3) Milling Machine Accessories and attachments

a)Vertical heads- Vertical heads are generally attached to the face of the column or to the overarm of a horizontal milling machine. The head is a semiuniversal type, which pivots only on the axis parallel to the center line of the spindle. For a fully universal head, it can be set to cut compound angles. Both types of heads are powered by the spindle of the milling machine and accept standard arbors and collets.

b)Rack-milling attachment- Rack-milling attachment bolts to the spindle housing of the milling machine. Its spindle is at a right angle to the main spindle of the machine. Both spur and helical racks can be milled at this attachment, and it can be used to mill worms. Some rack-milling attachments have an outboard support for the spindle, which makes it possible to take heavier cuts.

c)High-speed milling attachments- High-speed milling attachments can be placed on both horizontal and vertical milling machines when spindle speed is beyond the operating range. A gear train is used to step up the speed as much as 6:1, which allows more efficient use of small cutters. A high-speed milling attachment is fully universal.

d)Plain vice- Plain milling vices are actuated by an Acme threaded screw, and the movable jaws moves on either a dovetail or rectangular slide. The vices are usually cast of high grade gray cast iron or ductile iron and can be heat-treated. Steel keys are attached by caps screws. Vices of this type are classified by the jaws width and maximum opening.

e)Swivel-based vise- A swivel-based vise is less rigid in construction. The base graduated in degrees is slotted for keys that align it with the T slot in the table. The upper part of the vise is held to the base by T bolts that engage a circular T slot. When it is used on milling machine with semiuniversal head, makes possible milling compound angles on a workpiece.

f)Arbors-
· Style A arbors consists of the tapered portion that fits the spindle, the shaft on which the cutter fits the spacers and nuts. The shaft has a keyway along its entire length. The outboard end of the arbor has a pilot that fits into a bronze bushing in the outboard support of the milling machine overarm. One or more cutters can mount on the arbor, either adjacent to each other or separated by spacer and shims. This type of arbor is used primarily for light and medium-duty milling operations.
· Style B arbors are used heavy milling operations, especially where it is necessary to provide support close to a milling cutter, such as instraddle milling operations. One or more bearing may be place on the arbors as near to the cutters as possible. An outboard bearing support is used for each bearing sleeve on the arbor.
· Style C arbors are use to hold and drive shell end mills and some type of face milling cutters. In some cases, they can also be fitted with adapters for mounting other types of cutters.


g)Special tool holders- For some operations that require the use of tools with nonstandard shank sizes, chucks can be use to hold the tool. These chucks are available with Morse taper or straight shanks. Either type can be use in milling machines when the proper adapters or collets are available.