Burner comparisons

J

Jason Fry

Joined
Jun 5, 2008
Messages
3,215
I've found all kinds of info on venturi vs. blown, on how to build a burner from hardware store parts, and the like. Specifically, I saw a design for Reil's burner, and I saw Zoeller's Z burner and sidearm, and I found the T-Rex. My question is this... is one of these preferred over the others? Are there any significant differences, or reasons one is better?
 
Forgot to add, if these details make a difference. I plan to hook up a thermocouple and PID for temperature readings, but not to go all in with the SSR and all. Right now I want it for heat treating simple steels and for forging. I currently have forged only about 10% of my knives, but it's an area I want to expand. While the progression of this skill set almost inevitably moves toward forge welding, I'm a long way from there, and not particularly interested right now.
 
jkf96a said:
Surely somebody has tried more than one of these burners and can shed some light?
Click to expand...

I've tried all the burners you have mentioned above. All will do the job if designed/assembled correctly. It really depends what you want to do and what your preferences are. My current preference is a blown burner using natural gas instead of propane. I run at less than 1psi and can get to over 2300 degrees in 15-20 minutes. I'm using this set up because I hate to go fill propane tanks when I can just tap what I need out of the wall. Like I said, it is all about designing correctly for what you want to do.

If you are going to buy one instead of making one, the T-rex is about the best off-the-shelf venturi burner out there. As IG said, a blown burner will usually be more efficient with gas (if designed correctly).

Eric
 
Three votes, plus Kevin (i've read that at least 6 times already :) for blown... may have to go that way. More fuel efficient sounds good. Is a 6" pipe with 1" of insulation going to be too small?
 
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I have 4 gas forges in my smithy, 2 @ 8", 1 @12" and 1 @ 6".
The 6" is like a rocket-ship, it is good for forging and making cable Damascus, but you are limited in the height of a billet that will fit into it.;)
 
As I was pointing out, think ahead when planning your first forge. Many rush out and build one on the quick, and then soon realize that it isn't as big or useful as they need. I would use 8" as a minimum shell (10" would be better). Go with 1" wool and refractory coating on an 8" and two inch wool and coating on a 10" or 12".
Darren Ellis carries everything you need and has a lot of forge building info ( and pictures) on his FAQs. He has burners and burner kits,too.
http://forgegallery.elliscustomknifeworks.com/
Click on "Refractory Supplies" to go to his main site. From the forge gallery, you can see that there is a huge difference in the way forges look from the outside, but they are all about the same on the inside. The main thing you want is for the burners to enter the chamber at a tangent. The flames need to swirl around the chamber, not fire straight into it.

Final note. - Maybe not for the first forge, but worth consideration:
If someone had told me in the beginning that a poured refractory shell would be so efficient ( far superior for HT), and long lasting, I would have done that early on. Few have one because the old tried and true Kaowool is simple and easy. To make a refractory lined forge ( simplified instruction), you pour a hollow cylinder of refractory the size of the forge chamber. Make it about an inch thick. Use some sort of metal sleeve for the outside and a cardboard tube for the inside. ( Carpet tube or similar. Paint the tube with cheap spray paint to keep the cardboard dry until the refractory sets.)After the lining is cured, you will tear/peel/cut out the cardboard. The metal outer skin stays on. It can be 8" stove pipe or some other thin walled pipe/tube ,it does not need to be heavy ( but it doesn't matter) . Wrap the refractory shell in a layer of 1"or 2" Kaowool and make a sheet metal shell that wraps around that. This will make the most robust forge you can ask for. The above is sort of simplified, the burner ports, IT-100 coating, and bubble alumina floor, etc. will be the same as a wool lined forge. With some planning and forethought, you can pour the lining with the main shell, burner tubes, wool,outer skin, and cardboard tube all in place.)

Good luck, and post your ideas and plans here for those who have built a forge or two to help you with your design. Photos are always a help.

Stacy
 
Thanks for the link, Stacy. I've looked over the supplies on Ellis' site a half dozen times, but hadn't ever seen the forge gallery. Based on the consistent stream of input from the forums for the last six months, I decided not to do a one brick or a soup can from the get go. Planning on a 6 or 8 inch pipe, probably 12-14 inches long, with firebrick doors ala Indian George, with 1" of Kaowool with a thin coat of satanite and then ITC 100. Still thinking about burner options, but you have really got me convinced to go blown. Like I said before, I intend to go with a thermocouple and PID for temp awareness, but not to go all in with the SSR for temp control. I've sold a few knives recently, so the funding is in place, now I just have to get past a bathroom remodel and I'll get after the forge building.
 
Stacy i'm with you, I wish i would have done a cast forge. i also say go with forced air, thats what i have and its great.
 
bladsmth said:
you pour a hollow cylinder of refractory the size of the forge chamber. Make it about an inch thick.

Stacy
Click to expand...

Not to horn in on the thread or anything but;

Would it be bad if it were two inches thick and does it have to be coated inside with the wool and cement? Would there be any benefit to using small pieces of wire for reinforcing?

I'm picking up some refractory cement today and I'll be making my own mix with perlite and sand.
 
69 I think Stacy said that the wool was to be put on the outside of the poured sleeve with another piece of metal around the wool. As far as being 2 inches thick I would not think that would hurt anything. The ITC100 is a coating for the inside to make it more efficient and to protect the refractory. If I am wrong I am sure Stacy will correct me. :)
 
Just as an aside, the one fact that is never included in these discussions of Blown burners vs. atmospherically aspirated burners is ORIFICE SIZE. I have witnessed long winded arguments about how "I can run my forge on 2 LBS pressure, etc" If you have a 1/4" orifice at 2 LB PSI and a blower at an unknown CFM vs. a #60 drill orifice in an atmpspherically aspirated burner at 12 LB PS!, who is using more gas? I dont have the math to reach a scientific conclusion, but atmosphericly aspirated burners are very efficient IMHO. I built four MONGO (Ron Reils name, Also known as Alfred burners from the ceramic dept at Alfred Univ. in NY state.) burners for my wife ceramic kiln (based on readily available and published designs) that are superb. They can hold A 30 CF Kiln at 2300 F for hours, all with out blowers. Of course the kiln has a high stack that creates a fierce draft. Maybe we need higher exhaust stacks on our forges! I sent my drawings to Rob Reil and they are still posted, as far as I know.
 
Just as important as protecting the Kaowool, the Satanite also protects your lungs from the ceramic fibers. It is important to wear a respirator when working with Kaowool as the dust/fibers are very bad to breathe. If not coated, the fibers will break up and be ejected into your shop as the forge is used.

I used two thin coats of Satanite and a thin coat of ITC-100. It is holding up well (no exposed Kaowool) after over a year.
 
i'm using some of the plistix 900 from larry zoeller for the forge i'm building and so far i hate to say i'm not impressed with how it covers. i have tried mixing it different ways and finds that it is pretty lumpy and doesnt cover very well. i think i might go the expensive route and do a coating of satanite and ITC-100 next time

jake
 
The lining coating of refractory cement ( Satanite or Plistix) should be mixed to a thin mud consistancy....sort of like pancake batter. It is spread on the wool to go into it a bit as well as coat it. Using rigidizer on the wool first is a good idea, or it tends to mash down. Go slow, and build it up in layers. Once the refractory coating is about 1/4" thick, let it dry well, then cure it with short firings of the forge burner. Heat it a little and let it cool down. Then heat it a little more, etc, until it gets up to a several minute run ( use thin refractory to patch and cracks on each firing). Let it cool down completely. Coat the lining with ITC-100, let it dry, cure it with slow heats, ........and the shell will last a long time.

Stacy
 
Just whatever you do, don't pour your whole shell out of an inch thick mizzou castable, or similar castable.

That stuff has a rather high thermal mass, and isn't a great insulator either. The foirst poured forge I did was out of mizzou, and I never did get patient enough to get that puppy up to a decent forging temp.
 
Dan is right, don't pour the liner directly into the pipe.
That is why there is an insulating layer of wool on the outside of the castable shell. It may take 15 or 20 minutes to get up to temp, but once there the heating will be from the hot shell and not from the flames. In a controlled forge the heat can be +/- 1 degree once fully soaked.
Stacy
 
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