Rate of Feed, Feeding Too Slow See Figure

RATE OF FEED

The proper rate of feed depends on several factors: the hardness and moisture content of the wood, the depth of cut, and the cutting diameter of the bit. When cutting shallow grooves in soft woods such as pine, you may use a faster rate of feed. When making deep cuts in hardwoods such as oak, you should use a slower rate of feed.

The best rate of feed is one that does not slow down the router motor more than one-third of its no load speed. If you feed the router too fast, it will take large chips out of the wood and leave gouge marks. If you feed the router too slowly, it will scorch or burn the wood.

Feeding Too Fast

See Figure 20.

Clean, smooth routing and edge shaping can be done only when the bit is revolving at a relatively high speed and is taking very small bites to produce tiny, cleanly severed chips. If you force the router to move forward too fast, the RPM of the bit becomes slower than normal in relation to its forward movement. As a result, the bit must take bigger bites as it revolves. Bigger bites mean bigger chips and a rougher finish. Also, because bigger

bites require more power, the router motor may become ovedoaded.

Under extreme force-feeding conditions, the relative RPM of the bit can become so slew--and the bites it

has to take so large--that chips will be partially knocked off (rather than fully cut off). This causes splintering and gouging of the workpiece.

The router is an extremely high-speed tool, and will make clean, smooth cuts if allowed to run freely without the overload of a forced feed. You can always detect force feeding by the sound of the motor. Its high-pitched whine will sound lower and stronger as it loses speed.

Also, the strain of holding the tool will be noticeably increased.

TOO FAST

Fig. 20

Feeding Too Slow

See Figure 21.

It is also possible to spoil a cut by moving the router forward too slowly. When you advance the router into the work too slowly, the revolving bit does not dig into new wood fast enough to take a bite; instead, it merely scrapes away sawdust-like particles. Scraping produces heat, which can glaze, burn, or mar the cut and in

extreme cases, can even overheat the bit ,destroying its hardness.

In addition, when the bit is scraping instead of cutting, it is more difficult to control the router. With practically no load on the motor, the bit revolves at close to top RPM, and has a much greater than normal tendency to bounce off the sides of the cut (especially if the wood has a pronounced grain with hard and soft areas). As a result, the cut produced may have rippled, instead of straight, sides.

Feeding too slow can also cause the router to take off in a wrong direction from the intended line of cut. Always grasp and hold the router firmly with both hands when routing.

You can detect when you are feeding the router too slowly by the runaway, high-pitched sound of the motor or by feeling the wiggle of the bit in the cut.

TOO SLOW

Fig. 21