The local brewery uses immersion heaters in the hot liquor tank. This runs
at about 78 C so develops a fair amount of limescale. Any idea where we
might find a 2 1/4 bsp thread chaser to clean up the threads when replacing
elements? (£300 for a "proper" tap is a bit of an investment).
I'd wondered about fabricating something from three or four 5/8 BSW or UNC
taps (which also have 11 tpi) on an adjustable or "soft" mandrel.
Tank and bosses are stainless, so hydrochloric acid not a good idea.
(Chief beer taster. I get to check a pint out of every barrel they produce.
£50 a week; not much, I know, but it's all I can afford)
Alternatively make your own tap from a bit of, eg, EN8. For that job
you might not even need to harden it.
Have you tried plumbers' merchants in case there's a standard item for
less money than a proper tap?
Thanks, I had wondered about doing that, so I'm pleased to have several
endorsements. Most of the old elements have brass nuts, but I think there
might have been a steel one there as well. Part of the problem is that there
is a bit of pickup and distortion, so it needs to be done a bit carefully.
Might make the thing up with slit right through the ring so it can be
collapsed if it jams.
Havn't been able to find a purpose made tool anywhere, but I thought if they
do exist someone here would know. The Travers link posted elsewhere is the
As has been suggested the standard trick to make a "poor man's tap" is to
grind flutes into any bolt or fitting of the same thread size such that A)
the flutes are completely below the root diameter of the thread and B) the
leading edge of the flute is vertical in the clockwise direction so it acts
as a cutting edge just like a proper reamer.
I make these routinely for non standard thread sizes for cleaning out bolt
threads in engines using old bolts and the edge of the wheel of my bench
grinder. You only need to flute the first few threads for it to work nicely.
They'll clean out crap and corrosion and even correct light damage in soft
materials although of course they won't cut a new thread like a proper
Alternatively as the tanks are stainless steel not soft brass you could use
a small rotary wire brush in an electric drill such as these.
One of those would whiz through limescale without hurting the thread itself.
I use those in my high speed rotary grinding equipment for cleaning out
cylinder heads and engine blocks. You can get smaller ones for use in
Dremels and similar and in fact the high speed of the Dremel would maybe
make it worth getting one of those too. A cordless one like this
would make it easier to use without having to rig up extension cables to
each tank. Dremel do their own brushes in carbon steel, stainless steel and
brass. Brass would be very gentle on the steel of the thread while still
removing the limescale although I doubt they'd last very long. Ideally for a
steel brush you'd want wire of 0.3mm diameter or less. The 0.35mm wire is
more aggressive and less able to reach into the roots of the threads. With
0.3mm wire brushes I can even clean up aluminium cylinder heads without
marking the alloy if I don't run the brushes at too high a speed. With
0.35mm wire it tends to scratch a bit at high speed although on stainless
steel it would be fine.
Be aware though you do tend to lose strands of wire from time to time so
you'd need it to not be a problem if one of those fell into the tank. I'm
sure everything is filtered at some later stage though.
Good idea, not sure why I didn't think of that; I have mains and battery
dremels although the batteries are getting tired, and I have a birthday
coming up so might just drop hints around the family.
But I'll also try to knock up something from an old element.
I've only used the cheap wire brushes that tend to come in the kits and as
you say they don't last long. I'll order myself some better ones.
The beer isn't really filtered, but it gets strained to remove the malt and
hops which would probably catch any lost wires. Also, it's "real", i.e. cask
conditioned, so anything which reached the barrel will end up in the yeast
layer at the bottom, and anyone who drinks that probably wouldn't notice....
(I'm not being totally flippant, there will certainly be carry over of shed
limescale from the hot liquor tank, but you don't find that in the beer).
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.