Setting up my first forge

[BenRufenacht]

I am looking to buy a Devil's Forge DFHS2 + 2D 5.2" forge. I know I could build one, but for the price of these things, it doesn't seem to be worth it.

I want to get this thing set up properly, so I don't plan on using whatever powdered rigidizer they include with the forge, and buying some supplies here. From reading through the many, many posts, I have gathered that I should first apply a coat of Rigidizer to the wool insulation, then put on a layer of Kast-O-Lite 30 (I know this will be tricky with the two doors), then a coat of Plistix. Is this the correct procedure?

I have also gathered that the included fire bricks will not make a good floor? Should I find a kiln shelf, or just use the Kast-o-lite as the floor?

Any input would be appreciated. Thanks.

[Mikey98118]

No; you soak the ceramic wool completely through with the rigidizer, first; it is not a "coating." Next, you heat set the rigidizer. Then you use whatever coating you decide on.

[BenRufenacht]

Noted. It makes sense to coat all of the fibers to stiffen the blanket.

[Mikey98118]

The thickness of coloidal silica rigidizer in water, is so low as to add almost nothing to the cross section of the cramic wool fibers it runs down; until it reaches a point where one fiber touches another on. Then the rigidizer collects at all of these points, turning them into welded joints-- this is what makes the spongy mass stiff.

[MCalvert]

Regarding the kast-o-lite30, my floor is made up of this with a coat of plistix/matrikote. I find that it gets super hot, and my reheats for whatever I'm working are really fast when it lays on that floor.

[Mikey98118]

Yes; that is exactly the way it is supposed to work

[BenRufenacht]

So I am hearing a thick layer of kast o lite with the plistix is all I need for a floor? That simplifies things.

[Mikey98118]

Ideally, about 1/2" hard refractory thick on the floor. The Plistix well do as much as the Kast-O-lite as a heat cheild, wall the hard refractory well do much to support the layer of Plistix. You want to use these materials together to get the most use from them both.

[BenRufenacht]

Ok, I have soaked my ceramic fiber with the rigidizer. I am letting it dry overnight. Do I need to take a torch to it before I apply the Kast-o-lite?

[Mikey98118]

Yes, or your can simply heat up the whole forge; it works either way.

[BenRufenacht]

I coated the inside of my forge and forge doors with Kast-o-lite. The inside seems to be good, but the doors are crumbling. The photos are just after I fired up the forge to full heat.

Should I just chip out the Kast-o-lite from the doors and just use a coat of Plistix? I am at a loss on what to do with the doors.

[Frosty]

Without redesigning your doors the KOL is going to chip off when the door closes. Even if it's not in direct contact with the forge shell the angle iron is and it WILL move with the heat and KOL isn't flexible so it'll break up. You can see how the frame is pulling away from the KOL in the pic. Yes?

I'm thinking a line of stove rope around the shell where the door makes contact MIGHT help. 

I've stopped trying to make hinged doors because of how the refractory seems determined to break up.

Frosty The Lucky.

[BenRufenacht]

Is there anything else I can coat the ceramic blanket in the doors with that will hold up better? I have some satinite like stuff that came with the forge? Can I just coat the blanket with Plistix, or will that fail as well?

[Latticino]

Kastolite has enough insulating value at 3 - 4" thickness to work as a effective door. No blanket required.  I made mine with an angle frame cast in place and a simple side slide mechanism from random parts I had in the shop.

[Frosty]

I wish I did but no matter how tough a hard refractory is it's in a frame with a considerable COE (Coefficient of Expansion) it moves a lot as it heats and cools and hard refractories move very LITTLE. 

The best I've seen is from Mikey and the thermal baffle. A porch of some sort in front of the openings, I like refractory but if it's below the openings far enough steel might be okay. Baffles rather than doors, they let exhaust gasses out of the forge chamber so NA burners don't suffer high back pressure, where doors can be a problem for anything but gun burners. The baffle works by heating up and reradiating IR back into the forge chamber which is how the liner in the forge works. 

Mike likes high alumina Kiln shelf, it's really tough stuff, is impervious to forge welding fluxes and our forges don't get hot enough for them to notice. 

You've noticed how hot it is standing in front of a HOT forge. Yes? You weren't close enough to be catching heat off the dragon's breath but it's still hotter than blazes. Yes? I can feel either of mine from 40' away and it'll make you red in a minute or two inside of 15'.

My next forge build won't have "doors" it'll get baffles. 

And there's Latticino! Typing at the same tie I am again I see. He's built more kilns and furnaces than most everybody I know, his opinion is well worth consideration. 

Frosty The Lucky.

[BenRufenacht]

What do you mean by baffles? Like refractory bricks partially blocking the opening? Do you have photos?

[Latticino]

Frosty,  appreciate the confidence. I may not have made more quantity than some, but certainly have made a lot of different types. ..

Essentially my side slider door acts as a baffle as well as a door proper.  Since I'm running a forced air burner I have a lot less concerns about back pressure. Still the trick to keeping the metal frame cool enough so the metal doesn't expand away from the refractory is limiting the exposure of the frame to heat.  I try to have a static frame of castable on the forge opening so that the castable portion of the door covers over the static frame opening (face of castable on door is larger than the opening).  With the frame justified to the outer face of the door, and the door's castable covering the forge side of the frame a little,  the radiant and conductive heat paths between forge interior and metal frame are blocked by refractory. 

Another trick is to run a bead of weld inside your angle iron door frame before casting to make some friction to hold the castable in place without generating a crack initiation failure point.

I like side slide and 4 bar parallel path lifting doors since they keep the heat radiating from the door pointed away from you and the end of your stock.

Lots of description for a 1 minute sketch.  Will try to add visual aide tomorrow if anyone wants one.

[BenRufenacht]

I would appreciate visual aid. Thanks for all of the additional info. At least I will have a better idea of what to do for my second forge.

[Mikey98118]

Two things to consider:

(1) No refractory (and I am a BIG fan of Kast-O-lite 30) even begins to compare with the toughness of high alumina kiln shelf.

(2) A kiln shelf works best when used a a cradled part, whether it is a floor plate, or the hot-side of a baffle wall.

A baffle wall takes far less effort to install and maintain than a door plate. The ONLY advantage of a hinged of sliding door, is too allow occasional  access for large parts, or crucibles, in a forge. I'm a fan of such schemes; that doesn't mean they are worth the effort for most people. Practical beats perfect every time

Ugh; I just hate those words

Finally, it is just plain DUMB to make a hinged or sliding door that touches the the body of a forge. The forge needs to breath, so why not let most of the hot exhaust gases escape up the top of a space between the forge wall and the door, while most of its radiant heat gets reflected back into the forge? A lot of the problems people a struggling with in forge doors aren't necessary to begin with!!!