A taper shank drill uses friction to remain stationary in the spindle of a drill press, although there are a few different taper shank drills; they all work on exactly the same principal. The two common tapers are Jacobs and Morse. The end of the drill is machined with a tapered profile; the inside of the spindle has an identical taper except it is mirror image. When the drill is pushed into the work piece the pressure seats the two tapers and they remain immobile due to friction. The friction seating is usually reserved for smaller, light duty applications. When the duty becomes severe the friction is often not enough to stop the bit from rotating in the spindle so there is a keying system machined to the top of the bit which engages with a driver in the spindle. Taper shank drills are used in a professional machine shop as mounting and dismounting the various size drills is quick and effective.
There is a lot of force used when drilling and if the bit is not properly engaged in the spindle it is not difficult to damage the machine and the work piece. In the case of a straight shank drill it is locked into a chuck which has three or four moving jaws. A taper shank drill does not use jaws to hold the bit, it uses friction. The amount of friction which is created between the bit and the spindle is surprising great, but, at time there is a need to rely not only on friction, but on a locking tab. The bit is driven easily into the spindle, engaging the tab with a corresponding slot. When the operator wishes to remove the bit, a taped wedge is inserted in the side of the spindle, given a sharp tap, dislodging the bit.
The Morse taper is a standard which is used by most machinists. Although the normal method of use is to engage the taper shank drill directly into the spindle, the Morse system also has several accessories, including a conventional chuck. The check fits the paper but then smaller drills which are not available in a taper design can easily be used in the same drill press.
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