109 - Bench Plane Tune-Up.pdf

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BENCH PLANE
TUNE-UP
© 2007 August Home Publishing Co.
B
ench
P
lane
T
une
-u
P
If you’re restoring an old bench plane,
chances are it’s in need of a little tune-
up. But that’s also true for a brand
new plane right out of the box. Either
way, a simple tune-up will turn a bench
plane into a precision tool.
SHARPENING THE BLADE
The best way to end up with good
results is to start with a sharp blade.
THE EDGE.
The cutting edge of the
blade is formed by the intersection of
two surfaces — the back and the bevel
of the blade. To get a sharp edge, you
want these surfaces smooth and flat.
FLATTEN BACK.
When flattening the
back, I “sand” it on a flat surface like
a piece of glass, see Step 1 above. Start
with 220-grit silicon-carbide sandpaper
and sand until there’s a consistent set
of scratch marks. Then polish the back
using progressively finer grits. (I work
up from 400 to 2000-grit).
This takes some elbow grease. But
the nice thing is you only have to do it
one time. Once the back is flat, you just
need to concentrate on the bevel the
next time you sharpen the blade.
NOW THE BEVEL.
Now it’s just a matter of
making the bevel as flat and smooth as
the back. The secret is to hold the blade
at a consistent angle. To do this, I use a
honing guide, see Step 2. Basically, this
is a rolling clamp that holds the blade at
the desired angle.
Here again, the idea is to proceed
from a coarse to a fine grit. The trick is
SHARPEN THE BLADE
1
Using oil as a lubricant, sand the
back of the blade across a piece
of silicon-carbide sandpaper.
2
A honing guide ensures that
the blade remains at a consis-
tent angle as you’re sharpening.
It takes more than a sharp blade to
plane a surface smooth. The cap iron
that’s attached to the blade also needs
some attention.
The purpose of the cap iron is
simple. To prevent tearout, it “breaks”
the shaving as the blade slices through
the wood. To do this, the nose of the
cap iron is curved.
SAND EDGE.
The problem is that if the
edge of the cap iron doesn’t sit flat
against the blade, the shavings can
wedge under the cap iron. This
can create a “log jam” of shav-
FITTING THE CAP IRON
ings, making it difficult to plane
a surface smooth. To prevent
this, the curved edge of the cap
iron needs to be sanded smooth
and even, see Step 1 at left. Here
again, I use 220-grit silicon-car-
bide sandpaper.
POSITION CAP IRON.
Once the edge
is sanded smooth, it’s important
to position the cap iron properly.
In general, I attach the cap iron
so it’s about
1
⁄
16
" from the front
Lower the back end of the cap iron
After smoothing the edge of the
edge of the blade. But for fine
slightly, then sand the front edge
cap iron, tighten it in place behind
work, when I want paper-thin
by making a few smooth strokes.
the leading edge of the blade.
shavings, I set it about
1
⁄
32
" from
the front edge.
knowing where to start. This requires
matching the grit to the condition of the
bevel. If there’s a nick in the edge, I start
with 180-grit sandpaper. But this is too
coarse for most work. For example, 220-
grit sandpaper is fine for a new blade.
If you’re just touching up an edge, you
may want to start with 800-grit.
EVEN PRESSURE.
Regardless of the grit,
the key is to apply pressure evenly
across the blade. The only exception
is if the blade is out of square. In that
case, apply a little extra pressure on
the “high” corner to square the blade
as you sharpen.
BURR.
As you work with each grit, a
burr will start to form on the back of the
blade. You can’t see it, but you can feel
the burr by running your finger up the
back of the blade. When you get a nice
even burr across the entire width of the
blade, remove it by alternately sanding
the back and bevel with the final grit of
sandpaper used to polish the back.
FITTING THE CAP IRON
1
1
2
www.Woodsmith.com
© 2007 August Home Publishing Co. All Rights Reserved.
ADjuSTING THE FROG
1
To adjust the opening of the
throat, first loosen the screws
that hold the frog in place.
2
Then turn the screw at the
back of the frog to adjust
the size of the throat opening.
3
To check the size of the open-
ing, tighten the frog down
and then reinstall the blade.
With the cap iron in place on the
blade, you’re almost ready to start
planing. But first you’ll need to
adjust the throat opening where
the blade projects through the
bottom of the plane.
The goal here is to size the
opening so it “matches” the position
of the cap iron on the blade. This
way, they both work together to
create nice even shavings.
ADJUST FROG.
To do this, you’ll
need to adjust the position of the
frog. Start by loosening the screws
on the top of the frog, as shown in
Step 1 above. Then turn the adjust-
ment screw at the back of the frog
to adjust the opening, see Step 2.
After reinstalling the blade, check
the size of the opening, see Step 3.
Note: Tighten down the frog before
reinstalling the blade.
So how do you know that the frog
ADJUSTING THE FROG
is adjusted just right? Basically, it’s a
trial and error process.
As a rule, start by adjusting the
opening so it’s about twice the setting
of the cap iron. For example, for fine
work, I’ll open the mouth to
1
⁄
16
" (twice
the cap iron distance of
1
⁄
32
").
Then after reinstalling the blade,
check the setting by planing the
edge of a scrap. The shavings should
come off the workpiece smoothly
and evenly without jamming in the
opening of the mouth.
REFERENCE SURFACE.
To check whether
There’s one last thing to consider
when tuning up a plane — the flat-
ness of the sole.
If there’s a slight bump in the
sole, it will prevent the cutting edge
of the blade from making full con-
tact with the workpiece. And if the
sole is dished out, it’s almost impos-
sible to plane a surface flat.
FLATTENING THE SOLE
the sole is flat or not, you need a flat
reference surface. Here again, a
piece of glass works fine.
To check the sole, draw lines
across it with a marker, see Step 1
below. Then sand the plane across
a piece of silicon-carbide sandpaper,
see Step 2. After a few strokes, check
your progress. Any low spots will
show up as dark lines, see Step 3.
Note:
Be sure to sand the
plane with the blade in place (and
retracted). This will “stress” the
body of the plane as if it’s in use.
The idea is to continue sanding
until the lines disappear. Then polish
the sole on progressively finer grits
of sandpaper (up to 400-grit).
Finally, give the metal surfaces
a coat of paraffin wax. Unlike a
machine oil, the wax will protect the
plane without leaving a residue on
the workpiece that can ruin a finish.
FLATTENING THE SOLE
1
2
To flatten the sole, start by drawing
squiggly lines across the sole of the
plane with a permanent marker.
2
Then “scrub” the plane on a sheet
of 220-grit silicon-carbide paper
that’s taped to a piece of glass.
3
Any dark lines that remain indicate
low areas. So continue sanding
until the marks disappear.
www.Woodsmith.com
© 2007 August Home Publishing Co. All Rights Reserved.

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