Counterbore

Part 6 - Muzzle Adapter Ring a. Material- 4130 steel, annealed OD- 1.110 .005 X. 5 long ID-. 4531 drill/ x 28 tap Counterbore rear-. 55 ID x. 15 long. This aids in starting threads when installing on rifle. 

Interchangeable gear cylinders are available with variable nozzle L/D ratios by counterboring from the inside of the rollers to reduce the die length or by using replaceable nozzle inserts to increase the die length. 

F2 - Filters made from zero volume unions with 1/8" OD X 2 pm screens. (Both components, Valeo Instruments Co., Inc. union—part ZVU-125) Union ID enlarged to 0.073" from 0..029" counterbore machined in tubing ends against screens... 

In addition, molded holes can be custom designed to aid in insertion of leaded components (entry radii or countersink) or to provide recessed mounting of hardware (counterbore). Furthermore, holes can be oblong, rectangular or parallel to the plane of the molded substrate. Possible hole geometries are illustrated in Figure 1. 

Other gages measure the proper dimensions of the breech-screw and its thread, ana those of the counterbore of the barrel which receives it others, again, the form, dimensions, and position of the. sights. 

Twist drill Spade drill Trepanning cutter Center drill Combination drill Countersink Counterbore... 

For reasons of appearance, and also because of the available screw length, the screw head is often located below the surface of the plastic. Therefore, the hole in the plastic must be counterbored and will be specified as such, even though it is molded, not counterbored by machining. ... 

There are many considerations in specifying the shape of the counterbore. In molding, every hole in a plastic piece is created by a pin (the core pin). The core pins are often subjected to unbalanced side forces, caused by high injection pressures and poor flow conditions in the mold as a result of the gate location, which will deflect these pins. 

LC = Length of clearance holes LB = Length of counterbore LT = Length of screw hole LE = Length of engagement... 

LB Length (depth) of the counterbore LB is dependent on the overall design parameters. Where appearance permits, there is no need for a CQunterbore, and the screw head will seat on the flat top surface. In many designs, however, the screw head is desired below the top surface LB is then usually greater than the height of the screw head. 

Example 2 A relatively deep top A. short screw with long counterbore,... 

The exceptionally long counterbore, requiring a core pin which is easily deflected and difficult (or impossible) to cool internally, and of SI515W to a lotig counterbore, d i g... 

Combination drills known as Subland drills combine a number of operations in a single tool e.g. drill and ream, drill two diameters, drill and chamfer, drill and spotface, drill and counterbore. Fig. 8.10. Each cutting edge has a separate land and flute. Fig. 8.11, which enables cutting to take place and resharpening to be easily carried out. 

Counterbore cutters are made from high-speed steel and may have parallel or taper shanks. 

A spotface cutter. Fig. 8.15, is used to provide a flat and square seating for a screw, bolt or nut on the surface of the workpiece, usually on the surface of a rough casting which would not otherwise provide a sufficiently accurate seating. The spotface is similar to a counterbore cutter, but has teeth on the end only. It will cut to only a very limited depth and caimot be used to counterbore. Counterbore cutters, on the other hand, can be used to spotface. 

Install the lock washer with the surface with counterbore outwardly and fix it on the lock nut by screw. 

Reaming may be used to size holes accurately, but diameters produced may also be affected by thermal expansion. Pilot holes may help when the hole is to be reamed or counterbored. Reamer speeds should approximate those used for drilhng. Reaming can be done dry, but water-soluble coolants will produce better finishes. For thermoplastics it is recommended that a reamer 0.001 to 0.002 in larger than the desired hole size be used. Tolerances as close as 0.0005 in can be held in holes of V -in diameter. 

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