Craftsman 315.175070 Owner's Manual

TOO SLOWFEEDINGIt is alsopossibletospoila cutby movingthe routerforward too slowly. When it is advanced into the worktoo slowly, a revolving bit does not dig into new woodfast enough to take a bite; instead, it simply scrapesaway sawdust-like particles. Scraping produces heat,which can glaze, burn, or mar the cut -- in extremecases, can even overheat the bit so as to destroy itshardness.In addition, it is more difficult to control a router whenthe bit is scraping instead of cutting. With practicallyno load on the motor the bit will be revolving at closeto top RPM, and will have a much greater than normaltendency to bounce off the sides of the cut (especiallyif the wood has a pronounced grain with hard and softareas). As a result, the cut produced may haverippled, instead of straight sides. See Figure 14.=Too-slow feeding" can also cause your router to takeoff in a wrong direction from the intended line of cut.Always grasp and hold your router firmly withboth hands when routing.You can detect =too-slow feeding" by the runawaytoo-highly pitched sound of the motor; or by feelingthe "wiggle" of the bit in the cut.DEPTH OF CUTAs previously mentioned, the depth of cut is importantbecause it affects the rate of feed which, in turn,affects the quality of a cut (and, also, the possibility ofdamage to your router motor and bit). A deep cutrequires a slower feed than a shallow one, and a toodeep cut will cause you to slow the feed so much thatthe bit is no longer cutting, it is scraping, instead.Making a deep cut is never advisable. The smallerbits -- especially those only 1/16 inch in diameter --are easily broken off when subjected to too much sidethrust. A large enough bit may not be broken off, but ifthe cut is too deep a rough cut will result -- and it maybe very difficult to guide and control the bit as desired.For these reasons, we recommend that you do notexceed 1/8 inch depth of cut in a single pass,regardless of the bit size or the softness or conditionof the workpiece. See Figure 15.DEPTHOF CUTWIDTHOFCUTFig. 15To make deeper cuts it is therefore necessary tomake as many successive passes as required,lowering the bit 118 inch for each new pass. In order tosave time, do all the cutting necessary at one depthsetting, before lowering the bit for the next pass. Thiswill also assure a uniform depth when the final pass iscompleted. See Figure 16.2ND PASSIISTPASS2ND PASS1STPASSFig. 16DIRECTION OF FEED AND THRUSTSee Figure 17.ROUTERFEEDDIRECTION4ROUTlENDIGRAINSJFIRSTI= ROTATIONROUTERFEEDDIRECTION Fig. 17The router motor and bit revolve in a clockwise direction.This gives the tool a slight tendency to twist (in yourhands) in a counterclockwise direction, especially whenthe motor revs up (as at starting).Because of the extremely high speed of bit rotationduring a "proper feeding" operation, there is very littlekickback to contend with under normal conditions. How-ever, should the bit strike a knot, hard grain, foreignobject, etc. that would affect the normal progress of thecutting action, there will be a slight kickback-- sufficientto spoil the trueness of your cut if you are not prepared.Such a kickback is always in the direction opposite to thedirection of bit rotation.To guard against such a kickback, plan your set-up anddirection of feed so that you will always be thrusting thetool -- to hold it against whatever you are using to guidethe cut -- in the same direction that the leading edge ofthe bit is moving. In short, the thrust should be in adirection that keeps the sharp edges of the bit continu-ously biting straight into new (uncut) wood.16