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The mortiser is nothing more than a horizontal drill, fixed, using specific bits. To dig the mortise, the workpiece, mounted on a height-adjustable carriage, is moved forwards and backwards and laterally in front of the wick.

Use a mortiser

Tenon and mortise, the classics of traditional carpentry

The mortise and tenon joint is undoubtedly the most popular in traditional carpentry. This is why the mortising machine is part of the usual equipment, although often optional, woodworking machines: combined and some blocks "de-plane". More and more competed by her independent cousin square chisel, it still retains many followers.

Structure and operation

On most combinations, the mortiser is on the side of the planer-jointer, which it uses to drive the chuck. A provision that is not without consequences: embarrassing during the corroyages, it is often necessary to disassemble and reassemble. However, it is heavy and the rotational speed of the jointer unsuitable. Still widespread, the old combined (composed of stand-alone machines on the table) do not suffer from these defects.
The mortiser is generally integral with the planing table, which it uses the height adjustment by steering wheel. Rigid, independent mounted devices are found only on heavy combinations. The table, or carriage, moves in the horizontal plane. Adjustable stops limit its travel, determining the depth and width of the mortise. Some mortising machines allow to adjust the alignment of the table and the axis of the mandrel.
The workpiece is clamped on the table by one or, better, two presses. During slotting, the carriage is moved back and forth and from right to left using two independent levers or a single ball joint that combines the two axes. The second system facilitates manipulation, but sometimes to the detriment of precision.

Highlights

Unlike their drill counterparts, mortise bits cut across their entire length. Most are currently equipped with chip breaking indentations. The helical cut versions allow better evacuation of debris and have a better performance. But, at equivalent quality, they are more fragile than straight. Depending on the direction of rotation of the machine, there are wicks on the right (the ordinary meaning) and on the left: do not fool yourself!
Wick packs often only offer even diameters. However, intermediaries are available individually. Sizes smaller than 6 mm are rare. The very large mortises are executed by a series of parallel cuts, starting with the cheeks.
On single-speed combinations, the mortiser rotates at around 6,000 rpm, like the planer. The wick must support the pace and be very sharp so as not to burn the wood. Prefer machines offering a second, slower speed. Never use ordinary wicks: they are unsuitable, therefore dangerous in this configuration.

Tracing and clamping

Tracing the outline of the mortises on the woods is not specific to the mortiser wick. However, do not neglect it during a series work on the pretext that the machine is equipped with stops. A clear and precise registration will facilitate the adjustments and will avoid many errors or reversals of symmetrical parts.
Preferably use a mortise truscan with two adjustable spacers. Otherwise, a simple snap is enough, making two passes instead of one. Always spectacular when executed by a man of the Art, the pencil tracing guided by the fingertips on the song of the piece is not precise enough.
The machining force is important, the element to be digged is securely clamped to the table, using the (or) presser (s), abutting against the flange. Plan a maid to relieve the cantilever of a long piece, or get help.

The settings

The depth stop is easy to adjust by raising the table and the room just below the wick. To then adjust the height, the cutting edges are positioned vertically and matched to the grooves of the mortise cheek. As it is often necessary to be wrong to see better, pay attention to parallax errors! The lateral deflection is finally adjusted by placing the cutting edges flat to align them with the ends of the line.
When working in series, the height and depth settings keep themselves, but not the length. Also, glue two pieces of adhesive on the edge of the table to delineate the first mortise. By aligning the lines of the following on these marks, you will find the setting.

machining

The key did not stay on the chuck? Start the machine and let it take its diet. Push the lever fully (to the right or left), bring the wood into contact with the wick and enter gradually,
to the stop. If the mortise is deep, come out regularly to "débourrer", especially with a straight wick. Repeat at the other end of the mortise, to delimit it.
Complete with a series of close holes, even secant (not always easy to achieve because if the wick ripe, the trolley follows). Finally, join these holes by lateral movements, in passes of deeper and deeper.
Some users of single-lever mortising machines prefer to machine at one time, in a sweeping motion from left to right and digging progressively. This method is recommended only with sufficiently rigid machines.

Useful details

At the end of the machining, the mortise has rounded ends. You can either round the tenon to the grater or square the mortise. The traditional tool is in this case the chisel, characterized by its very thick blade. As it is just retouching, here we can settle for an ordinary wood chisel.
It is better to machine the mortises before the tenons. In the event of a defect, it is always possible to modify the thickness of the second, while the width of the first is dependent on the diameter of the wick.

Anatomy of the machine

Anatomy of the machine

A table or cart
B Position positioning stop
C Mandrin
D Presseur
E Lever
F Adjustable side travel stops
G Depth adjustable stops
H Height adjustment flywheel

Locks of mortiser

Locks of mortiser

In straight or helical cut, the mortise drill bits cut while moving laterally, resulting in sharpening along their entire length. Chip breaker indentations facilitate clearing.

The mandrel

The mandrel

The mandrel, usually placed at the end of the jointer shaft, is similar to that of a drill. A metal sheet surrounds it on recent machines, thus avoiding the projection of the forgotten key in place.

Clean the table

Clean the table

Even a tiny chip can be enough to deflect the mortise. Clean the table before placing a new part. Do not blow, but use an old brush instead: your bronchi will appreciate.

Keep the room

Keep the room

A good maintenance of the part is essential, because the pushing force to the machining is important. If your slotting machine has only one presser, try placing it in the center.

Adjust the depth

Adjust the depth

To adjust the depth, the simplest is to bring the surface of the room just below the wick. One meter or one ruler will help the precise positioning of the stop at the desired depth.

Adjust in height

Adjust in height

On small machines, the height adjustment is done with the flywheel of the planer table. On the biggest, he is independent. Set up to limit the mechanical games.

Set the travel

Set the travel

If the tracing has been traced, the adjustment of the movement presents no difficulty. The cutting edges of the bit must be positioned horizontally (and vertically when adjusting the height).

Drill in abutment then join

Drill in abutment then join

Start machining by boring the two ends of the mortise. Then fill the gap with a series of parallel holes, then join in with a side scan. On single lever machines, it is possible to dig all the mortise in a rotational movement by gradually increasing the depth. The wick must be in perfect condition.

Squaring or rounding

Squaring or rounding

The ends of the mortise are rounded, while the sides of the tenon are straight. We have the choice between squaring the first (which corresponds more to the tradition) or round the second.

Avoid splinters

Avoid splinters

Through-hole mortises are common, for example, to fit an opening pin locked by a key. To avoid splinters coming out, brace a martyr behind the room with a clamp.

Tilt the room

Tilt the room

When the mortise is not parallel to the edge, a beveled wedge must be made to tilt the workpiece. The presser of the machine is not enough in general, we must add clamps.

Digging obliquely

Digging obliquely

If the mortise must widen obliquely to the song, do not place the piece haphazardly, off stops... Making a whistle positioning wedge will only take a few moments.


Video Instruction: How to Set Up and Use a Mortising Machine | Hollow Chisel Mortiser