Steel Rule
Spirit Level
Lock Bolt
Protractor Head
Lock Bolt
Lock Bolt
Square Head Direct Reading Scale
Spirit Level (Reverse Side)
Scriber
Center Head
Laroy S. Starrett
(1836-1922)
Congratulations on your purchase of a Starrett
Combinaton Square. Starrett was the first and is still the
best combination square available.
Invented by our Laroy S. Starrett, in 1877, the
combination square was literally the driving force in the
founding of The L.S. Starrett Company in 1880.
After more than 130 years, this practical and versatile tool
is still commonly utilized in a wide variety of applications.
Description and Components
The combination square includes a hardened steel
graduated rule and movable combination square and miter head with spirit level
and scriber. The square head has a precision ground 90° square face and a 45°
miter face. It is a highly versatile layout tool for scribing right angles and parallel
lines, and a measuring tool that can be used as a tri-square, miter, depth gage,
height gage, and level.
The Center Head is an available attachment that provides an easy means of
accurately locating the center of cylindrical or square work.
The Protractor Head is another available attachment. It has revolving turrets with
direct-reading double graduations, a full 0 to 180° in opposite directions. This
permits accurate and quick direct reading of angles above or below the blade.
Complete Sets are available including the rule and all three heads in a fitted case.
Applications: Combination Square Center Head
Applications: Combination Square Protractor Head
Tips for Using Squares and Center Heads
• Ensure that the square is clean and located against a flat surface – irregularities
such as burrs on metal or knots on wood adversely effect accuracy.
• While the steel scriber can be used on any material, it is most commonly used for
metal. A carpenter's pencil is normally used on wood, but a light cut with a utility
knife will produce a finer line, and is also useful for cross grain scribing.
• When using a center head on a piece that may not be completely round, scribe more
than two intersecting lines to achieve the best possible accuracy.
starrett.com • 978-249-3551
Form 955 20M/S 01/10 Specifications subject to change.
Introduction, Assembly & Applications
The Starrett Combination Square
Assembling and Reconfiguring Your Combination Square
This tool was designed as a square that would move up and down a ruler blade
with precision, thus allowing a wide range of applications. The tool consists of a
blade with a machined groove on the center of one side and a square head with a
lockable assembly and specially designed bolt to engage the slot.
• When installing the blade into the head,
be sure to align the bolt with the groove.
• Look at the machined slot on the head
and note the position of the bolt.
• If the bolt is in the wrong position,
loosen the spring loaded lock nut, press
down and turn the post until the bolt
aligns with the blade slot, slide the
blade into the head and lock the nut.
• Follow the same procedure to attach
center and protractor heads.
• The blade has two or four graduation
types along its edges. To reverse the
blade and see different graduations,
loosen the nut, remove the blade, rotate
the bolt 180°, flip and re-insert the
blade, then lock the nut.
Applications: Combination Square with Rule & Movable Head
With 289C Clamp
Block & Scribe
Complete Combination Square Set includes
Blade/Rule, Square Head, Center Head,
Protractor Head & Case
