A friend has asked me to build a kneehole writing desk. The material is to be quartersawn/riftsawn red oak, with white pine for the drawer sides, backs and bottoms, copying the look of one he found in an old photo.
I’ve been playing with design issues for several hours, and there are some joinery issues that still stump me, and there weren’t any plans for similar desks in the various books I have.
To minimize cross grain issues, I’m thinking the side, back, and interior panels will have vertical grain. For strength, I’ve drawn the drawer dividers 4 1/2″ wide. The top would be 1″ thick.
Based on a design presented by Will Neptune in FWW #130 May, 1998, the end panels would essentially be doubled in thickness, to bring the inside face flush with the insides of the legs. The top drawer rail would be dovetailed into the top of the legs, and tenoned into the “doubler.” The middle and lower drawer rails would be tenoned into both the leg and doubler. The drawer runners would be cross grain to the doublers and inside panels, so construction would have to reflect that.
My concern is joining of the drawer rails with the inner panels. My thought for the middle rail is to make shallow dados on the middle rail and slip into rebates in the panels. The lower rails would have to have tenons flush with upper face and corresponding mortises in the inner panels. Still seems like the inner panels would depend on butttons, figure *’s, or similar and the top, to withstand the pull of gravity. And there’s not a lot supporting the inside edge of the lower drawers.
The only option I’ve been able to think up is to make the inner panels as thick as the legs, but I’m not sure that would any better support the weight of the lower drawers, and that’s going to increase the pull of gravity.
Has anyone seen better designs, or been able to examine surviving 1800’s kneehole writing desks? Thanks for your help.
Replies
Don,
I'd suggest you back up to the beginning. Traditional design is to run the grain on the ends and back "the long way"-- horizontally, and tenon them to the legs. A vertical grain back that wide, even qtrsawn is gonna be on the move , and inherantly weak, prone to splitting.
So, horizontal grain, tenoned into the legs, make some provision for them to swell and shrink (they won't move much if they are qtrsawn), by dividing the tenons into two or three, with an inch or inch and a half between them, and make the mortises for the lower tenon oversized. I glue the top tenon fully, spot glue the middle one, and let the bottom float, so the seasonal movement all happen at the bottom. (You can haunch that bottom tenon if you want to hide the over-long mortise)
Instead of doubling the ends (a waste of stock). just make fillers of 7/8" (or whatever thickness you need to fill the space)x 2" wide stuff. These can be tenoned into the front and rear legs, in line with the drawer rails, and the drawer bearers applied to them. You could make the fillers/bearers in one, thicker, piece, "L" shaped in section, but that will cause heartburn for some repairman down the road when the bearers wear and must be replaced (damhikt).
I'd run the grain on the inner panels, or partitions, front to back, as well. They can be stub-tenoned into the backboard, or simply dadoed and glueblocked. At their fronts, tongue and groove, or better, tenon them to a front stile, which can be the same width as your front rails.
The top and center front rails, I'd make full length, and tenon them into the legs at each end. The top rail can be mortised to accept tenons on the end of the front stiles, or the front stiles can simply be notched to let the rail pass over, and be screwed together from the top. The lower full length rail can be half-lapped to the front stiles, that is notch both rail and stile for half of their widths and slip together. Mortise the back edges of the rails to accept tenons on the ends of the center drawer bearers.
The lower-most front rails can be tenoned into the legs on one end, and either stub-tenoned or dovetailed to the front stiles on the other.
Ray
Ray:
Thanks for taking the time for such an in-depth reply.
I went back and forth on grain direction of the panels. The challenge to horizontal direction I couldn't answer was joinery at the ends of the wide drawer rails. Seems like wide rails would be advisable, I drew I think 4.5" wide, to reduce sagging. At the front edge, the rail can be tenoned into the vertical grain leg without problem. But at the back edge of the rail, it would be tenoned into a doubler or runner fastened to the outer panel, that will move up and down 1/16" or more seasonally, depending on wood used. My concern is that this seasonal movement would try to crack the rail between the front and rear tenons,
Any thoughts?
Don,
No need to have the rails as wide as 4.5", but simply tenoning them into the legs with a double tenon, and letting the balance of the rail pass by the leg and abut the case end is sufficient strengthwise.
Ray
FWIW, Don, I agree with the direction Ray is suggesting. If the top and middle drawer rails are made full-width, so they attach to the legs, the overall structure would be stronger. Also, with that change, the other design elements start falling into place.
As to sag on those rails, I'm not sure that the added width (4.5") will do all that much to limit potential sag. A face frame might do more to add to the strength.
Thanks everyone for the replies. My desire is for a "standard" approach that can be used for more than one desk with drawer design, hence the desire for a wide divider (4") to minimize chance for sagging. And with the wider divider is a strong wish to join more than just the front of the divider to the leg.
I'm going to try the following on a sample hall table. Top "doubler" 1 1/2" "thick" top to bottom, bottom doubler 3/4" thick. Top divider will be dovetailed into top of leg and upper doubler. Lower divider will be double tenoned into leg and tenoned into lower doubler.
If the lawyer continues to show interest in a kneehole desk with upper and lower drawers on each side (requiring a 10" wide apron) I'll only offer with frame and panel side, interior, and rear panels. The doublers could be securely mounted to the stiles of the side and interior panels without significant cross grain risk, I think. I'd much rather over-engineer the desk than under-engineer. Hope everyone has a good week.
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