It's a Philly thing, but I'll call it Just A Wood'N Box Of Dirt.

Scrounged up some scrap wood consisting of some 2" thick planks, butcher block, 6" newel post and other wide planks to be assembled with leftover nuts and bolts from treehouse and firewood shelter builds. Gonna be bloody heavy but nice and sturdy (I tend to overbuild).

I have to dig out some storm swales around the property so will dig deep to get some soil clay to fill the box.

Should be around 25" x 35".

 

 

Mix the clay at about a 2 to 1 ratio with sand.  It will help prevent the clay from contracting and cracking when it dries.  If you can find local "wild" sand, great but "plsy dsnd" from the hardware store or big box works great and is not very expensive.

"By hammer and hand all arts do stand."

When you add the dirt" don't make it wet, just enough moisture you can pack it hard is perfect. Ditto the sand in the mix though I generally go a little higher than 2-1.

Frosty The Lucky.

Frosty, do you use somewhat more sand or more clay than 2:1?

GNM

I have a bag of tube sand I randomly move from place to place for no good reason so maybe it's finally found it's purpose.

Yes George, I like 3-4 pts sand to 1 pt clay and temper it like it was molding sand. I've always treated any sand to be packed like I learned to temper and pack green sand molds. About the second time I break down a portable dirt forge it gets enough ash mixed in to cement together in the HOT zone to need breaking up with a mallet or hammer to break down again. I don't resort to riddling it though, that'd be silly even for me.

All I've ever used for the box is just a handy box and often not the same one an old steel drawer out of a salvaged file cabinet made a nice one though I had to add a couple 45* elbows to the tuyere pipe. If it were a shallower drawer I could've just angled it in from the far end. 

I've described my trailer park side blast forges before, they were a pile of dirt on an old kitchen table with a short tuyere pipe poking into the bowl, later trench. I packed it with the shovel in lifts as I piled it ad scooped the bowl/trench. 

Working in the soils lab influenced me a lot too. It wasn't until a few years ago I found out that casting sand uses bentonite clay which would only require maybe 1 pt. in 7-8 pts sand to pack reasonably hard and a 55lb sack was less than $40 so I toss some in every time I mix up a batch. 

I mix it differently every time I dig out an old box. I burn propane almost exclusively so it's a long time between solid fuel forges and I don't keep notes I go by feel instead. Not much specific help eh? 

Frosty The Lucky.