Making a tusk tenon for knockdown furniture.pdf

M AKING A T USK T ENON

FOR K NOCKDOWN F URNITURE

B Y T HOMAS R ETTIE

In the Middle Ages, like today, peo-

ple sometimes needed portable

furniture. While we tend to think

of medieval furniture as usually

large, massive, and immobile, there

were many instances when furni-

ture needed to be broken down

and moved from place to place. In

the home, space was at a premium

and bulky items such as tables were

put up when not in use. In the

workshop, a table might be moved

to where the light was best, or tak-

en to market for use as a counter.

Even in death, prized furniture

might be sent with the deceased to

the afterlife, as with the Viking

burial ship uncovered at Oseberg.

A 16th Century German work table with tusk tenon joints

(after examples in Jost Amman’s “Book of Trades”).

The problem in making portable

furniture is in devising joints that

are strong when put together, but

that are easily taken apart and re-

assembled. Today we have a

profusion of temporary metal and

plastic fasteners, but in a time

when nuts and bolts had to be

forged and cut by hand, economi-

cal solutions were more limited.

technique called drawboring. In

drawboring, the holes for the peg

are slightly offset so that the peg

will pull the joint tighter when it

is driven in. As the wood expands

and contracts over time, the peg

can be driven further to keep the

joint tight. The peg can also be

driven out, allowing the joint to be

disassembled if necessary.

The use of tusk tenons dates back

to at least the Vikings, whose mo-

bile society made knockdown

furniture a practical necessity.

While not widely adopted in En-

glish joinery, keyed tenons are seen

frequently on German furniture,

particularly on boarded benches,

work tables, and counters. They

are also evident in heavier framed

construction, such as printing

presses, looms, and post-and-beam

buildings. Tusk tenons even made

a brief comeback in the Arts and

Crafts movement of the late 19th

and early 20th centuries.

have no problem in making a tusk

tenon joint.

As in all woodworking, there are

many choices in the tools you can

use to make a tusk tenon. If you are

using hand tools, you will need, at

a minimum: a saw and a well-

honed mortising chisel. A

marking/mortising gauge is also

helpful in laying out the cuts, and

a brace and bit can speed things up

when removing wood from the

mortises.

One solution is the tusk tenon.

Also called a keyed tenon or

wedged tenon, the tusk tenon is a

kind of mortise and tenon joint

that uses a wedge-shaped key to

hold the joint together.

With a tusk tenon, a key is used

instead of a peg to hold the joint

together. Not only is the key easier

to remove and replace, it also pro-

vides added strength and stability

to the joint. Because the key is out-

side the joint, tusk tenons can only

be used with through-tenons (that

is, joints where the tenon goes all

the way through and out the other

side of the mortise).

If you have access to power tools, a

drill press or mortising machine

can speed things along, but you

will still need a chisel to cut the

sloping side of the mortise for the

key.

AND

M ATERIALS

, T OOLS

OOLS ,

,, AND

AND

In a common mortise and tenon

joint, a protrusion on one part (the

tenon) fits into a hole on the other

part (the mortise). Usually the joint

is then locked with a peg using a

ATERIALS

Tusk tenons require no particular

skills beyond the ability to cut a

mortise and tenon. If you have not

attempted one before, you will

want to try a few for practice be-

fore forging ahead with tables,

benches, and the like. Most basic

woodworking books will provide

instruction on mortise and tenon

joinery; in short though, you will

need to be able to cut a straight line

and make a square hole. When you

are confident with mortise and

tenon joints in general, you should

Mortising chisel and

mortising gauge.

Pegged mortise and tenon joint.

Tusk tenon joint.

, ,

S KILLS

, T

KILLS

KILLS , T

OOLS

For a strong joint (and less cursing

when you cut the mortises), you

will want wood with clear, straight

grain and no obvious cracks or

knots. In general, hardwoods such

as oak and poplar are excellent, but

I’ve also had good results with soft-

woods such as pine, fir, and

hemlock if they have a clear grain.

I normally begin by making the

tenon (others may start with the

mortise). The distance from the

shoulder to the end should be long

enough to pass through the mor-

tise with at least 4 or 5 inches to

spare on the outside. You can al-

ways cut it down later if you find

it too long; it’s much harder to add

wood back if it’s too short.

AKING THE

THE T

TT ENON

ENON K

KK EY

EEY

EEY -M

--M ORTISING

ORTISING THE

TT ENON

ENON

I find it convenient to next make

the tenon key. The key should be

no more than one-third the thick-

ness of the tenon it will pass

through. Ideally it should be just

slightly thinner than the thickness

of your mortising chisel. If the key

is too thick, it may split the cheeks

of the tenon.

The mortise that will hold the key

must have approximately the same

wedge-shaped profile as the key.

Hold the key against the side of the

tenon and trace its profile, then

carry the lines across to mark the

outline of the key-mortise on top

and bottom.

AKING A M

MM ORTISE

ORTISE AND

AKING

ORTISE

AND

When making a through-mortise,

it is a good idea to cut in from ei-

ther side to avoid tearing or

splintering. A useful rule of thumb

is never to cut a mortise that is

more than one-third the width of

the stock you are working with.

T ENON

JJ OINT

OINT

The key-mortise should be placed

slightly closer to the shoulder of

the tenon than the depth of the

mortise, so that the key will pull

the shoulder towards it when it is

driven in.

The key is wedge shaped; straight

on the inside edge and tapering on

the outside, with the grain running

the length of the key. The top of the

key can be flat or rounded (round

will be less prone to splitting). In

general, the longer the key, the

more stable the joint will be.

Begin by making the mortise and

tenon joint. The particulars of this

joint will of course depend on the

piece of furniture you are making;

the examples shown below are for

the trestle table shown on page 17.

Depth of

Mortise

Shoulder

Key-Mortise

Shoulder

Grain

Mortise

Tenon

Tenon Key

Tenon with Key-Mortise

M AKING

T T

K K

- -M

T T

K EY

THE T

AKING

THE

ENON

EEY

ORTISING

THE

M AKING

M M

ENON J

ENON

Assembled Joint

Tusk Tenon Used with a Bed Rail

V ARIATIONS

There are variations of the tusk

tenon that can be used when the

tenon is too thin to accommodate

a vertical key. Instead, pegs or hor-

izontal wedges can be used,

although this is usually a less se-

cure configuration.

If using horizontal wedges, use two

key-mortises per joint to prevent

“racking” (that is, where the joint

is no longer perpendicular). Either

taper the key mortises to match

the wedges, or use two wedges

(one from either side) per mortise.

Joint with One Wedge per

Key-mortise

Joint with Two Wedges per

Key-mortise

ARIATIONS

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika: