Compound angles

**Rocker** · 28th March 2004, 09:45 AM

I am making the splay-legged table described in an article by Garrett Hack in Fine Woodworking #168. The table has legs tapered at 0.5 degrees on all four sides; the shoulders of the aprons are also angled at 94 degrees and the leg mortises are parallel to the outer faces of the legs. See the diagram below.

Obviously, when the legs and aprons are assembled, the tops of the legs need to be trimmed so as produce a horizontal surface for the attachment of the table top. Hack suggests planing them level, but there must be a way of trimming them on an SCMS. Can any mathematical genius out there work out the required angle settings?

Similarly, the bottoms of the legs need to be trimmed, so that the bottoms of the legs are flat on the floor. What would be the compound angle settings for them?

Rocker

**Rocker** · 28th March 2004, 03:43 PM

Well, I eventually decided I would need to rotate the table leg 45 degrees to make the cut; that I would make a guess that the angle between the diagonal on the top of the leg and the horizontal should be 3 degrees; and that I would use a cradle on a table-saw crosscut-sled instead of the SCMS. This is a pic of the set-up.

Rocker

**Ian Runge** · 29th March 2004, 02:42 PM

Rocker ...

So I guess you don't need any help in working out those compound angles now, eh? Just when I was about to grab my calculator.

When I was browsing around the trade-in section of Gregory Machinery a couple of years ago (a mistake, some would say) I came across and bought a Multi-router - a device that lets you cut mortices and tenons on compound angles really easily. But you still have to work out the angles that you want to set the machine at yourself. Being an engineer this is a challenge that can't be easily passed up, but after lengthy calculations it usually comes down to something simple.

Last year, for example, I finished a couple of bar stools that had splayed, curved legs with armrests and cross-members at compound angles and I sat down and worked out the standard formulas. (I'll attach a photo). I got rubbished by quite a few "friends" for trying to be precise with "wood for heavans sake." But few woodies seem to want to do the calculations. E-mail me off-line (or on line) if you are still interested!

Ian R.

**Rocker** · 29th March 2004, 03:51 PM

Ian,

Yes; I am interested in any standard formulae you have worked out for compound angles. Why not post them here? There may be others, apart from myself, who would like to have some aids in dealing with compound angles.

I envy you the multi-router; but, at a price of over $3000, I could not justify one. I get by with shop-made morticing and tenoning jigs.

The mortices and tenons in my rocker design were easy enough to make, since only the side-rail to back leg joints were compound-angled.

Rocker

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