This is rev 1 of a custom modeled adapter to inflate a stand up paddleboard.
one side is a Halkey-Roberts HR style valve that I modeled by measuring the adapter. The other side is a 1/4" NPT adapter. The intention is to use a 1/4 NPT to Schrader adapter, so I can inflate the paddleboard using an air compressor.
I had previously purchased a "slingshot adapter" on Amazon, but it didn't fit my paddleboard (CBC iSUP); it wouldn't seal properly and didn't have the small beam in the center designed to keep the valve open. It was also way overpriced.
FIRST PRINT: Printed in PLA, quality isn't as high as I would like. The 1/4 NPT worked but I had to force it a bit to get it seated, and you can see where I torqued it a bit. I haven't tested it yet to inflate the board as its in the 20s outside.
The NPT adapter I used is the Milton S-684-4 1/4" NPT Tank Valve https://smile.amazon.com/gp/product/B001PLI4BA/