As a designer, I like to think I can anticipate everything. Most architects and builders do. It is, after all, our job to figure everything out before mortar hits brick, or rain hits roof, or ass hits seat. However, design is not that simple. Prototypes, drafts, and painstaking iterative improvement are an integral part of any good design process.
My process, in particular, is based on prototyping, debugging, and then, hopefully, forward progress. That said, sometimes things just go sideways on a fella. Recently, I reported on a productive weekend in the shop, working on some new chairs made from an old feta cheese barrel, designed to address some of the shortcomings of my Scrap Armchairs. One of the main problems with those chairs, the flat seat and back, would be solved with the nice, ergonomic curve of the barrel staves. I worked out a new frame, built it, cut mortises to accept the barrel staves, and glued up the whole thing.
What follows is a photo-illustrated journal of the complete failure of that process. I thought it might be useful to show how something fails, why it fails, and what lessons to salvage out of the whole mess.
|Chair frames, made from reclaimed old-growth pine (maybe fir, not a wood ID expert). Simple notched joints, glued and pegged with dowels for additional strength. |
|Cutting tenons into the barrel staves. |
|Laying out for the mortises.|
|Drilling out the mortises. |
|Squaring out the mortises to accept the tenoned barrel staves. |
|Ready for assembly. |
|Clamped up, which is where the trouble began . . . the hardwood (maple) staves served as wedges in the softwood frame, splitting the legs along lines of weakness in the grain and along knots. As the clamps tightened up, popping, cracking, and much cursing was audible throughout the shop. |
|FInished! Looks ok in photos, no? Not Photoshopped to conceal flaws, just photographed from a distance. |
|Hell, even supports weight! Structurally sound! A little ergonomically suspect for the shorter among us, but altogether quite comfortable, with nicely-reclined back, curvy stave seating surface, and perfect height off the ground. |
|Oh shit. Where'd that come from? Stave just popped that weak-ass joint right apart. |
|Those tenons don't fit so tight, huh?|
|One of many fatal flaws in the frame -- a crack right where the frame would take the most stress in use. |
So, what did I learn?
1. Use hardwood for the frame. This will make for cleaner mortises, resist splitting, and, being as hard as the staves are, prevent the staves from acting as wedges splintering the grain of the frame.
2. Cut the back legs out of a wider piece of stock, orienting the grain on the bias for maximum strength and split resistance.
3. Despite my preference for the visual lightness of the thinner frame pieces, I should thicken them up, from 1-1/2" to 2" or so, striking a medium between the chunky Scrap Armchairs and these.
4. Lower the arms an inch or so for better ergonomics for shorter folks.
5. Widen the seat -- impossible in this case given the fixed width of the staves. That said, the seat, at fifteen inches wide, is narrow, especially since the arm design constricts the user. Fifteen inches would be fine for a side chair, one where there are no arms to hem in hips, but this arm scheme sacrifices some ergonomic freedom in the name of aesthetic unity.
6. Screw the joints and plug the screw hole to hide the fasteners. Dowels alone proved to be too weak.
7. Positives? The seat angle, height off the ground, and use of the curved staves were a home run, comfort-wise. I could definitely watch a whole football game in this thing. The profile is handsome.
Failure is design. We tend to only see the successes. Now I'm back to the drawing board, kicking and struggling to elevate my next project to a new level. I think it's easy -- and I've been guilty of it, to some degree -- to make something look good in pictures, slap it on the interwebs, and revel in the accolades, when, in fact, the piece doesn't work very well. The design world is addicted to a pretty picture, and all too eager to gloss over the messy mechanics of the process.
This project has been humbling and educational. As Mr. Samuel Beckett said, the key is to fail better each time.
It's always good to get knocked down a peg once in awhile -- keeps me honest.