DIY Mash Tun Build – Assembly

by Daniel on April 22, 2012

If you have read my post with a shopping list of the parts needed to build a mash/lauter tun (MLT) with a 10 gallon picnic cooler, you’re now ready for the assembly.  You need to have two wrenches, at least one 3/4″ wrench, and a second the same size or adjustable in order to tighten these parts together.


  1. MLT assembly 3

    removing the stainless braid from the hose

    Remove the plastic spigot from your cooler.  Use a wrench to hold the plastic nut on the inside and then remove the spigot on the outside.  Remove everything except for the inner rubber seal/grommet.  If you bought new from Home Depot, you’ll have a white rubber grommet.  The used one I bought had no seal, so I purchased a grommet from ACE Hardware for cheap (see previous post).

  2. Optional:  Make a mix of hydrogen peroxide & vinegar 1:2 ratio and soak all the brass parts in it (see prev post) in order to remove trace amounts of lead and such. 5 minutes is all you need.
  3. Wrap all threaded ends of your parts with a few wraps teflon tape – do this in a clockwise fashion so that when screwing a part on, it is with the grain of the tape.
  4. If you haven’t already, use a hacksaw to cut the ends of your stainless steel supply hose off (I had the guys at Home Depot do this for me).  Grab one end of the stainless steel braid with needle nose pliers and PUSH toward the other end of the hose, it should begin to slide off quite easily.  If you pull, it’s like a Chinese finger trap and you’ll just ruin the braid.


  1. Apply some keg lube (food grade petroleum jelly) to the grommet and then pass the brass nipple through the hole.  The lube makes it easy for the nipple to fit through.  Oh yes, I said it.

    MLT assembly 1

    grommet and brass nipple

  2. On the inside, slide the stainless steel washer over the nipple.
  3. Screw the female-female coupler onto the nipple also on the inside (see photo below) – you can’t tighten this fully until you’ve attached the ball valve on the outside (step 5)
  4. Externally, add the 3 fender washers to act as spacers which will allow a tight fit of the ball valve.

    MLT assembly 2

    adding fender washers and ball valve

  5. Attach the ball valve, followed by the male barb connecter.

    MLT assembly 4

    ball valve & male barb

  6. Tighten the outside and inside parts simultaneously with your wrenches until very snug.
  7. Continue internal assembly: attach brass “tee” to the coupler, tightening so that the arms of the tee are horizontal.

    MLT assembly 5

    tee attached to coupler

  8. Attach female barb connectors to each end of the tee.

    MLT assembly 6

    barbs attached

  9. Make a circle with the stainless steel braid with one end on each female barb connector.  Tie down with zip-ties.  (Stainless steel hose clamps often still corrode because the screw part is not stainless).

    MLT assembly 7

    completed false bottom assembly

  10. Test!  Make sure the ball valve is closed, add water and let sit to check for leaking.  Then open to make sure it drains properly.

Happy brewing!  Check out my other easy DIY projects here.

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