MachineryHouse AL-346V, Instruction Manual

Page: 25 / 82

- 23 -
Centers
Some time you need to use dead centers, live center, and adapter sleeve (see Figure 24) to adapt the centers into
spindle bore. When installing centers verify that all mating surfaces are clean and free of nicks and burrs.
Tip: Hand-held tapered bore wipers make this task very time efficient, and offer consistently clean bores.
Solid dead center
Dead centers are typically used in low speed turning
operations to increase rigidity for close tolerances. The
solid dead center is installed at the spindle end of the
lathe because the workpiece, center, and spindle all turn
together by the use of a lathe dog. One end of the lathe
dog is clamped to the workpiece, and the other end the
tail, is inserted into a faceplate slot shown in
Figure 25.
Figure 24
Tip: If the tail is too large for a slot, install the 3-jaw chuck, open the jaws so the workpiece can be supported by the
center and the tail of the dog can rest against a jaw.
Carbide-tipped dead center
When the workpiece is supported at the tailstock end of the
lathe, the workpiece will spin on the tip of the fixed center.
To eliminate the tip of the center from wearing out at this
point of contact, the carbide-tipped center is used.
Nevertheless, during turning operations this tip must still be
lubricated vigilantly, or the workpiece will wear, resulting
in increased end play and poor turning results. Typically,
when using centers, the tailstock quill should be locked and
protrude, but not too long.
Figure 25
Live center
If the workpiece must be spun at higher speeds, the live center is inserted into the tailstock. Unlike a dead center, the
tip of the live center is supported with precision bearings that allow it to support and spin with the workpiece. As a
result, virtually no wear occurs, and the workpiece can be turned with less concern about developing end play from
tip wear. However, when using live centers, accuracy can suffer as a result of having bearings support the end of the
workpiece.
Installing center in tailstock
1. Center drills the end of the workpiece to be turned or threaded.
2. Feed the quill out about 25mm (1"), wipe clean and insert the center into the quill bore
(see Figure 26). To help
prevent wear, place a dab of grease on the point of the
center.
3. Position the tailstock so the center presses against the
workpiece, then lock the tailstock in place.
4. Preload the quill into the workpiece. The force against
the workpiece will fully seat the tapered center.
5. Lock the quill into place. However, keep in mind that the
quill may need to be adjusted during operation to remove
any play that develops between the center and the
workpiece.
Figure 26
Page 25 Instructions Manual for AL-346V (L555D) 01/09/2017