2 - Building the Barrel Head Blank
The blank is the flat square construction, made from three prepared and joined merrains, which will later be cut round.
Blank Planning
The prepared merrains are laid out on a table. At this stage you must make decisions about the location and orientation of your staves. Some boards have an unsuitable edge, either (primarily) because of a deformity like a knot or crack, or (secondarily) because it is unaesthetic. These edges should be located on the outside edge of a blank.
My staves sometimes have a strip of sapwood on them, so if possible that edge will go to the outside of the blank, which is partially or totally removed when the round is cut. I believe sapwood is much less desirable in cooperage primarily because the tyloses have not sealed up the capillary tubes in the wood. This is not an issue in these barrels because the capillary tubes are not open to the air, they are pressed up against the stainless steel can.
Edge Jointing
Stave edges which will be joined together are “jointed”, which means squared up and smoothed, such that when pressed together there are no gaps. Possible tools used for this operation: Hand plane (my current favorite but slow), jointer, router table with straight bit and carefully-prepared fence seen here. Even a table saw with a fine blade might work for this process.
It is nice to have joints that are both super-flat and super-smooth, but between those two qualities I believe that flatness is more important.
Dowel Hole Drilling
Dowel holes are drilled in the joints between the staves. Two dowels per joint, without glue, usually provide sufficient strength to survive the remaining procedure until pressing the barrel head. A jig for locating the dowel holes is a good idea if you plan on doing this more than once. Since the dowels should be perpendicular to the barrel face, a drill press or some other drill guide should be used.
If you don’t have a jig, one complication might be that your stave edges are not parallel, so the drill press may be drilling angled holes, which could make joining the staves more difficult. A wedge under the stave and a level to judge the top drilled edge might be useful in extreme cases.
Joint Waxing
A very thin strip of beeswax is painted onto the joint edges as insurance against leaks. Any brush will do.
Beeswax should be melted in a double-boiler or a temperature-controlled induction burner set to 180-210 °F to avoid smoke, discoloration, burning yourself, a giant fireball, etc.
Stave Joining
The waxed and doweled joint faces are joined to form the blank.
Don’t be gentle. A heavy hammer or mallet will help to tighten the joints, but use a block to distribute the force. A press may be used with great care. If you see beeswax squeeze-out, stop.
If the wax is very cold it will be hard enough to hold the joint open more than you’d like. Soft, but not melted, wax is better here.
Blank Face Planing
If desired, the blank can be planed or sanded at this stage. It can also be planed later in the process.