angle iron and sheet gauge size for arch

[TC matt]

I'm starting from scratch and building a new arch. my pan is 2x4 w/ no dividers. I planned on designing it much like Brian Ks. what size angle iron and sheet metal do you recommend? I was thinking of 1.5x1.5 1/8 angle and 12 gauge metal. Could I go with a lighter gauge? I'll be using ceramic blanket and fire brick to insulate. Also, I was going to spot weld the sheet on, (like Brian's) but do I need to worry about making it airtight? Lastly, how to attach insulation to sheet metal?

[Haynes Forest Products]

12 guage is fine and maybe a little heavy BUT it will make the rig stronger. I would just brick it if your using wood. I like 2" for the frame because you can have better attachment to the bigger size. Are you welding or bolting together? AS far as ataching the insulation If its brick gravity and mortar are your friend so just fit and mortar.

[vtsnowedin]

My 3x8 Grimm has 18 gauge for all the sheet metal in the arch. The angles are 1.2x1.2X3/16 and there are only two of them (the top rails). The sides have a two inch shelf bent into them and the bottom sheet drops in and is pop riveted into place. The bottom sheet is narrower then the top of the arch so the bricks lean out and gravity helps hold them in place so your not relying on the mortar or the insulation behind them to hold them in place.That's important if the arch will spend winters in an unheated sugarhouse and go through freeze thaw cycles when the bricks are damp.
Most of the home built riggs I see here are way over built in the frame of the arch but there is no harm in that.

[Brian Kloepfer]

I'm starting from scratch and building a new arch. my pan is 2x4 w/ no dividers. I planned on designing it much like Brian Ks. what size angle iron and sheet metal do you recommend? I was thinking of 1.5x1.5 1/8 angle and 12 gauge metal. Could I go with a lighter gauge? I'll be using ceramic blanket and fire brick to insulate. Also, I was going to spot weld the sheet on, (like Brian's) but do I need to worry about making it airtight? Lastly, how to attach insulation to sheet metal?

Matt I used 1 1/4 x 1 1/4 x1/8 angle iron and 16 gauge sheet steal.

[RileySugarbush]

I used 1 1/4 by 1/8 angle welded for frame and 16 gage for the skins. Since I was planning on insulating well I put a bead of hi temp silicone between the sheet and the angle. Attachment of the sheet metal was with self drilling and tapping screws every 4 to 5" and went very fast. I used 12 gage for the front since it supports the door. No brick under the flues, just ceramic blanket, so the floor in that area is only 16 gage. This construction is totally solid and I wouldn't change a thing.

[Gravel]

As long as you insulate it you can use smaller material, which is what I would do for the price of arch board, I insulated my homemade 2x6 for $100, makes a huge difference! I used angle iron from bedframes that were free and not very heavy material!!