What forge do YOU have?

Geoff Flato said:
Stacey, any reason not to make the entire thing from castable other than the improved insulation of the wool?
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Castable refractory isn't insulation, it is a refractory that will absorb and evenly hold the heat. It will slowly heat through and the other side will be very hot. It needs a layer of insulation around it to hold in the heat. Once heat soaked, there is no other setup that equals it for evenness of heat. It takes longer to heat up than a 1/4" of satanite, but is worth the wait. The only negative is it add a good bit of weight to a forge, so it isn't suitable for portable units. That isn't usually a problem, and with putting the forge on a rolling cart, the forge can be rolled around as needed.

If you just cast a forge from Cast-o-lite with no jacket of insulation, it would eventually end up glowing on the outside if it ran long enough.

I will also comment that I always say to "coat with ITC-100", but in the case of a cast liner, I don't think it really does much ( or nothing).
 
Stacy E. Apelt - Bladesmith said:
Castable refractory isn't insulation, it is a refractory that will absorb and evenly hold the heat. It will slowly heat through and the other side will be very hot. It needs a layer of insulation around it to hold in the heat. Once heat soaked, there is no other setup that equals it for evenness of heat. It takes longer to heat up than a 1/4" of satanite, but is worth the wait. The only negative is it add a good bit of weight to a forge, so it isn't suitable for portable units. That isn't usually a problem, and with putting the forge on a rolling cart, the forge can be rolled around as needed.

If you just cast a forge from Cast-o-lite with no jacket of insulation, it would eventually end up glowing on the outside if it ran long enough.

I will also comment that I always say to "coat with ITC-100", but in the case of a cast liner, I don't think it really does much ( or nothing).
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Thanks, that makes perfect sense.
I think I'll try putting together a vertical before too long.
 
How much in terms of weight of castable would be used in a vertical forge say 20# propane tank size? Assuming a 2" layer of Kao wool.
Trying to figure out if a 22# bucket would be enough, or if I'd need a 55# sack
Knowing me I'll probably do something a bit bigger than I initially planned
 
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I want to slightly change my above post. Castable refractory is an insulation, but it isn't the same type insulation as wool is. The rest of what I posted is the same.


For your hypothetical propane tank forge:
Let's say the cylinder is 12" wide and 12" tall.
That makes the internal size for the liner 8X12 ( 2" of wool around the inside).
If you pour a 1" thick liner, that would be 8X12OD 6X12ID.
The volume of the liner would be around 300 cu.in.
Cast-o-lite is 90 pounds per cu.ft, so the dry weight of the refractory is around 15 pounds. It is heavier in actual use because some water molecules get tied up, so let's say the refractory will weigh 20 pounds.
A 2" thick liner would give a 4" chamber, and weigh about 35 pounds.

A 3" thick by 14" round slab base would weigh 50 pounds.
The 12x2"top would weigh around 20 pounds.

Add the tank, extra metal for various things, etc. and the forge would weigh somewhere around a hundred pounds.


In a larger 16X16 forge, the weight is significantly higher. The liner will weigh around 120 pounds, and the forge body could easily weigh another 100 pounds.
The base and top add another 120 pounds. All total 350 pounds.

Cast-o-lite 30 is much lighter than other refractories. If using regular refractory, like Mizou, the weights are 50% higher, around 140 pounds per cu.ft..
It also has a slightly lower thermal conductivity ( which is good).
By comparison, Inswool is only 8 pounds per cu.ft.

The other good thing about a cast liner is that even though it will take longer to get up to temperature, it will quietly hum along while sipping propane once up to temperature.
This is the perfect situation for PID control.
 
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Okay, thanks. It looks like I'll need a few buckets at least.
The stuff I'm looking at is 95% alumina, 3250 degree rated. Each 22# bucket will make a 12x12x1.5" piece.
I think I'll call around to some industrial sources and see about buying something like Mizzou by the sack instead, enough of those buckets would add up to an expensive forge real fast
 
If you weren't in Canada, I could give you all you would need. I've got around a ton on hand.
Other refractory will work nearly as well, but is heavier. Check around and find what the local boiler supply companies have.

A 4000km road trip would be fun, but not cost effective.
And, I wouldn't want to try and explain the big 90 pound sacks of white powder in the back of the vehicle to the border guards.
 
I've done some looking around, and I can get 2500 degree hard castable, and a non Kao wool brand ceramic wool blanket from a local industrial construction supplier. Other than that I'd be having to get something shipped.
If the 2500 degree castable would be sufficient I can buy it by the 25kg sack locally for less than what shipping a bag would cost. If I'd need something higher there is a refractory/foundry supply company on the mainland I could try, but it's a ways away, and the sort of place that usually sells by the pallet
 
You have a good point about the boarder... The sacks of white powder would probably raise even more eyebrows than the pickup loaded with 8 or 10 vises I brought up from Seattle this spring
 
2500 refractory would be fine for forging, but insufficient for making damascus. You really need 2800 or higher.

Just to explain, while the welding temperature for damascus may be 2350-2400, the chamber is exposed to flames at higher temps. 2500 just won't hold up long.
 
Stacy E. Apelt - Bladesmith said:
2500 refractory would be fine for forging, but insufficient for making damascus. You really need 2800 or higher.

Just to explain, while the welding temperature for damascus may be 2350-2400, the chamber is exposed to flames at higher temps. 2500 just won't hold up long.
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That is helpful! I'll have to put that on my forge building list.
 
That was about the feeling I had...

The places around here just stock Vesuvius moldit D, the 2500 degree hard castable. I'll call around a bit and see if any of them can bring in one of their high temperature products. At least the ceramic wool and low temperature castable are easy to find. Might try making a smaller vertical for general forging work first, that way I'd at least figure out the tricks for working with the stuff before bringing in a harder to get product
 
Ok here it is. This thread convinced me to abandon, or at least postpone the horizontal ribbon forge I was building. Tonight I test fired my new craftsman vertical forge. Cast floor, 2" wool, forced air burner.

Holy crap this thing makes more heat at 3 psi and partial opening of the needle valve than my significantly smaller 2 burner venturi forge did at 20 PSI and wide open. Still some finishing touches but I am a believer!

IMG_20170829_42429.jpg
 
kuraki said:
Ok here it is. This thread convinced me to abandon, or at least postpone the horizontal ribbon forge I was building. Tonight I test fired my new craftsman vertical forge. Cast floor, 2" wool, forced air burner.

Holy crap this thing makes more heat at 3 psi and partial opening of the needle valve than my significantly smaller 2 burner venturi forge did at 20 PSI and wide open. Still some finishing touches but I am a believer!

View attachment 757869
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Sweet! I've changed my mind a lot but I've decided to go with a vertical forge as well. I had the same idea to make the shell with a air compressor. What size air compressor did you use for yours?

Once again that things awesome!
 
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