Subject: Re: Side Blast Forge Question

From: [email-masked]
Date: Sun, 24 Mar 1996 21:25:52 -0500

I have been entertaining thoughts of building a watercooled, side-blast forge
similar to the one shown in the COSIRA book, "The Blacksmith's Craft".  I
already have a good, Buffalo brand railroad-type forge with electric blower
along with 2 gas forges, so this would be another unit to give some different
heating characteristics (I hope).  I can put a good, Champion electric blower
with airgate on this forge, but I'm wondering if anyone out there has any
experience with them and is it worth the effort to build.  The type of work
that I do consists mostly of ornamental smithing such as small to medium
architectural projects and craft items.  Some of my thoughts are as follows:

1.  It appears that the cast-iron, bottom blast pot is a fairly recent
invention and the side blast was the predominant style for thousands of
years.  I can't tell if the bottom blast became popular because it is better
or that it was easier to produce commercially.  I've read that the
watercooled side blast types tend to freeze in harsh climates (not a problem
in Texas) and spring leaks due to the thermal cycling.  It seems that the
side blast would use more fuel since the air is constantly pushing against
the far side of the fire, but maybe one could put a fire brick in place to
contain it.  A possible advantage is the ability to make a long fire or an
oddly-shaped one (bricks again).  I also speculate that the tendency of
molten clinker to blow up on the work will be reduced, but I have no proof of
this (I have very dirty coal, so this is wishful thinking).
2.  I plan to use stainless pipe to create the tuyere - probably 1" centered
inside 2" to allow water circulation - the tank could be stainless or
galvanized because it won't get hot enough to cause problems.  However, I
wonder if stainless could be used without water, because it would sure be
easier to build.  Maybe let the blowpipe stick out 12-16" from the back of
the hearth and let it burn off.  It would be a simple matter to build another
one when the burn-off reaches the hearth.

I would appreciate information from anyone that has had real experience with
this type of forge and what the advantages/disadvantages are.

Thanks,     hollis

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From: Chris Kilpatrick <[email-masked]>
Date: Sun, 24 Mar 1996 21:34:12 -0800

Read up on japanese smiths, except for the water cooling(?), they use 
the same setup. Apparently oxidation is a problem, that's why the 
japanese used a clay slurry to dip metal in before returning it to the 
forge.  No, I am not talking about tempering! I am talking about a 
passivation layer to slow/prevent the production of scale in an oxygen 
rich environment, similar to but better than boric acid.