Once a cooler, now a mash/lauter tun

The next step on one's journey as a homebrewer seems like it could go to either all grain brewing, temperature controlled fermentation, or kegging. Kegging seems like it's mostly about convenience instead of economy (plus I kind of like bottles - easier to share and transport), and temperature control is a little more of an investment. After looking at prices on Northern Brewer, all grain brewing seems to cost ~$3 less for a batch than extract, so after brewing 18 times, it'll be like I've made money! But you also have a lot more options with what kinds and quantities of malts you can use, and I assume that finding a recipe and buying the grain will save even more money.

And here's what a savings of six cents per bottle looks like!

You can buy all sorts of fancy mash/lauter tuns online, and there are just as many resources to build one. This is definitely the more economical route, so that's the way I chose. I probably took too much time researching and planning, but nobody had it quite 100% spelled out as much as I liked. I wandered between Palmer, Brew Your Own, and various threads on Home Brew Talk, but eventually I found Brulosophy's post on a Mash/Lauter Tun Cooler Conversion and this dude's YouTube video and Home Brew Talk thread that were very similar to Brulosophy's  technique. They have the parts listed well, but I drew out a schematic to make sure I had everything covered.

Drawing out all the parts really helped figure out the connections and parts needed. No one has this. It's all lists and descriptions and pictures of the finished product.

Here's my list of parts (make sure all the brass and stainless steel is lead free):

Part	Cost	Source
48 quart Coleman cooler	$27.49	Amazon
1/4" threaded plug	$2.07	Home Depot
1/2" stainless braid (30", enough for 2-3)	$3.50	Home Depot
2x hose clamps (came in a 10 pack)	$0.77	Amazon
1/2" female threaded barb	$2.38	Home Depot
2x 3/4" o-rings (came in a 10 pack)	$0.45	Home Depot
2x 3/4" flat SS washers (came in a 10 pack)	$1.80	Amazon
1/2" pipe nipple	$4.47	Home Depot
1/2" ball valve	$7.60	Amazon
1/2" male threaded barb	$2.52	Home Depot
Total:	$53.05

I chose the 48 quart (12 gallon cooler) based mostly on the price, but this table indicates that's a great size. A 10 gallon mash tun can hold enough grain to make a 10 gallon batch at an OG of 1.068 or a 5 gallon batch of 1.136, which should be adequate. It was a little tricky getting the valve off until I realized that the cap on the front is also the nut that holds the valve on.

Here are all the parts, laid out in order. I've got an extra washer there that I was planning on using, and it doesn't have the threaded plug, but I did get one later.

These are all the tools I used: a hack saw to cut the braided steel hose, an adjustable wrench, pliers, and a screw driver to tighten the hose clamps.

You only need 6-12 inches of braid; I used a hack saw to cut ~9 inches off, then I used my pliers to pull/push the braid off the rubber hose inside.

It's pretty much a big finger trap. Pull, and it tightens up.

Wrap the male threads with Teflon tape, attach the ball valve and barbed connection, and use a hose clamp to attach the braid to the female threaded barb. The pipe nipple gets an o-ring, a washer, and the gasket from the cooler's valve. Push it through the cooler, attach the other o-ring and washer, and then thread the ball valve attachment and the braid attachment onto the pipe nipple. Use a wrench to tighten it up, add some water to check for leaks, and you're good!

I noticed that it was a lot easier to tighten up the hose clamps outside of the cooler than inside of the cooler, so I recommend attaching the plug and the barbed connection to the hose, and then screwing that onto the pipe nipple. Using a longer pipe nipple might have been a good idea as well.

Inside view and outside view of the mash tun plumbing after assembly.