Combination machine
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A combination machine is a woodworking machine that combines the functions of two or more separate machines into a single unit. For example, a combination machine might consist of a tablesaw with a side mounted jointer. Another common example of this type of machine is the jointer-thicknesser (also known as an over-under) which combines the function of a jointer with that of a thicknesser.
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[edit] Design
Some combination machines run all of their functions from a single motor; others may use more than one. Cutter heads are often shared: for example a jointer-thicknesser may use the same cutter head for both functions. The machines rely upon well thought-out designs which allow the user to switch from one function to another easily.
[edit] Advantages
One rationale for the production of these machines is space saving. A combination machine takes up much less space than the equivalent separate machines. This makes them popular with hobbyist woodworkers. There may also be a cost saving over purchasing separate machines, although some top end combination machines can be quite expensive.
[edit] Disadvantages
There are a number of disadvantages of combination machines. Set up time is increased when moving from one function to another and back. In many cases, machine settings are lost during the change over and have to be re-established when changing back. In some lower end machines, there may be compromises in design which limit the function or robustness of the machine. Finally, they represent a single point of failure in that a mechanical problem with the machine will generally mean that none of the machine's functions are available.
These disadvantages are offset by the small size of the machine footprint and potential cost saving and so they are very popular with hobbyists and workshops in which space is limited.
[edit] The Shopsmith
The Shopsmith is a lathe-based multi-tool that uses a single motor to perform lathe, tablesaw, and drill press functions. Variations include horizontal boring and disc sander.
Originally invented by Dr. Hans Goldschmidt of Atherton CA. in 1947 and made by the Magna Corporation in the late 1940's, 1950's and 60's, the ShopSmith Mark V was resurrected in the ShopSmith Corporation in 1972 by John Folkerth, current Chairman of the company.
ShopSmith also manufactures and markets a variety of add-on tools that can be run by the base unit motor. Some of these tools include a band saw, shaper, jointer and planer.
One of the unique features of the ShopSmith MARK V is its method of speed control. Rather than multiple pairs of pulleys or an electronic speed control, the Mk V uses a Reeves-type continuously variable transmission consisting of two variable diameter pulleys controlled by a dial and worm gear. Not only does this give theoretically infinite speed variation between the maximum and minimum speeds, it is also simple enough to be serviced fairly easily by a hobbyist.
The Shopsmith is well-known among lawyers in the United States. An injury suffered by the user of a Shopsmith gave the Supreme Court of California the opportunity to create the modern rule of strict liability for defective products in 1963.[1]
[edit] European Combination Machine
Several companies in Austria, Italy, France and Belgium manufacture what is commonly known as a European combination machine, which typically contains a sliding-table saw with a scoring blade, a shaper, a thicknesser, a jointer, and a mortiser. These machines generally have 3 motors, one for the table saw, one for the shaper, and one shared by the thickness planer/jointer and mortiser.
European combination machines are geared for the serious hobbyist or professional woodworker or cabinet maker. They are constructed of cast iron and heavy gauge steel, weigh from 1000 to 2000 lbs., and range in price from around $5,000 to over $30,000 U.S. dollars.
Manufacturers include Knapp, Felder, Robland, Mini-Max, Hammer, Kity, Rojek and others. Hammer, Rojek and Robland manufacture entry level models, MiniMax mid-range models, Felder and Knapp high-end models. Hammer is a brand of Felder. Robland purchased Knapp from the Metabo group in 2000.
The European combination machine allows efficient processing of both rough-cut timber and sheet stock (i.e. plywood). The sliding table can work in conjunction with either the table saw or the shaper. Outfitted with an 8-foot sliding table and outrigger, a single person can cut 4'x8' plywood very accurately and efficiently. Changing between most functions takes only a few seconds.
The sliding table allows a straight edge to be cut on rough lumber, without the use of a fence. It also allows a cut to be made accurately at any angle across a sheet of plywood in just seconds - something that cannot be done nearly as easily, if at all, on a table saw. Used in conjunction with the shaper, the sliding table allows molding, door panels, rails and stiles, to be milled quickly and more accurately than a stand-alone shaper.
[edit] References
- ^ See Greenman v. Yuba Power Products, 59 Cal. 2d 57 (1963).
