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Darthpinkeye

Order to layer bricks and kaowool

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Howdy, long time lurker first time poster. 

I’m working on making a propane forge in addition to my coal forge. 

I have fire bricks (2700 degree), kaowool, and refractory cement. 

What would be the best order to put these in? 

I was planning on wool, then bricks so the interior is brick lined for durability. My concern is that it just may not work well. I need to be able to weld in it. 

I live just a bit south of Fort Worth in Texas. I’ve read people like to know where you’re coming from. 

Thank you for y’alls input and patience while I get up to speed with proper posting etiquette. 

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Welcome to posting. We won't remember your location after leaving this thread, hence the suggestion to edit your profile to include it. Here are other hints to help.

https://www.iforgeiron.com/topic/53873-read-this-first/

Can't help with the brick question having never built a brick forge. One thing about bricks, are they hard or soft bricks? Soft won't work for long because they don't take the thermal cycling well and flux will eat them up. From what I've heard K26 bricks are best.

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Thanks for the link to the read first post .

The bricks are the hard kind I purchased from amazon. (Rutland products fire brick)

I’d like to build the thing to last  I have everything but have not assembled any of it yet .

I was planning on 2.5 inches of insulation total on each side.  External measurements 14x9 and 18 inches long with an internal 9x4.5.  That way I could easily put a movable brick in the back to make my heated area smaller if needed.

Thank you for your time.

 

 

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1 hour ago, ThomasPowers said:

Why not build it to work well rather than build it to last?

 

That works too. I’m just not sure how to do that. So I’ll take any input I can get about the construction using the stuff I have on hand, or can get at a decent price.

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Have you read the Forges 101 thread? So many questions answered there....

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Your brick is one of the newer bricks made of cast refractory; their advantage is that a whole line of bricks between hard and soft bricks become available.

Bricks made of refractory are also easy to read the particulars on because all you need to do is match the cubic foot weight and use temperature of the brick manufacturer's castable refractory to be reasonably assured that you have the same product. You are much more likely to get detailed information about the brick that way.

Your brick is probably semi-insulating, which is acceptable, but it also has a low use temperature for a hot-face. What to do? Make sure that some higher temperature product, like high alumina kiln shelf, or Kast-O-lite 30 is placed over the brick wherever the flame is aimed at. You would also be well served by brushing on a heat reflecting finish coat inside the forge. 

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Thank you so much for the feedback. I’d read the 101 post several times and gone to a few sites and read as many posts as possible. I was unable to find if there was a preferred substance (wool or brick) to be exposed. I guess I was just over thinking it. 

 

Thank you Mikey. 

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11 minutes ago, Darthpinkeye said:

I guess I was just over thinking it.

You asked a needed question, so you are not overthinking things. As your forge build continues, more thinking will become necessary. You needed to get those points clear in order to avoid working yourself into a comer. The points still to be considered are just details.

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Questions concerning dimensions, what to use as a shell, or even if to have one, are nearly impossible to change when you blow them; most everything else is what I think of as changeable details; these range between irritating to down right easy to deal with (the difference is often in your mind). You can utterly screw up a burner, and so long as you made the burner port's tube with a large enough diameter, you simply need to change it out (and give the old one to an enemy). If you screw up the port tube, then you have a REAL problem.

Everything that mounts on the forge shell is only an add-on; if it is screwed on it's child's play to change; if brazed or welded on it is a lot more work to change. I was a long time welder; the hardest thing for new guys to learn was lightly tacking parts together, then KNOWING what they thought was right before finish welding. With heating equipment. The hardest lesson was to avoid welding in areas where it would result in warping the part during thermal cycling.

Look first to see which category a desion lands in, and don't sweat the small stuff.

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9 x 4.5 x 18 is around 720 cubic inches.  in my oppinion that is to large to use brick.  I guess the question is have you already purchased enough brick to make this?  If the answer is yes then use brick as your shell with 1" of kaowool on the inside (you can use 2" but that may be overkill as the brick is also insulating) coat that in 1/4" kastolite30 (3/4" on the floor) and coat that in a layered of matrikote.  

 

If you dont already have the brick use some sheet metal to make your shell and follow the above instructions (using 2 1" layers of kaowool)

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Darth - or - Pinky? . . . Hmmmm, Pinky it is. :P

In the reading you've done so far on this and other sites, you've been looking for clarification right? Found any? Right there is a major problem with the web, anybody with a connection, camera, keyboard and opinion puts it online as an expert. No different here, lots of opinions with various degrees of expertise from decades to zero. Random advice is hard to evaluate without knowing how the things work so avoid it. You have a coal forge and I assume some experience using it. How may times has someone given you advice based on their grandfather being a blacksmith and they maybe got to turn the blower crank? I hear that all the time doing demos.

My advice is pick ONE set of proven plans and follow them. Do NOT mix and match designs, ideas, etc. or you won't know why it doesn't work. You need knowledge and experience to get to a point where you can pick and choose features from different set ups with much hope of success.

Like all of us when we got started the forge you're planning on is WAY too large and worse it's long and narrow. Starting out with a shape that REQUIRES multiple burners is adding a level of difficulty for no good reason. 

Maybe the most important bit of advice I can give you is don't get in a hurry. All doing things in a rush accomplishes is making your mistakes permanent more quickly. Keep us posted, we'll help.

Frosty The Lucky.

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I intend to try cement board as the shell of an octagonal shaped oval forge, just as an experiment. Even aluminum can be used as a shell, if enough care is  taken to keep the shell well clear of exhaust gases, and if enough insulation is provided to keep the shell well below 400 F. Sheet metal can be a good choice too, especially if it is combined with ceramic parts (high alumina kiln shelves or Kast-O-lite 30) as forge ends. The more forethought and imagination involved the more we get in return for the money and time given.

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I still have that problem where I get real excited about a project and don't take time for due diligence.  I hoped that my lollygagging on my gas forge helped me think things out a bit more. 

Before I read these latest posts I was going to, foolishly, weld both my burners instead of tacking them in place.  Like most newbies I thought I was smart enough to make up my own plan.

I think i'm still going to use the materials I have already purchased, bricks and kaowool and see what happens, but keep an eye on the future.  

 

Binesman thank you for suggesting the kaowool on the inside, it seems more efficient than brick.  I don't know how I've missed hearing about kast-o-lite until now, it sounds like a godsend. 

Frosty I've been following your posts for a few years now and have always been impressed with your kindness and wisdom.  I'm used to people calling me by all sorts of names, the only one that's ever ticked me off was ambulance driver instead of paramedic  :). 

Mikey you're ideas are solid and have helped me get closer to the right mindset about this project.  This forge isn't the goal, it's the first step in a process of refinement and fun.  

 

Thank you all.

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Mike: Concrete backer board will work just fine, it'll certainly take more heat than Al. 

Pinky: Adding emergency vehicle driver to EMT is no dis, it's an advanced skill. I owe my life to fast response by the local volunteer FD. The flight medic who restarted my heart a couple times on the 13 minute flight to Anchorage stopped in to see how I was doing after I came back from wherever I was. The story he told was scary and inspirational, I've also stopped by Station 61 to say thinks to the EMTs who stabilized me enough for the life flight. I guess nobody expected me to survive even the critical care unit. A too bad penny I guess. 

Try not to get taken into Mike and my speculations and experimenting with burners and forges, we've both been doing this for a couple few decades, leave experimenting till after you have the working tool. Hmmm?

KISS is key when you're breaking into a craft, we all tend to fall into the trap of wanting the best tools and equipment when we're new. Normal, normal. Perfection is an illusion at the human level. 

The order I recognize as effective from the shell in goes like this. Shell, brick pile in your plans. Next layer in is the insulation, 2 layers of 1" ceramic blanket, rigidized and flame cured individually. Last is the flame face. The common consensus currently is Kast-O-Lite 30 li about 1/2" thick. A LITTLE thicker where the burner flame strikes directly will make your forge last longer. The last liner layer is optional, Kastolite is in itself good enough to not require further treatment. However an IR re-radiating kiln wash makes a forge more efficient and extends the life of the rest of the liner. ITC-100 is the best known name but is NOT formulated for what we do. In reality it's a release agent to prevent gunk from sticking to furnace flame faces, the 70% zirconium content is for it's nearly inert nature not it's IR re-radiating properties. It's also CRAZY expensive, go with something formulated for our purposes. Wayne Coe sells small quantities of Metrikote or Plistex. Both of these are intended to fire onto the flame face of propane forges and form a strong IR re radiating surface that doesn't notice little things like borax based welding flux.

In summary: Shell, Kaowool refractory insulation, cast hard refractory flame face, kiln wash.

Make your burner port(s) as you build and treat them just like the forge liner. Insulation, hard liner flame face, kiln wash. This will let you make the burner port(s) the burner's flare and to a degree shape the flame. Save shaped flares for when you have some experience it's a LOT trickier than it sounds. Anyway, a flared burner port also keeps the mixing tube farther away from the H-O-T-N-E-S-S.  

Extend the liner out and around the doors, though using brick for the liner this isn't necessary or maybe desirable.

Frosty The Lucky.

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Everything here is very informative to a beginner such as myself.Thank you all.One thing I did not see mentioned but have wondered about was if I should use anything to bond the (I have ceramic insulation) to the old air compressor tank that I have?Everything else seems pretty cut and dry except for the insulating of the burner(s) ? I’ve only seen pictures of just plain metal pipes?Like the kind used to run gas lines to your home.

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The burn is supposed to take place off the end of the pipe and not inside it.  Heating the pipe so that it ignites the fuel/air mixture inside the pipe is double plus ungood!  So no insulation.

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The only service to the burner's mixing tube or nozzle flare insulation can be is to shield it from the IR radiation of the forge chamber. This is the main reason to hold the end of the burner back inside the ceramic blanket liner. You want to keep the burner as cool as reasonably possible.

A dedicated refractory or insulating refractory on the burner tube hasn't seen much benefit in my limited experiments.

Frosty The Lucky.

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