marking a shoulder line of a dovetail joint by hand, making knife

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Marking a shoulder line.
To be successful in making woodwork joints, you need to be able to accurately mark a shoulder line using a marking knife and try-
square.

In the previous chapter I dealt with transforming my Japanese marking knife from one that had a very acute point, to one that had a
‘front edge’. If you have not viewed that chapter, you will need to do that to benefit from my marking out methods. To view that
chapter go to My Japanese marking knife

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I own two engineers try-squares, a 50mm(2”) and a 150mm(6”).   I bought the small model with the intention of using it when
marking out small pieces of timber.   In practice I find that I use the larger model on nearly every occasion.

Utter basics.
The workbench. It does not take long before shavings and sawdust get in the way, and it is best practice to keep the bench clean.

The try-square.
A try-square is a tool that get picked up and returned to the bench during the marking out process, and it is pretty easy for a small
piece of sawdust to be picked up from the bench, attach itself to the try-square, and ruin the marking out process.   Make sure it is
spotlessly clean before every single line is marked. In practice I tend to wipe the inner face of the body of the try-square with my
finger.

A practice piece
Most of the large D.I.Y stores sell timber that has been machined to excellent tolerances.   I would suggest for a person new to the
craft collect some pine that is in the region of 68mm(2 ¾”) by 21mm(7/8”) and has been planed.

You also need to check that the timber is perfectly flat and square, so take along your try-square and straight edge, and select a
sample that fits that standard.

The chisel/knife tidy
I would recommend one of these to help prevent damaging the knife. (this is mentioned in the chapter My tool sharpening system)
alternatively a piece of soft material to place the knife on.

How I hold the marking knife.

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how I hold a marking knife showing thumb and index finger position

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showing thumb position when holding a marking knife.

showing middle finger position when holding a marking knife.

My engineers try-square.

copy of trysquare009 copy

Utter basics again
1        It is only the outer
edge that is used for
marking shoulder lines.
2        I use the inner edge
for checking the flatness of
timber.   With regular use
the outer edge becomes
worn, so it makes sense to
use the inner edge.

Positioning the try-square to marking a shoulder line.
There are basic rules for marking shoulder lines with a try-square. The body of the try-square is always up against the face side or
face edge of the timber during the marking out process. As always, there are exceptions.

One of which is when marking out dovetails joints. The end of the timber, when accurately prepared, will also become an accurate
datum surface, which I refer to as the face end.

Depending on where the shoulder line is being marked will determined where the try-square is positioned on the timber. The
illustration below shows the two positions required when marking a piece of timber to length.

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the position of the try-square when marking some shoulder lines

Holding the try-square when marking the face side.

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the traditional face side and face edge markings

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and another method of holding a try-square

Marking the face edge.
When marking the face edge of timber the finger positions are similar. In this case I would only ever use the index finger on the
blade, not two as I do on occasions when marking wider timber.

What I would recommend to a person new to the craft is to cramp the timber in the vice when marking the face edge. In this way
the timber is nicely secure, and it makes the marking out process so much easier, with a much greater chance of success. The
more skilled you get you may find that this is not necessary.

When marking out thin timber, 3mm-6mm wide (1/8”-1/4”) I find that it is best to push the timber up against another piece of
wood. I will deal with that method when making the home made dovetail templates.

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holding the try-square when marking the face edge

Marking the first shoulder line.
I would recommend that beginners work from one end of the practice piece, and progress toward the centre. By concentrating on
marking in one direction at a time, I feel that you will build your skills quickly.

And as a reminder go through a check list.
Are the following items clean:-

the workbench.

try-square, and then ensure that you check it ever time you pick it up from the bench.

Now you checked that the face side and face edge when it was bought as flat, but is it still flat. It may seen a bit
extreme but like most things in life, this advise comes from experience, and time consuming mistakes.

the marking knife, check that it is still sharp.

if you have made a chisel/knife tidy I would suggest that you use that.

And this is the method that I would recommend. Hold the knife as shown and position and hold the try-square around 1mm(1/16”)
from the end, gripping firmly.

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positioning the try-square for marking a shoulder line

And when I have the
try-square as
illustrated I am
checking that the inner
face of the body is
tight up against the
face edge.

When I mark a component to length by hand, this would be my method of working.

Using a marking knife and engineers try-square, I would firstly mark one line completely across either the face edge or face side,
depending on the job I was carrying out.

Using a steel rule an marking knife, I would then mark the component to length with a line around 3mm(1/8”) long.

The first exercise is easy because you don’t have to mark to a line, so I will deal with that first.

Some timbers are soft and easy to work and allow you to work with fine detail, whilst others, and I include English oak in this list,
can easy chip, causing problems in the marking out process. Because of this I have adopted a method of working with this timber to
prevent ‘break out’ or chipping.

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trysquare014
scene 3

marking one the corner of the wood to prevent it chipping during the marking out process

and another view

a close up view of marking a corner to prevent chipping

and the knife is
positioned like this,
and lightly pushed up
against the edge.

and this small mark
will prevent any
chipping away of the
grain when marking
timbers like English
oak, elm and the like.

The knife is now
positioned as illustrated
and with the wrist
firmly locked in
position.

You move the arm
backwards, whilst the
tip of the blade is kept
tightly up against the
outside edge of the
try-square, in a vertical
position.

and a close up view
showing that the tip of
the blade is over the
edge. My aim is to
make the shoulder line
around
0.5mm deep(1/64”)
and I achieve that by
making three light
passes of the knife
whilst the try-square is
held firmly in position.

after which you will
have one line at right
angles to the face
edge, and in the region
of 0.5mm deep(1/64”)

Having marked the face side, the
next job is to mark the face
edge. Either cramp the timber in
a vice or if you are more
experienced just rest it on the top
of the workbench

Position the try-square around
12mm(5/8”) away from the first
knife line.

Place the 'front edge' of the
marking knife, into the first knife
line, as illustrated.

and a different view.

Whilst the knife is in
that position

I slide the try-square
until it touches the
back of the marking
knife

I check that the inner
face of the try-square
is still up against the
face side

I tighten the grip on
the try-square, then
remove the 'front edge'
of the marking knife.

and position it just past
the edge.

Again I am looking at
marking the shoulder
line in three light cuts.

Lock up the wrist and
move the knife
towards your body,
remembering that it is
only the shoulder joint
and elbow are bending.

The wrist remains
locked.

And the two remaining lines are
marked in the same manner,
remembering that the leading edge
of the marking knife is located in
the mark you have just made.

This is a method that I have found
extremely successful. It is
however a skill that needs learning
and building up with practice.

and after a number of practice runs
you will end up with a piece of
timber looking like this.

Marking a component to length
Having marked a shoulder line around the four surfaces of a piece of wood so that they join up successfully, the next skill building
exercise is to be able to mark a piece of wood to length.

In this instance I want to mark a line that is 100mm(4”) away from the existing knife line.
I place the steel rule as shown below with the 100mm(4”) line, aligned with the knife line I have just made. I hold the rule firmly and
mark a line around 3mm (1/8”) long in position A

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trysquare014
scene 14

how I marking a piece of timber to length using a steel rule

viewed from this
direction.

leaving a small mark
on the face side.

Then I would place
the tip of the knife in
the mark, and
carefully slide the
try-square up to it,
so that the back of
the blade is up
against the outside
edge of the
try-square.

like this

Then I remove the
knife, reposition it,
and mark the corner
with the 'front edge' to
prevent it chipping
away.

It is repositioned again
as shown, and with
the wrist and arm
locked in position and
only the elbow and
shoulder joint moving,
the line is marked
using three light
marks

Next, reposition the
timber in the vice if
possible, place the
'front edge' of the
knife in this line and
slide up the
try-square so that the
back of the blade is
up against the outer
edge of the
try-square.

Keeping firm hold of
the try-square,
reposition the knife as
shown and again make
three light strokes of
the knife.
And the whole
procedure is repeated
until the four lines
meet up.

Summary

There are so many important things to remember when marking a shoulder line on a piece of timber.

Keep the workbench and tools spotlessly clean, and check the try-square every time it is being used to mark a line.

Before you mark a line, check that the timber is still flat and square using the try-square.

Is the marking knife still razor blade sharp right at the point.

If you have made a chisel/knife tidy I would suggest that you use that.

I am not in my workshop on a daily basis, so before any project I will still have a few practice runs marking lines before working on
the project in hand. c

I hold the knife in my
right hand, and grip it
between my thumb and
middle finger about 50mm
(2”) from the tip of the
blade, with my with
index finger on top.

If your finger are two
close to the blade there is
a possibility of damaging
them during the marking
out process.

In this image you will see
where the thumb is
positioned

(I have removed my
index from the knife for
clarity- this would
normally be on top of the
knife)

and in this image, the
position of the middle
finger.

Terms that I will use.

The first image shows a
piece of pine with the
traditional face side and
face edge markings.

I have drawn these in felt
tip pen. In reality I don’t
use a felt tip pen, and I
have only done so because
the photographs will be
clearer.

my thumb is pushing the ‘inner
face’ of the ‘body’ of the
engineers try-square up against
the face edge of the
timber

my index finer is pushing the
blade of the square against the
face side and is close to the top
edge

and my three fingers are on
the opposite edge, gripping the
timber.

So effectively the thumb and
the three fingers are gripping
the wood and the square,
whilst the single finger is
pushing the blade against the
face side.

The fingers can see seen
clearer from this angle.

And sometimes I may place
two finger on the blade of the
square. There is no hard and
fast rules.

In this position the three fingers
are pushing the body of the
try-square against the face
edge, one finger is holding the
blade onto the face side, and the
thumb is gripping the edge.

and viewed from this angle you
can see the thumb gripping the
timber.

like this

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