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Drilling a bung- faster runoff?

I currently use a small piece of copper- 3/8 ID? shoved through a bung in the bottom of my cooler:
(this shows a plastic tube, but I’ve since changed to copper, because I think the plastic warms and then is constricted and squeeze by the bung.

I tried mounting a nipple to a ball-valve and using washers on either side, but since I’ve drilled the hole flush with the inner floor of the cooler, the washer never sits flush. I’ve tried various thick o-rings and rubber washers, but nothing seals the inner washer against the wall. I’ve also tried sanding one of the inner plastic washer/nut that seals the spigot on the inside of a bottling bucket on one of its’ edges to get it to sit closer to the floor and thus pull the outside washer to the cooler… but it still leaks.

I think the only other option is to shove a thicker piece of copper through the bung, but then I’d have to drill out the bung to get a thicker diameter.

Has anyone tried to drill a bung? (yes, I know that sounds funny).

I spoke to mullerbrau and since he brews 35 gal batches, he has a long time to wait to drain because he is heating the water. My smaller gallon 5 and 10 gal batches heat quick and I’d prefer to drain faster.

Any suggestions other than siphoning over the side?

You could try using Food Grade Silicon sealant, that’s what I did to seal the inside of the cooler.

Hey learning more, my advice is to ditch that cooler and spend the money on a new cooler that you can add a full 3/4" or 1/2" port valve to. I mash in a 165 qt cooler with a full 3/4" port valve with as big a barb as I can pull off on the outside (i think it is 5/8"), on the inside I just added a 1/2" npt kettle screen. I previously had used the Denny Conn ss braid method, but man I LOVE this new kettle screen, it practically paid for itself in time saved on the very first batch. Snag a cheap used cooler off C-list, start saving yourself the time on brew day and you will be so happy you did. GO BRONCOS!

Holy moly! A 165qt cooler?! That is a 41 gallon mash tun. I would think I would have massive heat-drop with all the headspace, not to mention a different path of lautering.

I’m using a 52qt cooler right now and it is just right for 10-gal batches, and too much for 5-gal batches.

the other option would be to plug the hole with epoxy, then re-drill.

What food grade sealant was it? Some people mentioned 100% silicone products are good, but checking in Home Depot, the 100% silicone sealants have a hazardous warning on the side.

I’ve also heard aquarium sealant is a good idea, but I don’t think it is cheap.

I had the same problem when I put a ball valve on my cooler. The cooler wall is not stiff enough to compress the o-ring without deforming, so you end up putting a ton of pressure which deforms the wall and allows a leak path. And because you are using pipe threads, you don’t have the support that would be provided by a nut or flange to reinforce the flimsy wall. Using a very thick o-ring or a gasket behind the washer helps since it can move with the wall a little better.

A better option is to use a fitting that is designed for the purpose, called a bulkhead (NB item 7557). It has large flange to support the flimsy wall around the sealing surface, and a long enough nipple to fit an NPT nut and a fitting. Other types have straight external threads just for sealing and separate internal threads for NPT connection. You can also do it with an NPT reducer or even by soldering a washer onto a pipe nipple.

But to your question, drilling a rubber bung with regular bits is very difficult because it is so pliable. You could try freezing it with dry ice and drill it before it defrosts. I think in industry they use “cork borers” or “tube drills” which are nothing more than a thin walled tube with a very sharp edge. They can be had on McMaster for $11 each or $35 for a set of 7 (item 6122A12). My guess is that these work best with a solid stopper.

Lube the outside of the pipe and the inside of the bung and mash them together. Im sure you can fit a 1/2" pipe through 3/8" hole in a bung.

learningmore: Just Google Food Grade Silicone Sealant. I just borrowed some from a person who did a buffet installation here in town.

[quote] I had the same problem when I put a ball valve on my cooler. The cooler wall is not stiff enough to compress the o-ring without deforming, so you end up putting a ton of pressure which deforms the wall and allows a leak path. [/quote] Sorry to stray from the bung drilling :smiley: , but I had this problem with my cooler. My cheap solution was to glue a piece of wood to the front and I put epoxy in between the walls of the cooler where the ball valve would be. It strengthen things up a bit. Ugly…but it works.

Learningmore, i wasn’t trying to persuade you into a 165qt cooler, the point was that I do very large batches and so how fast I can get my first and second runnings out of the cooler are very important. It was adding an hour or more to my brew day before going with the kettle screen and very large barb on the out.

I have a 3/4 ball valve:

And I screwed it unto a nipple- but I can’t seem to secure it on the inside. Maybe I will just need to get another cooler.

[quote=“learningmore”]And I screwed it unto a nipple- but I can’t seem to secure it on the inside.[/quote]Get a 3/4" threaded stainless pipe and screw that into the valve, slide a stainless washer on the pipe, then insert the other end through the cooler wall and put a stainless washer on the pipe followed by a 3/4" to 1/2" reducer. Screw the fitting down tight against the cooler wall and make sure you get a decent seal (you may have to change to a shorter or longer pipe). Remove the fitting and the washer, apply some aquarium-grade silicon sealant to the area right around the pipe, and then screw the fitting back on to seal it up tight.

Now you can attach the 1/2" fitting of your choice to the pipe.

DAP Aquarium Silicone Sealant.

http://www.acehardware.com/product/inde ... Id=1419409

This is a great idea. I’m definitely going to give this a try on the next cooler build. Thanks!

This is a great idea. I’m definitely going to give this a try on the next cooler build. Thanks![/quote]
Instead of wood (I cringe at the thought for some reason), may I suggest you use a piece of 1/2" High Density Polyethylene Plastic like they use for plastic cutting boards. It cuts and drills as easy, if not easier, as wood with no swelling or cracking. You can pick up a small cutting board at the dollar store.

Just started a new thread with my solution to the problem that has been discussed here, its titled:

The Denny Conn cooler mash tun easy fix

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