Everything about the Incra Guaranteed Squares from the bulletproof packaging to the accuracy guarantee is impressive. Click image to enlarge

INCRA Guaranteed Squares

The name is their promise

Text & Photos by Tom Hintz

   The most frequently used angles in woodworking are 90 and 45-degrees. Whether setting up tools, checking the accuracy of the cuts they make or insuring the overall alignment of a project, these angles are always very important. The accuracy of the tools used to measure them can make a big difference in how projects turn out.

Initial Impressions

   The INCRA Guaranteed Squares are impressive from the shockproof box they come in to the Certificate of Accuracy attached to each one, promising accuracy within 0.001" at any point along the blade.

   The fit and finish of the components is first rate. All edges are smoothly dressed and flat surfaces given a matte finish that eliminates glare. The attention to detail extends to the precisely machined handles, secured to the blade with Allen-head screws, countersunk below the surface. Rivets are cheaper and require less labor to install, but are not as precise.

Quality Materials - Manufacturing

Securing the blanks for machining with bolts rather than clamps is more costly but produces a super-accurate finished product. Click image to enlarge

   INCRA routinely chooses manufacturing processes because they are the most accurate, not the easiest, fastest or cheapest. That philosophy in machining was applied to making the INCRA Guaranteed Squares and results in the remarkable accuracy these tools bring to the shop.

   A case in point is a threaded hole near the end of each blade. While convenient for hanging on pegboard, that is not why they were created. Actually there are three of these holes, two of which are hidden by the handle pieces. Their real purpose is securing the blade blank during machining. The more common practice would be using automated clamps to quickly secure the blank during machining but INCRA chose bolting them in place because that increases accuracy in the finished product.

Each Incra Square comes with this written guarantee of accuracy. Click image to enlarge

   The blades are machined from a solid piece of ¼"-thick aluminum alloy, chosen for its hardness, durability and stability. The combination of high-quality materials and precision manufacturing allows INCRA to guarantee the accuracy of the finished product. INCRA is so confident in the strength of the material that they took the bold step of stating on the packaging that accuracy will remain even if the square is dropped! The woodworker can rest assured that with normal care, INCRA Guaranteed Squares will remain accurate for many years to come.

   The INCRA signature gold and red colors result from a hard anodizing process that is again more time consuming and expensive to apply but insures corrosion will not be a problem.

In The Shop

Whether checking the squareness of a fence (Top) or the bevel of a blade (Bottom) the Incra Guaranteed Squares are very accurate and easy to use. Click images to enlarge

   To check the accuracy of the INCRA Guaranteed Squares they were compared to high-dollar machinist squares, checked with a precision digital protractor and even put on a super-accurate digital/laser inspection plotter, the only device that could measure an error. The 45-degree square maximum error of 0.0005" and the 90-degree version 0.000224", a little less than one quarter of one thousandth of an inch from perfect. That ended our attempts to find errors.

   Both the 90-degree and 45-degree INCRA Guaranteed Squares are available with 5"-long or 7"-long blades, all carrying the same accuracy guarantee. The 5"-long versions were chosen for this review because they fit the equipment in my shop best.

   The combination of the handles and blade, all machined flat, provide a solid, accurate base for standing the INCRA Guaranteed Squares on a surface to measure table saw blades, jointer fences and more. The 45-degree version can also be stood on the end of the handles and blade, making it easier to check blade and fence angles that run very close to the table surface.

The recess at the inside corner is a nice touch that insures the square fits the outside surfaces without interference. Click image to enlarge

   Both versions of the INCRA Guaranteed Squares have a machined recess at the inside corner of the blade so the point of the piece being measured does hold the square out of line, producing a false indication of an out-of-square condition.

   In every situation encountered, the coloring and matte finish made reading the INCRA Guaranteed Squares easy to "read." Very small gaps between the blade and workpiece could be seen clearly, which makes identifying necessary corrections a much easier task.

Conclusions

   The INCRA Guaranteed Squares are high-quality tools that make setting up equipment and insuring square edges on project pieces a fast, simple task. Tough, high-quality materials and state-of-the-art manufacturing mean the INCRA Guaranteed Squares will remain accurate forever with normal care.

   If minimizing errors in your woodworking is important, INCRA Guaranteed Squares should be in your toolbox. The INCRA Guaranteed Squares have a street price of $39.99 (1-15-2005) for the 5" version and $49.99 (1-15-2005) for the 7 ½" models.

   Check Woodpecker's pricing on the Incra Guaranteed Squares.

Visit the INCRA web site!

Do you have a comment about this page? - Email Me!

Back to the Tool Reviews List