Request for Refractory Casting Form Methodologies

[ede]

I have read of iforge members that use sonotubes for refractory perimeter casting instead of the plastering method.  I've also heard of members that use sections of linoleum.  I've even seen photos of wood forms used for end pass throughs on end caps that turned out really well.  I am interested in seeing some step by steps, process shots and write ups on the matter for advanced form building in gas forges.  There have been some great castable refractory form builds on this forum, I think it would benefit the community to see more on your approach to this subject.   Anyone care to share their approach?  

 

[Mikey98118]

You can also use plastic pipe, or stove pipe, and cut the "mold" free with a cutoff wheel in a rotary tool afterward.

[Latticino]

Not to mention use of bent sheet metal covered with clay, carved sacrificial polystyrene foam to be "melted out" using a solvent, suspended heavy duty plastic sheeting to form a catenary to pack refractory onto...  Lots of ways to skin that cat.

Sorry no in process photos or step by step procedure.  Why not try a couple of options and post your own?

[Hammerfall]

I Laos my kaowool flat, sprayed it with water, smoothed on my mizzou, and waited 10 minutes. I put it into my round forge vertically inside of a cardboard box and finished the top edge. I waited 45 minutes pulled it out and did the other end. I waited 45 minutes again. I pulled it out of the box recoated the seam, which was the floor and put on a little thicker layer. Let it set overnight fire it at a mid temp and let it cool down. It has worked great ever since. 

[Frosty]

9 hours ago, Latticino said:

Not to mention use of bent sheet metal covered with clay, carved sacrificial polystyrene foam to be "melted out" using a solvent, suspended heavy duty plastic sheeting to form a catenary to pack refractory onto...  Lots of ways to skin that cat.

Sorry no in process photos or step by step procedure.  Why not try a couple of options and post your own?

Catenary? Don't you mean annulus? I googled catenary as I'd only heard it in reference to the relations between two floating objects on waves. What I found instead was the arc formed by a slack chain suspended in a gravity field and references to 18th cent mathematicians. 

I formed my first hard inner liner by using sono tubes and ramming the refractory into the annulus (gap) between the tubes. For the detail oriented the inside sonotube had an OD of 6". The outside sonotube had an ID of 7 1/2". Leaving an annulus of 3/4". 

I rammed the plastic / rammable, refractory (Pyramid Super, Air set) in using a 5/8" sq. bar and hammer till it was rock hard. I stripped most of the outside tube and hung a light bulb in the chamber to speed setting. This long defunct refractory did not dry, it set on contact with air. It sounds picky but is a distinct difference. Stripping the waxed outside from the sonotube allowed air contact and sped setting. Just before stripping the outer tube I used a sacrificial hole saw to drill the burner port.

The next morning I lit 5-6 charcoal briquettes and dropped them in the chamber and let it burn the inner sonotube out.

To insert the the liners in the forge shell I wrapped the 1" 8lb. Kaowool around the hard liner and compressed it with a double sheet of news paper and tape, same as using a ring compressor to put pistons in an engine cylinder. I rotated the liner till the burner port lined up, clamped the burner in place and lit it off for about 5 minutes. Let the liner cool and fired it again to dull red.

That was it. The liners were just a little bit jiggly till the news paper compressor burned off and the Kaowool expanded to fill the shell.

That was my first gas forge and is still on the shop floor collecting dust. It's about 600 cu/in and ran with my first functioning T burner. A 1" burner in a 600cu/in too large forge, classic example of building what you THINK is the right piece of equipment before you know what you need.

Frosty The Lucky.

[Latticino]

23 minutes ago, Frosty said:

Catenary? Don't you mean annulus? I googled catenary as I'd only heard it in reference to the relations between two floating objects on waves. What I found instead was the arc formed by a slack chain suspended in a gravity field and references to 18th cent mathematicians. 

Nope, actually was referring to a catenary.  Just imagine a tarp loosely hanging in a curve between two fixed edges (like two parallel table tops for example.  The refractory material is initially coated onto the tarp, then the tarp is raised from both ends carefully up into place.  If the refractory is the right consistency it will form into a nice, strong upside down arch.  Never done this myself as I made an arch form that I coated with a layer of clay instead, but theoretically it should work.  All about timing and correct mixture consistency.

Of course I've also done an annulus, in my case using vinyl flooring (as I've mentioned before).  That will also work, but will need to be packed carefully from the top of the annulus.

I really like your method of compressing the wool for insertion into the interstitial space.  Very clever.  I usually just seal the blanket and cast the refractory right over it.  May have to try your technique next time I reline.

[Frosty]

Got it, catenary, a new word for my vocabulary or a new use for an old one. Cool.

I haven't tried that since I made my first forge and gave it up that refractory wasn't that plastic. 

Frosty The Lucky.

[ede]

On 5/2/2017 at 10:20 AM, Latticino said:

Not to mention use of bent sheet metal covered with clay, carved sacrificial polystyrene foam to be "melted out" using a solvent, suspended heavy duty plastic sheeting to form a catenary to pack refractory onto...  Lots of ways to skin that cat.

Sorry no in process photos or step by step procedure.  Why not try a couple of options and post your own?

Thanks for the ideas, Latticino.  Why would one put clay on the bent sheet metal, as a release for the refractory?  

 

On 5/2/2017 at 8:10 PM, Hammerfall said:

I Laos my kaowool flat, sprayed it with water, smoothed on my mizzou, and waited 10 minutes. I put it into my round forge vertically inside of a cardboard box and finished the top edge. I waited 45 minutes pulled it out and did the other end. I waited 45 minutes again. I pulled it out of the box recoated the seam, which was the floor and put on a little thicker layer. Let it set overnight fire it at a mid temp and let it cool down. It has worked great ever since. 

Sounds like a slick method Hammerfall.  Are you happy with the results?  

 

On 5/2/2017 at 8:41 PM, Frosty said:

I rammed the plastic / rammable, refractory (Pyramid Super, Air set) in using a 5/8" sq. bar and hammer till it was rock hard. I stripped most of the outside tube and hung a light bulb in the chamber to speed setting. This long defunct refractory did not dry, it set on contact with air. It sounds picky but is a distinct difference. Stripping the waxed outside from the sonotube allowed air contact and sped setting. Just before stripping the outer tube I used a sacrificial hole saw to drill the burner port.

Is Castolite considered a "rammabvle refractory"?  The most recent one was hand plastered with Castolite. Of course the problem with hand plastering is gravity when you get to the ceiling.  The next one I do will be actually "Cast" and the ends will be filled.  

Here's a picture of the results.  

 

[Latticino]

4 hours ago, ede said:

Thanks for the ideas, Latticino.  Why would one put clay on the bent sheet metal, as a release for the refractory?  

Is Castolite considered a "rammabvle refractory"?  The most recent one was hand plastered with Castolite. Of course the problem with hand plastering is gravity when you get to the ceiling.  The next one I do will be actually "Cast" and the ends will be filled. 

Yes that is the intent of the clay. Did that when I had a cheap source.

No I don't believe that Casto lite is considered rammable.

[Hammerfall]

I went 1/2" thick a bit thicker on the bottom seam,  and it's held up great.

[Frosty]

Kast-O-Lite is a castable, not really a rammable. However I use a putty knife to force it into the burner block molds between the crayons, basically ramming it in. If you're going to use the double cylinder method like I did on my first forge use enough water so it flows like wet concrete and "rod" it in with a rod about half the width of the annulus between the molds. That or vibrate it. 

You don't really want enough water it flows you want it as stiff as you can work reasonably well, the less water the stronger and higher the temps it will take. However, you don't want it so stiff you sort the agragate when you rod or vibrate to force bubbles out and fill the voids and corners.

It's not really very picky stuff within reason.

Frosty The Lucky.

[Mikey98118]

I've watched videos of guys vibrating the castable, and it does as much to make it flow as too much water. I plan to vibrate from now on.