Dom and I began on Saturday evening where we cut our teeth of making the first bottom. Things went well, and we learnt a few things that would make today even easier such as placing the metal one way round made it easier to spin.
First up was cutting the perforated stainless steel sheet into a square just bigger than required...
and as you can see we nailed the centre point of the false bottom which acted as a point to rotate the metal around. A piece of string was then attached to the centre nail and measured the exact radius that was required. This was the diameter minus about 7mm clearance for the beer line seal divided into two. The metal was rotated whilst the pen was held at the string at the exact length...
you can also see that the corners of the square where cut off to make rotating the metal easier (less chance of catching part of your body).
Next up was angle grinding to size along the marked line. Here I held the angle grinder rigidly and controlled the depth of cut without letting the angle grinder move in our out, whilst Dom rotated the metal. He found that the angle grinder wanted to pull the metal around so had to hold it back and let it advance at the correct speed - too fast and it wouldn't cut fully through. The depth of cut is important as we were using stainless steel 0.8mm cutting disks. Too deep and the back of the disk catches on the bit that has been recently cut and can cause the disk to shatter.
Keeping a small (1-3cm) of extra steel around the disk meant that the whole thing could be cut out in one go. Previously we found that cutting in from the edge resulted in the off-cut pieces dangling and catching on the bench when rotating - which meant cutting it off every now and then.
After this we re-marked the radius with a permanent pen to see it there where any areas that drifted from the original line. Most of the time it was spot on but occasionally went further out by up to 2-3mm. For this we used a belt sander to reduce these areas to bring the metal into a perfect disk shape and also tidy up some of the metal burrs left from angle grinding. A final tickle with a file removed any remaining burrs.
Next Dom added some string to enable lifting out of the mash tun and we fitted a temporary split beer line to check fit.
Then we measured and marked out the holes for the stainless handles and drilled them to 4mm to accept the handle screws...
and the end result is four false bottoms...
One for Dom's new 80l thermopot, One for Skiptonians new 60l thermopot, one for my new (upgrade from 50l) 80l thermopot and one for Tron (who made a visit today and brought his 80l thermopot to check fit - nice to meet you by the way
by the way just trying your ale - very citrussy, much like a more palatable brewdog punk IPA).One (to be made) is also reserved for 196osh - I'll PM you for dimensions)
That means we have enough 316 (marine grade) 2mm holes, 40% open space (better than most as it will aid wort drainage), 1.5 mm thick (chunky stuff
) to make another 3 false bottoms. So for £60 we can make one as seen above which will come with stainless handle and screws to support the false bottom off the bottom of the mash tun, and split beer line to create a seal around the edge (pick up from Liverpool/Rossendale/Skipton is free!, delivery would cost extra) We can make any size and can customise to requirements (subject to additional costs - PM me to discuss).ONLY 3 will can be made so PM me quick if you are serious
) and get them delivered.
