Starrett Steel Combination Square with Square Head - Precise 150mm

Our review of the Starrett 150mm Combination Square finds it best suited to tradespeople and precision-minded hobbyists who need a durable, accurate layout tool. The biggest reason to buy is its measured focus on repeatable accuracy: a hardened, photo-engraved blade with a 35 graduation type and crisp markings makes it easy to register and transfer dimensions. Built with a cast iron head, reversible lock bolt and included scriber and spirit level, this square is a practical everyday instrument for anyone who values long-term reliability and clear, legible measurements.

Key Features

• 35 Graduation Blade: The blade carries mm and 1/2 mm divisions on both sides so measurements and fractional layout are fast and less error-prone.
• Hardened Steel Blade: The hardened, photo-engraved steel resists wear and keeps the graduation marks readable through heavy use.
• Cast Iron Square Head: The precision ground 90 and 45 faces on the cast iron head provide a stable reference for squaring and mitering tasks.
• Reversible Lock Bolt: The reversible lock bolt secures the blade at measured positions and keeps the setting stable during transfer or marking.
• Integrated Scriber and Spirit Level: The included scriber and spirit level expand functionality for scribing, depth gauging and quick leveling checks.
• Versatile Layout Tool: It functions as a tri-square, miter, depth gauge, height gauge and level, reducing the need for multiple single-purpose tools.

Who It's For

This combination square is aimed at toolmakers, mechanics, carpenters and serious DIY users who need a small, accurate layout instrument for bench and site work. It suits anyone who values readable graduations and a tool that will withstand regular use in a workshop or on a jobsite.

Less suitable for those who only need a cheap disposable square for occasional, rough work; budget shoppers looking for the lowest price may find this investment heavier on cost but pay off in longevity and accuracy.

Pros & Cons

Pros

• Exceptional readability and accuracy from the photo-engraved 35 graduation blade.
• Solid build with a hardened steel blade and cast iron head that stand up to workshop conditions.
• Multi-function layout tool including scriber and spirit level reduces the need for extra gauges.

Cons

• Some users may consider the price high compared with basic squares, making value perception mixed.
• The cast iron head adds weight, which may be unnecessary for casual users who only need an ultra-light tool.

Specifications

Blade length	150mm
Graduation type	35 graduation (mm and 1/2 mm both sides)
Blade material	Hardened steel, photo-engraved
Head material	Cast iron with black wrinkle finish
Head faces	Precision ground 90 square face and 45 miter face
Included accessories	Reversible lock bolt, scriber, spirit level

Our Verdict

The Starrett 150mm Combination Square is a durable, accurate layout tool for professionals and serious hobbyists who value long-term reliability and clear graduations. While not the cheapest option, it delivers precise squareness, readable markings and multi-function utility that make it a solid value for those who will use it frequently.

Frequently Asked Questions

Is the blade readable in low light?
The photo-engraved graduations are crisp and legible, though like most metal blades they are easiest to read with adequate light.

Can the square be used for depth and height gauging?
Yes, the square head and reversible lock bolt allow use as a depth gage and height gage in layout and measurement tasks.

Is the head replaceable if damaged?
The tool is built with a cast iron head for durability; replacement policies depend on the vendor, but the design is intended for long service life rather than frequent replacement.