A couple forge questions.

Knife freaky

Knife freaky

Joined
Dec 1, 2016
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These are dumb questions but I need to ask them so I can understand how to do this correctly. This forge will be a vertical forced air forge just so you know.

I am building the burner and forge off of recommendations by Stacy E. Apelt - Bladesmith Stacy E. Apelt - Bladesmith I think I understand everything but these few things.

1. What size hole do I need to drill in the forge body before welding the burner sleeve over it?

2. What size burner sleeve do I need?

3. Does the burner sleeve and the actual burner assembly need to be threaded that way you can just screw to burner into the sleeve? Of course I wouldn't seal that part or anything because I might want to use the burner in a different forge or something. I know the rest of the burner assembly need to be sealed up.

Sorry for the dumb questions. I know I'm probably over thinking this but…

Daniel.
 
To tell you what size sleeve to use, post up some info on how you are building the burner. If it's just a 3/4" pipe with a possible flare, I used 2" or 2 1/2" pipe and have set screws/bolts that thread into the sleeve and pin the burner in place (8 of them). I use some kawool to seal mine off by stuffing it in the gaps, and it can be easily removed, and you'll want to seal it.
 
KnuckleDownKnives said:
To tell you what size sleeve to use, post up some info on how you are building the burner. If it's just a 3/4" pipe with a possible flare, I used 2" or 2 1/2" pipe and have set screws/bolts that thread into the sleeve and pin the burner in place (8 of them). I use some kawool to seal mine off by stuffing it in the gaps, and it can be easily removed, and you'll want to seal it.
Click to expand...

Yep I'll post up how I'm building the burner when I get off work this evening. Sorry I forgot to post it when I made this thread.
 
OK:
The hole in the shell needs to be at least the same as the sleeve ID. It is easiest to make it the sleeve OD and slide the sleeve through the shell a bit and weld it from both sides. I use a hole saw to do this.

The sleeve should be large enough to allow the burner tube to be passed through it and positioned in the forge. About 1/4" clearance is good. You don't want it snug .... and certainly not threaded. Things swell a lot when they get hot.

Place three 1/4" holes at 120 degree spacing around the sleeve for the burner retainer bolts. You can tap them for 1/4-20 and put in standard hex/socket head bolts.Some folks just drill the holes a bit over 1/4" and weld 1/4-20 nuts over them. If you are really OCD, you can put a second set of three bolts about an inch from the first, but one set will retain the burner fine.

When the forge is all set up, and the burner position is tuned for best operation (move it in and out between the outer shell and the chamber wall to get the best burn), the sleeve can be filled up with wadded up pieces of Ins-wool. Do not cement it in with satanite or other refractory cement. That will be a big problem when you need to change, move, or adjust the burner in the future.

Making a flared/tapered hole in the lining and coating it with a good layer of satanite and then ITC-100 will make the burner more efficient. Round the hole end out into the chamber. Flames hate any abrupt angle. The flared hole should be about 1/4' wider than the burner tube at the shell, and 1/2" wider at the chamber. The round over as it enters the chamber should be about 1/2" radius.
 
KnuckleDownKnives said:
To tell you what size sleeve to use, post up some info on how you are building the burner. If it's just a 3/4" pipe with a possible flare, I used 2" or 2 1/2" pipe and have set screws/bolts that thread into the sleeve and pin the burner in place (8 of them). I use some kawool to seal mine off by stuffing it in the gaps, and it can be easily removed, and you'll want to seal it.
Click to expand...

Got it! Thanks! The burner will either be 1" or 1.25" I haven't decided yet. It will probably be after Christmas before I get it set up so I've just been thinking a lot about what I need to get. Lol.

Stacy E. Apelt - Bladesmith said:
OK:
The hole in the shell needs to be at least the same as the sleeve ID. It is easiest to make it the sleeve OD and slide the sleeve through the shell a bit and weld it from both sides. I use a hole saw to do this.

The sleeve should be large enough to allow the burner tube to be passed through it and positioned in the forge. About 1/4" clearance is good. You don't want it snug .... and certainly not threaded. Things swell a lot when they get hot.

Place three 1/4" holes at 120 degree spacing around the sleeve for the burner retainer bolts. You can tap them for 1/4-20 and put in standard hex/socket head bolts.Some folks just drill the holes a bit over 1/4" and weld 1/4-20 nuts over them. If you are really OCD, you can put a second set of three bolts about an inch from the first, but one set will retain the burner fine.

When the forge is all set up, and the burner position is tuned for best operation (move it in and out between the outer shell and the chamber wall to get the best burn), the sleeve can be filled up with wadded up pieces of Ins-wool. Do not cement it in with satanite or other refractory cement. That will be a big problem when you need to change, move, or adjust the burner in the future.

Making a flared/tapered hole in the lining and coating it with a good layer of satanite and then ITC-100 will make the burner more efficient. Round the hole end out into the chamber. Flames hate any abrupt angle. The flared hole should be about 1/4' wider than the burner tube at the shell, and 1/2" wider at the chamber. The round over as it enters the chamber should be about 1/2" radius.
Click to expand...

Thank you sir. You perfectly answered the questions I had.

Thank you both for your time!
 
Here's what I use on my forges. I don't use flares because I find them pointless after the forge has heated up. I've got about 10 hours of scientific testing behind this belief, but other still swear by them. I also don't plug the gap around the burner. I've found this area to intake a bit of air and my chambers run almost perfectly neutral. I had lesser results with a larger tube and same size port.

Small 30k burner uses 1/2" sch 40 tube, with a 1" ID pipe for a port
Larger 100k burner uses 3/4" sch 40 tube, with 1.5" ID pipe for a port
I've done up to 200k BTU burners using the same size without issues, but haven't done bigger
 
Thanks for the advice Atlas Knife Company Atlas Knife Company I wasn't planning on using a flare at all because I do agree it is of little to no benefit once the forge heats up. This is just based off research I've done on this forum and across the web no actual testing. The idea of not stuffing wool between the burner tube and the burner is interesting I'll have to try both and see how it works.
 
One thing Charles ( Atlas Knife) may not have been considering is that Knife Freaky's project is a blown forge.

There is no need for any extra air draw in a blown burner. (so stuffing the gap merely prevents a heat leak)
Blown burners don't use flares at all.

I like a 1" blown burner. It will do pretty much everything from HT to welding.
A 1 1/4" blown burner will run a large dedicated welding forge.

I like to chamfer both ends of the burner tube from the inside, to reduce turbulence. Nothing drastic, just rounding the inside corners.

The burner kits and/or assembled burners from High Temp Tools and Refractory are great burners for those who don't have the ability or time to scrounge or locate the parts.
The addition of an expansion chamber, as per Kevin Cashen's testing, adds a smoother and more efficient burn, but is not a requirement. A regular blown burner can be upgraded to one with an expansion chamber easily later on. You only add three additional parts.
 
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