Woodworker's Central
Woodworker's Gazette
Gazette Archive 12/24/01

Incra Precision Marking Rules
A Tool Review By Sheldon Grand

Relatively late in life I learned the old saw (pun intended) "Measure Twice, Cut Once." I wish these Incra measuring tools had been available at that time because I'm sure my measurements (and cutting) through the years would have been much more accurate.

I find it interesting that Incra refers to these tools as "rules," a term I've always associated with machinists' operations, rather than "ruler" which I've generally associated with carpenters and other workers in wood. I find the distinction completely justified.

There are six basic configurations of the tools, many graduated in either fractions of an inch or decimal/metric - you choose the territory comfortable for you. Each of the "rule" parts of each tool is made of stainless steel. All of them work with a standard 0.5mm mechanical pencil, or a lead pencil or metal scribe sharpened to a very fine point. Slots and round holes at corresponding positions are punched into the rules as guides for making your preferred type of marks. Rules numbered 1, 2, and 3 (below) are available in lengths of 6", 12", and 18", individually, or in a set of three in each length.

1. The Precision Marking Rule. This most basic device allows measurement and/or marking between any two or more points on the work piece. Simply use it as you would any other rule or ruler.

2. The Precision T-Rule. It seems to me that this is the most versatile of the tools in the collection; as the name implies, it serves many functions of a draftsman's t-square, with added functionality of measurement and marking. It is designed with a removable "T-Bar" affixed to one end of the rule.

By placing the bar of the tool against the edge of the work piece, you can make your mark (using slot or hole) at the desired distance from the edge - in 64ths of an inch!

While holding your pencil or stylus (your marker) vertically at the desired distance from the edge of the work piece, you can draw a line parallel to the edge.

Positioning your marker along the side of the rule, you can draw a line perpendicular to the edge (as with any t-square or woodworker's square).

And you can make vertical measurements using the scale at the end of the rule (limited to the three inch height of the rule).

3. The Precision Bend Rule. This tool is essentially an angle iron (made out of stainless steel) with slots and holes allowing simple marking of the edge and face of a work piece without moving the position of the rule once it is in place.

You can also use it to measure by placing the two "legs" of the angle flat on the work piece (with the "v-joint" at the top) allowing you to view at an angle not as easily obtainable with a flat instrument.

And while holding your pencil or stylus (your marker) vertically at the desired distance (limited to the seventh-eighths inch height of the rule) from the edge of the work piece, you can draw a line parallel to the edge.

4. The Precision Marking Protractor. If you do much work with angles of varying degrees, this tool is for you; because of the necessity for being really accurate in cutting and fitting of work involving angles, I try to stay away from them; at such time as I can no longer avoid working with them, I'm certain the slots and holes in this tool will ease the burdens of both measuring and marking; slots and holes for degree-marking are graduated in units of one degree through a 180 degree arc.

5. The Precision Centering Rule. This tool allows finding and marking the center of a work piece up to twelve inches wide without making any arithmetic calculations; it seems to me this might be particularly useful in mounting already-round work pieces on a dead center in the wood lathe.

6. The Precision x-y Marking Rule. This is designed to locate and mark the intersecting point of two perpendicular lines.

For a full look at the available tools, and their configurations and recommended prices, see Incra's web site, www.incra.com and click on the Incra Rules button on the left hand side. Where cost is a substantial consideration, I'd recommend starting with The Precision T-Rule in the 12 inch length; at a list price of $34.95, it's not cheap; is it worth it? Absolutely.

Sheldon Grand

After publication of the review, Dan Bailey advised that there is available a "three-inch T-rule.... it is hard to find in catalogs but it is portable in a pocket, adequate for sliding lines near an edge, and does not impinge on clamps for narrow strips."

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