[SS-Propellant] Casting Apparatus-- Heating

[Rich Hansen]

    Hello,
   
 I've been giving some thought to Richard's design
concept, specifically the heating of the vessels. 
It appears that I was way off thinking electric heat
would be insufficient, and given its relative simplicity
(compared to heated liquid heating), seems the logical
choice.
   
 They make heating mantles used in chemistry that would
do exactly what we need.  I've looked for pricing
on models for a 3 liter container (sufficient for
a 3kg batch size by my math?) and it appears to vary
from ~200 dollars to several thousand.  We would want
one that has a hole in the bottom, to facilitate the
draining of the liquid-- I'm still checking around
on pricing.  We could control the temperature fairly
well automatically with a temperature probe tied to
a PID loop controlling the power (many models operate
on a 4-20 ma signal), or manually with a thermometer
and variable power supply, in keeping with the KISS
principle.
   
 Or we could wrap the vessel in nichrome, or resistors,
or whatever.  We'd need to develop and test a temperature
control scheme in this case.
   
 As far as stirring goes, I think the idea of a motor
connected to paddles is good, although I envision
a downward facing cone shaped container as the main
mixing box, with the motor at the top and a shaft
down through the center, with paddles attached, and
a drain to the mold on the bottom.  We could shape
the paddles so they push the slurry down.  I will
draw a sketch tomorrow.
   
 In any event, if we can find cost-effective heating
mantles, I think they are the way to go.  Please comment
on the above.  I am assuming our budget is 'as cheaply
as is safe'.
   
  Thanks,
 Rich Hansen
 rhansen at mc2inc.net
  
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