17 years ago
I've been using home made kiln (omega PID + SSR + nichrome wire +
some refractory bricks) to heat treat A2 and similar for some time
now and it all works great.
I am thinking about moving up - expanding the internal volume somewhat
and that will require going 240V (I want to be able to reach reqd temps
in minutes and with my 9x4x4 cavity 110V @ 15A barely makes it).
I will keep most of electronics - only replace the spiral to longer
one. About wiring - do I get it hooked up between 2 hot legs of 240
( in series with SSR of course) ? I will use the ground to ground the
oven . Otherwise I'd need to use 2 spirals in parallel (hots to
neutral) and doing that will
require 2 SSRs (what pros/cons of these 2 methods ?). Was thinking
about getting an electrician to give me a dedicated 240V in garage,
with 20A breaker .
And about argon: for now I use tool wrap steel and it works OK, but
I do get some scaling and softer decarb in the outer layer - which I
grind off. Even using the paper-in-the-foil-bag trick. Assuming I have
a top-load oven and it's rather air tight below the lid, can I simply
flood the interior with 2-3 CF of argon before starting the heat treat
cycle ? Being heavier than air , will it stay "put" inside of the oven
- even when heated up to 1800F-2000F ?
I know some people keep moving inert gas through the oven throughout
the cycle (at slower rate), might need to do the same. Drill a smallish
hole through firebrick, stick some time of copper tubing with connector
to attach the argon hose to - am I correct in my thinking ?
What are typical prices for smaller argon bottles (need pure argon I
reckon, not the CO2 or Oxy mixes) ? Will also need a flow meter .
Also am I correct in assuming that argon is 100% to use ?
Any advice's most appreciated :)