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I Forge Iron

Burner Tuning Question


LeeHene

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The main run to my burner is 1" black iron. Propane is fed in from a simple tee. The 90⁰ fitting before it goes into the forge is also a reducer for the 3/4" burner tube. The burner tube is 6" long.

The diffuser is made of four 3/8" OD pieces of hydraulic tubing, 1 1/2 inches long. I tack welded in sets of two, then tacked the two sets together.

They didn't fit, so I spent a lot of time with the Dremel. Once I got them to at least start in evenly, I flipped it over onto a chunk of wood and gently persuaded it all the way in with a 3lb sledge.

1/4" OD tubing would probably fit about perfect, but I used what I had on hand.

Im still not 100% happy with stability of the mixture. At times it fluctuates between green and blue. I think my next step will be adding a twisted piece of flat stock inside the 1" line to help agitate the propane and air more.

I can confidently say that this setup would supply two 3/4" burners, without a doubt.

20230304_151318.jpg

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Dear Lee,

Good for him.  You will be able to do the tempering evenly more easily by watching the oxidation colors.

I do have to comment on PPE though.  Shorts and open top boots are not optimal.  Something hot going down the top of the boot can cause some really bad injuries.  Long pants over the top of open top boots are a much safer combination.  I had a friend who caught a piece of hot metal from a hot cut in the top of his open top boot and had to undergo some serious reconstuctive surgery on his foot and ankle.  And it never was quite right even after surgery and rehab.

"By hammer and hand all arts do stand."

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Another comment about safety. Quenching in hot oil on a wood floor is inviting a disaster if the quench tube were to turn over. The shallow pan would not contain the burning oil and the fire would spread like wild fire, possibly burning the building down and causing injuries. Our shop has a gravel floor and we always quench outside for safety's sake.

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I have seen various water based quenching solutions featured on blacksmith sites over the years, and have heard people describing them as better than oil; they are certainly a whole lot safer...

Even straight water will do okay for quenching, if the blade is then buffed to a shine, before color tempering; that's how why used to harden steel for chisels and punches for jewelry class. We would heat to red, water quench, buff, and then pass a burner back and forth a few inche away from the tool, until it turned straw yellow, and immediately quench again; it worked just fine.

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We were using some salvage steel given to us from tines of an old farm implement.

I tried quenching a small piece in canola but it failed the file test. We then tried Parks 50 (in the video) but it still didn't skate a file afterward.

Last, we quenched in water, and that did it. It's in the oven now, finishing the last of two heat cycles at 400⁰F. Working steel has a steep learning curve.

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Mikey, several posts back you mentioned unburnt fuel and leftover superheated oxygen can cause scale. I was only aware of oxygen causing it.

So too rich OR too lean can both cause scale to form?

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No; either I messed up what I was trying to say, or you are misremembering it.

It is the  super heated oxygen, landing on super heated work surfaces that creates rapid scale buildup, while your parts are being heated in the forge. In fact, slightly de-tuning burner flames to ensure incomplete combustion (creating a reducing forge atmosphere) is a favorite way (for some) to avoid scale buildup, while parts are being heated in the forge; this can't eliminate scale completely, because oxygen content in ambient air well still create some scale on heated surfaces, while you shape the part on an anvil.

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Depending on the burner orientation ambient air CAN be drawn into the forge with the internal flame flow if one or both ends are open enough. Which creates the situation where scale forms in the forge even if the flame is reducing. 

I do not believe that situation exists with  your set up but if scale is forming IN the forge under a reducing flame it's a possibility.

Frosty The Lucky.

 

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3 hours ago, Frosty said:

Depending on the burner orientation ambient air CAN be drawn into the forge with the internal flame flow if one or both ends are open enough. Which creates the situation where scale forms in the forge even if the flame is reducing. 

I totally agree, which is why I have been recommending variable chokes to control the amount of secondary air that burner flames can induce into the forge for years. That was a timely inclusion to the discussion, Frosty. However, I don't think that the exhaust openings are a significant source of air in the average forge, since the burner's flames will be creating positive internal pressure (back pressure).

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Yes, and it definitely is a possibility. How burners are situation and aimed can radically change what's going on inside any forge. while we predict what will happen inside a forge, we tend to assume that people haven't change the game plan we have in mind; but some people will; it's ironic that knowing more "than the average bear," can actually lead us into trouble :unsure:

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Hey guys, another quick safety question...

When I first put the forge together, I didn't spray the fiberglass wool with rigidizer, I simply coated it with the HellCoat that came with the forge kit. I tried to do reccomended curing time and slow break-in, but cracks formed after firing it up a time or two. Coated it all with 100HT a short time later. That cracked in the same places after a few uses.

Do you think the cracks pose much danger for airborne particles while forging? They close up a good bit once the liner heats up, but I still don't want to expose my son to something potentially cancerous!

(I did search for an answer, but pretty much every result partained to new forge construction.)

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You applied the hard refractory in too thick coats or didn't allow enough time to dry/cure in between. If you're worried about it, mix the ITC-100 thin enough to flow into the cracks easily and let it dry a good long time. Hanging a lightbulb in the forge will speed the process.

As a FYI the insulating liner is "Ceramic Wool" refractory, NOT fiberglass.

Frosty The Lucky.

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Rigidizer, when used commercially, is a pretty loose term. We, (and most sellers) use it to describe colloidal silica rigidizer. What you describe, is something that is sold as 'rigidizer,' bit is a completely different product. If You can't get a permanent fix with thinned out ITC-100, then you would be better off to use a 1/2" inner layer of Kast-O-lite 30. You could even do the job with Plistix 900...but only if you have the inhuman patience needed to build up a 1/4" layer from a whole lot of paint thin coats :P

And, of course, you'll need to fire cure between every individual coat.

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  • 4 weeks later...

Hey guys, something I've noticed from day one is that my flame seems to flicker slightly, regardless of the level of propane, forced air burner or venturi, pressure setting of the regulator, or any range of valve settings. Is that normal or do you think it's the regulator fluctuating?

(No frost on the tank.)

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The only reason it concerns me is because the flame breifly shifts to greenish color when it does that. I wonder if it's causing more scale on my work than it would otherwise.

Im still trying to get forgewelds down, so anything that would make it easier for me is a plus. :wacko:

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That could be a matter of buying better quality propane. Exchange places like Blue Rhino tend to prefer the least expensive propane available and the propane at the bottom of the supplier's tank has all the odd stuff that isn't refined out. There are waxes, oils, less than flammable gasses, etc. most are heavier than the gas blend they're after and only get included right at the end of a refining run.

Anyway, it's a factor that might be worth considering.

Frosty The Lucky.

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Frosty, I had no idea, good to know!

I've been getting my tank refilled at a local hearth and patio place. I believe their tank is filled by a national propane supplier for business and residential.

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Can you access their supplier? Small tanks like at service stations, RV rental/sales places collect impurities so if you don't get filled right after they do their tanks are collecting the gunk. I get mine filled at Petrolane's main yard here in the Valley and only hit them on Wednesdays when they get their tanks filled. I'd have to ask to know which Wednesday the delivery is coming this month but that's just a phone call. 

Used to be anybody filling propane tanks had to have someone certified on duty so I spent a day taking the class and am full of this kid of stuff.

Another tip for everybody. Do NOT let the person filling your tank turn the supply valve off HARD. Firm pressure is plenty if the valve is new, reefing on it damages the seats and you'll have to reef on it every time after that until they won't seal at all. 

Frosty The Lucky.

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