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j.w.s.

Ribbon burner for demo's

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Here's a new forge I'm currently building as a portable unit for doing demonstrations. I've still got some work to go. Ribbon burner is made from 3x3x3/16 tube and refractory, using crayons as part of the form. She's not quite getting up to the temperature I'd like and I think I might need to pick up a larger fan in order to get there.. looks to be hovering around 1900-2000F. I could also have a little debris in the plenum, because, like a dumb*ss, I didn't take the paper off the crayons like I normally do - you can see in one of the pictures that it's not burning quite right. Just lined with fiber because I can't afford ITC-100. Wondering if a watered down slick of Vesuvius 3000 (refractory cement) painted on the wool and dried for a few days would help get me to my welding heat. Any thoughts?

 

 

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Is the cross sectional area of the crayon burner ports larger than the supply pipe? If you don't keep increasing the area you can run into back pressure problems. It's also a pretty large volume to heat with what appears to be a small burner. (Small by burner port cross sectional area. Sorry for the long descriptive.)

 

On the other hand it sure looks like a nice even temp. Bet it'd make a dandy heat treat oven.

 

Frosty The Lucky.

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I'd Try a larger blower with a gate so you can control the volume of air. If you can't afford ITC-100,try getting some kiln wash from a local potter if there is one near you.

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The burner itself is 7x3, I cut the hole with my cnc table so I'd have to look at the dxf file for the exact cut dimensions but I believe the refrac is set into a 2x6 opening (about 1/2" set inside to secure it to the plenum), 24 crayons (3 rows of alternately spaced), I cut a baffle for the inside and welded it about 3/16th from the roof of the burner (only on the ends so fuel mix would spread throughout the plenum) with about 10 1/4" holes spaced on either side of the inlet. Supply pipe is 1 1/4". The interior of the forge is roughly 11x6x6 (.23 ft3). Frosty, what do you mean by the cross sectional area of the crayons? By my calculations the burner orifices equal 1.84056 in2 and the supply pipe is 1.22718 in2, a 60% increase in area from feeder to burner. I've built a burner with similar dimensions in an even larger forge and get to welding temp quite easily, so I keep thinking that my blower is a tad smaller than I need and / or I need to coat the inside of the forge. Worst case scenario, I add another inch of wool to the sides and bottom and shrink the volume I suppose. It's just a forge for doing demo's afterall. :)

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Ok, here's the result of my tinkering the past day and a half. I added another inch of wool on the bottom and a ceramic welding plate on top. Reached good forging heat but still not hot enough to weld. This morning I stopped by my favorite toy store in the world, Paul B's. Found a blower 1/25hp rated at 148cfm for $124 so I picked it up. Managed to escape its clutches with only $155 on my card which is pretty darn good. Added some Artu drill bits, a new steel brush and a brass brush to the shop along with some misc fittings - anyway, I digress. Cut out a mounting plate on the CNC table, welded a 2 - 1 1/4 fitting to it and wired everything up. I've always used a ceiling fan type dimmer switch to control fan speed. Wow! Now it'll blow out the fire at full crank, so knocked it back to about half, adjusted my gas to about 12psi and I think I've got a pretty darn good box capable of hitting welding heat. I can still dial everything down and keep it around 2000F for general forging. I picked up an old analog thermo-galvanometer at the Cabin Fever Expo this past weekend and I think I'll experiment with hooking it up to a type K thermocouple just to see if I get results - I'd love to have some sort of temperature gauge on this but would really like it to be analogue, even though I've got a few PID's that would work, I'm going for looks on this baby.

 

-J

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