I originally posted my project description to TheBrewingNetwork.com but rather liked my naughty tech post so I am posting it to my blog as well. I have modified it from its original text a bit.
This project was started by the original owner of the cooler. I picked up a few home brewing items from him and he tossed in a cooler he had started to make into a mash tun but willingly gave it to me for free. I now see why he abandoned it and went with a 15g keg as a mash tun. I was determined to make this work and eventually did but not without a bunch of grief. I ran into several issues right from the start. First, I needed a new ball valve since the one he tossed in did not appear to possible to make work. It seemed like nothing was gonna work right. At first my nipple was too short. I push it through the properly sized hole but there is no way I can make my nipple reach far enough for it to work. Then I find my nuts either don't reach or are too close. As frustration mounted, I almost melted the damn thing in the fire pit but decided give it one more try looking at it like an engineer this time.
I started with the folks at More Beer in Los Altos (B3) who hooked me up with a pre-built kit for a weldless stainless steel valve. The kit contained everything I needed to install a ball valve in the collar. The drain plug was already popped out and a properly sized hole was already drilled. My nipple poked through with just the right amount of resistance.
At this point, I realize that the cooler is way too thick for my nipple to reach all the way through. I struggled trying to make it work but I could not get my nipple in far enough. At this point, I probably could have replaced my short nipple with a longer one but that meant another 30 minute drive to More Beer on the off chance they had long nipples. Instead, I used my Dremel to make a larger hole in the outer casing so I could get the 1 5/8" washer against the inner casing. Even with just the inner wall thickness, the nipple was too short. I first had my nut close to the casing but with the nipple o-ring and washers, my nipple was not long enough. When I moved my nut to the other side I had too much nipple and could not get my nut tight against the wall. I spend over an hour of frustration and a roll of teflon tape poking my nipple in and out of the hole and moving my nut every which way.
Rather than continue and risk long term damage to my nipple, I stopped to consider how to engineer a solution. I eventually came up with a solution to have my nut on the outer threads of my nipple and fabricate a copper nipple ring to slide over my nipple and close the gap between my nut and the outer washer. Off to Home Depot I went for a 2" piece of copper tubing I could cut to the proper length. After an hour and $50 (why the hell can't I go to home depot and not spend at least $50??) I was back home and ready for one final push with the nipple. I cut the copper tubing into a 3/4" ring and slid it over my nipple against my nut then pushed my nipple through the outer washer and cooler inner casing. I slid my nipple o-ring against the inside wall and slid a washer over my nipple and finally screwed the coupler onto my nipple. I cranked it down, backed away and admired my hack job.
Now it was time to fill the new mash tun with water and check for leaks. After a couple minutes, it looked like to was gonna hold water so I packed up and headed over to a friends to brew a Malty Pale Ale. Several hours later, I checked on it and was happy to find my nipple was not leaking. One more check the next morning and still my nipple didn't leak one drop. I think my mash tun is ready for my first brew. Here are a few pictures of my handy work. Unfortunately, there are no separate picture of my nipple setup. With this finally done, I am not taking it apart to take pictures!