A live center is held in the tailstock of a lathe and supports the unchucked end of the work while allowing it to rotate easily on a bearing, as opposed to a standard “dead” center that does not rotate. If the point of the center is not in perfect alignment with the shaft, or if the center mark on the part is not dead-on, the part will “run out” (wobble), making precise machining impossible.
An adjustable live center allows you to precisely position the center point. The center is attached to one plate, while the shaft is part of another. Two slightly oversize holes in one side allow adjustment screws to be loosened, the center located and then locked down where you want it. In this manner, highly accurate centering can be achieved. If the ultimate in accuracy is your goal, the adjustable live center will help you achieve it.
The Purpose and Use of the Adjustable Tool Holders
The accuracy that is attainable by adjustable tailstock tools is governed by the amount of skilled effort you put forth. Only someone new to the machine trade would talk about “perfect” alignment. In the machine business, you talk tolerances even if you can’t measure an error because now the error has to be assumed from the tolerances of your method of checking.
These holders are simple to use. The holders are divided into two parts with flanges. These flanges are bolted together with two screws. The clearance holes for these screws allow the front to be adjusted in relation to the rear. The rear section has a witness mark (groove). This mark should always be located at the top so the holder is located the same way in the tailstock each time.