Q: What's the difference between the 4" and 6" sizes?
Both hold the same 0.001" squareness tolerance, so the choice mainly comes down to reach; pick the 6" combo square when the extra length is more comfortable to hold on larger stock.
Starrett Cast-Iron Combination Squares
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A versatile, classic design, Starrett's standard combination squares are useful for joint layout or machine set-up and as depth, height or marking gauges. They have machined cast-iron heads with a black wrinkle finish and reversible polished steel rules with photo-engraved scales.
Except for the 4" size, each comes with a steel scribing pin and a built-in level vial for determining level or plumb. The 4", 6" and 150mm models are square to within ±0.001" over the full rule length; 12" and 300mm sizes are square to within ±0.002".
Imperial rules are graduated in the 4R style (with increments in 8ths, 16ths, 32nds and 64ths); metric rules are graduated in millimetres and half-millimetres on both faces.
The 4" rule is 1/16" thick by 5/8" wide; the 6" and 150mm rules are 0.080" thick by 3/4"/19mm wide; the 12" and 300mm rules are 0.090" thick by 1"/25mm wide. Rules are straight and parallel within 0.001" per foot.
The four-piece set includes the cast 12" square/miter head and rule, a non-reversible bevel protractor with a level vial and a cast center-finding head, all in a fitted foam-lined hardshell case. The protractor head and center-finding head are also offered separately.
Both hold the same 0.001" squareness tolerance, so the choice mainly comes down to reach; pick the 6" combo square when the extra length is more comfortable to hold on larger stock.
No, the 4" size is the one exception in the line and doesn't include the scribing pin and level vial built into the larger sizes.
The 12" four-piece set includes the square and miter head with rule, a bevel protractor with its own level vial, a center-finding head, and a foam-lined hardshell case.
Yes, the reversible rule is engraved with imperial graduations in 8ths, 16ths, 32nds and 64ths on one face and metric millimetre and half-millimetre marks on the other, depending on the model chosen.
The 4", 6" and 150mm sizes hold squareness to within 0.001" over the full rule length, tight enough for precise machine set-up as well as fine woodworking joinery.
| Materials | Cast iron (head); steel (rule) |
| Dimensions | 4": 1/16" × 5/8" rule; 6"/150mm: 0.080" × 3/4" (19mm) rule; 12"/300mm: 0.090" × 1" (25mm) rule; straightness within 0.001" per foot; squareness +/-0.001" (4", 6", 150mm) or +/-0.002" (12", 300mm) |
| Includes | Combination square; scribing pin and level vial (all sizes except 4"); 4-piece set adds bevel protractor, center-finding head and foam-lined hardshell case |
| Color/Finish | Black wrinkle finish (head) |
| Package Quantity | 1 item or 1 set |
| Warranty | Lee Valley Satisfaction Guarantee |
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Starrett Cast-Iron Combination Squares
A versatile, classic design, Starrett's standard combination squares are useful for joint layout or machine set-up and as depth, height or marking gauges. They have machined cast-iron heads with a black wrinkle finish and reversible polished steel rules with photo-engraved scales.
Except for the 4" size, each comes with a steel scribing pin and a built-in level vial for determining level or plumb. The 4", 6" and 150mm models are square to within ±0.001" over the full rule length; 12" and 300mm sizes are square to within ±0.002".
Imperial rules are graduated in the 4R style (with increments in 8ths, 16ths, 32nds and 64ths); metric rules are graduated in millimetres and half-millimetres on both faces.
The 4" rule is 1/16" thick by 5/8" wide; the 6" and 150mm rules are 0.080" thick by 3/4"/19mm wide; the 12" and 300mm rules are 0.090" thick by 1"/25mm wide. Rules are straight and parallel within 0.001" per foot.
The four-piece set includes the cast 12" square/miter head and rule, a non-reversible bevel protractor with a level vial and a cast center-finding head, all in a fitted foam-lined hardshell case. The protractor head and center-finding head are also offered separately.