*improved* Fermonster carboy blowoff tube adapter

Last crawled date: 4 years, 3 months ago

UPDATE: I improved the design a bit, went with a non-polygonal bottom screw so you can use your hands. I also recommend printing this with 6+ walls or heavy infill so it remains strong enough to tighten appropriately. My early tests with 4 walls and 15% infill broke in some stress tests. I have included the files with the top and bottom separate, as well as together. With them separate, if your tolerances are too tight you can scale the bottom up 0.5-1% to improve the thread interference.
The Fermonster carboy comes with a screw lid that accepts a #10 airlock bung, but if you don't want to use an airlock you'd still need to buy a bung to accept a blowoff tube. I designed this to use standard silicone tubing (14mm ID) which I had laying around.
This blowoff tube adapter fits the #10 hole perfectly, the nut on the underside has relief for the structural ring on the underside of the hole. You do need an Oring for the underside of the top piece (lubed with Keg lube) if you want any sort of seal there.
I also wanted to keep this low profile, so its a 90 degree side exit so I could keep 2 of these in my temperature chamber.
The threads are tight, this is alleviated by using some keg lube on them, and then using expanding jaw pliers and "working" the threads in. After a few passes the resistance is minimal. Once you have this installed, you shouldn't need to remove it, just sanitize around it.