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Tooln's Forge Build


MLeonard
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I don't post much or often but read a lot here.  A little back story on me.  I've retired now for just about 2 years, since retiring I've started making knives.  Being on a retiree's budget I try to keep thing low cost.  My first forge was made from fire bricks.  I've been collecting pieces here and there to build something larger.  In the past week I've finally started on it.  Here are some pics of what I have so far.  I'm looking for any comments good or bad and always open for suggestions.  The body is an old air compressor tank.  I also have parts to make 3 burners as the forge body is 17" long and 12" diameter.  I plan to mount the burners around the 1 o'clock position.  The board is about where the floor will be and plan is to aim the burner at the #1 position.   I plan to do the interior as described out below.  

2, 1” layers of ceramic wool each rigidized. 

A coating of refractory 3/8” Kast O Lite 30 or equivalent

A IR coating ITC 100 or equivalent

Kiln wash the burner flare.  

Pick apart my plan and tell me if I'm on the right track or way off.  I know there's a lot more knowledge here than I will ever have.  

Thanks

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Only ever built one gas forge so not any kind of expert but I think you might want a pass through hole in your door.  I wonder where your exhaust is going to go if you close the door and how much heat you will lose if the door is open.  I built mine using a compressor tank (aspirated with a single burner) as well but cut both ends off and use soft fire brick to close up the ends.  That way I can configure the opening in the front to accommodate whatever is getting heated and the back can also be configured to allow for pass through for heating long pieces.

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Posted (edited)

I do plan on doors on having a pass through both front and back.  Back door will have angle iron mounts so I can put some fire bricks on it an adjust as needed.   Back door will is also hinged.  

Edited by MLeonard
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Looks like you've got good fabrication skills.  It also looks like you are well on your way to a good forge.

 

Take my opinion for what it is worth, but 3 burners is a lot for a 17" long forge, and is not at all budget friendly in the amount of gas it would consume.  I think 2 burners would give you plenty of heat.

 

Also, others on here have voiced opinions that the bell reducer flares are not particularly useful in a forge application.  I believe it is because the transition through the insulation of the forge does all the work of the flare.  That transition needs to be tapered at something like 12 degrees.  I'm not much of an expert on that, but I'll just leave this here as a prompt for one of the burner guys to chime in.

 

Keep us posted with your build!

Edited by Brian Dougherty

-Brian

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Thanks Brian, I do not plan on using the bell reducer,  I will form the flare in the wool & IR coating.  Depending on how much heat I was each burner can be controlled individually.

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I agree with Brian that three burners is overkill.  Once you've got the insulation in there, it'll be much smaller, like 13" x 8".  And yes, bell reducers are not burner flares and do absolutely nothing.  The taper is wrong. But they look cool, so somebody on the internet started using them and it caught on. Kind of like wide ties or skinny jeans, all looks and zero function :lol:.  Sculpt the flare into the cast-o-lite 30.  The angle is the same taper as a dixie cup.  Finally, and this is down to personal preference, do you want a hot spot, or do you want fully even heat?  Both have their advantages and disadvantages.  If you want the most even heat possible, run the burners in on a tangent (parallel with the floor) rather than the straight shot you have now.  If you like the idea of having a hot, but slightly oxidizing, spot on the left side just above the floor, the way you have now is fine.  Finally, don't waste your cash on rigidizer.  It lowers the insulation value of the wool and is unnecessary since you'll have the cast-o-lite lining. Same with the kiln wash. ITC-100 is great.  It'll give you another hundred degrees or so once the cast-o-lite is up to heat. That can make the difference between a forge that welds easily and one that struggles.  

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Thanks Allen but I'm a complete idiot when it comes to math.  My understanding of a tangent is where a line touches a curve.  But them you say parallel to the floor this is where I get lost.  Is it possible to explain better or draw something to help me understand.  Thanks

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Here's a rough MS Paint sketch.  With this kind of burner entry you don't really need a flare, the lower edge of the hole acts as a flame holder.

 

tangent burner entry.jpg

 

And here's a link to hightemptools: http://www.hightemptools.com/supplies.html

And here's a video of what a good swirl flame looks like.  This is a blown burner, but the end result is the same.

 

 

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Here's a small update, nothing fancy.  Did a little more work on the forge.   Both doors cut in, hinges made and installed. Real simple door latch and handle's. So far I have $12.00 into it and that was for the handle springs. I kind of got ahead of myself when I drilled the holes for the burners. I'm going to relocate them for better burn and efficiency. Thanks for the suggestions guys.  Not a problem with the old ones just weld in a patch. Material for this will come from the opening I cut into the doors. I'm not going to cut those out until I get the forge lined, this way I'll know exactly where the floor will be.  Slow process now as I'm waiting for ceramic wool to line the forge. 

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That's a very nice build coming along, a little large in my opinion.  I have not tried it myself, but it has always been suggested to me, to make some kind of removable wall within the forge body to block up the space you don't always need. I wonder about what other opinions are about doing that.

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Posted (edited)

My wool came today so I cut 2 layers.  There will be a 1" firebrick floor and another layer of wool.   Fire brick and riditizer wont be here till the end of the week.  Im going to reposition the burners once the floor and kast layer of wool is in.

 

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Edited by MLeonard
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The rigidizer lowers the insulation value of the wool and does nothing good for a forge that is going to have a lining.  It is meant for unlined ovens, kilns, etc.  But if you want it, someone will be happy to sell it to you!

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Final layer of wool and firebrick floor was put in today.  I also relocated the burner ports.  Kast o lite liner comes next.

 

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Each of the 3 burners will have a ball valve.  Is putting a needle valve in each a waste of $$$,

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Three burners is too much for that forge, but a single needle valve between the regulator and the manifold is all you need there.  And even that isn't necessary, it just makes it easier to fine tune to atmosphere.

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If you are planning on building Frosty Tee burners for your forge I strongly recommend that you follow the directions for same exactly.  Of course you can certainly build your own take on his burner design, but they you may be in for more experimentation with tuning than necessary.  https://www.iforgeiron.com/topic/43976-t-burner-illustrated-directions/  You will note that the Tee in question should be a reducing one (and not one with a reducing fitting added).  Hard to tell from the original photos what you have.

 

I see (3) layers of 1" blanket in your forge.  With a nominal 1/2" to 3/4" thick Kastolite inner liner your forge will become very long and small diameter.  Unless you switch to a ribbon burner you may end up having trouble getting an even heat. 

 

Kastolite actually makes a better, mildly flux resistant floor than a fire brick (though a fire brick can be removable and replaced).

 

I recommend that you design your doors with different hinging systems (unless those are only end caps and there will be door openings cut in them.  As currently setup, when you open the door you will both have to swing it out at least 90 degrees (having a full opening) with the radiant heat from that door going where you don't want it.  I'm a fan of pivoting, sliding, or 4-bar linkage door systems where the inner face of the door when open  stays in the same plane as when it is closed.  This is a good idea at least for the "front" door.

 

I have to respectfully disagree with Alan regarding rigidizer.  Properly applied it is just a thin skim coat on the surface of the blanket.  Any nominal loss of insulation value from that is easily offset by the gain in insulation value from not having the blanket "matt down" during Kastolite liner application.  I mixed my own rigidizer from fumed silica and water (available cheap at  fiberglass boat builders supply shops).

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2 hours ago, Dan Hertzson said:

Properly applied it is just a thin skim coat on the surface of the blanket.

 

I'm glad you added this, Dan.  Most of the people I've seen use it literally soak the blanket in the stuff. I shall add that to my future recommendations.

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Alan,

 

I just apply it with a, disposable, atomizing spray bottle (like for windex).  I find the sprayers aren't good for much else after the water evaporates and leaves behind the silica powder, but I guess I could try to clean them out...  Not an issue as I only reline my forge very irregularly.

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I do plan on a skim coat of rigidizer before coating with Kast o lite.  Also the door will have openings cut into them making them more of an end cap than a door.  After the kast o lite the diameter will be 4.75-5"  which should be more than large enough for anything I plan on forging.  3 burners over kill, maybe but it's to late now, besides they will all have valves so I can use 1, 2 or all 3 or combination of them.  Being my first build I'm happy with it.  

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Not necessarily a matter of size of stock that you are putting in, more an issue of both having enough diameter to fully develop the flame from your burner and also to avoid having that same flame directly impinge on your stock (both creating hot spots and localized areas of higher decarb/scaling).  Frosty Tee burners have a realtively short and bushy flame when correctly tuned, so you may be OK.

 

I've always wondered with those forges with multiple burners and aspirations of shutting one off periodically:  How do you avoid having the forge radiant heat travel up into the burner mixing tube?  Please just be sure that tube isn't too hot if you decide during forging to turn it on and get "MORE POWER"...

 

Door openings will be critical as you are making a forge with Naturally Aspirating burners.

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  • 2 weeks later...

     This forge looks very similar to the one I built/use.  I posted mine on this site just like u did.  If you are going to be doing forge welding I would recommend making the firebox conical so flux will drain out and using bubble alumina in the bottom just up from the brick on both sides.  Flux is fairly caustic will eat into a lot of materials.  I used it on mine and the floor hasn't needed a single repair yet. 

     I would also recommend a pyrometer.  I used one in mine since I don't see color well and it has been very useful.  With 3 burners and that much insulation you might have a tendency towards overheating.  I just recently had issues with that while making canister damascus.  Turns out just 200 degrees made a big difference.  I will say this, your forge looks like its coming along nicely!

Edited by Tim Cook
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