I've been reading up on some different HT treating techniques, for those of us just using coal forges, and one idea I've seen is using a piece of pipe in the fire to hold the blade in, to help even out and control the heating process.

I was thinking of giving that a try.  I don't have any scrap pipe I can use since what I have is galvanized, but I do have a 40" chunk of 2x5 tube.  The walls are 3/16.  I was thinking of cutting off a 12 or 14 inch section, welding some scrap on one end to close it off, and just using that.  

My question is, do you think this would be an okay option?  As I got to thinking about it, I wasn't sure how the rectangle shape of the tube would effect things.  I'm not great at physics or thermal dynamics, but it does seem like a round pipe would radiate the heat inside more evenly.  So, just wasn't sure if this was even worth trying, or if I should just wait until I run to the hardware store next and just get some black pipe.

Well one of the nice things about round is that you can rotate it in the fire to get a uniform heat on the whole thing.  Harder to do with sq...

2 minutes ago, ThomasPowers said:

Well one of the nice things about round is that you can rotate it in the fire to get a uniform heat on the whole thing.  Harder to do with sq...

Ahhhh... hadn't thought of that.

You'll get the most even heat by placing sq. corner down. This makes the heat flow evenly on two sides AND prevents the blade from laying flat on the surface being heated. Still, round is better but use what you have. I'd make a couple test coupons before putting hours of hard work (your blade) in it.

That's just me though, I'm kind of lazy.

Frosty The Lucky.

instead of welding a piece of scrap in, just toss one end in, heat to red, and then hammer shut. 

Also, I have used this method in my coal forge, and it makes trying to watch for descalecense MUCH easier as the flames are not right against your piece in the fire. I used a cheap piece of 2 inch diameter round pipe for mine, works great. just keep in mind you can easily burn a hole in the pipe and not notice it till you finish your work with the pipe. 

 

 

 

Are there any videos or articles on this?  I’ve searched but I can’t find what I want because of all the videos and articles about heat treating of pipes. 

Do they need to be on-line?

No. Actually a real book would be preferable. I am not opposed to online, but real beats virtual for everything but searching a long article using keywords. 

I'm facing a similar quandary right now with my small single burner gas forge. the blade that I need to HT is about 6" longer than my forge not counting the tang. I was thinking about using a square tube with firebrick around it stuck through the forge to try and get an much even heat. 

For one of my earlier gas forges I lined a coffee can with ceramic fiber blanket and fitted it around my rear exhaust/stock port specifically for heat treating purposes.  I use a length of 2.25 inch diameter stainless pipe with the back end sealed off (I cut 4 slits in the pipe and hammered the resulting tabs inwards).  I throw a small piece of coal or charcoal in the pipe to scavenge oxygen as well. 

Keep in mind that when heat treating blades the tip will normally come up to temperature much quicker than the rest of the blade if you have even heat the full length of your blade.  IMO it's better to either have a cooler spot where you can place the tip while heating for a quench, or insert the blade tang first  and bring the tip up to temperature last right before quenching.  You can always "pump" the blade in and out of the forge or muffle pipe slowly to get an even heat on a blade that is longer than your forge as well.

I came here to ask a similar question. Does anybody have an opinion on wall thickness of the pipe?

Heavier is better than lighter: more even heat, and less risk of burning a hole in it.

Pipe or similar containers used this way are called a "Muffle" 

Another good use for a muffle pipe is to rig a stiff wire or skewer down the center to cook hot dogs. Mmmmmmm.

Frosty The Lucky.

Hmmm...  I wonder how long it would take to cook a brat in my forge. It would certainly make it smell a little better. 

A 1/4 lb. Hebrew National hot dog in a 2" dia. red hot pipe took 2 passes about 15 seconds each to make it golden brown and delicious. Blacksmith Macrowave cookers vary your cooking times may differ. You have to shoot marshmallows through with an air hose to have more than a sugar smoke smell.

Frosty The Lucky.

When we do a Y1K smelt we always cook in the reducing "exhaust" where the heat is immense but things can't burn as there is no oxygen!

No, it pyrolizes. Mmmmmm. Now THAT'S toast!

Frosty The Lucky.