Double Oven Conversion project:

Actually a continuation of my original post  the heating elements and one thermostat are now on Ebay - in case anyone is looking to add electric heat to their rig.

 

  I plan to use 4 inch stovepipe for the stack, and use 4" aluminium blast gates, as draft controls at either side of the firebox, and to control the draft in the stack.  I am still pondering how and what type and size  of hole to cut between the firebox and the cook chamber.

Things I have learned:  

• My 70 year old half inch drill can get away when the on-lock jams as the hole saw catches.  
• Tools can cost more than parts.
• You can cut stovepipe with the right vintage snips.
• Self cleaning ovens are a bad idea.  (soot is collected in sealed steel boxes, and the fumes are vented into your house)

So far - side draft holes are cut,  as is the chimney.  After considering using registers, I decided to use 2 4" holes side by side between the firebox and the smoker.  They will be adjusted with steel plates sittin on top of them.  The firebox is probably too big, so I am entertaining filling it partially with firebrick.     

The Double Oven Smoker is now complete and functional.  

The blast gates work well as vents.  There is one on each side of the firebox, and one at the base of the chimney.

Each 4" hole drilled through the walls of the stove went through the inner enameled steel shell, fiberglass insulation, and the outer steel shell. The drill bit was a 4 1/8" bimetal hole saw from the Depot, which is the perfect size for 4" stove pipe.  (The drill was an vintage 1/2 inch 2 handed drill from the 1930's that once belonged to my grandpa George - this is exactly the kind of crazed project he would love) To prevent smoke and grease from entering the interior insulation I lined each hole with 4" stove pipe, used stove gasket rope as a seal and used self tapping screws to secure the pipe to the shell via tabs cut into the pipe.  

I drilled 2 4" holes between the firebox and the smoker, one would have probably been sufficient.  

There is a need to adjust the openings between the firebox and the smoker. for now, I  settled on magnetic part trays from Harbor Freight, they are just the right size to use much like drain stopper in a tub.  Just be sure to remove the rubber covers.

It would be nice to come up with a way to do this with a lever from the outside.

So far, I have placed a thermometer on the side of the smoker section. 

The entire shell was painted with flat black stove paint. 

 The firebox is bigger than it needs to be, I have added a number of heat bricks to it to fill in the space.

 It holds heat at about 220 with a small fire if you keep it tended, it will drop back to 180 for 3-4 hours untended.  With a  larger fire (defined as a full load from the standard charcoal starter, the heat will easily go to 400 + in the smoker, not something you want vry often.

 I need to do more tweaking of draft and fire size to get it to hold at 230-250. 

The smoker burns less fuel than my old 2 door brinkman.  It is very well insulated, since fiberglass is packed between the inner and outer steel shell.  It loses very little smoke at the seams between the upper and lower chambers. 

The budget was naturally overrun, mostly due to the need to buy some expensive drill bits.  Parts came to about $120.  The 4 1/8 hole saw added another $55.  The stove itself cost just $37.50.  I made back about $15 selling stove parts on Ebay.  

Here are some better pics of the completed smoker:


Above - the side showing the blast gate vent and thermometers.


Closeup  of thermometers.


The front - glass doors and a handy storage nook where the controls used to be.



Firebox with small fuel basket.


Firebox with large fuel basket.


Blast gate as draft control on stack.


Smoke chamber showing holes to firebox, and magnetic plugs to adjust smoke and heat transfer.

OK - 4 years later - here is my experience with it:
The smoker holds heat pretty well, you would expect that because of the insulation. The "sweet spot" temperature wise is a bit unstable - you can get it to hold about 230 for a long time, but it will easily jump to 375 if you are careless, or drop back to 180 if you let the fire die down too much.
I could have gotten by with a single hole between the fire box and the smoke box.
The chimney should have been cut through the upper back wall and then elbowed to vertical to avoid creosote drips - I keep a drip pan in the top rack to avoid this.
The firebox is too big, I have moderated this by partially filling it with firebrick.
One layer of the firebox window cracked from excessive heat.
The 4 inch smoke pipe is too large, 3 inch or maybe 2 inch would have worked. However - 4" is the standard around here, I suspect that smaller pipe is no longer acceptable safety code for wood stoves.
The metal blast gates have held up well.

If I built another - I might try a 36 inch free standing range, and use the lower drawer as a firebox. This would probably create a better ration between firebox and smoke box. Gas ranges ave too many vents to be successfully converted, but I could be wrong.