Recommendation? What's the Optimal Muffle Pipe Material and Geometry?

J. Keeton

J. Keeton

Joined
Nov 15, 2005
Messages
1,194
I've been using a scrap piece of 2x3 square tubing as a muffle pipe in my forge while heat treating. Open with no back.

*Note this is the piece I've been using... I accidentally melted it recently which is why it looks so jacked up:





Questions:
  1. What is the appropriate material for a muffle pipe?
    • (Stainless, mild steel, etc)
    • my mild steel version make a mess with slag
  2. What is the optimal geometry of the muffle pipe?
    • (U shaped, Square, etc)
  3. Should the muffle pipe be closed?
  4. Should you put any material towards the back of the muffle pipe?
    • A piece of wood?


Thanks,
JK
 
I don't always use a muffle, mostly for 1095 when I want precise control of the temp.
I just use a round steel pipe about 3" dia, whatever length you need, and about 3/16" -1/4 thickness (cross section)
Never closed mine, never used wood. I wouldn't overthink this... :)
 
I use a 2 1/2 black pipe from the plumbing warehouse. I "ovalized" it some and I welded a cape on the end.
When I use it I put a little piece of wood in the end of it. The wood eats the oxygen up and the steel stays almost scale and decarb free
 
If you live close to a muffler shop or any other automotive repair shop that does exhaust systems, you probably have an endless supply of pipe for free. You can get pipe from 1 1/2" to 2 1/2" and usually in lengths up to 3 ft. out of their scrap drumb (Ask first!).
This thin walled tube is nice since you can reshape it if you don't want round and it is easily cut.
Jim
Oh yea, Did I mention it is free.
 
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