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Posted by Steve Smith on December 3, 2006, 8:52 am
Please log in for more thread options I misunderstood. I was picturing a large weed burner. You're right, your
burner is undersized compared to the volume, and the heavy firebrick
isn't helping matters.
This is a burner that works great and is cheap and easy to assemble:
http://ronreil.abana.org/design1.shtml#Reil
If you weld, you can come up with better ways to hold the jet. Alignment
of the jet with the burner bore is important.
If money is easier than time, buy a sidearm burner from Larry Zoeller
(see my other post).
I'm using one of these burners in a forge 11" diameter (outside), 15"
long with 2" of Durablanket S insulation and a flat floor (so it is a
half cylinder inside). This works fine, but I wouldn't make a single
burner forge any larger.
If you want to get a little fancy when you build a bigger forge, add an
idle circuit to the gas flow. You should have a shutoff valve of course,
from there you run two gas pipes. One goes thru a second shutoff to the
burners. The other route goes thru a needle valve to the burners. Adjust
the needle valve for the lowest pressure the burners will run at. Now
you can switch between full bore and idle with the flick of a valve. You
will need a regulator--most non-blower burners run in the 3-10psi range.
Another nice thing to do (I haven't tried this yet--I'm building a
larger forge this winter) is to make air curtains at the open ends of
your forge. This is a narrow stream of cool air, maybe 1/2-3/4" by the
width of your forge opening. This is supposed to help reduce heating on
stock sticking out of the forge (and your hands). You still need
firebrick or doors. I'm going to use a crossflow (tangential) blower
like this:
http://www.herbach.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=HAR&Product_Code=TM03BLR4713&Category_Code=FAN
You should coat the wool products with something to seal the surface
and keep particulates out of the air. Larry sells some coatings that are
also IR reflectors (somewhat increasing your forge temp), but they're
expensive. I use Satanite, which is cheap. You paint it on (glop it on?).
You need 2300F rated Kaowool (Durablanket S is the same rating). I
usually buy the 3000F bricks. The fireplace type bricks will crack
eventually from thermal stress. The high temp bricks won't, but they
crack from being dropped. :)
Steve
Prometheus wrote:
>wrote:
>
>
>
>>Your forge is plenty small. Your firebrick isn't the right stuff, as
>>others have mentioned, but it should work a lot better than it is. I
>>think your torch is at fault. What to do about it is the tricky part.
>>
>>If you can post a picture or two, it may help us figure out what to do.
>>Otherwise, you can try adjusting your burner. Try to figure out some
>>kind of choke to reduce the amount of air. Try reducing the pressure
>>(you are using a regulator?) and see what happens.
>>
>>
>
>Unfortunately, photography is one thing I don't do- seems like the
>couple of times I bought a camera, I managed to break the things right
>away. Got sick and tired of throwing away $$$- so no pics.
>
>
>
>>Here are some flame pictures:
>>http://ronreil.abana.org/richtolean.jpg
>>
>>
>
>The "neutral" flame best illustrates what the flame looks like out of
>the torch. It's not a terribly fancy one- just a standard one that
>screws to the top of a skinny propane tank and adjusts via a knob at
>the back.
>
>I'll try to describe the setup in words- there may be something you
>can spot from the description alone.
>
>The firebricks are layered to make a chamber that is about 1" x 1.25"
>x 9" long, with one brick stood on edge to block the back. Each brick
>has is 1.25" x 4.5" x 9". To direct the flame into the forge, I
>drilled a hole halfway down the nine inch length through the narrow
>part of the brick, so that the hole is 4.5" long. The nozzle of the
>torch is a tight fit in the end of the hole, and when looking into the
>opening of the forge, the flame comes straight out of the hole, hits
>the far wall, splits in two and swirls back along the top and bottom.
>
>The torch nozzle is essentially a bit of bent pipe with no end on it.
>It does not have air holes near the tip (It just occured to me that
>that may be important, as the end is fitted into the hole.) I have
>been running it fully open.
>
>What happens after the bricks begin to heat up is that glowing red
>spots about 1.5" wide gradually develop on the bricks themselves-
>first where the flame is coming through the hole, and then spreading
>to the top and bottom of the chamber shortly thereafter. As you can
>probably guess, the metal is most efficiently heated right on those
>spots.
>
>At the mouth of the opening, there is a fairly consistant blue flame
>extending out about 1".
>
>
>
>>http://ronreil.abana.org/flame.jpg
>>http://ronreil.abana.org/sidef.jpg
>>http://ronreil.abana.org/burner2.jpg
>>They come from here:
>>http://ronreil.abana.org/design1.shtml
>>There are more pages on this site of interest--you could spend between
>>now and Christmas reading it all.
>>
>>The firebrick you have is probably intended to hold heat. This means it
>>will be slow to heat up. A piece of 1/8-1/4" steel rod held in the
>>flame will show rough heat changes a lot quicker than your forge body.
>>
>>
>
>I believe it is- several hours after turning the forge off, the bricks
>were still very warm to the touch. They were sold as fireplace
>liners.
>
>It worked well enough to make what I needed, so I suppose that might
>be where it's at for a little while. I got the boss to agree to let
>me take a little time to make a metal forge body with the equipment at
>work, so once I figure out how to make an appropriate burner, I can go
>that route and buy some of that kaowool and line the inside. Lots of
>overtime right now, especially with people missing work for the
>hollidays, so I might be able to get something more respectable
>together fairly soon.
>
>
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