PRECISION STRAIGHT EDGES
A straight edge is a very useful shop reference and layout tool. You can use it to check for flatness on critical jig substrates and components and qualify the output from your jointer and planer. Moreover, you can interrogate the tablesaw, jointer, router and fence castings for divots and flatness. With the straight edge you can track and isolate potential sources of error.
The straight edge can be used to extend the blade of the short machinist's square. Since the ends are square you can also use it as a length standard. I mill and hand hone the edges straight to an accuracy (min.) of .0008"/length of bar. The instrument is made & inspected in America by me; it is not a farmed out product.
There are knife-lines on the centerline, equidistant from the centerline and on both sides to facilitate center finding. With only 3 lines/side, you can't confuse the centerline with the others. The aluminum bars measure ~1.0 in. width x .25 in. thick x 8.00" and 12.00" long. Parallelism is within .0015" and therefore a pair of them can be used as winding sticks*. One end is drilled for easy storage. All edges have been machined and deburred. The tool is hand and wood friendly. You can draw, scribe or knife along its thick edges.
In my view, when the work, casting, substrate or inspected surface deviates by more than .004" corrective action may be necessary. 4 mils is my threshold of suspicion. Joints get sloppy or jam. Assembly is sometimes frustrated with a 4 mil interference, deviant fences and substrates have trouble registering the work, and so on. As such, the Edges are supplied with a brass .004" (.5" x 12") feeler gage for inspection. A visual inspection always has merit but with the gage you'll have more objectivity. Moreover, both materials are non-magnetic, won't pick up stray shop steel fibers, stick to magnetized castings or surfaces, nor will they rust. Order one for yourself or for your woodworking pal.
Order on line or by mail. Supply your name, shipping address, email & choice(s). I will get back to you on delivery date, terms, and product availability. Please, no third party money handlers, (bank service checks acceptable). This transaction is between you and me.
US Mail orders to:
1427 KENORA STREET
ESCONDIDO CA 92027-3940
Material: Machined and hand ground 6061 Aluminum.
Length: Both lengths (8" & 12"): + or - .0025".
Width: From ~.940'-.970", parallelism: + or - .0015"/length of bar
Straightness: Better than .001"/length of blade
*Winding sticks will indicate twist but only on flat stock. If the stock is randomly cupped the readings will be ambiguous. Use the straight edge first to qualify flatness.
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Copyright © 2009 Pat Warner
Last modified: Tue Oct 11 08:53:48 PDT 2005