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joints are some of the strongest woodworking joints. They are used
extensively in cabinet and furniture making. The special mortising
accessory for the Mark V eliminates tedious hand work when cutting
mortises for mortise-and-tenon joints and other joints calling for
a square cavity.
The acessories that are used for mortising are: (A) worktable,
(B) rip fence, (C) mortising attachment, (D) mortising hold-down,
(E) drill chuck and (F) chisel and bit. (G) The internal tubes
and telescoping legs of the extension table system suppor
the table (Model 510 only).
To perform mortising
operations, set up the Mark V in the drill press mode and use the
accessories shown in Figure
attachment is slipped over the collar on the quill. Position the
arm to the right or left and secure with the Allen screw. To secure
the chuck, turn the spindle by hand so the tapered flat faces away
from the arm and secure the setscrew. Warning: The chuck must
be secured while the flat of the spindle faces away from the arm
of the mortising attachment. Caution: Place a scrap piece of
wood on the worktable to protect the bit and chisel if they are
dropped. Insert the chisel in the adjustable sleeve and secure it
with the setscrew (Figure
8-2). Insert the bit through the chisel and into the chuck and
lock with the chuck key.
Insert the chisel in the adjustable sleeve and secure it with
the setscrew. A piece of scrap stock protects the worktable.
Be sure to remove the chuck key. The adjustable sleeve of the
mortising attachment is positioned so there is a gap of 1/32" to
1/16" between the cutting edge of the bit and the chisel (Figure
There must be a clearance of 1/32"-1/16" between
the bit and the chisel.
Since the rip
fence is used as a guide for the workpiece, the chisel must be square
to it. Place the head of a combination square against the fence
and the chisel (Figure
8-4). Make the adjustment by turning the adjustable sleeve;
then secure it with the setscrew.
hold-down which attaches to the rip fence, keeps the workpiece from
pulling up when the quill is retracted.
The side of the chisel should be positioned at right angles
to the rip fence. Check it with the head of a combination
The final step
is to adjust the quill feed stop for the depth of cut needed. Caution:
If the cut is to go through the workpiece, use scrap wood to protect
Before using the mortising accessory, read and understand these
Important safety Instructions:
danger zone during mortising operations extends 3" around the bit
and chuck and 5" beneath the bit. When you perform mortising operations,
be certain your hands and fingers aren't beneath the bit when you
advance the quill. Never reach in toward the bit or beneath it to
clear away scraps. Turn off the machine and let it come to a complete
- Wear proper
eye and ear protection.
leave the key in the chuck. Remove the key from the chuck immediately
after securing the bit.
wear jewelry, gloves, ties, loose clothing or clothing with long
sleeves. Keep long hair tucked under a hat. Jewelry, gloves, ties,
clothing and hair could become entangled in the bit.
the worktable at mid-chest whenever possible.
- Use the
rip fence as a backstop and hold the stock firmly against both
the worktable and the fence.
Before you begin
any mortising operation, set the Mark V to run at the correct speed.
To do this: turn the machine on, turn the speed dial to the correct
speed and let the machine come up to speed.
speeds for mortising range from speed setting H (1600
RPM)to G (1450 RPM). For the most part, the correct
speed is determined by the size of the mortise you want to make
and the material you're using. Generally, you can use faster speeds
with softer woods or smaller mortises. Use slower speeds as the
materials get harder and the mortises get larger.
All of the following joints can be made by working with mortising
bits and chisels: (A) through, (B) keyed, (C) haunched, (D)
blind, (E) loose wedged, (F) three-way, (G) twin, (H) notched,
(I) open-faced, (J) concealed haunched, (K) through wedged.
Click on image to see larger view.
All the joints
shown in Figure 8-5
can be made using the mortising accessory.
workpiece on the table and depress the chisel to do the cutting.
Use only enough pressure to keep the bit cutting (Figure
8-6). Pressure required will vary with the size of the chisel
and the hardness of the wood. Softwoods such as pine cut easily,
while hardwoods such as maple require considerably more pressure.
If you can't make the cut without exertion, it is probably because
the edges on the bit and/or the chisel are dull.
Work with the correct speed and use only enough feed pressure
to keep the bit cutting. Mortising cuts need a heavier feed
than simple drilling, but if you must really lean on the feed
lever, check the chisel and bit for sharpness.
The rip fence/worktable
V-block arrangement can be used to hold round workpieces. Be sure
to mark the workpiece so the cuts will begin and end on the same
line (Figure 8-7).
The fence/table V-block arrangement can be used to hold round
workpieces for mortising. Be sure to mark the workpiece so
the cuts will begin and end on the same line.
Two factors that may spoil a mortise: (A) Chisel tends to
lead off twoard the cavity already formed, and (B) workpiece
tends to drift away form the chisel as the cut is being made.
Click on image to see larger view.
which tend to spoil a mortise are illustrated in Figure
8-8. To eliminate these, cuts should be made as shown in the
order given in the second detail of the drawing. The general rule
is: Always make the end cuts first. Start with 1/4 n deep cuts,
never less than threequarters of the full width of the chisel. This
may not be possible on the last cut, but keep as close to it as
you can. Repeat until desired depth is achieved.
shoulders. The chisel will drift away, leaving a tapered side. Many
workpieces split because tenons are forced into mortises with slopping
sides. If necessary, use a smaller chisel.