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nprovos

Forge from Kast-O-Lite 30 LI

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As I needed to rebuild my forge, I noticed that I could not find a lot of articles where the forge shell was cast from refractory concrete. Here is my experience with using Kast-O-Lite 30 LI. My need for a new forge

arose when after some extended forge welding and bloom consolidation the roof of my forge caved in. For the new forge, I decided to go with a refractory concrete shell that can take all the abuse I might throw at

it. Kast-O-Lite 30 LI seemed like it fit the bill with a maximum use temperature of 3000F which is not something I am likely to reach unless I am over boiling iron. (It was what I had at hand from another project,

for general forging Kast-O-Lite 26 would be better suited). Here are some of the steps I went through:

 

The construction used five pieces of concrete: Two sides, one roof, and two pegs. Where the pieces met, I had to split the angle, so used 22.5 degrees on each side of the different pieces. The end result was

going to be a shell that would support itself. The first step was creating the forms from 2x4 and some wooden boards. The forge itself is about 13in long, and about 9in high. To get the angles, I used a

bandsaw with a swiveling table that I could dial to 22.5 degrees. The measurements that determines the spacing of the pieces were all done on the outside and piece of 2x4 was attached to the board with wood

screws. Here is how they looked like.

DSC_5907.jpg

 

I lined them with packing tape since I did not want to spend the time to sand and coat them. Although, the packing tape turned out to be not so much fun to work with, so next time using some polyurethane and

vegetable oil might be better. I used almost the whole 55 pound bag to fill the forms. Kast-o-lite is mixed with 20% water by weight. Using a whole bag is recommended as the water can be measured more

precisely then. I mixed this in a big 5 gallon bucket with a mixing attachment to my power drill. You are supposed to mix for 3 minutes and then cast within 10 minutes. Afterwards, the pieces need to dry for at

least 24 hours and should be covered to slowly dry out the surface. Here is how that looked like.

IMG_20120812_094546.jpg

 

After drying out they had to remove from the forms which was not so easy. Essentially, I had to unscrew one of the wood pieces on each form to get enough leverage to lift the piece out.

IMG_20120814_181801.jpg

IMG_20120814_181805.jpg

IMG_20120814_183517.jpg

 

The curing schedule for Kast-o-lite is quite complicated and basically requires a programable oven. Since the pieces are all 2in thick, the curing schedule is as follows: Heat up to 250F with a rate of 100F per

hour. Hold for one hour. Heat up to 500F with a rate of 100F per hour. Hold for one hour. Heat up to use temperature with a rate of 100F per hour. I heated it up to 1500F. The whole process took a little bit

longer than 16 hours. Here are the cured pieces

IMG_20120815_121740.jpg

 

The cured pieces fit together fairly well:

IMG_20120819_083252.jpg

 

However, actually fitting them in the forge was more difficult. I had undersized all the pieces but did not account for the heat warping of the sheet metal that made up the outer shell of the forge. Even the

undersized pieces where too thick to account for the bowing in of the sheet metal. This took some adjustment with a grinder till everything fit together.

IMG_20120819_092335.jpg

 

I closed up all the gaps with refractory mortar and am now looking forward to using this for more forge welding.

IMG_20120819_122555.jpg

 

I hope somebody is going to find this useful.

 

Niels.

Edited by nprovos

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Great idea Niels! I have used a castable in the floor and spread around the inside of kaowool. This is very nice, that thing should have some thermal mass when it's up to temp. I just may try this. Thanks for sharing

 

Zeb

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I am curious what are the advantages to this type of forge lining? Propane? Why the rectangular shape? What kind of mixer? blower? thing? are you using? What did you use for the floor? Looks like a really nice forge.

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Wonderful...do let us know how it holds up.

 

Ric

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I am curious what are the advantages to this type of forge lining? Propane? Why the rectangular shape? What kind of mixer? blower? thing? are you using? What did you use for the floor? Looks like a really nice forge.

The concrete hopefully requires less regular patching than my previous setup which was kaowool coated with a refractory mortar. The main difference between kaowool and the concrete is a higher thermal mass and less heat insulation.

 

In general, it's a propane forge using forced air. The floor is just fire brick.

 

Wonderful...do let us know how it holds up.

I am curious myself :-)

 

Niels.

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i use the kastolite for my work forges.. but i cast the whole shape in one shot... ... its not bad but not as efficient as the wool, or the IFB's, but holds up well..... also, becareful of borax, it'll eat it up

- i also coat the inside with itc100 and it'll run nice n hot

 

-good choice with the alumina brick bottom... that is tough stuff... the kastolite is not abrasion resistant... so if you use it for a floor, you should use a sacrificial mortar or surface ontop to prevent wear in

 

 

your furnace looks very Pro !

 

 

nice work

 

G

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I have seen Kast-O-Lite advertised as flux resistant but if people have had flux damage to the product, I'd go by that. There is also Mizzou, which is less thermally efficient but is flux resistant. That's what coats the inside of my welding/heat treating forge and it hasn't been effected by the borax flux to any degree that I can see. I haven't used my Kast-O-Lite forge for welding.

 

Doug

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ITC-100? Where Can one find this?

I plan on using kaowool, then coating with Castable using 1 part furnace cement to 4 parts (by volume) Perlite. Im looking for maximum efficiency, so my inside will be round, and slightly bottlenecked at the primary opening and the back of course. The backside has a square hole about 4x4, and will have a remote operated (by mechanical lever) 'door' covering. My burner will come in at the top, and 'swirl' the heat inside.

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The Kast-0-lites are kind of flux resistant. Mizzou will hold up much better and Bubble Alumina will hold up the best. I recommend covering the floor of a forge with either Mizzou or Bubble Alumina for forge welding. Satanite over inswool will not hold up well to flux, although it is great for the upper parts of the forge.

 

Eric- I sell ITC at Hightemptools.com

 

Nprovos- Great walkthrough of your process. Vaseline works great as a mold release also.

 

Wayne Suhrbier

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I had the forge running for 4 hours at welding temperature for bloom consolidation today. The Kast-o-lite walls are holding up well. It took noticeably longer to get to welding temperature which was not unexpected. I'll try some ITC-100 and see if that makes a difference. ITC-100 did not work so well for me when I had to patch the forge after every few forge welding sessions, but now it might work better.

 

IMG_20120825_123021.jpg

 

Niels.

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Sorry for reviving an old thread; this is just the topic I'm looking for. I am wanting to use kast-o-lite 30 or mizzou or something similar to line a foundry furnace and I am wondering what others' experience has been when doing the initial firing. As nprovos mentioned in the op the prescribed dry-out scehdule is very complex so I am wondering how other DIY'ers have accomplished their initial firing without having a huge computer-controlled oven. Any info or advice is really appreciated!

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When I build a forge using Kast-0-Lite I cast about 1/2" thick over 1" of Inswool, then allow over night for the casting to set overnight, then put the forge in the kitchen oven set at 500 degrees for 3 hours. After allowing it to cool I coat the Kast-0-Lite with either Plistix or Metrikote (similar to ITC 100 but much cheaper) and allow it to dry. Then the forge is ready to use.

 

Let me know if I can help you.

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For the furnace, we built using that stuff, we just eyeballed the firing. Run it for 30 seconds, let it cool. Run it for a minute, let it cool, etc. Till we brought it up to temperature.

 

Niels.

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I've played with solid refractory forges before.. and I now prefer to make them more like Wayne is suggesting. It just takes longer to come up to heat when you are using all solid material. My current forge is 3000 kaowool inside coated with plistix and castable refractory floor.. covered with.. something that is flux resistant. Can't remember what. It's not anyway. :-) But the outside is my own 'castable refractory'.. local iron oxide clay, sand and ground peat moss. I figured if it survives multiple smeltings it would make a nice shell for my forge. And looks cool too...

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Thanks for the responses. Wayne, thanks for the offer and I will give your method some thought. It looks like one 55 lb bag of castable goes a fairly long way, does anyone know what the actual volume a 55 lb bag will cast? I am using a 14" diameter propane tank as my shell and it's about 22" tall so I'm trying to figure out how much castable I would need for a 1" and 2" wall. Obviously I would need consideraly less if I used a thinner layer of castable.

 

Efficiency isn't my primary concern since I will be burning waste oil which is basically free but I don't want so much heat escaping that I can't reach the melting temperatures I want. It sounds like the refractory coatings like ITC100, Plistix or Metricoat will help out the efficiency alot if it ends up being an issue. I will post some pictures of what I'm working with here soon.

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For a 20# Propane bottle with 1" of Inswool and a 1/2" casting I use 4 5# bags of Kast-0-Lite and one pint of either Plistix or Metrikote.

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@nprovos  That is really quite interesting.  My question is where are the holes for the burners?  Or do you cut those in after your Kast o Lite sets?  I got a forge I just put satinite in mine, but I did not have enough to do the thickness I wanted so I've got to get more lol.  But sometime in the future I will be building my own and this yes is a great idea to consider doing.  Probably way less expensive than trying to spend money on metal and the time to weld it together.

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2 hours ago, AndyB said:

My question is where are the holes for the burners?

One burner, he has the hole cast in.  You can see it in the right-most mold in his 3rd picture (first post).  It is also visible in the 7th picture, and more after that.  

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I guess I wasn't looking close enough.

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This whole endeavor was not a successful experiment. Too much thermal mass. Takes too long to come up to heat and I struggled with forge welding.

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Check out the Ribbon Burner attachments at www.WayneCoeArtistBlacksmith.com 

Let me know if I can help you.  I prefer e-mails

Wayne

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