Thanks to my brew buddy, Monkeyboy, for demonstrating his DIY mash tun at my house this weekend.  It is a simple concept, design, and build.  I ended up building one in about 30 minutes for around $25. (i had an extra cooler lying around with a drain in it, that was threaded on the outside for easy attachments)

First thing’s first.  If you are an extract brewer, then you have probably never used a mash tun.  The short and simple definition of what it is, is an insulated container outside of your brewpot, where you will soak your grains in hot water in order to create the wort for your main boil.  If you are accustomed to brewing with extracts instead of all grains, you have been bypassing the mash to wort step by simply purchasing the extracts to put directly in the boil.  Both ways will still produce good beer, however, the all grain method will definitely be a less expensive method in the longrun for any brewer.

So, to build the aforementioned mash tun, the main structure of the device is an old cooler with a lid and a drain.  Youll want a cooler that can hold 10-15 lbs of raw grain and several gallons of water.  Other than that, size really doesnt matter.  I had an old cooler in the garage that was perfect for the job, so I grabbed it and we were off.


Old Igloo Cooler I had with a lid and drain

Old Igloo Cooler I had with a lid and drain


I took a trip to Lowe’s Home Improvement store and picked up the needed peices for about $25.  
Here is my bill of materials: 

1  12″ braided stainless steel toilet/sink supply line.
1 brass female to male threaded coupler
1 brass gate valve
1 brass female to barbed coupler
1 section of 3/8″ inner diameter rubber tubing
1 hoseclamp



Here are all the parts I purchased for about $25I took the drain assembly off of the cooler, and took it with me to the store to make sure all the parts fit correctly.


With all of these parts in hand, I returned home to assemble the mash tun. 

The first thing I did was to cut one end off of the braided supply line. 



Be very careful cutting braided stainless. It will poke you and cut you easily. Gloves are a good idea.


I then CAREFULLY pushed back the braided stainless steel as far as i could to expose as much of the inner rubber hose as possible.



I couldnt get the braid back much further, but thats okay, it will give the filter in the mash tun a little rigidity.


Then I cut the hose off as far as I could get.  After the cut, i pulled the braided stainless back over the hose and stretched it out to about 2 feet in lenght.  I then took a pair of needlenose pliers and rolled the frayed end of the stainless sheath up about an inch (like a tube of toothpaste).



Again, be very careful with the braided stainless.


This is your filter that will lie on the bottom of the mash tun and filter most of the grain out of the mash for you.  Mine luckily screwed right on to the inside of the coolers drain. 



Make sure your filter isnt longer than the width of the cooler. You dont want a curl or a kink when you have a mash tun full of hot mash.


You may have to get an adapter or two from your hardware store to make yours fit.  (take the drain into the store with you)  If all else fails, you can cut both ends of the stainless sheath, pull out the rubber hose all together, and then just use a hose clamp to secure the filter to the drain.



This is the drain taken off of the cooler and a test fit of the external hardware.


On the outside of the cooler, I simply attached the female to male coupler, then the gate valve, and then the male to barbed coupler.  Then the drain hose slides right on the barbed section.



External hardware assembled and ready to Brew!




Full view of completed Mash Tun


Voila!  A mash tun for your all grain recipes.  This how to will not be exact as all coolers are different and may need individual tweaking.

Its a simple process and probably can be done a thousand ways, but this seems pretty inexpensive and effective.