Woodwork Joints
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| For setting out joints see the paper
'Basic Setting Out 1' here
and follow the articles through. When you
have cut down the shoulders of a tenon properly, removed the
waste of a halving and chopped out a mortise all these skills
are repeated for most of the other types of joints.
Remember to cut the shoulder lines with a sharp knife and 'vee'
it partially to get a good joint. A tight
joint is not needed, just fitted well. If it is too tight
the glue will be forced out and any minor imperfection will
throw the frame out and into 'winding'.
There are numerous 'rules' for
beginners and improvers to learn and at times it seems like
there are too many. They are not my rules.
The 'rules' however, are the techniques handed down as the most
effective way of doing things. They reduce your
error and allow you to work more efficiently and above all - safely.
Later when you have learnt the techniques and you work
effectively you may find 'other' ways. But you will
understand and know the penalties when things do not quite go as
they should and why!
An important set of rules is
the order of work see here.
On many occasions if you cut a shoulder for instance before you
have worked the groove or rebate you may find it difficult or
tricky to use the plane or router, etc. on the reduced
length. These rules make it easier and reduces
error.
How to actually cut the
joints is well covered in the 'Stanley's
how to sheets'. These are excellent for
getting the basic techniques. If you read,
understand and practise these techniques successfully you are
70% a woodworker. You then need to know about
cabinet construction and lots of practise and experience to
become proficient. I would like to add just
one tip ~ when sawing to line or shoulder it should be well
defined with a sharp H2 pencil, or gauged or in the case of
shoulders, pre-cut with a sharp knife AND then saw as close to
the line, on the waste side of the line, as possible. Your
aim actually is to try and cut the line in half ! It
is a mistake to leave a little on to trim to the line
later. This is wasteful and the longer you
rely on it you will never cut a straight or accurate line or
shoulder. Remember if you are using powered
saws, the 'kerf' could be as thick as 4 to 5 mm's thick.
The basic joints:
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| To see detailed isometric
drawings of how the mortise and tenon joints are constructed see
the three different frame joints here.
a. Through haunched Mortise &
Tenon. The haunch is to prevent the joint becoming 'bridled'
and by reducing the width to 2/3 rds it reduces the tendency of
the tenon cupping and thus putting the frame in
'winding'. see
paper on M & T here.
b. Secret haunched Mortise and Tenon. The secret haunch
is achieved by cutting it at 45 degrees. This is needed
for instance when the top of the frame is exposed such as a cane
seat on a stool, etc.
c. Secret Haunched Stub Mortise and Tenon. The Stub hides
the end grain of the tenon coming
through. The M & T mid way to
receive a rail or runner, etc. would not need to be
haunched. However, it is prudent in all cabinet work
to have a small shoulder top and bottom of say 2 to 3 mm to hide
any 'blemishes' that may be exposed on cutting the mortise.
d. Corner rail to leg. The M & T is 'bare-faced' to
allow the cheek of the rail to line up with the outside of the
leg or stile. The meeting tenons are mitred to gain the maximum
length. Note that it is also 'haunched' to prevent the
joint becoming 'bridled'. ( A lower rail would not need
the haunch - see above)
e. Corner or 'L' bridle for a carcase frame.
f. Corner or 'L' dovetailed bridle, similar to above but
stronger. Some chair seat are done like this.
g. 'T' Bridle, Stile to mid-rail. A mid leg is often
jointed like this on a half round table.
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h. Corner halved or 'L' joint. With
countersunk screws to reinforce it. For Carcassing quality work,
etc.
i. 'T' Halved Joint - For Carcassing. The 'X' or cross
rail halving is similar where two rails cross but both rails
continue.
j. Mitred corner joint - hides end grain, suitable for
table top mouldings and picture frames, etc.
k. Halved corner Mitre Joint. As above but stronger. Use
where the end grain may be hidden. |
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l. Butt joint. often nailed with
round headed nails from the rail in a 'dovetail' fashion. This
is called 'skew' or 'tosh' nailing. Low quality carcase ~
carpentry.
m. Square through housing. Carcassing and carpentry.
Often strengthened with nails as above.
n. Stopped Housing - the stop or 'lap' is to give a
better line of view.
o. Dovetailed housing - helps to pull the carcase, etc.
together.
p. Stopped or 'lapped' housing or 'dado' for shelving or
partitions, etc. May be vertical or horizontal.
q. Stopped or 'lapped' dovetailed (single or double) housing
or 'dado'. As above for extra strength and resisting pull.
P&q above are often used
vertically as a divider. (turn the
illustrations 90 degrees left CCW). The stopped part of
the joint should be to the front to hide the dado or housing.
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r. Common halved 'T' frame dovetail.
For Carcassing - the dovetail resists the lateral pull. Soft
wood ratio is 1 : 6 and hard wood ratio is 1 : 8. There are
other ratio varieties for decorative purposes.
s. Common dovetail ~ corner joint.
t. Lapped dovetail ~ corner joint. Note that
for drawers the pins are much smaller and the face mark and face
edge are indexed on the inside. Numbers aid the correct jointing
and assembly.
More
Joints |
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text and grafics ©
G.E. Malthouse ~ all rights reserved
reference
sources: Furniture Making - E Joyce, Purpose Made Joinery - P
Brett - Collins Woodworking Manual - Carpentry &
Joinery, Porter & Rose - Woodwork Joints, Charles H Hayward |
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