[TheForge] burner adjustment

[Jerry Frost]

----- Original Message -----
From: "Gladish Family" <gladish@cnw.com>
To: <theforge@mailman.qth.net>
Sent: Saturday, May 04, 2002 3:59 PM
Subject: RE: [TheForge] burner adjustment


> Wow, Frosty, what  a great batch of info!
> I go back and forth on whether I really want to run a gas forge at all,
> since so far my efforts are so unsatisfactory. I want the convenience and
> steady heat of a gas forge and the ability to heat longer sections, but I
> want it to heat up quick like coal and give me that intense heat where and
> when I want it. After watching Bill Fiorini weld Damascus billets
> effortlessly in a homemade blown forge I know it's possible to make them
do
> whatever you need them to do, but I'm not there yet...
>

Localized heat is hard to get in a gas forge without getting creative. Other
than that I like them just fine. My little, old, prototype is HOT, fast to
heat up and fast to heat stock, once hot, but it's running about four times
the burner/cu/in you are.

> I'm running a single .030 jet (nominal, not actual- mig tip) and getting a
> 7" diam. x 18" cavity to a medium orange- nowhere near hot enough for my
> taste.

This is almost 700 cu/in, twice + the volume you should be heating with a
single 3/4" burner. I'm running a 1" burner in a 6" x 12" chamber and it
hits high yellow heat in about 10 minutes and will start generating
sparklers on a 3/4" sq. bar (started cold) in a couple minutes. A single
3/4" burner is enough in a volume like mine but I like overkill. <grin> A 1"
burner would be enough for your volume but would be pretty localized in an
18" chamber, two 3/4" burners will give you more even heat and three would
be better.

> Do you think it's possible to drive another burner off this "carburetor",
> and, if so, should I use some kind of "Y" branch, or will a Tee followed
by
> elbows still draw?
>

You'll need a 1" inducer to drive it sufficiently but a "Y" is better than a
"T" though "T"s work as long as you step the diameter up a bit. For example:
1" x 8" inducer tube to a 1 1/4" x 1" "T" with 1 1/4" nipples to burner
nozzle locations then bell reduced to 3/4" either before or after the elbow
then a 3/4" nipple into forge.

I'm still debugging this particular configuration but have seen almost
exactly this on commercial farrier's forges in the past so have no doubts it
will work.

> As is, with the nozzle about 1 1/2" back from the 3/4" bore, and a 3" long
> flare I can run it without choke at 8 to 30 psi without flutter or
chirping
> (back pressure). If I move the nozzle in close to the bore then it needs
> choke.

Okay, the reason you're having to put the jet so far back from the throat is
it's dia. 0.030" is pretty small, most people running 3/4" inducers start
around 0.040" a #60 drill bit. I'm running a 0.045" mig tip in my latest 1"
inducer which has a 1 1/4" "T" instead of the 1" "cross" I discribed
earlier. I drilled the "T" in my lathe so the jet would be properly aligned
with the tube.
The 1 1/4" "T" provided enough intake cross section to let the 0.045" jet
work pretty well. I still didn't have to choke it but I got a really strong
evenly shaped blue flame from 30 psi down below what the gage reads and it
was stable in the forge in a stiff breeze. Still won't burn out of the forge
and it still doesn't bothered me. Regardless it doesn't draw strongly enough
to run the manifold properly so I'll start drilling out the 0.035" mig tips
I picked up last week.

To run a manifold you have to have a strong draw or the back pressure will
pretty well do it in. The back pressure will also reduce the need to choke
the inducer. What this basically means is the inducers have to be set up as
singletons or manifold drivers. Still, it's just a matter of jetting and jet
positioning so you don't have to build a bunch of inducers.

It'll really help to know all the dimensions of your inducer: Bore dia. Tube
length, intake dia. and or intake port dia. As to flares I haven't messed
with them much so don't have a lot to say other than what's SUPPOSED to take
place according to the factory.

To start tuning your inducer as it is, open the other leg of the "T" and
then start opening your jet up beginning with a # 63 +/- drill bit and work
your way up till you get the fire you want. Probably around a #60 or #59.
Play test it every time you open the jet up another size of course.

> Actually, I could give it more air- it's a sidearm design with a tee
instead
> of an elbow, but one side is closed off.
> Now, that's in the forge. Out of the forge, just clamped in the vise, it
> needs a surprising amount of choke- like about three quarters of a square
> inch of open gate...depending on where that nozzle is set. More choke the
> deeper I set it.
> Sure wish I had somebody who had done this before to look at this rig and
> tell me why it won't put out more heat- blown forges seem to be able to
heat
> twice the area per burner...at least twice the fuel, too!
>

No problem Andy, we'll get you crankin. <grin>

> > I'm still ankle deep in mud in my present tarp tent "smithy". <sigh>
>
> No mud here, now, (got the driveway done- yay!) but only one wall on the
> smithy...
>
> Thanks,
> Andy G.
>

My pleasure

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks