Jointer

Safety

Culling Lumber

Culling is a process of assessing boards for straightness. When you buy raw lumber from a lumber mill, or processed lumber from a hardware store, it may be necessary to cull or assess each plank of lumber for straightness. By looking down the length of each board, you can find the straightest pieces. Of course, it is preferable to find perfect straight boards for your project because, the straighter they are, the better. However, most lumber on the market isn’t quite flat or straight.

We have 2 machines in the wood shop in the SOA to further process lumber and remove the high spots to make them flat and square: a Jointer and a Thickness Planer. They are most often used together in sequence to square-up, or “dress” lumber, for subsequent operations.

 A Jointer is used to flatten one face and one edge, and a Thickness Planer is used to derive a specific thickness with the faces of the boards being parallel to each other. A Table Saw can then be used to cut the last remaining edge parallel to the jointed edge.

Description of Jointer

A Jointer is a machine used to produce a flat surface along a board's length. The machine operates on the narrow edges of boards, preparing them for finished construction or edge- gluing into panels. A Jointer also has the width that enables smoothing ('surface planing') and leveling the faces (widths) of boards small enough to fit the tables on the machine.

The Jointer in the SOA Wood shop can accommodate surface and edge planing boards up to 12” wide.

The Jointer derives its name from its primary function of producing flat edges on boards prior to joining them edge-to-edge to produce wider boards. However, the Jointer is also ideal for flattening the broad faces of boards in preparation for the Thickness Planer and is often used in tandem with the Thickness Planer, to render planks of lumber into flat, uniform parts for further manufacturing.

Jointers will produce flat, straight surfaces and edges on planks of lumber, but have no reference surface parallel to the cutter head, and so, are often used in conjunction with Thickness Planers, to achieve finished boards for construction.

Design of the machine

Fundamentally, a Jointer's table arrangement is designed with two levels so that it consists of two long, narrow parallel tables in a row with a cutter head recessed between them. These are known as the “infeed and outfeed” tables. The outfeed table is set to be the same height as the cutter head. The infeed table is adjustable to be set below the height of the cutter head, typically between 1/32” and 1/8”, depending on how much material the operator needs to remove with each pass over the cutter head. The cutter head is driven by an electric motor. A moveable fence is normally set perpendicular to the tables, though some models may allow settings (adjustments) to various angles. Our Jointer allows fence angle adjustment from 0 degrees to 45 degrees.

To clarify: The work surface tables of the Jointer are referred to as the infeed table and outfeed table.

Infeed / Outfeed tables

The infeed table is the platform from which the work piece is fed into the machine and the height reference, or outfeed table is the platform on which the work piece is floated over lightly as it leaves the machine's cutting head. When facing the machine, the infeed table is on the right, and the outfeed table is on the left. The cutterhead is in between the two tables. The cutting blades are adjusted to match the height and pitch of (& made square to) the outfeed table. The work piece to be planed or “jointed” flat is placed on the infeed table and passed over the cutter head to the outfeed table, with care taken to maintain a constant feed speed and downward pressure.

Table Adjustment

The infeed and outfeed tables can be raised or lowered independently of each other and in relation to the cutter head by means of a crank wheel provided in front of each table. The outfeed table is normally set so that it is level with the knives when at the top dead center of the rotation of the cutter head. Therefore, the outfeed table should not be adjusted once it is set.

The infeed table is adjusted so that it is lower than the outfeed table and this gives the depth of cut. To move the infeed table up or down to set the depth of cut, turn the crank wheel in front of the table by first loosening the center locking knob counter clockwise, then turn the crank wheel clockwise for shallow cuts and counter clockwise for deeper cuts. Use the depth indicator to the right of the infeed table for reference. Re-tighten the locking knob. Do not set the infeed table lower than 1/8” below the cutterhead, because trying to remove more than 1/8” of material per pass, puts too much strain on the machine and presents a hazard.

Fence

The fence is a rigid metal plate mounted perpendicular to the in feed and out feed tables and is adjustable to cover or reveal as much of the cutter head as needed for a particular operation. When the fence is at its rear most position, the entire length of the cutter head can be exposed to accommodate boards up to 12 inches wide. The fence can be moved horizontally to cover a portion of the cutter head so that only the portion of the cutter head needed for an operation is revealed. The fence can be moved horizontally by first loosening the fence locking handle on the top of the fence bracket by turning it counterclockwise a couple of times. Then, the fence can be manually shifted over the cutter head. Always retighten the locking handle after moving the fence!

Our Jointer also allows fence angle adjustment from 0 degrees to 45 degrees, for making beveled cuts or “chamfers” along the edges of boards. To tilt the fence, it is necessary to unlock the side handle on the fence bracket by turning it counter clockwise a couple of times, then manually adjust the angle and re-tighten the side handle.

Cutter Head / Shroud

The cutter head on our machine is a spiral, or helical, cutting head. This configuration has 44 individually mounted, self-indexing knives that can be rotated to a new edge when necessary. The knives are arranged radially in the cylindrical cutter head such that their cutting edges protrude from the cylinder so that they will come into contact with the board being cut as the cutter head spins. The cutter head's axis of rotation is parallel to the table surfaces and perpendicular to the feed direction. The knives cut into the board in the direction opposite to the feed. The cutter head is extremely sharp, and is therefore covered by a spring-loaded Shroud, to prevent operator injury.

Shroud

The shroud is a large cast aluminum plate painted orange for visibility. It is mounted to a spring-loaded post and installed near the end of the cutter head with a locking knob. The shroud should be adjusted to within about 1/2 an inch of the fence, so that the shroud does not hit the fence when it swings shut after passing a board over the jointer. The shroud position can be adjusted by first loosening the locking knob at the front of the machine where the shroud post is inserted, by turning it counter clockwise. Then swing the shroud outward or inward toward the fence leaving a gap of about 1/2 of an inch. Lift the shroud plate upward slightly so that it does not drag across the top of the In feed and out feed tables, then retighten the locking knob.

Dust Collector

The dust collector must be operating when the Jointer is being used. The dust collector is located directly behind the jointer, between the Jointer machine and the wall. Its power switch is located on the left side of the motor housing, and consists of a large red button with a green center. To turn the dust collector on, pull outward on the large Red Ring. To turn it off, press the Red Ring inward.

Power Switch

The power switch for the Jointer is located on the front center of the machine. On the power panel, from left to right, there is an indicator light, a red “off” switch, and a green “on” switch to the right. The power indicator light simply glows green when there is power to the machine itself. The red emergency stop button or “off” switch is in the center, and the green “on” switch is to the right of it. To turn the machine on, the operator must first rotate the outer ring on the stop button and pull outward slightly until it “pops” out. Then push the green start “on” button and hold for three seconds to let the machine rev up.

Push sticks / Push Blocks

In order to provide a safe way to maneuver lumber over the cutter head on the Jointer, push sticks and push blocks are provided at the machine. Push blocks are orange plastic foam padded handles, kept on top of the machine, and push sticks are wooden handles with a kicker block on the end, located on the wall behind the Jointer. Both items are typically used to process lumber over the Jointers’ in feed and out feed tables. Typically, the left hand holds a push block with foam pad, on top of the board, and the right hand holds a push stick with the kicker block engaged at the trailing end of the board, to help push it along. The machine operator walks along with the board while guiding it with these hand-held devices.

Face jointing

A jointer may be used to flatten the face of a board, in which case the sole focus is to produce a flat surface on the face of the board and use of the fence at this point is recommended for safety and stability, but not critical for angular reference. This procedure is often performed prior to edge jointing so that the board has a flat reference face for subsequent operations. This is also a vital operation for preparing boards to be dimensioned using the Thickness Planer. (See Thickness Planer Document) The board is fed across the cutter head and onto the outfeed table. The knives in the revolving cutter head remove an amount of material and the relationship of the two tables and the fence keeps the board oriented in such a way that the result is a face which is flat and straight along its length and perpendicular to the board's edge.

Edge jointing

The fence needs to be moved so that only the minimal needed area is exposed on the cutting head. Adjustments of the shroud will need to be made in conjunction with the fence. In operation, the board to be edge jointed is held with its jointed face against the fence and the edge to be jointed resting on the infeed table. The board is fed across the cutter head and onto the outfeed table. The knives in the revolving cutter head remove an amount of material and the relationship of the two tables and the fence keeps the board oriented in such a way that the result is an edge which is flat and straight along its length and perpendicular to the board's face.

Operation

The basic procedure is as follows: mark each piece of lumber to be faced jointed with a pencil, making marks on the concave side or the cupped face of each board from edge to edge making pencil marks about 1 inch apart along the entire length of the board. Place the boards’ concave side down on the in feed table and use push blocks in each hand to maneuver the marked face of the board from right to left from the in feed table to the out feed table. Make subsequent passes while checking in between to see if all the pencil marks have been removed. It usually takes two or three passes to remove all of the pencil marks, which indicates that the board face is flat. Proceed to process all boards whose faces need to be flattened. Then turn the machine off.

Re-adjust the fence and the cutter head shroud to cover the cutter head enough so that only the amount of cutter head exposed for the edge of the boards is revealed. Proceed to run each board over the Jointer again on edge, with the jointed (flattened) face against the fence for reference. This will render the adjacent face and edge into a straight and crisp desired angle. Typically, it’s a 90° angle, but the fence can be tilted to different angles as described earlier. Once the boards have all been processed to this point, they are then brought to the Thickness Planer for further processing. Please see the Thickness Planer document.

Special cases

Straightening 'crown', (the curved face or edge of an extremely bowed board):

Straightening an extreme crown is a successive approximation sequence. Successive cuts are made from each end, made successively longer each time the board is turned end for end. After the crown is straightened, the work piece would next be taken to a table saw for a cut to make a new parallel edge—which then will likely be smoothed by another run through the jointer.

To straighten a piece of bowed timber, the guard is temporarily swung out of the way just far enough to allow the workpiece to pass through. (Lossen the shroud post by turning the locking knob at the base of the shroud counter clockwise a few turns.) The machine is switched on and the timber is slowly lowered to the machine table, with the concave side down. A few cuts are made on its lowest end. The timber is turned end for end and the same procedure is done to the other end. This is repeated as required with the operator sighting along the length of the timber from time to time to check on straightness of the timber. When the timber is almost straight, the guard is replaced and the last cut is made in the normal way.

Twisted material is treated in a similar way. The operator lays the timber on the bed of the machine and rocks it slowly from side to side to estimate the amount of twist. If there is, say, 1/8” of twist in the board, he holds the board level and takes 1/16” off one end, then repeats it for the other end.

Clean-up

Please be aware that there are 4 Trash barrels in this room, and that each one has a broom, bench brush and dust pan attached. You must use these items to clean up your work areas at each machine, when you are finished working there. Also, there are scrap barrels at each workstation to deposit scraps of material, which may be useful for someone else. Please do not put materials with stray hardware or glue on them, or food/drink items, only re-usable materials.