There are four physical characteristics of a setscrew:
- type of drive
- type of thread & diameter
- type of material
- type of point
Socket DRIVES vary also according to application.
Below are brief explanations of each.
Most commonly used; allows for ultimate tightening with convenient
hex keys. Occasionally used as tamperproof screw.
Allows for tightening with less chance of reaming the socket area.
It is a less readily available drive especially when coupled with
various points other than the standard cup point.
This head design provides extra strength in minimizing the possibility
of the head popping off under torque overloads.
Used to eliminate the need for special tooling. These screws may
be installed with a standard slotted screwdriver.
Setscrews may be manufactured in variety of material
to meet your applications. Below are the standard material available:
These special materials are also available upon
All socket products are manufactured with 3A tread
fit. Setscrews also fall into this category of threads. To further
increase the holding power of the setscrew, 3A threads with their
tighter external thread fit, complete the superior design for
any application. Class 3A does not provide for a plating allowance,
therefore all dimensions are measured before plating. Standard
plating on 3A thread fit can reduce the pitch diameter three to
four times the thickness of the plating. If your requirement is
for plated setscrews, mention it at time of quotation to ensure
threads will be manufactured to allow for plating.
* Socket drives may be machined, broached or forged
at manufacturer's option unless otherwise specified by the purchaser.
The setscrew is considered a compression fastener.
Its primary function is that of static holding power. It must
be able to withstand a specified torque without reaming or bursting.
As the screw is tightened, the force at the point creates three
types of holding power:
- TORSIONAL - Resistance to rotation
- AXIAL - Resistance to lateral movement
- VIBRATIONAL - Resistance to loosening from
It is critical to choose the correct point with
regard to application, material, hardness and frequency of adjustment.
Below are listed brief explanations of each point. Consult your
salesperson for more details and information.
Used when frequent adjustments will be made, or
for permanent setting on splined or grooved shafts. This point
will not damage the surface it bears against. For longitudinal
adjustment or rotational adjustment, grooves are ground into the
shaft to correspond to curvature to the oval point.
||Used frequently as an adjusting screw on a hardened surface,
ground for better contact with point. Preferred for thin wall
applications and soft plugs.
||Used for permanent positioning on soft or hardened shafts.
Deep penetrations of point gives the highest axial and torsional
holding power over all other points.
||Full dog requires a deep hole in shaft. Very similar to
DOG dog in style inactive design. See half-dog for applications.
||This is the preferred point. Used against hard shafts and
also in soft materials where high torque tightening is impractical
and cutting in of cup edge is not objectionable.
||Used for permanent location often instead of a dowel pin.
DOG closely fitted hole must be drilled in the shaft or use
on a milled flat. Preferred for hardened materials.
||Used when frequent adjustments will be made, or for permanent
setting on splined or grooved shafts. This point will not
damage the surface it bears against. For longitudinal adjustment
or rotational adjustment, grooves are ground into the shaft
to correspond to curvature to the oval point.
||Counter clockwise knurls prevent setscrew from
CUP under severest of vibrations even in a hole that has been
poorly tapped. Used as a quick and permanent locking method
in gears, collars and knobs. The design of the knurl in conjunction
with the cup point create the ultimate in holding power.