Wood planing machine: principle of operation, shaft, guides, knives. Installing and adjusting the jointer knives The gap between the knives and the table top on the jointer

An electric jointer is one of the main tools for processing wooden parts. Without it you can’t make furniture from solid wood, wooden doors and other products. This tool is also used for some carpentry work and interior decoration.

The working surface of the jointer consists of two separate tables, a rear fixed part and a height-adjustable front platform. Two or three knives are installed in the jointer drum.
No matter how carefully you work, the jointer knives have to be sharpened from time to time. Otherwise, the knives will tear out pieces of wood and the load on the engine will noticeably increase.

1. There are disposable knives made with two cutting edges. In principle, it is not recommended to sharpen them; if necessary, simply replace them.
Reusable knives are sharpened on a special machine, with a precisely set sharpening angle. In any case, you must first remove dull knives. Close to the topic.

2. We carry out the replacement with the machine switched off and completely stopped. It is better to work with thick gloves, with the shaft secured with wooden wedges.
We move the guard away from the knives, remove the guide so that it does not interfere, and install wedges to fix it in place. We drive the wedges in and lightly tap them with a wooden block, mallet or nylon hammer. Metal hammers are completely inappropriate here.

3. Unscrew the clamping screws on disposable knives. On reusable ones, loosen the clamping bolts so that you can remove the knife. Together with the knife, we also remove the clamping bar. Please ensure that all screws are present and do not fall inside the machine.
If you immediately install a spare set, then leave the clamping bar in place and place the new knife on top. More information.

4. Clean the nests with a wire brush. If necessary, clean the pressure bar from dust and resin. After sharpening, wipe the knife with a rag so that no metal dust or shavings remain.

5. Again we fix the shaft with wooden wedges, put the pressure bar in place and insert a knife into the gap. We slightly tighten the clamping bolts so that the knife does not dangle, but do not tighten it completely.

6. The cutting edge of the knife must be aligned exactly with the level of the fixed rear table. To control, take a planed block of hard wood, place it on the surface of a stationary table and move it towards the knife.
The block should lightly catch the knife and turn the drum a little.
In this case, there should not be a gap between the block and the table surface.

If necessary, loosen the bolts again and slightly raise or lower the knife.
It is necessary to check the correct installation on both sides of the cutting head to prevent distortions.

After installation, we finally fix the knife with clamping bolts, remove the wedges and check by rotating the head manually. It happens that new knives are wider than old ones and can cling to the edge of the work table.
In the same order, we install the remaining knives one by one.

All that remains is to put the guide ruler in place, set the angle to 90* and you can work.
If the drum hits the workpiece when planing, you may have set the knives too high, or the sharpening angle is not suitable.
With good sharpening and correct installation, it happens that after planing the part seems to stick to the table, but this does not last long.

Illustrations woodmagazine.com

Settings planing knives not difficult. Using a simple hour indicator, a homemade support for it and six simple techniques, you can achieve the ideal in half an hour.

The importance of setting planer knives is often underestimated and often neglected. But it doesn't have to be that way. There are many methods and devices (some very confusing, others too expensive) for setting planer knives.

Most carpenters do not want to spend a lot of time and money on maintaining their machine park. If your planer's blade shaft has adjustment screws, you can quickly make adjustments using an inexpensive dial indicator and homemade support for him. Start by making the support and then follow the steps below.

Step 1.

After unplugging the machine and removing the planing knives, clean the knives, fixing bars and grooves of the knife shaft from dust and dirt. Coat the parts with a thin layer of machine oil to make adjustments easier and prevent parts from sticking to each other.

If knives require sharpening, contact a professional sharpener. Note. When starting the engine, all excess oil will quickly fly away from the surface of the parts and will not stain the workpiece.

Step 2.

Place the knives in the cutter shaft slots so that they are lower than the back table. Turn the screws of the locking bars to lock the knives in place. Do not overtighten the screws.

Step 3.

Place the support with the hour indicator attached on the surface of the back table and rotate the outer ring of the indicator to set it to the zero mark.

Step 4.

Place the tip of the indicator on the middle of the cutting edge of the knife. The indicator should show less than 0. Note. The flat tip of the indicator makes it easier to align to the center of the edge, but an indicator with a semicircular tip can also be used.

Step 5.

Using a hex socket wrench and blade shaft adjustment screws, raise the blade until the indicator reads 0 along the entire length of the blade. Tighten the screws at both ends of the knife to achieve the desired height.

Step 6.

Alternately, as shown in the photo, tighten the locking bar screws until the blade does not move up and does not require re-adjustment. Check the knife height again and repeat steps 5 and 6 with the remaining knives. Check all screws and protective devices before starting the machine.

Based on materials from the magazine "Wood-Master"

When processing wooden parts, you cannot do without an electric jointer. Before starting work, you need to set up the machine; this applies to tools of any size and power. Both operational safety and the accuracy of parts manufacturing depend on correct settings.

And precision, in turn, reduces the time spent and improves the quality of products. Each jointer has two tables, one rigidly fixed behind the knives and a height-adjustable table in front of the knives.

Two or three removable knives are attached to the working drum, which also need to be positioned correctly. But it’s better to start by adjusting the table.

1. We set the tables on the same level and use a good building level to check the surfaces of the tables. They must be exactly at the same level; there should be no gaps or sagging under the ruler. If the edges of the tables sag, the part will turn out concave when planing.
If there is a gap in the middle under the level, then the edges of the parts will turn out to be curved outward.
Both are bad, the workpieces are bent and the plots are extremely difficult to trim accurately when gluing.

For a more accurate check, in addition to a ruler, you need to use two straight squares.
The squares are placed on both tables and connected to each other. At the junction you will see gaps that need to be straightened.

All jointers have adjustment bolts. They may differ in appearance and shape, but the principle of operation is the same. By screwing or unscrewing, we adjust the level of the surface of the fixed table. Then we fix the bolts with locknuts or additional clamps.

2. In addition to the general level of the tables, you must immediately pay attention to the angle between the tables and the guide ruler. Check this angle at all points along the entire length of the guide. On old jointers, sagging of the metal tabletop itself, or even bending of the guide ruler, may appear.

But with careful fitting and adjustment, an acceptable level can be achieved.
In any case, it is imperative to properly adjust the angle between the table and the guide; it must be exactly 90*. As a rule, the clamp for setting the angle is made with a handle, so you need to loosen the clamp, align the ruler with the square and tighten the clamp again.

3. When installed, the knives are aligned on the fixed tabletop. All knives must be set at the same level, otherwise only one, the most protruding one, will work. But one knife does not produce such a high-quality surface; it will tear the wood.
In addition, the load on the cutting parts increases sharply and, as a result, additional vibrations occur. Close to topic.

It is better to check the installation of knives using a planed block of hard wood. We place the block on a stationary table and move it in the direction of the knives.
The block should slightly catch and rotate the knives, but there should be no gap between the block and the jointer's work table.
In general, tuning accuracy is not measured in millimeters or even tenths of a millimeter. We are talking about an accuracy of 0.02 - 0.03 mm. .

4. Of course, knives, like the working surfaces of tables, must be adjusted across the entire width of the jointer. There are different devices for this, but craftsmen more often check the level using one block applied at different points on the table.

The work will be easier if you assemble a block of two bars and immediately check the level of installation of the knives at both ends of the drum.
Another method for fine tuning is to use a piece of glass no wider than the length of the knives. It is better to prepare such glass in advance and be sure to sand the edges to avoid cutting yourself.

Pictures woodmagazine.com

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Household and industrial jointers are widely used for wood processing. Just like turning, circular and milling machines, jointers are mandatory equipment for carpentry shops. They are easy to use and reliable. Working with homemade jointers requires accuracy and some skills.

Scope of application and purpose

Industrial and home-made planing equipment is used for one-sided processing of flat surfaces of wood products. The main area of ​​application of the machines is furniture and woodworking production. Perpendicular surfaces are planed on them, chamfers are selected at the desired angle from the sidewalls. Precision processing is important when assembling furniture; jointing equipment allows you to obtain a part of a given size. Planing mechanisms are often used at home in domestic workshops.

A jointing machine does not allow you to plan thickness to size, or make parts with parallel surfaces!

Classification of jointing machines

Depending on the number of planing devices, planing machines can be double-sided or single-sided. All planing devices are divided into categories according to the width of the planing surface, the length of the work table and the rotation speed of the knife shaft.

According to the processed width of the workpiece, mechanisms are distinguished:

• by 40 cm;
• by 50 - 52 cm;
• at 60 - 63 cm.

Compact homemade units for the home have a smaller processing width.

According to the length of the working surface, two groups of devices are distinguished:

• with a length of less than 250 cm;
• with a length from 250 to 300 cm.

Larger workpieces can be processed on long tables. The quality of jointing also improves.

According to the frequency of torsion of the working shaft, machines are divided into two categories:

• 4700 - 4800 rpm;
• 5000 rpm.

Industrial motors can operate at speeds up to 12,000 rpm.

The device of a jointing machine

The design consists of the main elements:

• working surface;
• bed;
• guide;
• knife shaft;
• circular fence.

The working surface consists of two plates: back and front. The level of the back plate coincides with the level of the top point of the cutter blades. The front level is set lower to the extent that the material is removed during processing. Typically the level difference is no more than 1.5 millimeters. This is enough to qualitatively process the surface of the part in two steps.

The plates are made of cast iron, and to make the table more stable, stiffening ribs are provided. The edges of the slabs are covered with steel plates that protect them from destruction. They are also chip breakers.

The knife shaft is located between two plates; cutters are attached to the shaft. For high-quality processing, it is necessary to select the same cutters. As a rule, single-edged knives are used that can be sharpened. Double-edged cutters, when severely dull, are thrown away and replaced with new ones; they cannot be sharpened. As a rule, machines for household workshops are equipped with cutters made of tool high-speed steel. To work with dense types of wood or pressed boards, carbide-tipped cutters are used.

The guide is fixed with bolts in the provided holes. The ruler can move in the transverse direction depending on the size of the part.

A circular fence is installed on the front of the slab; it fits tightly to the guide due to the spring. The fence covers the knife shaft. The movement from the motor to the blade shaft is transmitted through a belt drive.

The optimal size of wooden parts for processing on a jointer is from 100 to 150 cm. Too long parts hang down and create inconvenience when working at home, while short ones are dangerous.

Setting and selecting mode

Before starting work, you need to calculate the thickness of the material being planed and the speed of movement of the workpiece (for equipment with an automatic feeder). The size of the layer depends on the initial state of the tree and is determined experimentally. To do this, several (no more than five) workpieces are processed. If untreated areas remain on the surface, the slab is lowered slightly. If the workpiece is warped by more than 2.5 mm, processing is carried out in two stages.

When the height of the slabs is set, measure the gap between the edge of the cutters and the jaws of the slabs, which should be from 2 to 3 millimeters. To determine the gap, a calibrated plate is used, which should be inserted into the gap easily, but without gaps. If the gap exceeds 3 mm, the part becomes covered with tears; if the gap is less than 2 mm, the cutter is destroyed.

In addition to setting the slabs in height, it is also necessary to determine the location of the guide. When processing wooden blocks, the gap between the ruler and the left edge of the knife shaft should be slightly larger than the width of the block. Gradually, the knives become dull and the guide moves to the right, involving other parts of the cutters in the work. The ruler moves across the tabletop on a rack and pinion device driven by a flywheel. To make a corner chamfer on an edge, the guide is installed using a template or square and secured with a screw.

Automatic feeders regulate the feeding of parts without stoppers, with low pressure. When processing edges, they are placed parallel to the ruler.

The correct settings of planing equipment are determined experimentally. Allowed errors are:

• on the plane no more than 0.15 millimeters per meter;
• perpendicularly - no more than 0.1 millimeter per 10 cm.

Working principle of a jointer

One person is enough to operate single-sided jointing equipment at home. He examines the condition of the workpiece and places it with its convex plane up on the front plate. With both hands he presses it against the ruler and points it at the cutters. Next, the already trimmed side is pressed with the left hand to the surface of the back plate. The master inspects the processed workpiece: if it is not planed enough, he sends it to the knives. It is advisable to avoid processing very warped workpieces, since too thick a layer of chips is removed. The remaining workpiece may turn out unacceptably thin.

When processing two perpendicular planes, the larger area is used first. Then it is applied to the guide and the second one is planed. The double-sided machine allows you to process both sides simultaneously.

• If “burns” or “mossiness” appear on the surface during processing, it’s time to sharpen the cutters;
• When working with parts shorter than 40 cm and narrower than 3 cm, they are held only with special pushers, and parts of complex shapes are held with templates;
• If the planed plane is curved or has the shape of an impeller, you should check the level of the tabletop plates and the blade shaft.

DIY jointing machine

homemade machine - side view

The frame of a small tabletop machine for home can be made from metal pipe rectangular section. More powerful homemade design will be obtained from a 40 mm corner. The width of the bed depends on the size of the knives and the planned planing width.

At one end, two guides are welded to the frame, the upper edges of which coincide with the surface of the frame. In the middle of the frame, a knife shaft mounted on a pair of ball bearings is attached to bolts screwed into pre-prepared holes.

The working surfaces for the desktop machine for the home are made of thick plywood laid on bars. And to regulate their level, homemade overhead bolted connections are provided. Four connections for each plate: a pair at the front and a pair at the back. A vertical block with a hole is attached to each part of the tabletop from below. A long threaded pin is threaded through the block and the upper horizontal of the bed, with the help of which the position of the table top relative to the knife shaft is changed.

There is another option for homemade fastening of the work surface: there are grooves made in the frame (4 pcs.), in the movable tabletop there is the same number of holes into which threaded pin heads are inserted. By tightening the nuts and moving the pins in the grooves, they change the distance between the blade shaft and the edge of the tabletop.

The back plate is installed motionless and adjusted in height to the knife shaft. A board or chipboard of a suitable size can serve as a guide ruler.

When choosing a motor, you should proceed from the nature of use of the future machine. For household needs A power of 750 W is sufficient, but a motor with a power of at least 1.5 kilowatts can cope with more serious tasks.

A few more options for homemade jointers:

Review of factory models

W0108


W0100

A jointing machine is available in almost all educational workshops of schools, most training and production plants and various industries. Setting it up and especially accurately installing the cutters on the shaft is a rather labor-intensive operation. Their correct installation should ensure:

1. strictly cylindrical surface of rotation of the cutting edges;
2. parallelism of the plane of the rear table of the machine and the generating surface of rotation of the knives;
3. displacement of the front table relative to the rear table by the thickness of the chips being removed.

To adjust the jointer, it is recommended to use a block of solid, well-dried wood, carefully jointed on all four sides. However, the accuracy of setting knives with its help, even for an experienced installer, does not exceed 0.08-0.15 mm (the difference in the sizes of the cutting circle radii).

In order to increase the accuracy of knife installation and reduce the time for setting up the machine, we suggest using the device shown in the figure.

Figure 1. A beam with an indicator for setting up a jointer

A dial indicator with a division value on a dial scale of 0.01 mm must be installed in a block 2 jointed along the bottom surface, 200 mm long and with a cross-section of 30X40 mm. To do this, at a distance of 50 mm from the end (on the side 30 mm wide), a hole is drilled along the diameter of the indicator sleeve (8 mm). In the middle of the same side from the end to the hole, a cut is divided with a hacksaw, and at a distance of 20 mm from the end, in the middle of a 40 mm wide edge, a hole 0 6 mm is drilled for a coupling bolt with nut 5, which serves to secure indicator 3 in the block.

When setting up the machine, the device is installed on table 1, 7 and the readings of the indicator arrows are recorded on a sheet of paper. Knife 10 is inserted into one of two grooves on the shaft body 9 so that the cutting edge protrudes 2-3 mm above the chip breaker 6, and is slightly secured with the middle bolt 8. Then the block 2 with indicator 4 is moved along the back table 1 until the tip 4 of the indicator will not fall on the cutting edge of the knife 10. The arrow readings at this moment should correspond to what was recorded earlier. If there are discrepancies, then you should slightly raise or lower the knife (or the back table). The adjustment continues until the indicator readings are the same both at the middle point of the knife and along its edges. After this, the knife is secured. Based on the same (recorded at the beginning) indicator arrow readings, the second knife is installed.

To adjust the front table, add the thickness of the chips being removed to the previously recorded indicator readings and set the table based on the resulting amount.

The use of the device in training workshops is not limited to the installation of planing knives when setting up a jointing machine. With its help, you can check the parallelism of the surfaces of the rear and front tables of the planing machine, install milling knives in cutter heads, check the correct set of saw teeth, etc.