Reprinted with permission from MLS Machinery, Inc.
Jointers are considered a standard machine found in most common woodworking shops from the one-man shop to the larger operation. In larger shops they are rarely used because other machines might have similar functions such as moulders or planers. A jointer basically makes a piece of solid wood the same thickness throughout. Initially when solid wood comes into a factory it is not 100% level, it might be thicker on one end than the other or might have variations in tolerance purely because of the natural growth of the tree.
Once a piece of wood is cut from a log and possibly not dried properly (all lumber is normally dried in kilns prior to being used) it will warp and cup. Therefore to start working on a solid piece of wood it has be jointed first so that it has a uniform thickness on all four sides before the part can go into the next operation, E.G. sanding.
A jointer has two tables and a fence with a rotating knife, one table will normally be set a little lower than the other. As the wood feeds over the knife it will cut the material down in the areas where it is too thick. The tolerances used are minimal so the levels of the two tables are set very close to each other, just enough to take out the thicker parts of wood that are not level, this allows less wastage of good material.
Planers, jointers, table saws, band saws, normally fall under the general machine categories and are considered as standard machines for most small shops.
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