Basic descriptions of various types of routers commonly found in wood shops, including CNC router equipment. November 13, 2008

Reprinted with permission from MLS Machinery, Inc.

Routers/Water Jet/Laser Cutting/Engraving
Routers can be considered as standard machines. These routers are manually operated and have a single head. The parts are pushed through the router cutter manually. The Z axis (depth) is controlled by a foot pedal which allows the router head to go up and down. They all have a table and the depth of throat is measured from the neck of the machine to a pin which protrudes from under the table and is directly in line with the router bit above. This pin is used as a guiding point while routing. A jig is used which is an exact copy of the part that is going to be routed. This part is now put on top of the jig and the operator sets the jig over the pin; the operator pulls and pushes the jig around the pin that protrudes just above the table so that he does not visually see the pin but he can feel it as it is going around the shape of the jig. At the same time, because the router bit is located directly above the pin and has been lowered into the wood, the exact shape of the jig will be made on the part that he is working with.

These machines are used for many applications and are very popular. They are used a lot in the speaker industry to cut out the holes for the speakers; example, the tweeters, mid-range and woofers which are the normal three holes you have in a speaker. They are also used to make the grill covers that go on the front of the speaker. Routers can go into small, as well as larger shops; many large shops might have a number of these machines because it is still cheaper than a C.N.C. (Computer Numerically Controlled) machine, but might not be as productive.

As discussed under C.N.C. Routers and in this category, all machines route from the top while the part lies on the table. The only exception to this rule is the inverted pin router that works from the bottom and the following pin is from the top. Onsrud - Inverted Pin Routers are patent protected for this,

Routers C.N.C./Single/Two Head
C.N.C. (Computer Numerically Controlled) routers are similar to routers but with many additional options. All routers have a table of some sort, which in a C.N.C. type will normally have a vacuum hold down to hold the piece in place so that the panel or whatever is being routed does not move. The router heads come from the top. In some cases these machines might have two tables so while one table is being worked on the other can be re-loaded. C.N.C. routers can come in many sizes and configurations from 1 12 heads or larger. A 12 head machine has 12 separate routing heads that can all work at the same time. Each head can be programmed to do a different operation or they can be programmed to do the same; therefore making 12 different parts or 12 identical parts at the same time.

The standard C.N.C. router is normally between one and four heads. The routers are programmed to do certain functions, very much as seen under the point-to-point boring machines which had C.N.C. routers attached to them. Point-to-point routers are normally much lower in horse power; a traditional point-to-point C.N.C. router might only be between five and ten horse power; while in C.N.C. routers the horse powers are normally 10-18.

The reason why a person should choose a C.N.C. router as opposed to a point-to-point, even though the point-to-point will do a lot more operations, is that if the predominant function is routing you would use a C.N.C. router; if the predominant function is drilling with some routing, then use a point-to-point boring machine. Most C.N.C. routers today have what are called ATCs (Automatic Tool Changers), also discussed under point-to-points. This allows the router to be pre-programmed so that it can automatically go to a holding bay (a docking station) where it can pick up a different tool to do a totally different function; example, such as shaping the edge of a panel with a 90 degree or 180 degree edge as discussed under post forming, or in some cases it might be some fancy work on the surface of a door panel or a component might need some drilling work done. The ATC will automatically pick up the required tool to do the operation. Some C.N.C. routers also have piggy back drills attached, that is, a maximum of two drills can be attached per router head.

C.N.C. routers normally have three axis, X, Y, and Z. Z being the depth of cut, that is how deep you want the cut to be in the surface of the piece; X and Y being the length and the width. There are C.N.C. routers that have five axis for special purposes, we discussed this briefly under presses for making curved chair parts. In this case three axis are not enough. The router has to be able to also rotate around itself in a forward/backward motion and in a round motion as well so that it can get to all the sides and edges of a non-flat panel. In most cases discussed so far under point-to-point or three axis C.N.C. routers the applications were flat panel, that is, the part sits flat on the table. Under five axis machines the part no longer lies flat on the table, it could be curved and the height of the part could be 18" off the table. This is also often used when designing automobiles and the first miniature sample is made in wood to get the appearance, in this case three axis are not enough to get the detail that is required so a five or even seven axis machine would be used.

Traditionally, however, three axis would be the norm. Note, these machines are also normally very expensive. It should also be noted that because of the popularity of the C.N.C. router, smaller less fancy light duty machines have now become popular and are produced by many manufacturers using a standard P.C. computer. These machines start at about $19,000 US, but are for small production runs or smaller shops with nested based routers which is a relatively new concept, a complete say 4 x 8 panel can be routed to produce multiple parts. By visiting nesting software, wastage is dramatically reduced and efficiency and speed can be increased

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