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Making a rule joint

Making a rule joint (post #123828)

Anatole_Burkin on Fri, 01/25/2002 - 08:25

Woodworking Events

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The joint between the hinged leaves of a drop leaf table is referred to as a rule joint. One edge of the joint is essentially a thumbnail profile; the other edge (the leaf that drops) is a mirror image of the first. Done well, the hinged leaf should swing freely but close with a minimal gap and no binding. David Salisbury, who works at the Colonial Williamsburg cabinet shop, began by explaining that the rabbets in the profile are typically 1/4 in. to 5/16 in. wide, at least on most of the period furniture he has studied. The process requires the use of a rabbet plane to establish the rabbet. Next, Salisbury beveled over the edge using a skew smoothing plane. (See attached photo.)

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by Anatole_Burkin in reply to Anatole_Burkin [original] on Wed, 01/23/2002 - 00:09

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Rule joint continued ...

Last, David Salisbury moved on to a round plane (see attached photo). Round planes were made in pairs; one cuts the roundover; the other shapes the matching cove. The reason he begins with a skew plane, he said, is to reduce the wear on the round plane, which is more difficult to make and sharpen. Using the skew plane first also speeds up the process somewhat, as it will remove material quickly. To my way of woodworking, the process feels like slow motion. But it's very interesting to see how early cabinetmakers did consider and adjust their way of working to be as efficient and practical as they could, given their technology.

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by Sal_Maglie in reply to Anonymous [original] on Thu, 01/24/2002 - 11:07

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I was always under the impression that rule joints like these were made from match planes that were specifically made for this task, or a double bladed single plane in the "come and go style" that renowned planemaker Todd Herrli has classes on making every now and then. Or were these kind of specialty planes only reserved for the more well to do woodworkers, and the masses just left with hollows and rounds to do the joint?

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by John_Adams in reply to Anonymous [original] on Thu, 01/24/2002 - 14:58

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Sal;
Actually, rule joint pairs, both fenced and unfenced were relatively uncommon outside of the big factories, and surviving examples in the smaller sizes command premium prices to today's users. I've only acquired two pair to use in over 30+ years, the most recent were described by the seller as a simple pair of hollow & round, but the subtle profile difference in the photo was a giveaway.(Hint: Look for a 90 degree shoulder on the round, with cutter exposed there, and keep in mind - these often cut more than the usual 1/6th circular arc.) BUYERS BEWARE: Even the slightest of warpage will render these unusable, though they remain very collectible.
Mr. Burkin fails to mention that if the joint is executed properly and the hinge pivot is correctly located, when the dropleaf is raised, the leaf will rest on the top at the rabbet surface (to support any centrally placed load without sag), moving out of contact in the first few degrees of lowering. When the leaf hangs vertical (at rest) there will be only a hairline separating the exposed rabbet/quarter round, from the leaf, and one should not be able to see through to the underside of the table, as the edge of the leaf will be 1/16" minimum above the bottom line of the table top. The leaf contacts the top only at the extreme, raised, in-use position.
Picky, picky, picky...yea, I know; but if it's worth doing, it's worth doing it right. For proper strength, dedicated drop-leaf table hinges are a must, as they provide one elongated leaf to bridge the gap at the cove surface. Placement of the hinge pivot point determines whether the joint "performs" or not. I'll try to follow-up with some images later today.
John (who wishes he were at Williamsburg for this seminar)

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by Danford_C._Jennings in reply to Anonymous [original] on Thu, 01/24/2002 - 16:43

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Sal,

The rule joint according to Joyce:

< Obsolete Link >

There was alson an article by Jefferson Kolle in the October 1999 issue (#138) of
i Fine Woodworking
on the construction of a Pembroke table and the rule joint. FWIW.

Dano

Source:
i The Encyclopedia of Furniture Making,
by Ernest Joyce, Drake Publishers, Inc., page 346, copyright 1970 by Ernest Joyce.

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by John_Adams in reply to Anonymous [original] on Thu, 01/24/2002 - 18:40

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Mr. Jennings;
Excellent! I find myself at my real job ... away from reference material and scanner, but you've covered the material quite well! Perhaps I'll post a snapshot of a dropleaf later this evening.
I alluded to one point, without ever stating it clearly, ....the hinge is not depended upon for support of the load placed on the table leaf.
John

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by Danford_C._Jennings in reply to Anonymous [original] on Thu, 01/24/2002 - 18:53

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John,

Thank you. Actually, the image posted is from an earlier posting of mine in a rather lengthy discussion that took place on this forum last spring about this subject.

IMHO, what is most critical for this joint to perform correctly is that the center of the hinge's barrel be in a direct line to the edge of the top rule joint's fillet.

Please, whenever some one addresses me as "Mr. Jennings", I always look over my shoulder to see if my father is here.
b ;)

Dano

PS. Sorry for the long load time, I forgot that it was posted before the jpg size restriction was implemented.

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by Sal_Maglie in reply to Anonymous [original] on Fri, 01/25/2002 - 08:25

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Thanks for all of the good information. I already knew the basics of the rule joint, I was just wrong about my assumptions regarding the historical aspect and how it was made way back when. I took the liberty of doing some further research and found on the Williamsburg site that the city workers were more likely to have a dedicated plane for the job while those in the sticks had to make do with hollows&rounds and other tools to get the job done.

I also found an article in FWW #18(Fine Woodworking Techniques #3 also) that explains a different method using a Stanley #45, some moulding planes, a scratch beader, plus a few other tools to make the rule joints on a Jacobean double-dropleaf table. If you're into the teary eyed ways of an author waxing eloquently about using hand tools instead of machines, it's a fine read and well detailed with many photos.

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by rfcomm2k in reply to Anatole_Burkin [original] on Wed, 12/03/2003 - 20:22

Where is the attached photo?

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by UncleDunc in reply to Anonymous [original] on Wed, 12/03/2003 - 23:08

That post predates the move from the Web-X forum software to the Prospero software now in use. The attached pictures didn't make the transition.