pipe which continues out of the fitting in the other direction.
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Next I stood it upright, with the threaded end pointing down. I heated the entire lot with the torch, and pushed solder into the seam until it was pooling around the bottom of the fitting. This filled up all the gaps in the copper. I was left with a big dag of solder on the bottom end like this:
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Then, back on the lathe, drilled out the plug with a 10mm bit, filed the end nice and flat, and did a small amount of filing inside to smooth out the bore.
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Now there is still brass involved, but the way I see it the internal faces which contact the alcohol are only copper or solder, and the small ring of brass around the very outside on the end is unlikely to have any contact with alcohol, especially since I spanner tightened the fitting hard into the valve body. The soft copper / solder should seat fairly well against the stainless and take the brass out of the picture.
This was the first one I made, on the second one (which I used as the "upper" fitting on my parrot, since it would be submerged in alcohol more often) I made the solder plug even thicker, and when I filed it back I didn't re-expose the brass ring on the end face. So the second one is a straight solder face contacting the valve body, with no possibility of brass contact at all.
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