# DIY Conical Glass Fermenter



## BKBrews (5/8/16)

Has anyone done this?

I'm thinking about converting my 5L glass demijohn into a conical fermenter that allows me to remove the trub after primary fermentation is complete. I envision I would need:

- vinyl/silicon tube to fit OVER the bottle neck of the demijohn (tight fit required)
- pvc ball valve as per tubing size
- 2 X clamps to tighten tubing around bottle neck and ball valve

From here I would just drill a hole in the bottom of the demijohn (which is now the top) that is big enough to hold the bung that i normally use in the bottle neck. Build a quick stand out of wood and away we go.

What are your thoughts? Chances that the tubing/valve won't hold under the pressure of a full fermenter? 

I think I'm going to play with it regardless - it will be a rather cheap thing to set up. The ultimate would be to add a tasting tap as well, but that's getting tricky!!


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## Judanero (5/8/16)

Good for 4L experimentation batches maybe, the same principle would apply to an inverted 5L erlenmeyer flask.

I think the tubing would probably be ok, it is only~4L after all.


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## Lyrebird_Cycles (5/8/16)

The advantage of using a conical is that it's made of borosilicate glass so you could simply blow a hole in the top with a torch, thus mitigating the risk of cracking the whole thing when you try to drill it. The same thing applies to GL45 bottles (Schott bottles), the 5 litre size is expensive (over $100) but they are a whole lot more likely to survive the occasional bump when used in brewing. The standardised screw thread makes adding an adapter etc much easier too.


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## BKBrews (5/8/16)

Never thought about the blowtorch to make the hole - that's a good idea. The glass demijohn I already have is pretty standard, but you can get them for about $40 every day of the week.

What about 11L glass carboys? Still think that would be OK or is that sort of pressure going to cause issues on the tubing and clamps around the bottle neck and ball valve?


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## schtev (5/8/16)

I wonder if you might run in to issues with the glass being weaker at the top of the carboy. Maybe the curved top and neck is not really designed to deal with liquid bearing down on it? Only one way to find out I guess.


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## BKBrews (5/8/16)

My 5L is currently full of an IPA, so I will give it a test run when that's done. Can't hurt - should be less than $20 worth of parts.


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## MHB (6/8/16)

Of very limited value, the slope of the cone simply isn't steep enough to make the yeast slide toward the neck. Most CCV fermenters are a 60o cone (some 90o), well made commercial fermenters are electro-polished which makes the surface super smooth helping the yeast to slide off.
A friend of mine tried some glass fermenters made from the classic Italian tear drop bottles, a bung with two holes, one held a tube that went to the bottom, so when the bottle was inverted it became a breather letting the CO2 out - no need to drill the glass.
Even with the much steeper neck of the tear drop bottle it was of limited effectiveness.

A yeast cake is what we call a non Newtonian fluid, behaves rather strangely at times.
Mark


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## TSMill (6/8/16)

MHB said:


> Most CCV fermenters are a 60o cone (some 90o)


How do you make a 90 degree cone?


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## Lyrebird_Cycles (6/8/16)

TSMill said:


> How do you make a 90 degree cone?


Pi * sqrt2 radians = 254 degrees


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## MHB (6/8/16)

60o is popular because its the biggest cone you can make from a sheet as the length of the side is the same as the sheet width, and you don't have to do a much cutting, just weld what were the edge of the sheet together. Saves on metal and works out to be an equilateral triangle (3*60o)


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## Feldon (6/8/16)

TSMill said:


> How do you make a 90 degree cone?


Try putting some heads in first followed by some fine leaf.


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## TSMill (6/8/16)

Aha angle at the base of the cone, got it.


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