I need recommendations from those who forge/ laminate swords on an appropriate sized forge (and configuration) for a beginner to have a decent chance of success with.

I intend to construct a small gas forge for the primary purposes of forge welding laminated (cable damascus, pattern welded, etc.) knifes, swords and furniture for swords. It will be a long time (probably different location) before I have space or budget for trip hammers and such, so the amount of heated area needs to be appropriate for what little can be welded by hand hammering. I expect to build a vertical pipe forge for annealing and heat treating whole blades. So this question pertains to forge welding sections of blades as would be done with a 175 lb anvil and a 6 lb hammer.

My impressions so far are that it is not advantageous (decarburization) to heat a longer length of bar laminations or stock than can be realistically worked just after removal from the forge. I anticipate being limited to something like 6" to 8" welding length before it is time to return stock to the forge. Based on that expectation, I thought I would make a forge with a 12 inch inside length (about 300 mm long) with 4 inch (100 mm) square openings at opposite ends. The openings at both ends would allow stock not being heated for immediate welding to protrude from both ends. I have studied the more prominent do it yourself web sites on general construction of gas forges.

Opinions or suggestions from those who actually do this sort of thing would be appreciated.

You are correct in stating we are working only a few inches at a time, and it is over-kill to heat much more metal than that, because of the amount of scale increasing due to the larger surface area heated, than means more metal lost from the final billet due to that scale.

a propane forge is great for forging laminates. you may want a little mote than 4 inches wide because of future use and to allow room for the forge to even out the heat from the burner's exit.

Thanks. I appreciate the feedback Steve.

I thought I might buy two of the stainless mini burners (1/2" tube type as sold by Zoeller Forge http://www.zoellerforge.com/tubeburners.html) for uniformity.
I figure a small internal size (maybe 8" to 9" square) with openings of 4" to 5" wide, 3" high, could allow reasonable versatility. This would roughly approximate an internal volume of 1 cubic foot. If you have a preferred volume, aspect ratio, and opening size, I would love to hear it. Also, preferred kiln shelf material (silicon carbide?) for taking the brunt of Borax corrosion!

I will probably MIG weld ~12 gage mild steel sheet once I have drawn up the design and allowed for standard firebrick sizes. I also intend to construct an insulated slide gate cover for the extra opening in case of attempting shorter work such as knifes, scabbard chapes, etc. This will take me a few months, but the making of it is a large part of the fun!

Those dimensions are good, I would recommend getting a smallish blower instead of atmospheric burners, it is much easier to maintain a high-heat reducing atmosphere with a blower if you have electricity available.