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Looking for critiques on my first forge


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I've been lurking for awhile and read up on forge designs and what not prior to initiating this build.  I went the homemade route for my first forge mainly because I like to make things and I had some stuff laying around all ready I could use.  Price for supplies was a concern as I am just getting into this and, while still supportive, my wife wasn't as enthused to spend hundreds of dollars on a commercially produced forge or pro-grade materials.  

 

I found an old charcoal chimney I've had for years and decided it would make a good light duty forge body.  It's made of aluminized steel and has seen many red hot heat cycles as I used it to get my charcoal smoker going many times.  I cut it up a bit and rearranged some of it's parts as well as added a few of my own to give it the form you see here.  The body is insulated with 1" kaowool all the way around with an additional 1" strip on the floor, underneath the fire brick.  I also put another 1" strip around the rear opening to choke that down a bit and help hold heat in.  I use a fire brick over the rear opening to close it off or open it a bit to allow for pass through of long material should I ever need that option.  I do the same in the front to help hold heat in.   The burner, which I purchased pre-made, is pointing directly at the forge floor, if need be I can make some minor adjustments to have it point more tangentially and the depth it protrudes into the forge body is easily adjusted as well.  I used Simmonds air set wet refractory mortar (3000F) for the refractory liner over rigidized kaowool.  I used fumed silica to make my own rigidizer.   I baked it in the oven to help cure the refractory and then it sat out in my garage for a good week or so.  Despite this, the refractory bubbled a bit and had several hairline cracks after the first real fire, I kinda expected this would happen though. 

 

Anyways, I am looking for critique or advice here.  Having looked on several sites and watched about a hundred youtube videos, I think the flame looks pretty good but that's why I am here, for advice.  The burner is a simple Tee burner with no air choke control.  I can add this if you guys think it is necessary.  The outside gets hot to the touch but I can keep my hand on it for several seconds and the burner tube is the same while in use.  Since I took these pics, I have added a coat of plistix I purchased from Mr. Wayne Coe and coated the face of my fire bricks I use to cover the openings as well.  I also painted the exterior with a high heat flat bbq grill paint.  It's still pretty fugly but looks better. LOL.   

 

 

 

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Welcome aboard!  I like the resourcefulness of using the old charcoal chimney.  Since this is a starter forge to see if you like doing this, it's not a big deal that the mortar will crack and fall off over time.  Just patch it as you go.  It's not really meant to be a forge lining, it's mortar for thin joints between firebrick in fireplaces and kilns.  It'll last enough to see if this is something you want to invest more money on better materials.  We all used Satanite (another mortar) for years before we figured out it wasn't the best stuff. 

 

For better results, though, take the bricks out of the forge itself.  They aren't doing you any favors unless you're welding with flux.

 

As for the flame, once the forge comes up to heat you shouldn't be seeing the blue cone, it should be just a uniform glow inside.  Looks like a slightly oxidizing flame if the colors of the dragon's breath are accurate.  If you want to play with that, a simple bit of tape can act as a choke.  You'd be surprised how little blockage it takes to change the flame.  You've probably already played with holding a finger over one of the intakes to see what happens.  That's a big burner for the volume, so maybe a little choking would be a good thing.  

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I like having a tangential entry for my burner to reduce/eliminate hotspots, but that is more of a personal preference.  Some guys like having the hotspot and use it for specific purposes.  The biggest thing that I would say is that you're going to want a different table to set it on while you're using it.  My first forge table was unprotected wood too, let's just say that it went up in a blaze of glory!:D  You could put down some cheap ceramic tile, or even a piece of cement board, to help protect it.

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I will vouch for "no bricks" in the "learn from my fail" category: they seem like a good idea, but my quite nice looking brick-lined forge takes FOREVER to heat up.  Stays hot for a very long time, too. (Can be good and bad... if I turn it off and close it up, I can go eat lunch and take a nap and come back two hours later, then be ready to go again in just a couple minutes)

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I’m going to fire it up again later today without the floor brick and play with the fuel/air mix a bit.  Alex, I agree totally.  I had it up on the table for the first burn rather than the floor so I could see what was going on better. I have an old metal cart I’m going to mount it on that I can fix some hangers on the side for various tools, tongs, etc.    

 

By choking off a little air I am trying to move the direction of reducing rather than oxidizing correct?  Hopefully landing close to neutral?   What should I see change in terms of flame color?  Reduction of the blue cone in the middle?   Thank you guys for the feedback 

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Yep, you're aiming for neutral.  Full reducing will flood the shop with carbon monoxide, which is, as they say, not ideal. ;)

 

Let it come up to heat and look at the dragon's breath, not the burner flame. You want there to be a clear yellow flame with a tinge of blue just at the door.  A lot of blue with bushy yellow is way reducing, hard orange with no blue at all is oxidizing. We all see color a bit differently, though.

 

You can also tell by heating a clean piece of steel.  If it scales up inside the forge, it's too oxidizing.  If it does not scale at a yellow heat inside the forge, but then forms a light skin of scale when removed into shop air and cooling, you're just right.  

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This is with Plistix and no fire brick inside.  I tinkered with choking the Venturi a bit. I think I’m going to install some sort of adjustable choke plate, probably something similar to a smoker exhaust stack, just to have that control.  It got that 3/8” rod pretty hot, pretty quick with no scale build up until I pulled it out and let it air cool.  I messed with hammering on the end of that rod a bit.  Overall, I’m happy so far and excited to try something new.  I know it can be improved but I think it’s pretty stinking functional for now. Appreciative for a forum like this that’s willing to teach. 

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5 hours ago, Alan Longmire said:

For better results, though, take the bricks out of the forge itself.  They aren't doing you any favors unless you're welding with flux.

 

Can you really drag metal in and out of a coated fiber forge with no deleterious effects to the lining? I would think a one inch kiln shelf or a IFB split wouldn't add that much thermal mass to make preheat super long. Is that a thing for these types of forges?

 

T

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2 hours ago, Taylor Hendrix said:

 

Can you really drag metal in and out of a coated fiber forge with no deleterious effects to the lining? I would think a one inch kiln shelf or a IFB split wouldn't add that much thermal mass to make preheat super long. Is that a thing for these types of forges?

 

T

It depends if you have a coating that's only thick enough to contain the fibers like its painted on then it can be risky and you might want the brick floor method. With I think most coatings if you rigidize the wool and give it 1/4"-1/2" minimum you get a pretty hard face to move across material directly.

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You don't need to rigidize the wool at all if you are using a topcoat of refractory.  All the rigidizer does is lower the insulating ability of the wool.  It was meant for boiler lining and industrial car furnace lining, sprayed on to keep large flat sheets of wool from sagging under their own weight.

Adding a skim coat of refractory is far better, but more expensive on an industrial scale. 

A 1/2 inch layer of Cast-O-Lite 30 atop the unrigidized wool will be bulletproof.  

 

The two reasons we coat wool are to prevent loose fibers in the air and to protect the wool from flux.  Hot borax eats kaowool like boiling water on cotton candy.  

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Thanks for the info. Brian, I hope your new forge is working out. I'll be working on one for myself very soon. I have 1 inch blanket already, but I just returned from finishing up a fiber kiln rebuild for a friend and scored a couple of square feet of 3 inch thick fiber.

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  • 2 weeks later...

I polished up an old log I got from a local firewood supplier for a few bucks the other day and got my cheap anvil mounted to it.  I also watched a few videos on how to dress a hammer and cleaned up a bargain basement China Freight drilling hammer I've had for awhile.  I think I'm ready to really concentrate on learning a few fundamentals now.  I've had fun building stuff and collecting a few tools of the trade but it's definitely time to make something out of metal.  

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I take it the cardboard is just for now? It will go up in flames the first time you drop your workpiece on it.

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Yeah, that’s where I typically park my golf cart and I put the cardboard there to keep the battery acid off the concrete if one of the batteries boils over. They can get pretty warm sometimes while charging if I run them way down. I rubbed some teak oil on the anvil stand as well and didn’t want that on the concrete there.  Most work will be done on the side of the house I believe. 

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