lining a cast iron twyer

[meco3hp]

Hello,
Ok Glenn and I have been passing emails back and forth about verious BS subjects and one that we discussed was "lining a cast iron twyer". I have a "whirlwind" cast iron twyer, that I used in my new coal forge, and I was wondering if I should line it with a refractory. I've seen some that are and a lot that aren't. I also seen some that had the words, "line before firing" cast right into the bottom of the forge. I've also seen a lot of the old rivet forges that have been cracked and repaired over the years that I assume came from pouring water over the fire during fire maintanance, cooling the cast iron too fast and cracking it.

Whats your take on the subject?

[Strine]

I assume by twyer you mean the fire pot not the air supply inlet. I have used an unlined cast iron fire pot for years with out any drama. It's an upside down pyramiddy shape about 1/2" thick all over. Actually, come to think of it, it's two halves bolted together and that might be why any cracking stresses are relieved. It's the same now as it was when I got it cast, except for the rust..er.. patina. It's forerunner was an upsidedown cone thing in one complete unit. Eventually it cracked but didn't fall apart and was, and still is quite usable. I never apply water to the fire nor cool the pot down with water at the end of the day. I reckon that's just asking for trouble.



This shows the bottom where the air goes in

[mouko_yamamoto]

I never cool it down with water, except when it starts to rain. :x

"If I can only gets this done...Oh, what the heck!"

[irnsrgn]

Well, her goes LOL, I guess my grandfather, my father, my uncles and all the old blacksmiths I grew up going to meetings at their shops were wrong. They all used wet coal to bank their fires with and a sprinkler can to control the size of the fire while using it.

You NEVER pour water into a firepot, you sprinkle water on the sides of the fire to keep the fire from spreading and only sprinkle the coal when the fire is working and has an air blast coming in the bottom, what little water that seeps thru the coal (it should be packed well) to keep the air from going right thru it will turn to steam and escape up and away from the cast iron pot before it ever makes contact with the pot due to the heat of the fire. remember water boils or makes steam at 212 degrees and your fire is close to or exceeding 2000 degrees.

I use wet coal to bank my fires with and use a sprinkler can to confine the fire when working if I need a small fire, the coal seems to coke better and I use a lot less coal than letting my fire be uncontrolled. On some bigger old Cast Iron forges there is a tank built into one end, this was for storing wet coal not as a mini quench tank.

I have watched some modern day smiths who do not control their fires and I use about a 4th of the coal they use to do the same amount of work by controlling my fire. Coal is expensive and I try to use only what I need to get the job done.

And as for a socalled clinker breaker, the thing in the bottom of the forge is actually an airgate to control the air coming into the bottom and also to direct the air into a certain part of the firepot. If you look closely at the thing in the bottom you will understand how this works. It works very poorly as a clinker breaker and why would you want to break up a big clinker to start with when you can pull it out in one piece with a fire poker and get rid of it, and not disturbe your fire much either.

Most forges use a fire pot except the socalled small round rivet or horseshoe forges. And all they have is a grate to let the air in and keep the coals from falling thru.

A tuyere is actually the long tapered water cooled nozzle that sticks into the fire in a side blown forge.

As to lining your firepot, I have lined a few iron ones I have made with a product called SAIRSET, its a refractory cement for cementing the bricks in a forge or fireplace to seal them. A 1/4 inch thick coat will protect the iron and also act as an insulator. but constant use does errode it over time and it needs to be redone occasionally.

That's my 2

[meco3hp]

Irnsrgn,
I use wet coal around the edge of my fire also. I like to move the coal in from the edge of the fire as I work. I use a sprinkler can to lightly keep the coal around the edge of the fire damp. I just have better luck with damp coal. I never pour water onto the fire. I've just been told thatyou don't need to line the fire pot. My counter to that is why do you see so many rivet forges that are cracked and why do you see some forges that say "line before firing". I've got about 4600# of refractory so it's not a problem for me to come up with something to line it with. Thanks for the input.

[HWooldridge]

Some time back, I was fortunate enough to acquire a factory Buffalo forge that came off a local Air Force base in almost new condition. The AF apparently ordered several during WW2 and used them infrequently. I was therefore able to see what one looked like from the factory - complete with electric blower, rheostat, air gate and half hood. This has been my daily user for about twenty years and has the classic 12x14 Buffalo pot with large square clinker breaker.

The fire pot rested on the lower set of lips so the upper lips on the long sides were about an inch or so above the stamped steel hearth. For a long time, I used this setup with no refractory liner and just piled up wet coal on the sides of the fire. I can't say when it happened, but at some point, both long side lips cracked midway and the cracks ran to the edge of the pot and stopped. I do not know if this happened because the pot simply got too hot in use or from too much water. However, both cracks were in similar places on opposite sides of the pot so I think excessive heat was the culprit. After I discovered this damage, and wanting to save the pot, I lined the entire hearth with a mix of lime, sand, mortar and fire clay to the height of the upper lips. I raked the dry material flush with the lips and then graded a bit of rise toward the edges of the hearth so the coal would move downhill naturally toward the fire. The mix was put in dry and then sprinkled with water, which made it set hard in a couple of days. I have been using this now for some years with no further damage. The only real concern I have is that the steel hearth will eventually rust out from trapped moisture under the clay but I'll worry about that if and when it happens.

[Strine]

No Irnsrgn your anscetors, gee there's a lot of them, were not wrong. I hope I didn't leave that impression if so it was unintended. It's like this. You're three hundred miles from home, you've just spent the weekend bashing away at hot metal, generally for nothing and finally knock off time has arrived. You know there's a ton of stuff to load on to the ute, you relish the thought of a three hour drive home, four if you don't move now, You're cringing at how you will fair for a 5am start in the morning and of course it is impossible to finish such a weekend without enjoying a couple of beers with your blacksmithing mates. Is that incentive enough to douse the forge and fire pot in water, cool it down quick and hit the road. Sure is but I don't, plain and simple. And having spent all that hand cranking to keep the fire going while working I'm not about to douse, sprinkle or spray any sort of moisture on to it to reduce the fire. That makes me different, not wrong just different, but rest assured I wont loose any sleep over it. It's small beans compared to the heaftier woes of the world.

[Ten Hammers]

Wet coal concentrates heat. Lots of coal will coke better when wet. Given needs will make for different types of fires. A tight packed wet fire will heat and recover pieces of bar, square or rod incredibly fast. When dealing with larger pieces of sheet or whatever I build bigger fires. Sometimes it is necessary for me to have a big base fire (read on the bottom ) and rake some cover on top to heat a larger piece. Sometimes a cover piece of steel will heat the bottom piece faster (cover piece can be unheated). I mostly just cover with the busted up coal that is coking around the edge of the fire. I do use a lotta coal for this reason. I have been threatening to build a gasser for this specific reason. Also, I use the fire's top heat (read bigger fire, flames on top) for finish work. Hard to do this with a banked wet fire. You do get some interesting finishes when heating over the top of a wet banked fire. Green coal (that is coking from underneath and sides) emits different patina than hot, coked, flaming coal. This is true of wax or different oil finishes that I cook onto stuff I forge (mostly production). I have experimented using a weed burner (read pear burner for you folks down south) when cooking finishes on stuff and it works pretty well. A wet, banked tight packed fire that is maintained by use of a water can is absolutely the best way to get the heat with the most efficient use of the solid fuel ( read coal). This also controls scale in a different way than a big open fire. I have cracked cast forge tables (Canedy Otto forge). Round firepot setting in the factory cast table. The pot wasn't really that thick nor was the table. Big fires over fairly long period of time. The forge didn't break into 2 pieces but it was close. It was a cold winters day when this happened. Early in the morning. Shook the floor and made me say words I don't even say in front of Ma. I just bolted some angle to the bottom of the table and went on with using it until I could get the present forge table built from 3/16 plate. I then purchased my current firepot (Roger Lorrance sells them). Current is at least an inch thick. Seriously doubt that I or the next in line to use it will ever burn it out. This pot sets in the forge by gravity only and has a home built tuyere bolted to it. Junior's design on the tuyere and my own design on the airgate. The coal I have been getting is pretty much junk (not as bad as some but not good). Inconsistant. Sometimes all I can get is an orange fire runnin wide open air. I have been experimenting with local foundry coke (bustin it up from large chunk) and I am happier with it than the junk coal. There is a small learning curve and different ways of doing things. The coke gets plenty hot which is what I need. It leaves a different scale on the steel but that is manageable. I have never clayed a pot. Original pots (like the one Hollis was speakin of ) that have spaces on the sides between the pot and the table, I HAVE clayed these spaces with some stuff that the foundry uses to line ladles (clay like nasty stuff). I created ramps on both sides of the pot with this stuff to keep coal from falling out the bottom and make the table area a little friendlier for maintaining fires and green coal.. You can just use pieces of bar to plug these spaces but the clay stuff I used worked exceptionally well. My only experience in this area. Long read. May be worth something..:p

[ThomasPowers]

Folks spend too much time trying to put everything in a single box.

Coal varies a lot from place to place; some work reall well with water; some don't. Some types of work is improved by special types of fire. Trying to say that *your* method is the best one without taking all the variables into account is like me saying you all have breakfast wrong cause you don't eat what I eat for breakfast.

I have always held by the saying "In blacksmithing there is only *ONE* way to do things...and that's ANY WAY THAT WORKS!

BTW the old catalog I have for cast iron large forges calls it a water tank and a clinker breaker---I guess the manufacturer had it wrong 80 years ago...You had better go and put them straight!

Thomas

[irnsrgn]

thomas point taken, I didn't think I said my way is the only I don't think, but if I did I stand corrected, LOL, glad you are on top of things. have a good one and keep us straight

[frogvalley]

A clinker breaker is at the bottom of my firepot. Aso known as rattler to rattle the grate. Mine is a cam on a shaft, half a turn of the shaft moves it enough. The deep fire that I work does not like to pulled apart to remove a little clinker, and if you don't break it up it's sure to clog the grate.

My fire is always deep, the coal that I use is a nut coal, the size of a walnut which seems to need a deep fire to coke down well. Wet and pack, wet and pack.

Oh and I was taught to pull my fire at the end of a day or session, and quench if desired, pulling it and/or quenching it saves the most fuel and coke plus minimizes ash. My flue/chimney draws very well and will keep a fire in the pot burning for hours. Pulling it onto the hearth and quenching quickly before it heats up the hearth prevent cracking.

I am planning a relign of my old forge and am going to line my new coal forge.

Anyone have good recipes for homebrew linings/coatings?

[ThomasPowers]

irnsrgn; naw I'm testy'er than usual what with this broke up toe giving me conniptions!

Thomas