Making large-diameter mortises for chairs or staked tables
requires huge drill bits and a option to drive them. Often a
drill press received’t work as a result of the workpiece is simply too giant and
the angles are too odd. So listed here are some bits that work – and
some to keep away from.
To drive huge bits (1-1/four” and larger), you most likely want a
corded drill. I’ve tried utilizing a brace, however that’s a tall order
in exhausting woods. Battery drills, for probably the most half, aren’t as much as
the duty both. I want a corded drill with a standard
keyed 1/2” chuck.
The kind of bit can be vital. My favourite variety is what
will get labeled a “ship’s auger,” proven within the picture above. This
has a lead screw that’s lengthy sufficient that you could tilt the bit
for compound angles (the lead on a traditional Forstner is simply too brief
for something however shallow angles). The stable physique of the auger
retains your bit on observe with little probability for wandering. The
draw back is these bits are your most costly possibility – an
1-1/four” ship’s auger is about $25 at my ironmongery store. One other
model I’ve had nice luck with is WoodOwl.
An identical possibility is the shorter auger proven above. It’s about
half the worth of the ship’s auger. Its downsides are that its
spurs alongside the rim are pretty brief and ineffective. So the
entry gap is gonna get somewhat torn up. Additionally, it’s brief. So
it would wander in holes deeper than 2”.
The third sort of bit that I like is a spade bit with a lead
screw. The lead screw makes the bit pretty aggressive and
reduces its tendency to wander. These bits are normally about $6
and work surprisingly effectively.
What doesn’t work effectively for correct mortises is the normal
spade bit with a standard tip (i.e. no lead screw). This bit
jumps round and rattles an excessive amount of for correct work. It’s the
least expensive of the bunch, but additionally the least helpful.
Or perhaps this bit is the least helpful. Typically referred to as a “cup”
bit, I made a decision to provide it a go. The lengthy drill bit within the
middle lets you tilt the bit to virtually any chairmaking
angle. However the outer reducing rim is a joke. It clogs
instantly as a result of there’s no place for shavings to go. So that you
have to tug the bit out each 1/eight” and clear out its gullets.
Observe that these suggestions are for large-diameter bits.
For smaller-diameter holes, an auger and a brace are my
— Christopher Schwarz