Measuring and Layout — FAQ
What's the difference between a combination square and a try square?
A combination square features an adjustable blade that slides through the head for depth measurement and marking, while a try square has a fixed blade. Combination squares also include a 45° face and often a scribe and level.
Can I trust a $30 combination square for fine woodworking?
Yes. Modern manufacturing allows budget squares like the Stanley 12-inch to achieve ±0.001" accuracy. The key is verifying squareness yourself—draw a line, flip the tool, and check for deviation. Many affordable options outperform expensive vintage tools.
How do I maintain my combination square's accuracy?
Store it in a dry location to prevent rust. Clean the blade with a light oil coating. Avoid dropping it, as impact can knock the head out of square. Periodically check against a known reference and adjust if your model has set screws.
12-inch or 6-inch: which size should I buy first?
Start with 12 inches. It handles 90% of tasks including machine setup, panel layout, and framing. A 6-inch square excels for detail work like joinery and small boxes, but the 12-inch's versatility makes it the essential first purchase.
Why do some squares have both inch and metric scales?
Dual scales accommodate different project requirements and user preferences. However, check accuracy on both—some manufacturers etch one scale precisely and the other as an afterthought. For metric work, verify the mm increments are true.
What makes a square 'machinist grade'?
Machinist squares meet tighter tolerances (typically ±0.0005" per inch), use hardened steel construction, and have ground edges for maximum precision. They're designed for metalworking where tiny errors compound across tight-tolerance assemblies.
