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designing and building with wood channels my creativity and challenges my mind.
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Thursday, February 3, 2011

The All-Important Right Angle

A great jig for fast, square frames
Everybody knows that 90-degree right angles are a big part of architecture, furniture, and design.  But many have never experienced the difficult process of trying to make a perfect right angle.  No, I'm not talking about drawing one on a page, I'm talking about making a right angle out of something.  Doing that is no mean feat.  In fact, a good right angle is both an essential, and difficult-to-achieve, fundamental of quality furniture making.  When I first began making furniture, I thought I could rely on the accuracy of my power tools to achieve good right angles.  Almost a year later, I'm coming to terms with the fact that this is not a good way to make an accurate right angle.

But accuracy isn't the only imperative in a wood shop: speed is of equal importance.  Making accurate right angles quickly is essential to making a living in wood. 

Faced with the prospect of having to bang out several similar rectangular cases, I decided it was time to get a good right-angle fence of some kind, to use as a reference point & jig for making carcases.  My pie-in-the-sky dream was to embed an "L" of t-track in my bench.  But reality is a stern mistress.  And the reality is, I'm not exactly sure how such a thing would work in practice.  So instead of cutting up my bench, I decided to make my right angle portable.

Obviously, this angle would be no good if it wasn't SQUARE.  To ensure squareness, I used my big, high-end framing square, which purports to be accurate within 5/1000" over 12", to lay out two big blocks of cut-off bench top into an "L" shape.  Next, I laid on a piece of 3/4" birch, and screwed it over the junction in the "L".  Afterward I checked the angle using a feeler gauge to measure the space between the legs of my angle, and the legs of the big framing square.  Success! 

The coolest feature, in my opinion, is how this angle can be mounted on a bench: at the end of one leg is a dog hole, so that end can be secured with a round bench dog to the bench.  The angle rotates around this dog, and then can be clamped to the bench with an F-clamp or a hold-down.  I also added a bit of t-track on one leg to support a Kreg hold-down klamp. 

I tested the angle while cutting mortises for an aquarium stand.  It worked beautifully, and the stand came out nice and square, even at the joint lines.  I highly recommend building a big square like this.  With its high fences, I could even stand a 4' x 2' face frame up on end, and get a straight, accurate placement of mortises.

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