I’m planning a new desk, and have taken some inspiration from this design by Larissa Huff (hopefully mine will be a fraction as beautiful):
https://www.larissahuff.com/work/hurvitz-desk
I’m assuming that the case for the draws is solid wood. If that is right, then presumably, given the vertical grain direction on the side of the case, the tops of front and back legs will be pulled towards/pushed away from each other as the case expands and contracts. My concern is that this might in time put pressure on and weaken the joints of the front-to-back stretchers. Is this a valid concern?
Or would there be enough flex in the legs to absorb this movement?
Thanks for any thoughts!
Replies
I agree with your assessment, and that if the case sides are rigidly attached to the legs there would be some wood movement. Enough to be an issue? Maybe? It would be a little bit of movement over time that would concern me.
But how is the carcass attached to the legs? Screwed from inside? Sliding dovetails? Perhaps there is a way to allow for some movement. For example, if screwed from the inside, you could use oversize thru holes. There are probably other clever methods. I'm curious to see what other suggestions you receive.
It is not easy to predict the outcome, as it depends on the amount of humidity swing in the piece's resting place. Here in Tennessee, if a house has uncontrolled humidity, you could easily get as much as 1/4" of overall dimensional change. While it might not immediately break the stretcher joints, it would be a long-term stress that would be good to avoid.
I suggest that, since no-one who sees your desk is likely to have seen the web pictures, you should consider modifying the design by putting an upper stretcher under the drawer case, and only firmly attaching the case at the front legs. Or, make it more interesting by attaching the case only to the upper stretchers, having it visually float in the leg/stretcher assembly.
By the way, make sure you have the drawer stops at the front of the drawers, not the back, or the drawers could stick out at some point. Leave some space at the back for dimensional change.
Without any disrespect toward Larissa Huff, the fact that someone else has designed and made a piece doesn't necessarily mean it will be durable. There was a short article in FWW many years ago about an architect-designed production chair whose seat broke apart on a regular basis. The "fix" was just as bad, as it involved running a dowel cross-grain across the front of the chair seat, which then split the seat. I happened to sit in one of these chairs at a long board meeting, and it was ungodly uncomfortable.
You'd be doing yourself a huge favor if you act on your concerns and make the lower case out of veneered plywood. Put beefy solid wood edges on it and it will last a lifetime (or several). The back gets easier too, you could miter it into the rest of the box with no movement issues.
There are zero wear surfaces on the lower box, it's a no-brainer.
Wow, what a beautiful desk; I can see why it inspired you. Two thoughts:
1) Change the grain direction of the lower case sides to eliminate the movement that is concerning you.
2) Pose your questions to Larissa Huff. From her website, I get the impression she might be happy to answer a few questions if you introduced yourself as you did in your original post above.
I personally thinks fears over wood movement are unnecessary in this design or easily accounted for.
The reasons I would not be concerned:
Most modern houses are year round climate controlled reducing the impact and amount of wood movement.
I would expect maybe ⅛" of movement in the distance between the legs. The length of the legs between the drawerbox attachment and the leg stretcher can easily flex to accommodate that without undue stress on the stretcher joints and it probably could withstand ¼".
If you still have concerns attach the legs with screws though slotted holes in the drawer box.
I sort of argee that the movement issue is minimal for a climate-controlled home and it might be just fine. I don't think the slotted hole approach works for this situation. If the screws are tight enough to hold the desk in place on the legs they will (IMO) flex rather than let the case side move inside the slots. Gravity is also working against the slot thing.
The slotted hole approach works for 2 rigid structures to slide independent of each other, (case & solid top... table base & top) I don't think it applies here at all. Maybe if there was an upper stretcher, but not the desk as built on LH's website.
My issue with plywood is that what I have been able to find in my area lately has been very poor quality, and I'm not talking big box store trash. If the finish veneer layers get any thinner they will be translucent. The slightest ding or dent during construction is all but impossible to repair. Plus I just think solid wood finishes nicer and I can always see a difference.
As for slotted holes being a problem I will disagree. I'm not talking oversized round holes like are used to aligned drawer fronts, but horizontal slotted holes, a Domino 500 is great at cutting these. Using a screw that has a threadless shank at least the thickness of the drawer box side fitted to snuggly fit in the slot and it would be fine IMO. I might even say pin the front leg tight and slot only the rear one taking care to anticipate the type of movement anticipated.
I agree that the concerns, while valid, should be minimal. Two solutions have been mentioned; elongated screw holes and veneered plywood. Considering that the top and bottom of the bottom drawer box will not be seen, I would go with veneered plywood. Otherwise, it is just a waste of good lumber.
I don't think there is an issue, even with solid wood vs ply. I built a sideboard with a solid wood case, with vertical grain on the ends, pretty much following the method Will Neptune lays out here:
https://www.finewoodworking.com/1999/10/01/sideboard-strategies
The case is a box with the grain running all in the same direction. It's extremely strong, and has no issues whatsoever.
JC2, that WN sideboard is exactly the application I was speaking to in comment #6 above, a solid box with the legs as part of the strucure. In the case of the OP's desk project the legs are fixed only at the lower stretchers. Instead of moving with the case, the case will rack the legs open/ closed at the top, flexing the lower fixed stretcher joinery.