Quadruple Tapered Sliding Dovetail Locking Cleats

A week of travel, during which I was mostly without connectivity, and the final push to get through the first round of edits and annotations for “To Make As Perfectly As Possible: Roubo on Furniture Making” (T minus about 15 days and counting…) has taken a toll on these missives at Musings at The Barn on White Run.


Still, I wanted to wrap up the project on the gargantuan picture frame featured last time.



One of the critical things about a frame that large is that is must conform to the painting inside, and even the smallest deviation will result in calamity when projected out over ten or twelve feet.  The sub-assembly that houses the painting was assembled with mitered double mortise and tenon joinery at each corner, and the joints were not tight.  Originally they were glued together with hot hide glue, but for this project the desire was to prepare the ensemble for traveling exhibit, mandating as a result that the entire unit be disassemble-able.  Glue was out, so the joints had to be assembled and left friction-fit.  This allows for just enough wracking that the fit of the painting could not be assured.

Another solution was called f0r.

When first presented the problem I chewed on it for a great while, then proposed and devised an “after market” locking cleat assembly for each of the four corners, to be applied on the verso of the corners once the painting was installed and the configuration of the frame was established.


Using some 4×6 tulip poplar stock I had laying around I fabricated an analogous corner at about 2/3 scale,


then designed, fabricated, and installed a quadruple dovetailed cleat-and-lock system to be affixed to the corner.  It worked perfectly, and when presented to the curator and project conservator from the museum who owns the artifact, approval was enthusiastic and immediate.  Earlier this month I fabricated the four corner units, mostly on my table saw at home.  Each piece is tapered and beveled at 5 degrees.


A double-taper set of cleats is first attached to the assembled corner,


positioned so that when the mortises are seated, the cleat is perfectly aligned.


Then a double tapered locking pin is driven in to a double tapered sliding dovetail, rendering the entire assembly immobile.

The status of the project is that we will be installing the painting some time in the new year, and once the painting is fitted perfectly in the currently sorta-loose frame I will attached the new cleats, and the assembling process will be finished.