When fermentation goes wild

This thing is about fermenting beer (or other stuff). Usually an airlock will be sufficient for your fermentation, but sometimes – if the head space in the fermenter is tight or the yeast is too aggressive – you will need a blow off tube. I designed this after lessons learned (my fermentation spilled over for the first time). It's a custom lid for wide mouth mason jars.

Changes:

• 2021-04-20 streamlined everything to have less files, tweaked some defaults
• 2021-04-20 added OpenSCAD source files

Variants for your setup

I did a poll on two homebrew groups to determine the most used inner hose diameters and ended up with 7mm, 10mm and 12mm. Regarding the airlock opening: normally there is no airlock needed, because the jar itself acts like one. If you want to use a Plaato airlock or if you feel the need of some extra safety you may either print the files named "grommet" for a standard 13mm rubber grommet opening, or the "drill your own" which lets you – guess what – drill your own hole with the desired diameter. You will need to print the appropriate lid and a threaded mason jar blow off tube (or use a stock stainless steel tube with 1/4" OD thread).

Printing

Make sure to add supports to the lid, those are needed at the screw terminal for the blow off tube. It may be better to cut the thread of the terminal with a 1/4" thread tapper. If you decided to drill your own hole, you have to print the lower 1,5mm layers with 100% infill to drill into solid plastic.

Extras

If you do a cold crash, there is the chance of a „suck back” of liquid from the mason jar. You may want to try a second mason jar in between (so a cascade: fermenter – jar in between – jar with airlock or just an opening) with no liquid. I don't invented that by myself, but liked the idea of narddawg314 in his thing https://www.thingiverse.com/thing:2893259 . If you feel the need for such a cascade, pick the appropriate STL named „two barbtails”. The treaded post in those files is not needed, but perhaps useful for somebody.

Further modding

You may already be aware of rubber grommets which are used in plastic fermenting buckets. Select the STL named „grommet” to add the space (13mm) for such a thing. Other than that to improve sealing the mason jar you could order a silicone seal (have not tried it yet, but my order is on it's way!)

Change everything

Use OpenSCAD to edit all parameters and mess with everything else, too. You will have to install the threadlib as explained on GitHub: https://github.com/adrianschlatter/threadlib

Please help

If something isn't working properly, please let me know. Please like this thing, if it helps in your brewing process. I'm curious about makes, so please post them, too.