These are called deck doweling bits
and were used almost exclusively in the shipbuilding trade. All
that are marked were made in England and Scotland. I think these
bits were not used here in America because all I have were
acquired from English tool dealers and I have never found one in
any of my travels in the USA.
These bits were primarily use in
attaching deck boards to timbers in ship construction. Deck
boards were often bolted in place with copper bolts, nuts, and
The tools were used after another
bit had bored a hole into which the bolt was to be inserted.
Deck doweling bits were use to bore a deep hole as a countersink
to hide the bolts. The blunt cylindrical end of a bit was
inserted in a bolt hole, which served as a pilot hole, and then
rotated to bore a countersink.
After the bolts were put in place
and tightened, wooden dowels of the appropriate size were driven
into the countersink hole and trimmed flush with the deck
surface. As you can see in the photos, there are several
variations to these bits. Some have lead screws to pull the bit
into a bolt hole but this type is rather rare. One in this
assemblage could be used on two sizes of holes through the use
of a bushing cap on the pilot cylinder.
This photo shows three hand forged bits on the
These are all manufactured bits with smooth
and threaded pilots.