Full Chisel Blog

June 1, 2008

Bit Stock, Wimble, Sway or Sweep

Filed under: Drilling,Uncategorized — Stephen Shepherd @ 4:02 pm

The Brace, bit brace, breast stock or just stock this is the tool that turns the bit in a continuous action in a circular motion.  The leverage advantage of this tool is increased by the increase of sweep, circumference, radius or diameter reduces the effort to drill a hole.

I will of course not be able to illustrate all types of bit stocks as there are an endless variety of types and specialization for each trade and progression of tool manufacturer.  The earliest bit braces were called pad braces in which each bit was mounted into a pad (piece of wood, maybe with a ferrule and a square tapered wooden shank that fit into the brace).  The bits mounted in the wood were of the flat tapered tang type.  Here is an early brace with a pad that is an extension and has a square tapered hole in the end.


Maple body, cherry knob held on with wooden peg, beech pegs, morticed and tenon construction.  When I saw the original of this, it was by far the nicest bit stock I had ever seen and I had to make one.  Then on examining photographs I took at the Mercer Museum, I saw one just like it but the  short pieces were at a 45 degree angle, so it was the nicest one I have seen, I have not made one of those yet.

Here are my current brace of braces.  I love wordworking.  The top one I made, never happy with the knob and too lazy to make a new one.  I snapped the first one of these I made, so this one has an iron ferrule.

Brace of Braces

The one below the wooden un-plated brace is a transitional brace from the late eighteenth century/early nineteenth century as it has accommidations for both flat tang bits and square taper bits.  Well I could just go on talking about them but instead here they are:

Oh Chucks!

Now that nice little all iron (not my favorite drill in the winter) Fray & Pigg, Spafford pattern has the most unusual chuck.  There is a number under the knob indicating the sweep (radius) of the brace.  I have not seen this feature on any other similar chuck, looks to be factory original and holds small bits very well.


Here is an illustration of various chucks including round tapered friction fit chucks for smaller bits on early drills.

Many chucks

On the left is a brass spring chuck that is common on plated (inlaid reinforcement pieces on Beech or other wood braces) and held the bit with a corresponding notch in the bit. 

The next one on top is the round tapered bit that is removed by pushing a wedge in the notch to loosen the bit.  These are usually on bow drills and reciprocating drills.

 The next is the common square taper with thumb screw, and by far the most common type of brace in the early nineteenth century.  There were grades and craftsmen would choose a tool that would perform the required task and at the same time looked good, pride in tools, pride in craft and trade.  The next the Spafford or split chuck with a wingnut to tighten and secure the bit.  Introduced in the second quarter of the nineteenth century, manufacturers and people in the trades liked this pattern.

On the lower left is a split collet chuck, two jaw, three, four, etc., were made and tightening the sleeve forces the jaws together.  These have little travel and the bit needs to be sized properly.  Works for both reciprocating and continuous action drilling

The next is the two jaw chuck introduced in the nineteenth century and would hold square tapered bits and round bits as well.   This was considered an improvement of the common or Spafford pattern as it could accomidate square tapered tangs of different configurations.

The last is the Jacobs chuck with three jaws for round bits and is very late nineteenth century.  Will not hold anything but round drill bits.

Here is something I have noticed about wooden bit stocks, in particular ships carpenters braces.  Now for some reason we have some real early examples of ships carpenters wooden braces such as those recovered from the great ship Vasa and the tools recovered from the ill fated Dutch Nova Zembla expedition of 1596 and others.  These braces always have a lip on the sweep, for hanging on a peg and not falling off as the ship pitches.  As you can see my wooden brace does not have a lip in the sweep opening, but all ships carpenter’s braces have these lips, either on the chuck or knob end.


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