Part #4 Of Making Jim's Furnace
Part #4 Of Making Jim's Furnace
You can't melt metal without a little heat,
so now it's time to make the burner.
There are a lot of designs out there and I've looked at many of them,
but all-in-all I personally think my design is simple/ adjustable and
very efficient for our needs. There are just a few major parts to the
- 0-60 LP Regulator with Gage
- 15 or 20 foot of Rubber Gas Line
- 1.) It keeps the LP Tank at a safe distance.
- 2.) It keeps the tank out of your working area.
- A 1/4" 'BALL' Valve
- Some 1/4" Black Pipe Nipples
- 12" of 1" Black Pipe
(Threaded one end only)
- A 45° 1/4" pipe elbow
- A 5-1/2" to 6" Burner Feed Tube (Machined)
(I only use 1" Stress-Proof Steel)
- A Heavy Duty "Tweco®" .045" Welding Tip
- An Adapter to hold the Burner Tube (Machined)
- A 1-1/4" to 1" Reducer (Machined)
- Gas Rated Pipe Dope or Tape.
- For testing you will need a flash cone.
Ok lets get started with the feed tube machining.
I take a 5-1/2" to 6" piece of "Stress Proof" 1" round bar and center
drill then pilot drill it with a 1/8". I then bore a 1/4" hole all the way
thru. (DO NOT go bigger then a 1/4" (.250) !!! See why below.)
I then turn down the OD to .750 by 4-1/2" long and taper the end.
You don't have to drill the end for the 8mm welding tip as the
1/4" drill will over cut just enough for taping.
(ie: a .251 will give you a 100% thread and a .263 will give
you an 80% thread.)
Welding tip installed
Drilled/ Taper reamed/ threaded to 1/4" Pipe Thread.
Next we'll make the burner's reducer.
Start by facing off the boss, (both the side and face).
Next bore out the threads on the 1-1/4" end
to a 100% clean up and about 1" deep.
In the side of the boss drill and tap an 8-32 or 10-32
hole for a set screw, (Not shown here)
Now we need an adaptor to hold the feed tube into the reducer.
This is the easiest part, simply take a 2-1/8" (alum. or steel)
round bar, about 1-5/16 long.
Facing off both ends, then Center drill/ pilot drill and
bore out to .750" (+.005/-.000)
Turn down the OD to match the bore dia. of the reducer you
just made and make it about .750 in length. Just make sure
you're leaving a 1/4" to 5/16" shoulder.
In that shoulder drill and tap an 8-32 or 10-32 hole for a set
screw, the same as you did in the reducer. (Not shown)
Ok, Let's slide the pieces together.
The Feed Tube with the adaptor.
The Feed Tube with the adaptor and the reducer.
Now we're "ALMOST" done.
Now it's time to make the burner's Air Intake Tube.
The intake needs 4 - 1/2" by 1-1/4" long slots at 90°. (This is the 1"
by 12" long black pipe with threads only on one end and as an option
you might want to thread on the reducer now.)
Clamp it up in your drilling vise and Measure in 3/8" PAST
the last thread and center punch it then, go in 3/4" from
that mark and center punch that. Drill those two marks straight
thru with a 1/8" drill.
Rotate the pipe 90° and drill it the same way.
(Hint: Inserting another 1/8" drill in one of the thru holes will help
you make sure that your level and at 90°.)
Now drill those pilot holes out to the 1/2" size and cut out the
material between the holes to finish the slots.
(Of course if you've got a mill handy the job gets a lot easier.)
Assembling the Burner
Apply pipe dope or tape to the threads on the 1" pipe
and connect the reducer.
Clamp up the feed tube in a vise and screw in the welding tip then
a 4" or 6" black pipe nipple, (using pipe dope or tape on both parts).
Add a 45° elbow and then a 6" or 8" nipple.
Now thread on the 1/4" ball valve and your gas hose connects
to other end of the valve.
Slide in the adapter bushing into the reducer and tighten the
set screw. (I use 3/4" long allen cap screws, so if the socket
should ever strip out I can still grab it with a visegrips.)
Now slide the feed tube all the way into the adapter and tighten
the set screw and your DONE!.
Adjusting or fine tuning the burner.
(To test a burner "outside" of a furnace you
will need a test cone/ flash cone.)
For this burner your cone should be an inlet of
1-5/16" ID by 2-1/2" ID outlet and about 4" to 5" long.
First make sure your regulator is back off and the ball valve is
closed. Then hook up the tank and the hose to the valve, (if you
haven't done so yet).
Clamp the burner to the bench or in a vise and put the test cone
on the end of the burner tube, then make sure nothing is in the
line of "FIRE"; AT LEAST 10 Foot away.
Now you're ready.... Slowly Turn up the regulator to about
20/25, (O-60 regulator) and check for leaks.
With a long stemmed barbecue type lighter hold it in
front of the cone and very "S-L-O-W-L-Y" open the valve.
Now if your burner won't stay lit or it's making a popping sounds
or sounds rough, this is were you loosen the set screw on the adapter
and slowly back out the feed tube, just like tuning a carburetor you're
adjusting the air to gas mixture.
(You want a steady roaring sound and a rich blue flame.
Once you have that recheck the set screw to make sure it's tight.)
Let it run for about 5 or 10 minutes, then increase the pressure to 30/35
and see how it runs, then go to 40. (I've never had a burner that
required more than 40, most are 15/40 max.)
Compare the three settings and see which pressure works best.
If everything checks out and no problems
--- GO MELT SOME METAL ---!!!!