Milling Machine Attachments and Accessories

There are many accessories that have been developed for milling vertically and horizontally. These attachments help smoothen the milling process.
Special Heads
Several types of special heads have been created to give the milling machine versatility. The three main types’ of special heads are the:
 Vertical Heads
 Rack-Milling Attachments
 The Slotting Attachments

Vertical Heads
These special heads are normally attached to the face of the column or to the over arm of the horizontal milling machine. There are two types of vertical heads.
1) Semi universal heads-pivots only on the axis parallel to the centre line of spindle
2) Fully Universal heads-can be set to cut compound angle
Both of the two types of vertical heads are powered by the spindle of the milling machine and accept standard arbors and collets.
Rack-Milling Attachments
The rack-milling attachment bolts to the spindle housing of the milling machine. Its spindle is at right angles to the main spindle. Spur and helical racks can be milled with these attachments and can also be used to mill worms.
Slotting Attachments
This particular attachment is bolted to the column of a horizontal milling machine and can be swivelled 90 degrees in either direction from vertical position. It is used in toolmaking and prototype work for cutting keyways, internal splines and square or rectangular cavities.
Vises and Fixtures
All milling operations require fixtures, vises or other clamping devices to hold the work piece. There are 5 types of vises and fixtures. They are
1) Plain Vises
2) Universal Vises
3) Angle Plates
4) Indexing Heads
5) Rotary Table
Plain Vise
This type of vise is actuated by an Acme threaded screw, and the movable jaw moves on either dovetail or rectangular slide. The vises are actually made of cast of high-grade gray cast iron or ductile iron that can be heat treated. Steel keys are attached in slots machined into the bottom of the vise parallel with and perpendicular to the fixed jaws to allow accurate placement on the milling table. The jaw inserts are usually heat-treated alloy steel and are attached by cap screws. This vise is classified by the jaw width and maximum opening.. Cam-operated plain milling vises are mostly used in production work because of the savings in time and effort and the uniform clamping pressures that can be achieved.
Universal Vise
This type of vise is commonly used in the making of tools, dies and prototype work. This type of vise is the least rigid amongst all the milling machine vises. The base of the vise is graduated in degrees and held by T bolts. The intermediate part of the vise has a horizontal pivot upon which the vise itself can rotate up to 90 degrees.
Angle Plates
Several types of angle plates can be used to hold work pieces or work holding devices. Plain milling plates are available in T-slotted or blank form made of strong iron casting. Adjustable angle plates may tilt in one direction only or have a swivel base. These plates are very useful for holding irregular milling work pieces.
Indexing Heads
This attachment can be used in both horizontal and vertical milling machines to space the cuts for such operations as making splines, gears, worm wheels and many other curating divisions. This attachment can also be fitted to the machine for helical milling operations. There two types of indexing heads. The plain and universal type. The plain heads cannot be tilted but the universal one can. The indexing heads could also be used to hold work-holding devices. The spindle of the indexing head can also be fitted with chucks and collets. Most indexing heads have a worm and wheel reduction ratio by 40 to 1, requiring 40 turns of the hand cranks to make the spindle revolve once.
Rotary Tables
The rotary table comes in many different types of sizes by which it fits both the vertical and horizontal millimg machines. Most can be clamped with a 90 degrees angle to the face. The faces of this table have 4 T-slots and are accurately bored hole in the centre which is concentric. The base of this table houses worm drive mechanism, graduated in degrees and the handwheels can be graduated with and increment as small as 5 inches. Rotary table can also be geared to the table screw which can make cam plates to generate irregular shapes. The axis of the tilting rotary table can also be positioned between 0 degrees to 90 degrees. This particular feature is useful when the rotary table is used on a plain or semiuniversal milling machine.
Arbors and Collets
Arbors
There are three types of arbors which are style A, style B and style C.
1) Style A-consists of tapered portions that fits the spindle , the shaft on which the cutter or
cutter fitters, the spacers and the nuts
2) Style B-used for heavy milling machine operations especially where it is necessary to
provide support close to milling cuttersuch as in straddle milling operations.
3) Style C-used to hold and drive shells end mills and some types of milling machine taper,
shaft size and length from shoulder to nut.

Collets
Certain types of milling machine have bored holes that fit the collets. The collets are secured by a drawbar that is screwed into a tapped hole in the back of the collets and tightened from the top of the spindle.