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Thinking of making my first forge.... Ribbon!


ToMang07

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So after careful consideration, the only NA forge that I was considering was the Chile Habanero, but upon further investigation they are looking at a 20+ week wait time.

So, in the meantime anyway, my plan is to design and build a forge.  I have 2 options for the body, one is an old water tank from a portable water pump, the other is an air compressor tank, being the much larger one. (25-ish gallon.)

My thought process is to cut/clean/paint the tank on inside, then line with 2" 2600*F Kaowool. Then put the forge on it's end, plop a 8 or 10" pipe in the middle, and fill the rest with Kastolite 30. After that cures line with ITC100.

Open to suggestions/criticisms.

Now the burner.... I have found a lot less info regarding ribbon burners, however I believe I have enough of a grasp that I won't blow myself up. My thought is to build a 12-14" long by 2.5" wide burner body, cast into the Kastolite. I'm looking at a 125cfm blower that has both manual vents as well as it can be hooked to a variable speed controller. 2" piping from blower to burner, with some mixing blades. Still need to figure out where/how to pipe in the propane, but I have a 0-30psi regulator.

As far as positioning the burner in the cylinder, I can't decide if 90* from the top (Horizontally) or 45* from the top would be better.

I have nothing set in stone as of yet, but figured I would run my plans by some of you more experienced smiths and see what you thought.  I appreciate the input.

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For a first forge, you probably don't need anything bigger than a five-gallon pail overall. Anything larger is going to be just too darn big, which will take a LOT of wasted propane to heat up and run. 

The 2" of kaowool and a Kastolite layer is a good plan.

My ribbon burner is a NARB, so I have nothing to offer on the subject of blown burners.

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Again can you tell us why you need such a large forge?  Generally it's like buying a dump truck for your daily driver because you plan to buy a load or two of gravel each year.  If you really need to do a load of gravel every day; no problem; otherwise it's a lot of unneeded effort and expense!

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Unless you time it very carefully you will have a very difficult time getting an 8 or 10" piece of pipe out of your casting.  I would recommend sonotube, with a plastic sheet on top for release, and be prepared to slice it open to get it off (I presliced mine and used tape to join it).

Anything more than around 1" thickness of Kastolite will add significant thermal mass to your forge.  This is a mixed bag as it takes a lot longer to heat up, but cools more slowly.  As the others said, it all depends on what you will use your forge for.

 

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Well, if I'm gonna build one, I might as well build one; and I want to be sure it's big enough to do anything I need to do. I figure a ribbon burner is hotter, and will distribute heat more evenly, and from what I can tell the most efficient burner design of the gas fuel forges.

As far as the pipe.... I figure I can either do a cardboard cylinder and burn it out, or just cut a PVC in half and use duct tape to keep the refractory out, then just pop it into itself to remove from the casting.

The water tank is only a ~12" diameter, and the air tank is about a ~16" diameter, so if I had 2" Kaowool and 1" cement it would still only have 10" of space at most in the middle with the big tank, 6" in the smaller one. Yes, it'll be longer, but That's one of the reasons I was thinking doing a longer, skinnier burner vs. a large block just in the middle.

I'm not fixed on any design, but I only want to do this once, and do it right. I could do a smaller, more cost effective forge, however that is not my goal. I want to have one that is large enough and hot enough to do whatever I need.

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What is it that you want to forge that needs the length rather than a rear pass through? 

Usually when this shows up; people say swords and are surprised to learn that you should ONLY be heating about 6" of a sword at the time as heating more than you can work degrades the metal due to grain growth, decarburization and scale losses.  This changes as you get good and move up to power hammers; but the gas saved working with a smaller forge will pay for the longer one you need to build later!  (The idea of having it ready for later is counterbalanced by the fact that you will probably be relining it several times before you get to the using the length stage.)

Forges are cheap and easy to build, fuel costs are what add up!

Now there are reasons to have a large forge but they are usually large in cubic over length, (sculpture for instance needing a 3D space.)

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You're laboring under a few false opinions. A ribbon burner is NOT hotter nor more efficient than a single nozzle burner. Heat output is determined solely by how much fuel/air mix is burned per second in the furnace. Ambient temperature of the flame is determined by the air fuel ratio, NOT the shape of the burner.

You're falling for a really common mythtake, almost all of us have made, you aren't alone. Trying to build THE forge that'll last is a really common mistake. On what are you basing your opinion of what you'll need in the future? Even folk who've been building propane forges for years tend to make them larger than necessary. My last one is close but still too large and not the right shape. My first successful forge and burner is collecting dust in a corner and it's close to 30 years old. 

A small forge, say 4.5" x 4.5" x 9" running a single 3/4" NA (Naturally Aspirated) propane burner will allow a person to learn the blacksmith's craft reasonably economically. Door baffles at both ends allows easy access for awkward shapes and if you fid yu need a larger forge it's easy to clone the one you're using and mate them end to end for 18" length. 

The liner in a propane forge is a wear item, it WILL wear out, the extreme heat and chemical actions of a propane flame take their toll as do rapid thermal cycles and mechanical abuse. A really long narrow chamber as you propose is going to really get torn up as you try to slide long stock into it, especially COLD stock. 

I suggest you start out with a "Brick Pile" forge. They're easy to make and you can reconfigure them at will: larger, long and narrow, L shaped, T shaped, etc? No problem just rearrange the bricks. There is a fairly recent entry on the Insulating Fire Brick (IFB) market, the Morgan thermal ceramics "K-26." They are: excellent insulation, rated to 2,600f. and withstand rapid thermal cycling without damage.  From what I'm seeing locally K-26 IFBs are replacing the older not so robust IFBs. Last I checked you have to special order the older type and worse they were about 2x the price of K-26 IFBs.

The pic below is one example of the clamped IFB forges built in a club forge/burner clinic. The build method is easily modified, want longer use longer all thread and two longer pieces of angle iron on the bottom and such. These cost members IIRC $112 including the burner, regulator and hose. There was a substantial group discount, the club bought a pallet of k-26 IFBs, two 20' sticks of angle iron and two 20' sticks of all thread, nuts, washers, plistex, etc. in quantity. What didn't get used at the clinic is available to club members at the discounted price. 

Expect to probably have to spend more but these are HOT little forges, guys who'd never done forge welds were doing them as soon as they hooked their forges up and lit them. The pic is a freshly made forge the day of the build. 

FORGET ITC-100! It is NOT formulated as a propane forge wash, it is formulated as a release agent in large furnaces and pottery kilns, it prevents molten material from sticking to the interior of the furnace, kiln. Sure it's largely zirconia but it doesn't work as well in a forge. It doesn't fire hard and rubs off after a short while. There are much better products for our purposes.

Above I mentioned Plistex, while it doesn't contain zirconium it is high alumina so molten flux won't dissolve it. It's rated for temps well higher than a propane forge is likely to reach. It fires hard like a coffee mug hard so it doesn't suffer mechanical damage so easily and it can be patched very easily. 

You can buy small quantities of Plistex, Kaowool, etc. from the Iforge store the link is at the top of the page. I don't know if IFI carries K-26 IFBs  though.

Frosty The Lucky.

2050643347_Noweldforge07.thumb.jpg.0123d9d60d7eb859ecd598f9aef152da.jpg

 

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  • 2 months later...

It is certainly burning. It looks rich: there is a lot of secondary flame, but that should be adjustable once it's in a forge. Do you know what is causing the flame length variation that is apparent in the video?

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Truthfully I didn't want to play with it too much , I just wanted to make sure it will run, I have too much air, so I'm debating adding a "T" with another gate to bleed off air so I don't burn out the blower. But I wanted to make sure it will work before installing it into the forge. This weekend I will be welding up the stand for the forge and firing it up for the first time. Ended up not getting as much of an angle as I wanted for the burner the way it set, but I believe it will work as is.

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It's burning unevenly because it's so long and narrow with the fuel/air inlet aimed directly down the outlets. A larger plenum might give it enough volume for the flow to even out but with the inlet oriented that way the center flames WILL be long.

No ToMang, it is NOT getting too much air, it is burning rich. It needs more air or less fuel for a neutral flame.

Frosty The Lucky.

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Welded up a hinge for the rear door, and lined it with ceramic wool then Castolite,  it's curing.

I think for the front I'll weld on a piece of angle iron and use soft fire brick for the door. 

It's coming along!

20210530_121330.jpg

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Next time you take pictures stand with the light behind you. The pics you just loaded are all "back lit" meaning the camera is adjusting exposure on the much brighter scene outdoors, NOT what you're trying to capture. 

Did you adjust your air fuel mix? It was running pretty rich in the last pic.

Frosty The Lucky.

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I played with it a bit, only fired it the one time so far,  definitely not dialed in,  but saw in excess of 1800°F with no doors on. I have it coated with ITC 100 now and curing,  so next weekend I'll get it dialed in.  It had pretty even flame and it ran great at 1psi. Looking forward to breaking it in!

20210531_184015.jpg

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Well, that was unpleasant. I'm no fan of videos when a couple still pics will tell us everything we need to know. Having to listen to the sound of your blower for all 49 seconds was worse than the first part showing your blower plumbing and stuff. 

What you really wanted to show us was the burner working yes? I don't know how long it had been running but the ratio is closer. Is that all the hotter it gets? Maybe next time run it a while to let it come up to heat before taking a pic. 

The burner is turned up too high the flames should be on the burner block or you'll be blowing the flame through and out into the shop rather than keeping it in the forge as long as possible to transfer energy to the liner.

I usually don't start videos of forges, I don't know why I did this time. A video jerking around with the volume painfully loud rarely if ever provides more useful information than a still pic. 

Please just a still pic or two.

Frosty The Lucky.

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