Starrett Steel Combination Square 6in Blade - Precision Layout Tool

Our review of the Starrett Steel Combination Square with a 6in blade finds it best suited for tradespeople and serious hobbyists who need a reliable, long-lasting layout tool. The single biggest reason to buy is its combination of a hardened steel, photo-engraved blade with a cast iron head that delivers consistent accuracy and squareness for scribing, tri-squaring, depth and height gauging, and miter checking on a daily basis.

Key Features

• 4R Graduation: The blade's 4R graduation with 8ths, 16ths, quick-reading 32nds and 64ths enables precise fractional measuring for woodworking and metal layout tasks.
• Hardened Steel Blade: A hardened, photo-engraved blade resists wear and keeps markings legible over years of use, improving long-term readability.
• Cast Iron Head: The precision ground 90 square face and 45 miter face in a cast iron head provide stable, repeatable squareness for setup and inspection.
• Reversible Lock Bolt: The reversible lock bolt secures the blade firmly and makes adjustments easier when setting depth or marking from an edge.
• Included Scriber and Level: The package includes a scriber and a spirit level, adding utility for layout and leveling without needing extra tools.

Who It's For

The Starrett 6in combination square is aimed at machinists, carpenters, toolmakers, and dedicated DIYers who demand durable measuring equipment that holds calibration and delivers crisp graduations. It works well as a shop reference tool for checking other squares and for precision layout tasks that require repeatable results.

Those who primarily need quick, inexpensive squares for occasional household projects may find this model more tool than necessary and should consider simpler, lower-cost options. Also, users who require digital readouts or metric-only graduations should look elsewhere.

Pros & Cons

Pros

• Excellent build quality with a hardened steel blade and cast iron head for long service life.
• Very readable 4R graduations that support fine fractional measurement down to 64ths.
• Smooth sliding action and a reliable reversible lock bolt make adjustments straightforward.

Cons

• Higher cost relative to basic plastic or stamped squares, so value perceptions vary among buyers.
• The tool is manual and analog, so it lacks digital readouts some users might prefer.

Specifications

Our Verdict

The Starrett 6in combination square is a solid investment for professionals and serious hobbyists who need a dependable, accurate layout tool. Its hardened steel blade, clear 4R graduations, and cast iron head deliver long-term precision and durability, making it worth the price for regular use, though casual users may prefer a lower-cost alternative.

Frequently Asked Questions

Does the package include a level and scriber?
Yes, this model includes a spirit level and a scriber along with the reversible lock bolt.

How fine are the graduations on the blade?
The blade uses a 4R graduation scale with readable marks in 8ths, 16ths, quick-reading 32nds and 64ths for fine fractional measurement.

Is the head accurate for squareness and mitering?
Yes, the cast iron head has precision ground 90 square and 45 miter faces designed for accurate right-angle and miter checks.