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My forge build. Rate it please !


Jurassicfireart

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Hey guys this is my first forge build ever just kinda winged it. Wanted it to be a forge foundry combo unit ended up really not being as efficient as I imagined so I changed it up I'm looking for some solid input on my creation. I have used Ks4vplus refactory from Harrison walker and 3x9 high density fire bricks I  have a solid knowledge of refactory and fire bricks being a former meltdeck tech at a local ductile iron foundry.  I started with. 9" ID and added a fire brick to get metal up closer to the burners had huge gaps on the side  but it worked and got hot enough to forge some tongs and hardy hot cut stuff like that but my propane usage was crazy any way just filled in the bottom to try and optimize the space. Like I said any input on some modifications I could do to make my forge pack more of a punch for the propane input would be great thanks super new to forgeing but loving it.

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Forge liner looks like heavy refractory, not insulating refractory.  The former will withstand forging temperatures, but is a significant thermal mass and likely not a good insulator (which means it will bleed heat out to the skin of the forge and take a long time to heat up).  I found the following data online: 

the thermal conductivity of KS-4V PLUS depends on the temperature. At 400°F, 800°F, and 1200°F, it is 6.4 Btu·in/hr·ft2·°F. At 1600°F, it is 6.5. At 2000°F it is 6.6, and at 2400°F, it is 6.8 Btu·in/hr·ft2·°F. 

As a contrast, the thermal conductivity of Kaowool is around 1/6 of that, for the same thickness at a mean temperature of 1,000 deg. F (which would be reasonable for general forging use), and is tremendously lighter as well (6 #/CF as opposed to 125 #/CF).

In short, your burners look effective, and your forge is robust, but rather inefficient for a hobby user and will take a very long time to get up to temperature, if it ever does.

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It gets up to temp does take time thought around 30 mins. Great input thanks I would like to be doing some serious all day everyday kinda forging with this unit. Maybe something different would be better new design  and kaowool perhaps? do you think  that itc-100  kilnwash would help with thermal conductivity? 

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Welcome aboard, glad to have you. If you'll put your general location in the header you might be surprised how many of the gang live within visiting distance.

Check out the thread, "forges 101," it's the most current forge building thread. There are better and MUCH cheaper kiln washes than ITC-100. It's not intended for forges, it's intended to prevent high temp chemical erosion and prevent things from bonding to the furnace. Think keeping glazes from fusing to kiln furniture. It's also mechanically friable, it'll rub right off. There are better and some of the guys here have been experimenting with home brew versions that are darned promising.

Kaowool or the equivalent is typically rated to 2,300 f. or up to 2,6oo f. for the better. Neither will last long without shielding from direct flame contact and it's mechanically very weak when jabbed or rubbed by steel things. A castable high alumina hard refractory inner liner about 1/2" thick will provide a durable chemically resistant flame face. Washing it with a good IR re-radiating kiln wash ups both chemical resistance and thermal efficiency. 

My forges are made this way and depending on how large I have the chamber blocked, fro 300 - 700+ cu/in and one or two 3/4" NA propane burners it will go from room temperature to screaming turn your steel into a sparkler in about 10 minutes. I typically get a couple few days out of a 40lb. tank, say 18 hrs. or so. Normally I run off a 100 lb tank and don't bother to try judging economy. 

At present your forge is wide open so the burner flame is blowing through and out. The longer it stays in the forge the more energy is transferred to the liner where the IR can heat your stock. Putting the work in the flame isn't how an efficient forge works. They're "recuperative" furnaces, the fire heats the liner and the liner radiates IR which heats the stock. 

Speaking of which, at present your liner is a huge thermal mass with about the same insulating qualities as an equal thickness of limestone, a little better but not much. 

My forge is probably 1/10 the thermal mass and the chamber is as closed as I can make it without impeding the burner's. Keeping the fire IN the forge as long as possible.

If you were running a commercial forging operation cycling lots of pieces through the forge then a high thermal mass would be a good thing but you need enough burner to bring it to heat. Once hot it would transfer heat to stock very quickly simply because there is so much to offer. 

I can cool my forge from bright yellow white, say 2,600 f.+ to orange by loading a number of pieces in it, say 10 pieces of 1/2" sq. Your's would just make them that hot and you'd never notice a color change. Make sense? I'm a hobbyist with the occasional lapse into turning a buck I just don't need to burn 50 lbs. of propane a shift to keep up. 

Heck, if I were doing that kind of production I'd buy an induction forge, they're expensive to buy but very economical and fast, Fast, FAST in operation.

See you in Forges 101, you'll find most of your questions have been answered and with your background you won't have to leanr a new craft language to understand.

Frosty The Lucky.

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