Let’s take a closer look at how one of the most important machines used in woodworking is made and how it works: the combined edge and thickness planer.
The planer and thicknesser combines the functions of two different machines in a single tool: the planer and the thicknesser; precisely for this reason it is more commonly known as “combined plane”, or more simply “combined”.
The models available on the market are obviously different, especially those intended for intensive professional use. The latter, apart from planing and thicknessing, also combine additional functions such as that of mortising machine, circular saw and vertical milling machine, or spindle moulder ; however, these are machines characterized by very high prices, ranging from 1,000 to 4,000 euros and more, depending on the model chosen, the manufacturer and the characteristics possessed.
Generally, however, the best-selling surface and thickness planer is the one intended for the hobby user range; in this particular market segment, in fact, a wide range of models is available whose cost ranges from 250 to 1,000 euros. Furthermore, the number of buyers is greater because in this range are concentrated both simple DIY enthusiasts and hobbyists as well as small craftsmen and professionals who have low volumes of work, and who consequently do not have the need to buy. particularly expensive multifunctional equipment, intended for intensive and prolonged use.
Despite the wide variety of models on the market, and regardless of the different types produced, their characteristics are standard both as regards the structure of the machines and their operating principle; so let’s take a closer look at how a typical surface and thickness planer is made and how it works.
How the plane and thicknesser is made
The dimensions of the machine may vary according to its type, and in fact, countertop models can also be found on the market. It is obvious that the more compact the plane, however, the smaller the dimensions of the pieces that can be machined, but its structure remains roughly unchanged.
This is divided into an upper part, where the planing is performed flush, and a lower part where the thicknessing takes place. At the center of the structure, and in common with the two parts, is the knife-holder shaft, that is a metal cylinder connected to an electric motor; on the shaft are placed in turn the blades that will remove the wood during planing, called knives. The latter are held in place by a metal wedge, the technical definition of which is gib .
The accurate description of the shaft and of the locking system used for the blades is important as it could change according to the type of machine; what we have described is the most widespread system, obviously, but there are also others of more recent conception. This premise is important because the knives must periodically be removed from the rotating shaft in order to be subjected to maintenance, so it is good to know in principle how this part of the machine is structured.
In the upper part, therefore, there is a long work surface divided into two distinct sections, interrupted in the center by the window from which the knives protrude; the sections are defined as “entry” and “exit” in reference to the direction in which the workpiece is moved on the plane. Both sections are height adjustable; but while the outlet section is kept flush with the maximum protrusion of the knives, the inlet section is adjusted to be two or three millimeters lower.
The upper part is completed by the ruler, that is the lateral stop which acts as a guide during the sliding of the piece; the line can be adjusted both in width and in inclination, according to the needs of the case.
In the lower part of the machine, on the other hand, there is an additional reduced-sized work surface, called a shelf , also adjustable in height; furthermore, still in the lower part, but on the two sides of the knife-holder shaft, there are two drive rollers connected to the electric motor. To complete the structure, then, there are the adjustable protections designed to shield the window from which the knives protrude, in order to prevent the operator from running the risk of injury during work.
How the two parts work
Now that we have described roughly what a planer and thicknesser looks like, understanding how it works and how to use it correctly becomes much easier. The first thing to do is to adjust the height of the worktops according to the type of planing to be performed; then, once this step has been carried out, make sure to position the protective screen adequately to “close” access to the portion of the knives that is not covered by the piece of wood to be processed.
At this point you have to place the piece on the work surface on the side you want to plan, whether it is the face or the edge, and strictly following the direction of entry and exit, which changes depending on whether you are planing to thickness or flush.
During the surface planing the operator has to pay much more attention; the piece, in fact, must be pushed with the hands and made to slide on the work surface, accompanying it until it completely crosses the window from which the knives protrude.
What’s more, when the first portion of the piece arrives on the exit section, in addition to pushing it, it is also necessary to exert a certain pressure on it, in order to use the exit plane as a reference in order to ensure a perfectly smooth finish. In this case, therefore, the risk of ending up with your hands on the knife window, if you do not pay due attention, is much higher.
On the other hand, thickness planing is much safer, because it takes place in the lower part of the machine and keeping the window from which the knives protrude completely shielded.
In this case it is sufficient to adjust the height of the shelf and place the piece to be worked on it, from the inlet side, and then push it towards the drive roller which will automatically hook it and push it, first towards the knives and then towards the second roller. dragging, without the need for further interventions by the operator.