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Forges 101


Mikey98118

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4 hours ago, Mikey98118 said:

A drillpress needn't be expensive. An imported table mount drillpress is more than good enough for home shop use.

Yes I agree. I won’t use it enough to justify buying a top dollar machine when a harbor freight one will do just fine. I will need it and a tap set to do thebuild. That’s the only thing stopping me. 

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Once you learn how to go over a used one properly, a used one in great condition/good brand will often be cheaper and last such that your grandkids squabble over who gets grandad's drill press.  Meanwhile a brand new cheap one may be pretty much unusable. I've seen brand new ones with so much wobble/run out in the quill I wouldn't use them for drilling wood!

 

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Exhaust Opening Lips

Naturally aspirated burners have long turn-down ranges. Therefore, getting the size of an exhaust opening wrong is easy, while getting it exactly right becomes impossible. A baffle wall just outside of a deliberately oversized exhaust opening is the answer to this problem. But that leaves one detail out; namely that a ring, or at least a lip around the exhaust opening in the forge is still needed to divert super heated exhaust gases away from the metal shell, which will otherwise be overheated. 

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On 1/30/2019 at 1:38 PM, Mikey98118 said:

Exhaust Opening Lips

Naturally aspirated burners have long turn-down ranges. Therefore, getting the size of an exhaust opening wrong is easy, while getting it exactly right becomes impossible. A baffle wall just outside of a deliberately oversized exhaust opening is the answer to this problem. But that leaves one detail out; namely that a ring, or at least a lip around the exhaust opening in the forge is still needed to divert super heated exhaust gases away from the metal shell, which will otherwise be overheated. 

Great info

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I'm working on a design for the new forge I'm going to build in the spring, my current forge works and works well but its dimentions are somewhat limiting for what I need/want to work on.

I have several questions, since I want to hinge the burner side to allow me to open the opposite side for odd shapes, I'm looking for recommendations on how to stop the upper shell from flexing, I was thinking of welding a flange on the edges, thoughts? I'm also wondering how best to hold the forge closed.

Just a note, the dimentions of the attached plan aren't to scale and the angle of the burner will be adjusted once the shell is built and lined. 

20190202_110557.jpg

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I recommend giving the build_a_gas_forge.pdf over at Wayne Coe's website a read, as he uses a hinged design.  He uses hinges on both sides as the hinge/latch.  This allows him to knock out hinge pins on one side and open just one side or hinge pins on both sides and raise the whole top with fire bricks.  

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By not to scale you do NOT mean the penciled in dimensions do you? 

If you make the lift mechanism connect to the shell in a couple places and apply even pressure it shouldn't flex much if any. However a good way to reinforce/stiffen it would be welding a couple lengths of small, say 1" x 1" angle iron lengthwise on the shell, flanges down so it makes a long flute it should be plenty stiff. You WILL need to stiffen the edges, hinge and the other. I'd give thought to a heat shield for the side clams open or forge heat is going to warp the shell no matter how you reinforce it.

I'd just let gravity hold it closed, it's not a jet engine test stand. If you counter balance the lid for easy lifting, (on a side note; an idea I'm in favor of) leave it shell heavy so it can't open accidentally. 

Frosty The Lucky.

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@Another FrankenBurner I like the idea of two hinges and just knowing out the pin, I've looked at Wayne's plans a long time ago and dont know if I even noticed that.

@Frosty By not to scale I mean the measurements haven't been scaled back equally in the scale of the drawing. As for a heat shield I'm having a hard time picturing how to make one. On a related note I was thinking of having a bead of refractory at the junctions, similar to a horizontal S shape to help prevent heat loss. As for stiffening the long edges I was thinking of using my friends bead roller to add a ridge or two to stiffen that edge.

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Good, I don't measure drawings anyway, written dimensions are all that counts, I just wanted to make sure we were on the same page. Even then I think of this as a concept drawing, not a print. ;)

I'm still thinking on how to shield steel edges like this from forge heat. About the best I have in my dented head is to maybe wrap Kaowool around the edge then case it with Kastolite flame face. Another thought is tack welding thin stainless angle to the edge with a flange extending out to deflect flame out and away. 

Those aren't real suggestions, just maybe work thoughts, I haven't experimented so they're just that; thoughts from a dented head.

I'm sure getting tired of my forge shells warping though. :angry:

Frosty The Lucky.

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I wonder if welding angle iron to the edges as a stiffener and continuing the kaowool/flame face to the edge of that would work?

Another question, I've never welded stainless and only have a small mig welder which only runs fluxcore wire, would a heavier gauge mild steel angle iron work?

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VainEnd84, those S shaped edges are similar to what is called a labyrinth seal.  If the S is extreme enough then it should prevent any flames from blowing past.  Fragility of a thin casting should be a consideration,  though.

 

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2 minutes ago, HojPoj said:

VainEnd84, those S shaped edges are similar to what is called a labyrinth seal.  If the S is extreme enough then it should prevent any flames from blowing past.  Fragility of a thin casting should be a consideration,  though.

 

I did not know the name though I have seen it in other application thanks! And I was thinking that over the width of the insulation  2 1/4"  about 3/8"-1/2" height/deep for the peak and valley should be adequately strong.

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3 hours ago, Mikey98118 said:

If you cost out the ceramic blanket, and compare it with Morgan Thermal Ceramic K26 insulating bricks,  you may find the difference isn't too great to justify the increased strength of a brick arch in in a forge with moving parts; just a thought.

The only issue is I have yet to find a supplier in canada that has their bricks, and shipping plus duties for international shipping is prohibitively expensive, plus I already have more ceramic blanket than I know what to do with.

I have been looking into their products but haven't had success here. :(

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On 2/2/2019 at 10:50 AM, VainEnd84 said:

I'm working on a design for the new forge I'm going to build in the spring, my current forge works and works well but its dimentions are somewhat limiting for what I need/want to work on.

Take a look at this page.  Interesting build that might be what you are looking for... https://www.bladeforums.com/threads/table-forge-with-ribbon-burner.934512/

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I like it too. One of the guys in our club has been making forges with burners aimed up through the floor along one wall, just not ribbons. 

I'm impressed with the build, it doesn't have a couple few feet of flame shooting out the opening. Thanks for the link D. dont know how long Admin will let it stay, we're not supposed to post links to other sites. It's in my book though.

Frosty The Lucky.

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