To bore the initial hole in a shrink pot, I use an auger, typically this two-inch diameter T-handle auger. I found mine at flea market years ago. Large augers like this aren’t rare, but there are a few things to keep in mind when choosing one for boring into hardwood end grain.
The image below shows the edge configuration of this auger. There are many variations that will do the job well. This style has no scoring spurs, and for cutting into end grain none are needed. (This auger performs well on side grain as well, as when boring out timber frame mortises.) The two horizontal cutting edges slice wood from the bottom of the hole and the vertical cutting lips clean up the sides. The lead screw is not too aggressive and not too fine. If the threads were more widely spaced, it would take a deeper bite, maybe too much to expect in end grain. If the lead screw were too fine, it might not grip enough in end grain to pull the auger into the piece. In any case, more forward force is usually required to keep the screw engaged in end grain.
It would be tough to turn a two inch auger bit with a brace; much more torque can be applied with a t-handle auger. And like most tools, if it’s sharp it’s a pleasure to use. Sharpening is pretty straightforward. Auger bit files do a nice job, but lacking one, you may also get by with a narrow diamond paddle or a slip stone.
Remove material from the upper side of both cutters. I only use a light touch with the fine diamond paddle on the lower side to remove any burr.
Do the same with the vertical edge, keeping the junction well-formed and honed.
Here, I am ever-so-lightly removing the burr from the outside of the cutter. The most common problem I’ve seen on used auger bits of all sizes is sharpening that has been done on the outside edges. These edges cut the hole and establish the diameter. If the edges are rounded inward, a smaller diameter is cut and the rest of the bit can jam as it tries to follow into the narrow opening.
Here are three lengths of a cherry log that will become shrink pots. I still have to broaden the hollows (which I’ll probably make oval to use the natural shape of the rings in these pieces). The auger just provides a start. A narrower auger can be used. It will just leave more material to be removed otherwise. I usually leave the piece long for ease of holding in a vise. I bore a hole a little beyond what I need, saw off a length, then continue boring. I repeat the sequence until I bore through the last chunk.
I recorded a little video footage while I bored these a couple days ago; just simply the sights and sounds of the auger boring into cherry end grain:
I have some other posts about shrink pots. Just click “shrink boxes” in the category list to the right.