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A Test Cone is only used once in a while or for running your burner outside of the furnace.

Like most of us I don't have an English
Wheel or a roller that can do small
diameter cones, so I'm gonna try and
show you how to make it the Hard

A test cone may look simple enough... until you try and make one.

You might want to ask your kid for some help on this first part, unless you still
remember your high school trig. classes or you have a machinist handbook
laying around. Because it involves using a "Truncated Cone",
(A Google Search is what saved my butt.)

    The Cone Facts are:
  1. The inlet opening (Dia.)
  2. The outlet opening (Dia.)
  3. The length of the cones tapered side
  4. The straight length or height of the cone

So in my case I used: (I'll let you plugin your own numbers)
Inlet= 1-5/16"
Outlet= 3"
Length or Height= 4"

I'm going to be making this cone out of 12ga. steel or you could use 14 ga.
In stainless steel, I suppose you could try it with 16 ga. but I don't think it will
last to long. (But it would be easier to form, but then again you would need
a tig welder to weld up the seams.)

You will need to set up a way to hammer form the cone.

  • A heavy vise mounted on a solid bench
  • A 1" round bar 12 to 18" long
  • Some kind of a loose pivot point for the bar
  • A BIG Hammer!!! 5 lb.

When you first start out, you open the vise to about an 1-1/4" setting just the
edge on the one jaw, then holding the bar down against the part you hit the bar
HARD with one sharp rap right in the center of the pattern. Move the part over
about a 1/2" and hit it again. You repeat this all a long the pattern.

Seeing I used the entire cut out pattern that last mark on the upper right will be my first cutoff
line. (You will only use about 2/3 of pattern.)

As your pattern starts taking shape you keep closing the vise just a little on each pass and
you hammer each pass "in-between" the other marks.

Another thing you'll find is that as the cone starts taking shape it will get easier to do the
hammering, (Don' have to hit it so hard.)

Remember as you are moving the pattern along, you're making a cone,
so you move the small end just a little and double that on the large end.

After a lot of hammering and forming here's the finished cone part,
BUT! It's still needs a collar, so you have to cut a strip about 1" wide
and form that the same way.

After the strip starts to take shape try clamping it to a tube/pipe the same size
as your burner tube and form it around that, but remember to put a small shim
under it, (between the pipe and the strap or it may be to tight to slide on the burner.)

I think it looks pretty good!

After a couple of test firings, I'm going to slit the side of the cone and close
the outlet size down to 2-1/2".

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