Upgraded Blower Assembly
Fat-Boy Wood/Charcoal Melt Furnace
(Originally posted Mid-2001)
If you've been following the saga of the "Fat-Boy Melt Furnace", you were probably wondering when I would get around to replacing
that abortion of a wooden-box/Sand bucket blower that stuck out the side like a
turd in a punch-bowl.
At the time I made the Fat-Boy, I didn't know if it would work, and if it
did would I even use it often. Well mister, after almost 20 burns the blower has
more duct tape patching cracks and holding it together than original plastic. If
I didn't have a mortgage, or aspirations that my kids have it easier than me, I
would completely give my life over to the "Blast". The excitement of
poring that liquid metal and watching it drop down into the sand is a rush like
no other.
While casting out some more parts for my Lathe, I decided to move from
wood as a fuel and try some store bought briquettes. I had high expectations, 5
minute melts, no smoke, long burns (2 or three pots per load of coals). Beyond
the pronounced lack of smoke my results were a dismal failure. Sure the coals
would last for well over an hour but I could hardly bring the metal to a paste
let alone a watery liquid. After ruining a form that took me an hour to cut in
foam I resolved to find the problem.
I went back to
wood with similar results. I just wasn't getting the heat I had earlier. I could
see that there was air getting into the furnace, but a quick check told me more
was escaping around the edges of the blower than hitting the coals.
If I made a smaller air chamber and had a side vent like a squirrel cage I
could only improve on a bad system. I used a empty laundry detergent tub and
length of 2" PVC pipe. The pipe was cut and formed to follow the contour of
the tub as close as possible.
To keep them together I drilled an 1/8th inch hole at a right angle to the
tub and used a thin bolt and nut to screw it into place.
With what
little experience I have with Fiberglass and resin, I do know to plan out how
the mat will lay on the object to be covered. It's best to make any cuts to the
dry cloth before you get the resin out.
I opted for 4 layers of light glass on the top and 2 layers of heavier
glass around the outside, and stuffing the loose scraps around the exhaust to
help reinforce it. There is no reasoning beyond the fact I had both light and
heavy cloth on hand and the light cloth nicely covered the top of the blower,
and heavy fit well around the sides.
This is the first
batch of resin and cloth. It is layered on in thick slathering layers literally
running off of the edges.
I tried to get at least a 1/2" or 1 cm lip to form around the base to
use as a mounting point to the motor. This sloppy goop is left to setup for
about 20 to 30 minutes (depending on the amount of hardener added to the resin,
and the heat of the work area in which you're working.)
Once the setting
process starts, I like to push any major imperfections back into place like
folds in the cloth I forgot to cut or loose threads that won't stay down.
I layer a second batch of resin and cloth over every thing. Somehow the
second layer tends to stick and thicken nicely over the first (or this may just
seem to be the case).
Once I'm done with the resin, I placed a couple sheets of newspaper over
the top and placed a bucket filled with sand to keep the folds and creases down. After
about 45 minutes while still tacky but not totally solid I removed the bucket
and lifted the paper off.
After the
first coat of gray primer it looks pretty bush-league, but it's sturdy as hell.
I applied a healthy bead of silicon sealant around the base and screwed it down
with about 8 fine nuts and bolts.
The detergent tub seems to be well bonded to the glass cover and the pipe
seems well molded to the whole thing. I decided to just cut-out the pipe opening
and leave the tub as part of the structure.
The volume of air is greater than any that was being displaced before and
there are no leaks, even if the end is completely blocked. All that's left is to
remount to the furnace frame and hook-up the pipes.