Powers Buyers Guide

Screws
SELECTION GUIDELINES
The description of the size of the screw is usually listed as three figures:
1. The first figure indicates the gauge of the screw (g),
2. The second figure indicates the threads per inch (TPI),
3. The third figure indicates the length of the screw (mm).
e.g. 14-10 x 20mm = 14 gauge, 10 threads per inch, 20mm in length.
Often the second figure is not listed, particularly in timber screws, etc.,
e.g: 10 x 50 = 10 gauge, 50mm in length.
1. Gauge
The gauge of the screw is
determined by the basic size of the
thread outside diameter.
Gauge
2. TPI (Threads Per Inch)
The TPI is the number of thread
crests that can be counted along a
lineal measurement of 1” (25.4mm).
TPI
3. Length
Flush finishing (CSK) screws are
measured from the top of the head
to the point of the screw. Other
head profiles are measured from
the underside of the head.
Length
Length
Point Styles
SDS
Will self drill and thread without the
need for pre-drilling. Depending on
the gauge, thread pitch, thickness of
material and application, SDS point
up to 14 gauge, will drill through
steel up to 4.0mm.
No.5 Point SDS
Self drilling point with extra long
cutting flutes specially designed
to drill through steel up to 12mm
thick, cut their own mating threads
and fasten securely in one simple
operation. The total thickness of
materials to be joined must not
exceed 12mm.
Winged SDS
The specially designed wings on
these SDS countersunk head screws
will drill a clearance hole in timber.
This prevents the timber from rising
up as the screw penetrates the
metal, and negates the need for
pre-drilling. As the SDS point drills
through the metal base material,
the wings break off, the thread is
formed, and the head clamps down
to secure the timber.
Zip-It ® Point
Special self drilling point that
produces very clean holes in
thin sheet up to 1.5mm without
distortion, also soft woods.
Needle Point
The sharp needle type point is
capable of self drilling and fixing
through light gauge metal up to
1.2mm, without pre-drilling.
Type 17
Self drilling point for fixing soft and
hard timber without the need to
pre-drill. The slot at the end forms
a cutting edge which reduces
splitting of timber and swarf. It
will also penetrate thin sheet
metal if required.
Chipboard
Designed for timber to timber
applications. The combination of
a sharp point, coarse thread and
ribbed head eliminates the need
for pre-drilling and provides for
fast, convenient fixing.
Thread Styles
Coarse Thread (< 16 TPI):
Also known as spaced threads,
they are normally used for all
timber applications and for thin
metal (1-2.4mm).
Fine Thread (> 16 TPI):
Also known as metal threads,
they are only used in steel
applications. Fine threads are for
use with thicker metal
(2.4-12mm).
Buttress Thread:
Buttress thread is used for the
best holding power in thin metal
(0.5-1.2mm). Great for roofing
application, the thread firmly
supports vertical load on its
upper flank for greater strength.
Knurled Thread:
Knurled thread protects the
screw shank by enlarging the
hole in metal sheeting to
minimise damage to the
screws protective coating.
Reverse Thread:
Reverse thread removes swarf
beneath the surface of the fixture
allowing tighter pull down.
160 www.powers.com.au Detailed performance data is available for all Powers products