arch front advice

[asknupp]

Making a 2x8 airtight arch. Need some advice on making door and hinges.
How to make the door airtight?

[CharlieVT]

I've built a couple of air tight doors. One for converting my 4x10 oil fired arch to wood burning. Another was converting a friends 3x6 cast iron front to air tight.

Since you say you are making the arch, I suspect describing what I did in converting my oil burner would be closer to what you are doing. If you are converting a cast iron front, let me know and I'll try to describe that one.

The oil burner arch had a sheet metal front with a cut-out for the burner.

I cut out a rectangle from the front panel the size of the door I intended. I saved this piece to be used in fabrication of the door.
All of my materials came from the local hardware store: three different sizes of angle steel for the door; a steel tube and a solid rod of a diameter that just fit inside the tube; and flat steel bar for fabricating hinges and door latch.

http://mapletrader.com/community/attachment.php?attachmentid=9909&d=1413798149

Door handle: Flat bar welded only at the top and bottom serves as a spring-able base for the latch pivot. A piece of flat bar welded at an angle to the door frame causes the door to be pulled tighter the further the latch is pushed down. The flat bar that serves as the latch rides on the front of arch opposite the door to prevent bending torquing of the latch during closing:

http://mapletrader.com/community/attachment.php?attachmentid=9910&d=1413798151

Hinges: Metal tubing welded to side of arch creates lower part of each hinge. Metal tubing welded to flat bar to door creates a spring like hinge. Metal rod down through the metal tubes serves as the hinge pin. Since the hinges are mounted at the side of the arch rather than right next to the door, the door swings wide out of the way. This improves access when firing, but you need room for the door to swing. The long metal flat bar of the hinges also serve as "springs"; when the latch is closed the door gasket is held snug tight. (I've been experimenting with Air Over Fire; the tubing you see is connected to a draft gauge.)
http://mapletrader.com/community/attachment.php?attachmentid=9911&d=1413798152

The opening: Angle steel welded inside to create the opening. Angle steel welded outside to create the frame the door gasket seats on:

http://mapletrader.com/community/attachment.php?attachmentid=9912&d=1413798170

Click on the last thumb nail for a bigger picture of the inside of the door. The door was fabricated by making a frame of angle steel and then welding in the piece of sheet metal originally cut out of the arch front. A second frame of small angle steel was welded in to created a channel that the door gasket is tucked into. Holes drilled in the sheet metal for long bolts to support the insullation. Bolt heads were tack welded to keep them in place. Fender washers hold the insullation on the bolts. Stainless is necessary here as carbon steel won't last when exposed to the firebox. (You can see I need to replace some.)

HTH

[asknupp]

Thanks Charlie.
The front is going to be 1/4" steel plate. My original thought was to use my cut out for the door somehow. Will rope gasket make it airtight? My thought was welding angle around the cutout piece so that it then extended beyond the firebox hole.

[CharlieVT]

Thanks Charlie.
The front is going to be 1/4" steel plate. My original thought was to use my cut out for the door somehow. Will rope gasket make it airtight? My thought was welding angle around the cutout piece so that it then extended beyond the firebox hole.

If I recall my fabrication sequence correctly: First I made the angle frame that fit over/around the cutout in the arch front. Then I set that frame down on the work bench, and used it as a guide to fabricate the frame that makes up the outer edge of the door. Once that frame was welded up I just dropped into that frame the piece that was cut out of the arch front and tack welded it in. Then I welded in smaller angle material inside the door to create the channel for the rope gasket to press into.

I have a couple of pretty good blowers which I have to damper back or I get too much pressure in the fire box. Even with the blowers going full I don't get any sparks or smoke around the door, so, yes the rope gasket is air tight. I got the rope gasket from some online stove supply retailer. I just specified the length and diameter I needed.

HTH

[asknupp]

What size blowers are you using charlie?

[DoubleBrookMaple]

I can show you what I came up with last year after researching this subject. I am very happy with mine after one year of service. You can momentarily put your hand on the front of my door.

I built my arch with a flat door frame face, and welded up an angle iron door box with double layer of 18 ga sheet. Quite simple. I sandwiched 2 or 3 layers of blanket that seat against the arch door frame, then 2 layers of arch board that go into the inside of the arch door frame. Welded long nuts to door that bolts screw into holding all this in place. I used furnace cement to protect the bolts heads and washers that will need recoating this year.
My latch is something I am very happy with, and I added a momentary switch that cuts out the blower when the door latch handle is moved from fully closed.
Best if you go to my build thread to see pictures, or better yet, sign up and view all my pictures at dropbox for lots of detail.
Build Thread...
http://mapletrader.com/community/showthread.php?21969-New-2X4-arch-build-for-Smokey-Lake-Hybrid-pan
Dropbox pictures.
https://www.dropbox.com/home/Sugaring%202014/Evaporator%20build

[CharlieVT]

What size blowers are you using charlie?

My AUF blower is an old oil burner with the burner elements removed. Basically a big ol' squirrel cage blower.

Here's an old article which shows the kind of evaporator I have. Scroll down and you can find a pic of the old type oil burner I'm using as the AUF blower:
http://www.fs.fed.us/ne/newtown_square/publications/research_papers/pdfs/scanned/OCR/ne_rp388.pdf


The AOF blower is a Grainger #7C447 which is a 10 9/16" Dayton blower with a Century direct motor drive. I sized the blower using this reference: I did get a blower one a little smaller than recommended for my size evaporator but I figured since I am running a separate blower for the AUF this one would be okay for just the AOF.
http://www.uvm.edu/~pmrc/Combustion.pdf