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440 12-in. Combination Square

Johnson Level and Tool - 440 12-in. Combination Square

$29 (As of 9/27/2012)

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Editor's Review: John Tetreault

by John Tetreault

review date: September 27, 2012

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Editor Test Results:

Straightness/Squareness N/A

Manufacturer Specifications

Manufacturer Johnson Level and Tool
Manufacturer's Web Site www.johnsonlevel.com
Manufacturer's Phone Number 262-242-1161
Measuring Capacity N/A
Blade Size 12-in.
Blade Material Hardened steel

I have had three Johnson Combination squares - one 6, one 12, and one "heavy duty" 16. All of the squares were inaccurate when comparing the rise/run of the ruler when mounted in the head - 1/32 off at 8" from the horizontal edge of the head. On the 6" model, it was apparently off at the same measurement. I used a Starrett square and the method where one scribes a line on stock then flips the square and re-scribes to find the error. The 90 degree angle on the head itself was coming in at a true 90 degrees, however. The 45 was also an accurate 45 when looking only at the angles on the head. Again, compared to any line drawn with the ruler, things were off. I used a micrometer to determine if there was an error in the width of the rule, which there really wasn't, for all intents. The variance throughout the length of the rule was less than .001". With a little filing of the grove into which the rule slides, it was possible to get everything lining up to a true 90 and 45. Minor work compared to the amount of money spent, so I can't complain too much. Or, you can spend 100+ on something that you don't have to worry about out of the box.

Bought 2 of these squares for my woodshop -- 1 for general woodworking and the other for machine setup and depth gauging. Unlike most squares, the graduations are deeply-imbedded and are highlighted in black, making it easy to read. I've been using both regulary for over a year and the markings show no wear. I maintain the squares often, by sliding the end of a used candle across the blade surfaces. Then a quick wipe with a rag. This not only lubricates the slide action of the blade, but minimizes blade wear, prevents rusting and retains the highlighted markings. When hang the squares for easy access, I make sure the hanger does not come in contact with the bubble to avoid breakage. This square is well worth the money and truly deserves to be treated as a precision woodworking tool!

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