Trying to figure out appropriate forge size for burner- any help appreciated!

Hello all,
I got myself a box of firebricks, and stacked them so that the area
inside my little forge was 81 cubic inches. The only burner I have
right now is a plumber's style propane torch- and that's not likely to
change until well after the holliday season, whether I'd like it to or
not.
I'm guessing that the volume of the interior is just way too big for
what I'm doing- it will heat a 1/2" bar to a dull red, but it's even
slower than just holding the torch on it in the open air.
The interior dimentions as I've got the bricks stacked are 2" wide,
4.5 " high, and 9" deep. I've got a hole drilled at a approx. 30
degree angle (pointing slightly upwards, so the tank can sit nearly
upright) in the center of one of the firebricks on the side. The
firebricks are cheap fireplace liners from Menard's, 4.5" x 9" x 1.5".
There are some cracks where air can get in due to the roughness of the
bricks, and after a little experimentation, I made an opening of about
1.5" x 2" on each end by laying a firebrick on each end. That seemed
to work about as well as it was going to work- which is not very well,
of course.
I'm sure there are some problems with the design that will be
immediately apparent to someone with more experience, so I'm hoping
one of you guys will have an idea of how I can tune this up a bit.
What I *can* do within my resources and budget is cut the firebrick to
whatever size is appropriate for a propane torch forge, and make a
metal box out of anything from 11-20 ga. 1018 or 301 stainless that
the firebrick can slide into- I think I could also manage to get a
second propane or mapp gas torch. hopefully, that's enough to get me
going!
Any suggestions, and particularly info related to volume and vent
opening sizes will be really appreciated. I'm sure I'll upgrade to
something better with a real burner and that ceramic insulation soon
enough, but I'm just messing around on a budget for now.
Reply to
Prometheus
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Ron Reil has some very good Rules of Thumb at
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also are a lot of ideas on how to build your own burner. A few pipe fittings and such and you can make your own burner I currently use a "pile o' brick" forge with a Zoeller side arm burner and it works well
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's taken me over a year of use to figure out what configuration I would like to have. I just keep moving the bricks around to suit me.
Reply to
mark
Howdy,
I would suggest carving 1 brick and make a 1 brick forge until you're ready to step up to a larger capacity. Considering you've only got a plumbers hand torch.
If you do this you will definitely be able to get started.
Regards Charles P.S. 9 x 1 is a recommended ratio of bore to length. P.P.S. JTH-7 Bernzomatic Hose Torch
Prometheus wrote:
Reply to
Chilla
Thanks Charles-
I think I may have come up with something similar enough to that to work- instead of stacking the side bricks on end, I put them all on their faces, with the two bricks in the middle layer 1" apart. Then I put a partial brick on the back end to close the chamber, and tied the stack together with bailing wire. That made a chamber that was 9"x1"x1.25". Luckily, I had a masonry bit long enough to drill the 4.5" through one of the side bricks, and just put the torch right in the end of the hole.
It took about an hour to get really good, but after that, it was able to take a cool bar to a bright red-orange in about 3-4 minutes. It would do that right away, but it took a lot longer. Never got much hotter than that, but that was plenty. What was really nice about that vs. a single hollowed brick was that I was able to reheat the sheep's nose tool I was making after getting the angle and hook established by carefully sliding one of the middle bricks over a little to enlarge the chamber.
Not sure I understand this- is the bore the chamber radius, and the length the length of the chamber? If so, I guess I got lucky!
I'll take a look for one the next time I'm at the hardware store, thanks!
Reply to
Prometheus
All firebrick is not the same. For "quick action" you want lightweight brick (feels almost like styrofoam). Fireplace brick is harder and heavier. Pottery supply is the typical source for the lightweight stuff. Point being, it takes time and fuel to get the face of heavy brick up to temperature, and heavy brick does not insulate as well (it does, however, hold up to abuse better, such as having logs tossed at it)
BUT...
You don't need to go get those, since you already have some brick, if you get one of the other trick materials - find your local pottery supply (or one on the net) and get some high temp insulating blanket (eg, kaowool), which you can use to line the inside of this forge (or a coffee can - the stuff is that good). There are also coatings you can use (eg, ITC-100) on the face of the stuff. The lightweight, highly insulating nature of the blanket material will mean the thing heats up a lot faster. But that will come later, as you're not in a state to spend money on it until after the holidays - OK.
For now, If you are primarily heating small chunks of drill rod, I'd restack the forgelet such that you have two brick laid flat, so it's 1.5 inches high, and perhaps set them 1 - 1.5 inches apart, so the space is more like 1 or 1.5 x 1.5 x 9 - if you need a little more width, make it a little wider. Given limited heat input, the less excess space (and brick face exposed to the heat) the better.
Reply to
Ecnerwal
Your forge is plenty small. Your firebrick isn't the right stuff, as others have mentioned, but it should work a lot better than it is. I think your torch is at fault. What to do about it is the tricky part.
If you can post a picture or two, it may help us figure out what to do. Otherwise, you can try adjusting your burner. Try to figure out some kind of choke to reduce the amount of air. Try reducing the pressure (you are using a regulator?) and see what happens.
Here are some flame pictures:
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come from here:
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are more pages on this site of interest--you could spend between now and Christmas reading it all.
The firebrick you have is probably intended to hold heat. This means it will be slow to heat up. A piece of 1/8-1/4" steel rod held in the flame will show rough heat changes a lot quicker than your forge body.
Larry Zoeller isn't answering my emails--has anyone else been in touch with him? I'm wondering if I'm getting nailed in a spam filter or something. Maybe he's on vacation.
Steve
Prometheus wrote:
Reply to
Steve Smith
OK, it was my spam filter. Larry Zoeller is out there and responding. Ignore my last question.
Steve
Steve Smith wrote:
Reply to
Steve Smith
For sure the way to go nowdays, the internet wasn't going when I made my pOOpane burner. :/
Not my words but exactly my experience! :)
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My stuff ain't setup for forging just for heat treating knife blades and springs. The lighter colored bricks are insulated firebricks and are light-weight like styrofoam. No kidding, I've held one in my barehand while one face of the brick was at-least-orange-hot and turned that face toward my face and felt like it about singed my eyebrows. :)
~$3 each as opposed to ~$.50 each for the other heavy firebricks.
The first time using the new insulated firebricks I just about "melted;)" the O1 tool steel utility knife blank!
Ok, not metled but it sure as heck got all wiggly and jiggily and droopy. :)
Way-past the arrest point that I was watching for anyway. :)
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The "screens" are screwed into the threads :) and they just happen to be stainless steel... the material was picked up off the ground at my favorite scrap yard (catylitic converter type exhaust screen).
Since that picture I've screwed-in 1/2" pipe reducer bushings (with their own screens) right in on top of those 3/4" ones shown.
Slowed everything up and am getting better results in my heat treating of thin knife blades.
Alvin in AZ
Reply to
alvinj
At the Seattle ABANA conference this summer, Hank Knickmeyer's demo was set up with insulated firebricks, but they bought too low a temperature grade. The bricks he put over the opening of his forge (a very hot forge) kept melting on him. Everyone was amused.
Steve
Reply to
Steve Smith
Sorry my bad, length of the burner tube to the diameter of the bore in the tube.
Regards Charles
Reply to
Chilla
Not much help now, but years ago - I suspect even now - they have bags of Alumina mix that you mix up your own bricks or lay out a flay tray...
That stuff handles high temp - where the yellow bricks of air don't last.
Don't know a trade name but a kiln supplier or fire brick seller knows or can order.
Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.
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Steve Smith wrote:
Reply to
Martin H. Eastburn
Unfortunately, photography is one thing I don't do- seems like the couple of times I bought a camera, I managed to break the things right away. Got sick and tired of throwing away $$$- so no pics.
The "neutral" flame best illustrates what the flame looks like out of the torch. It's not a terribly fancy one- just a standard one that screws to the top of a skinny propane tank and adjusts via a knob at the back.
I'll try to describe the setup in words- there may be something you can spot from the description alone.
The firebricks are layered to make a chamber that is about 1" x 1.25" x 9" long, with one brick stood on edge to block the back. Each brick has is 1.25" x 4.5" x 9". To direct the flame into the forge, I drilled a hole halfway down the nine inch length through the narrow part of the brick, so that the hole is 4.5" long. The nozzle of the torch is a tight fit in the end of the hole, and when looking into the opening of the forge, the flame comes straight out of the hole, hits the far wall, splits in two and swirls back along the top and bottom.
The torch nozzle is essentially a bit of bent pipe with no end on it. It does not have air holes near the tip (It just occured to me that that may be important, as the end is fitted into the hole.) I have been running it fully open.
What happens after the bricks begin to heat up is that glowing red spots about 1.5" wide gradually develop on the bricks themselves- first where the flame is coming through the hole, and then spreading to the top and bottom of the chamber shortly thereafter. As you can probably guess, the metal is most efficiently heated right on those spots.
At the mouth of the opening, there is a fairly consistant blue flame extending out about 1".
I believe it is- several hours after turning the forge off, the bricks were still very warm to the touch. They were sold as fireplace liners.
It worked well enough to make what I needed, so I suppose that might be where it's at for a little while. I got the boss to agree to let me take a little time to make a metal forge body with the equipment at work, so once I figure out how to make an appropriate burner, I can go that route and buy some of that kaowool and line the inside. Lots of overtime right now, especially with people missing work for the hollidays, so I might be able to get something more respectable together fairly soon.
Reply to
Prometheus
Anyone have a good online source for these? AFAIK, there are no pottery suppliers in my neck of the woods.
Reply to
Prometheus
What neck of the woods is that? :)
Got mine at a brick yard in dumb ol Tucson. :)
They had several to choose from, different top temperatures and different insulation levels. Mine are the most insulating and are just like (no kidding) the material inside the ceramic kilns. (was given a rusted out mess of a cermic kiln back in the late 80's)
I was at the scrapyard one day and a couple guys were removing fire bricks from one of those rotary-glass-melters they use to make telescope mirrors at the UofA. Another college threw his whole works away, they found out where and high-tailed it over there and began stripping it of the more valuable parts. :) The fancy bricks.
The bricks they were removing looked kinda like fused clear glass beads and the guys were telling me how similar they were to the space shuttle tiles etc. They gave me the distinct impression my bricks were "ho hum" bricks. ;)
They looked like "mutt and jeff". :) I recognized the short fat one right away from TV (Science channel) and later saw the tall skinny one on TV.
Anyway, insulated firebricks would be quick and easy to fool with but IMO, from what I've learned here, that isn't the best way to get something worth while for forging.
"batting with a coating, inside a metal container" -a.c.b
Cheaper and better both, right guys?
Alvin in AZ (not a blacksmith)
Reply to
alvinj
That sounds really good actually. :)
There's some talk about putting some sort of replacable fireproof brick on the bottom of the forge when you are welding, flux eats it up instead of your lining etc.
Not sure what type of brick tho. :/
I'll shut up now, ok? :)
Alvin in AZ (not a blacksmith just a blabber mouth)
Reply to
alvinj
Ah, there we have it, I was wondering why you needed a masonry bit to cut the brick, a K26 fire brick can be cut with spoon. Buy 1 K26 fire brick make a hole through the centre, and a hole in the side for your propane hand torch (small blue bottle bernzomatic or something similar at a guess). Wire around the block in front and back and run two wires around the length of the brick.
1 K26 costs $8 AUD, so probably $5.50.
You will definitely be able to work faster, get higher temperatures and the gas economy will be better.
The brick will eventually degrade, and the wires help stop that a little, but if cost is the issue, this is definitely the way to go for knives and small tools.
Regards Charles P.S. Just to confirm how well this simple idea works, I used 1/2 a K26 and a 250g crucible to melt 90/10 bronze in about 5 minutes. Powered with a propane hand torch.
Reply to
Chilla
I used Bailey's.
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Pete Keillor
Reply to
Pete Keillor
West-central Wisconsin. I checked with the local brick yard, and they had firebrick in two sizes- 1.5" thick, and 2.5" thick. The thicker stuff was $1.60 a brick, so I am assuming (though I could certainly be wrong) that it is the heavy firebrick. They're kind of the only game in town.
That's the plan, a little way down the road- I'm just impatient!
Reply to
Prometheus
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fine person to do business with.
Steve
Prometheus wrote:
Reply to
Steve Smith
I misunderstood. I was picturing a large weed burner. You're right, your burner is undersized compared to the volume, and the heavy firebrick isn't helping matters.
This is a burner that works great and is cheap and easy to assemble:
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you weld, you can come up with better ways to hold the jet. Alignment of the jet with the burner bore is important. If money is easier than time, buy a sidearm burner from Larry Zoeller (see my other post). I'm using one of these burners in a forge 11" diameter (outside), 15" long with 2" of Durablanket S insulation and a flat floor (so it is a half cylinder inside). This works fine, but I wouldn't make a single burner forge any larger.
If you want to get a little fancy when you build a bigger forge, add an idle circuit to the gas flow. You should have a shutoff valve of course, from there you run two gas pipes. One goes thru a second shutoff to the burners. The other route goes thru a needle valve to the burners. Adjust the needle valve for the lowest pressure the burners will run at. Now you can switch between full bore and idle with the flick of a valve. You will need a regulator--most non-blower burners run in the 3-10psi range.
Another nice thing to do (I haven't tried this yet--I'm building a larger forge this winter) is to make air curtains at the open ends of your forge. This is a narrow stream of cool air, maybe 1/2-3/4" by the width of your forge opening. This is supposed to help reduce heating on stock sticking out of the forge (and your hands). You still need firebrick or doors. I'm going to use a crossflow (tangential) blower like this:
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You should coat the wool products with something to seal the surface and keep particulates out of the air. Larry sells some coatings that are also IR reflectors (somewhat increasing your forge temp), but they're expensive. I use Satanite, which is cheap. You paint it on (glop it on?).
You need 2300F rated Kaowool (Durablanket S is the same rating). I usually buy the 3000F bricks. The fireplace type bricks will crack eventually from thermal stress. The high temp bricks won't, but they crack from being dropped. :)
Steve
Prometheus wrote:
Reply to
Steve Smith

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