Ski-on-frame kayak, part 2

Steam-bending is a voodoo woodworking art. If you heat up wood, and it has enough moisture in it, the fibers will loosen enough that a previously stiff board can be bent into a new shape, which it will retain after cooling. At least some wood will. How well this works depends on a lot of factors including the species of wood, whether it is clean (without knots), whether the grain runs nicely parallel, how dry it is, whether it has been air-dried, or kiln-dried, how long you steam it, whether you pre-soak it, in water, or in water plus fabric softener! Some youtubers will tell you how easy it is, but even they keep extra pieces on hand for when they break one. Many years ago I had tried bending guitar sides over a hot pipe (no steam required), and that went OK, so how hard could it be?

I went to a specialty lumber store and bought some ash (kiln dried, as everything is that you buy at a lumber yard). I had read that ash was a good species for bending, even kiln dried. The gold standard for this kind of work is white oak, but supposedly only when it is green, or lightly air dried, and I just didn’t have access to anything like that. Following the book, I concocted a steam box from a sheet of styrofoam insulation and a lot of duct tape, and hooked it up to our old hot pot using some PVC pipe left over from a bathroom renovation.

I did some trial bending runs to get an idea how long I would need to cook the ribs and settled on something like 15 minutes. The idea here is to work efficiently by staging all the ribs, loading the steamer with a batch of 4 or 5 inserted at one minute intervals, and then inserting a new dry one at the left every time you take a cooked one out of the right.

I won’t go into the whole bending process itself – there are some great videos from pros out there you can watch if you care to. I’ll just say that it was nerve-wracking and fun, and it came out OK in the end, and even if some of the ribs did split out the grain here and there, nothing too terrible happened. One thing I might do different if I try this again though, is  to pre-soak the wood. I decided not to this time, following the advice of one knowledgeable-sounding site I found. That guy had nothing but scorn for the idea. Now I’m not so sure – it might have helped. I had to apply a *lot* of pressure to bend these ribs, and I get the idea it should have been easier. You can see one of the several failed attempts at the bottom of the photo. The room smelled like hot styrofoam the whole time.

The ribs outline the shape of the hull. Now we have really defined how the kayak is going to eventually sit in the water. Its hydrodynamic characteristics will all derive from this shape.

The next step is to fit out several longitudinal pieces: the keelson, which runs the length of the boat at its lowest point, and the chines, which run in parallel on either side. These all come together at the bow and stern where they meet two other pieces that form the pointy ends. The book had a fancy name for them, but for the life of me I can’t remember what it was. In this photo you can see the nifty lashing that holds these pieces to the ribs; the keelson is done, here, and the chines are being held in place with clamps while they are positioned for optimum boat shape (they will hold the skin just off the ribs).

Here’s the pointy end I was talking about.

Now it really looks like a boat! Just needs a few little odds and ends, and then a skin!

Oh I forgot to mention this cool part of the Greenland kayak design, the Masik. This is a curved piece of wood you brace your thighs against when paddling. I made this one out of a curved maple branch that fell off the tree in front of my house. You can see that tree’s shadow on the bricks there. It’s a giant, starting to die, but it still explodes in a riot of red, orange, and yellow every fall and buries us in its leaves. The piece I made the Masik from was starting to rot a bit, and it has some neat figure in the grain that I liked a lot. Shaping it was a fun challenge. I roughed it out with a chain saw and then went at it with a variety of hand tools. In this picture it’s still in a pretty rough state, but you’ll have to take my word, it worked out nicely.

 Oh no! Somewhere along the way this gunwhale developed a nasty-looking crack. More fallout from forcing them into too dramatic a shape? Oh well, it doesn’t go too deep – I hope it’ll be OK? Better get the skin on soon, that should help to hold it together, right.

I decided to skin the boat in canvas, and coat it with butyrate dope like an old airplane, in keeping with the generally old-fashioned gestalt. Sealskins seem to be out of fashion, and anyway, unattainable. Most people seem to use nylon at this point. It’s lighter and probably easier to coat since you can use something easier and cheaper like epoxy or urethane or some such thing. Cutting it is annoying though: you need a hot knife to melt the edges to prevent it from fraying. Canvas was fun to work with. I learned how to sew. A thimble was essential to get the big needle through several layers of the stuff. The thread is dental floss!

The whole process of stretching the canvas on, trying to keep as much tension as possible, was pretty fascinating. The traditional system is to lace up a very rough seam, like a giant shoelace, along the centerline of the deck, draw it tight, and then sew up with fine stitches. The book I was following had a different idea, which I tried, stapling the fabric to the gunwhales to tighten it, and then stitching along one side of the deck.

Oh I almost forgot to mention. There was this thing that drove me totally crazy right at the end of the project. Another steam bending step was required in order to create the hoop that forms the cockpit, drawing all the fabric together around the place you sit. The idea was to make this hoop by bending a single six-foot stick of ash around a form. I tried this three times and broke the darned thing every time. Maybe I didn’t steam it enough at first? This piece was bigger and thicker than any of the ribs. One time I think there was a weak spot in the grain. The bending itself is tricky – you are holding this thing under a lot of pressure, working under time pressure since the wood is only pliable for a short time after you take it out of the box. Finally, even the fourth time it broke, so I finally decided to make it out of two pieces, and glue them. Sigh, the only glue on the thing. But it got done

Once the stitching was done, and I had made the cockpit hoop, I died the fabric. You can see my first crude stitches on the stern before I figured out how to get the seam right on the corner.

Getting the skin stitched into the cockpit hoop was an exercise in trying to tension up the loose flaps in the middle of the deck. Following the system proposed in my book was pretty straightforward and a little magical; I drilled holes all around the hoop and stuck nails through the fabric just below the holes, levering them up and pushing them through in order to tension everything. Then I laced a length of cord through all the holes, removing the nails, and the twine draws everything up nice and tight.  Here’s a picture of the hoop with the nails holding the fabric to it:

The last thing is to coat the whole job in cancer-causing chemicals to make it watertight. As I said before I’m using butyrate dope. This is the stuff you may have sniffed if you ever made a model airplane. It is a toxic stew of VOCs (volatile organic compounds) – basically every chemical ending in “-ene” is in there. I bought a respirator, don’t worry, my glue-sniffing days are over.

Next post should be launch day. I’m super excited to see if this thing actually floats, how tippy it will be and whether it will track straight. Oh and hmm I guess I’ll need to name it (her?). That will be the hardest part.

Skin-on-frame Kayak, part 1

Before buying wood, I needed to figure out roughly how big a boat I wanted to make. The Greenland kayak design seems to be quite long and narrow – about three times your height, and barely wide enough to squeeze into, so for me that would have ended up around 17 feet (5m), and something like 20″ wide. I have been using a dinky 9′ plastic tub that is about 28″ wide, so this would be quite a leap. Besides, I don’t have anywhere to store a 17′ anything in my house, and don’t want to leave this labor of love outdoors where it would be subjected to the vagaries of New England weather. I settled on a 12.5′ length and 24″ wide. Maybe a little wide to roll, but since I’ve yet to learn how to do that and mostly paddle around in calm lakes and streams, this doesn’t seem like a big problem. Having settled that, I headed to the lumber yard to pick up some 2x construction-type softwood lumber that will make up the large longintudinal pieces: the gunwhales, keelson and chines, plus some clear pine for the deck beams and other assorted pieces. The ribs that make up the hull will be formed by bending them into shape and require some more specialized stock, and I haven’t yet figured out what to use, so those will be chased down later.

The first actual woodworking can begin! I needed to shape the gunwhales, which are the two large pieces, one on each side, that define the outline of the boat as seen from above (or below), and into which everything else will fit. I ripped these in the driveway using a circular saw and a simple jig to keep it aligned reasonably well:

hm, I guess the blade slipped a bit while resawing to 7/8″ thickness using the circular saw.

It’s important that these two pieces are cut from the same board and have the same dimensions. The symmetry of the boat will rely on their being held in opposing tension, so they need to behave similarly. I was a little worried about that wandering sawblade cut, but hoped it wouldn’t compromise the form too much! The first of many deviations from perfection, sigh.

Someday maybe I’ll acquire a machine planer, but I haven’t been able to justify it yet. And it’s still a pleasure to hand plane such clear pieces of softwood with a nice sharp blade. Here they are starting to look pretty clean after the saw marks have been removed. The ends of the gunwhales get tapered and shaped in the ends where they will rise up.

I splurged and bought this antique compass plane on E-Bay to shape those inside curves. This is an amazingly clever tool; its sole can be adjusted to a range of different curvatures. The one I got was probably 100 years old, but still in great condition. Whoever sold it had even kept the blade sharp, so I didn’t even really need to touch it up before using it!

Next, I measured and marked out the locations for all the deck beams and ribs. I love this marking tool: it makes it easy to get the same distance from the edge every time, and even has a two-point setup so you can mark both sides of the mortise at once.

Then I  cut the mortises for the ribs using a router with a jig to enable me to reliably and fairly quickly make the same cuts. The mortises for the deck beams need to be cut at a compound angle, so they will be done later using a less automated process, once the shape of the gunwhales is defined.

The rib mortises came out pretty nice

The form of the boat is defined using plywood stretchers that hold the gunwhales. I think this process was designed for a much longer boat which would have had a gentler bend. In this form factor, the pressure on the gunwhales was pretty intense, and it was hard to get the forms to stay in place. The one in the foreground below really wanted to slip forward. I was consumed with anguish for days worrying that I had veered too far off the plan I was following. One concern I had was that the gunwhale tips didn’t meet at a sufficiently acute angle. They were expected to end up nearly parallel, but in my setup they left a pretty gap where they met, as you can see below.

 After mighty struggles to force a tighter shape into the gunwhales, I finally decided to relax and let the wood dictate the shape. I added a breasthook to hold everything together in the stern. Cutting the compound angles on that block was a fun challenge.

Here is the boat really beginning to take shape, with all its deck beams in place. The curved beams are raised up to allow space for the paddler’s legs. This is going to be a pretty tight fit! You can see the variety of clamping systems I used to hold everything together. I had some major issues getting to this point. When I first tried fitting everything together, some of the beams were too short, or maybe the others were too long? I had measured so carefully! What went wrong there I’m still not entirely sure. I think maybe the shape changed while I was measuring? It was under so much tension, and possibly not held completely still. I had to re-cut some of the beams to get them to fit.

Another significant challenge was ensuring the symmetry of the arrangement. The whole setup did have a tendency to rack and twist ever so slightly, and if I didn’t correct for that, I would end up with a crooked boat that wouldn’t track straight. Again I think a lot of these issues resulted from having shortened the boat from its original design. If I did this again, I might consider using beefier spreaders, or some other system for shaping the gunwhales.

In the end the line I ran from end to end settled over the previously-marked midpoint of the center beam pretty well. Off by less than 1/8″ over 12′ – I’ll take it!

One more photo of this stage, after pegging and lashing the ribs in place and removing the clamps:

This was a major milestone, time to take a break. When we come back, it’ll be time to steam-bend the ribs!


Skin-on-frame Kayak, prelude

I’m reviving this blog years because I feel like sharing a project I’ve been working on: building a skin-on-frame kayak. I don’t propose to teach how to build a kayak; I’m just learning! Nor is this a history of The Kayak. This is a personal journey of escape and discovery. I will share what I learn, the mistakes and struggles. Hopefully it ends with me in a boat on the water. Maybe I’ll even learn to roll it. I hope folks will find this interesting. For me it has been truly life saving.

[Note: about this blog, and comments. No more comments 🙁 I would love to get your comments! But the internet does not make it easy. When I last checked I had almost 100,000 spam comments, and I don’t want to devote my life to defeating spam. So … if you want to reply to me, send me a note on twitter, where I am @msokolov].

I was largely working at home before the Pan***ic started, so at first I hoped it wouldn’t make all that much difference to me, but after months of basically never going anywhere except upstairs and downstairs, and occasionally out in the yard to fill the bird feeder, my life started to feel pretty low-dimensional. Eat, sleep, crap, work, rinse, repeat. Shower occasionally, and maybe cut my own hair. I think we’re all living some version of this. So I started coming up with stuff to do at home. Picked up the piano again, played some video games, but I found myself dreaming about a life out of doors.

I’m not sure exactly where I got the idea to work on making a kayak. Maybe because my daughter has been working on a fantastic boat restoration project. Maybe because a boat fantasy is a pretty good way to dream of a life of adventure while cooped up indoors during a New England winter during a raging pandemic. For whatever reason, the idea of building a boat crept up on me until it seemed I just had to do it. Over the years I’ve leveled up my amateur woodworking skills and tools, so I managed to convince myself I was ready for some kind of boatbuilding project, but I wanted to find something on the right scale, and a kayak is just about the smallest watercraft there is. Its prehistoric roots also gave it an appealing glamor. Early Americans made kayaks from driftwood, bones and animal sinew that were sturdy enough to use for hunting whales in the open ocean! Surely with modern tools I could accomplish something that wouldn’t sink?

I started by clearing out our semi-finished garage-turned-extra room and buying some books. Cleaning out the room rapidly devolved into a yak-shaving exercise. Where would all the stuff go? This included some large family heirlooms, a guest futon couch, a big piece from our youngest daughter’s senior thesis project, and these larger encumbrances were surrounded by the other more minute detritus accumulated over the years in this out of the way corner of our house. I am pretty ruthless about throwing things away, but a lot of this stuff needed to stay. What about the family VHS collection? Disney – in the trash. Unlabeled VHS cassette? It might have somebody’s birthday on it! I made a box to send to a digitization service some day. It was a challenge not to become overwhelmed by all the stuff. At one point, I thought I might pull up the ratty old carpet and tear down the sagging ceiling. I fantasized about trash bags full of plaster and watched online videos about pulling up carpet tacks. In the end I decided none of this was essential to my project though. Happily I was able to repurpose some of the items for use in my new workspace. Here’s a glimpse. At least I would have decent light, especially after rewiring some defunct standing lamps we had stashed away in the basement.

The workspace

I bought a random sampling of how-to books about kayak making. There has been an explosion of books in this area: apparently I’m not the only one with this itch. The one I ended up settling on as a guide was Building the Greenland Kayak, by Chris Cunningham. This book’s esthetic appealed to me, as did its detailed instructions. The kayak design it presents is (I believe) closely copied from traditional models in its shape and parts. The ribs that form the hull are bent wood, and the joinery is all dowels and lashings; no glue or screws are used. The materials called for are adapted somewhat for modern usage, mainly in the covering, which is not going to be sealskin, but nylon or canvas (I chose canvas). Cunningham also presents various construction techniques adapted for whatever power tools may be available. He indicates possible approaches using only hand tools at every step, but it certainly would be a lot more work to mill the long stock without a circular or table saw. Apparently one traditional method of making ribs flexible enough to bend was to chew on them. I opted to save my teeth and make a steam box.

Another book I enjoyed reading on the subject was George Putz’ Wood and Canvas Kayak Building. This book is encrusted with salty Maine wisdom! I think its designs are less fussy to build, and probably a bit more comfortable, if heavier, than the bent-rib Greenland variety. Rather than bent ribs for a frame, Putz’ boats deploy a trestle-like amalgamation of cross-members along with floor “timbers” for their hull, and he has no pretense of traditional construction, relying on screws, glue and other fasteners throughout. I might try these ideas next time. I also consulted Fuselage Frame Boats, by Jeff Horton, which presents yet another approach to wood kayak construction; plywood frames to shape the hull (the fuselage).

Finally I should mention Brian Schulz of Cape Falcon Kayak. I chose not to enroll in Brian’s course or buy his plans, but I did learn a lot from the videos he has posted online, especially his excellent advice about steam bending.

I have lots more to say, but not today. Next time I’ll start gathering materials and making the first cuts.

Skin-on-frame Kayak, part 1

Site migration

OK it’s 2018 and it is officially time to stop hosting blogs in your basement. I’m moving this blog and various other stuff out of my laundry room server and into the cloud.

The move promises to replace the nagging fear of attack by bitcoin miners, death by power outage, hard drive failure, or flooding with a $3.50/month bill. That’s what AWS Lighstail hosting costs today for its very lowest tier. I also plan to restore my vanity email domain using this server, since for a few years now I have been unable to maintain that at my house due to Verizon’s SMTP port blocking. I’m also planning to move some larger archives (music, pictures, etc) to S3 and relay them here using S3-FUSE. I think this micro-host might just be enough.

Insecure Cat

Do you see the cat?

My Long Trail

I began to realize how excited I was only a couple of days before I left. I could hardly sleep for thinking about my upcoming trip. Meal plans and other logistical details kept spinning through my brain; the last I checked the clock was 3:55 AM. This is actually good I think.

I’d been casting around for some meaningful way to spend the 5-week early summer sabbatical time I had blocked out months before thanks to a new company policy (thank you Safari!). I considered launching an effort to climb state high points, and did a warm-up climb of Mt Greylock, the highest point in Massachusetts, but something about the plan never quite sat right with me. It would provide an excuse to go to Hawaii, sure, but would also require me to go to some only mildly diverting places, like someone’s back yard in Rhode Island, and Hoosier Hill in Indiana. Even the more dramatic high points are often not among the more interesting hiking trips in their area, and are usually beset with crowds seeking the obvious. I knew this from previous climbs of Washington in New Hampshire, and Whitney in California. And then there was Denali: I wondered just how much time, effort and resources I would want to devote to this program, which couldn’t possibly be completed in five weeks.

Then some plans I had made for the early part of my time off fell through, and I realized I might just be able to squeeze in an end-to-end Long Trail trip. I spent four happy summers at camp in Southern Vermont, and some of the most memorable times I had were backpacking trips on and around the LT, a trail that stretches the length of Vermont, passing over the main ridge of the Green Mountains on the way. The idea of hiking it end to end was always in the air on these trips, and it has stayed with me for more than 30 years now.

The LT is the spiritual ancestor of the more well-known Appalachian Trail, and coincides with it for 100 miles or so. The distance, about 270 miles, is a great deal more manageable than the AT’s 2200-odd, but the walks both seem to promise a similar kind of communitarian ascetic experience. A big part of the draw for me was to pare down my life to bare essentials; to focus my attention on basic issues of transport, shelter and survival. I hoped to gain some perspective on my everyday life through a period of detachment, and I felt that an extended hiking trip would challenge me while maintaining my attention.

This is the story of my end-to-end Long Trail journey.

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The two most common Solr performance blunders, and a rant about the dumbification of computer programming

Recently I’ve seen friends at work fall into a couple of well-worn traps, and I wondered – why do these same simple but devastating problems keep turning up again and again? The answer lies in deceptive software API’s, and the solution I think may come from video games. But before explaining all that, I want to just describe these two problems in a little detail.

Many programmers learn to deal with databases. Fewer work with full text search indexes like Lucene. I think newcomers to Lucene often bring with them the mental models acquired from databases, since they share many similarities. Both implement an “atomic” transactional model in which writes don’t become visible to readers until after a commit point is passed. This is critical in a transaction processing environment to ensure that two things succeed or fail together: for example, the concert ticket doesn’t get allocated to you unless ticketmaster confirms your credit card, and your card doesn’t get charged unless you get the ticket.

Lucene implements this model, but it isn’t designed to support transaction processing of that sort: it’s mostly optimized for batch updates and superfast querying across large numbers of documents (Yes, Lucene experts, I know about soft commits and near real-time, but that’s a story for another evening). This design criterion led to tradeoffs that tend to make committing expensive, very much more expensive than it is in a typical database.

Programmers writing their “Hello World” Lucene program don’t particularly need to be worrying about performance problems, but as soon as they start using Lucene for its intended purpose – indexing and querying large amounts of text – they do need to worry. Too often though it seems we fall into the trap of committing after every insert, causing a dramatic fall-off in indexing (and querying) performance, even to the extent of making a search service non-responsive. A very common version of this problem manifests itself in Solr, where you can see the dreaded “PERFORMANCE WARNING: Overlapping onDeckSearchers” message in the logs.

There are pounds and pounds of curative blog posts, wiki pages and stack overflow answers explaining this problem, why it arises, and what to do about it. And thanks to search technology, it’s pretty easy to find them if you go looking. But an ounce of prevention would save a lot of headaches here.

My number 2 most common Solr performance blunder is `fl=\*`. Solr search results include the values of fields stored in the index associated with the result document. Typical search applications show a title, with a link to a full version of the document, and possibly an associated contextual ‘snippet’. A few other fields like date, publisher or book title might be included too. Such applications must store the full text of every document in the index to make it available to the snippeting component (the highlighter, as it’s called). However, if that text is *retrieved* as part of the search result, and the documents are not tiny, this practice vastly increases the amount of data that needs to be transferred, often leading to a 10-100x slowdown in search performance. Programmers tend to do this because it’s just easier to retrieve all the fields (that’s what `fl=*` does) than to list explicitly only the fields required to display the result.

No decent Solr tutorial will lead a programmer to do this, and again, there is plenty of good information explaining how to select fields, but the Solr default is to select all fields, so this is a very easy trap to fall into. And it becomes even easier not to notice that this is happening when your queries are mediated by a middle tier.

I maintain an API for searching across multiple different backend data storage and indexing systems, and in that API we once defaulted to returning full document results. I believe our thinking was that beginners would have everything they need and not stumble over having to learn too much of a complex API even to get started. But I got tired of leaning over people’s chairs with a knowing grin and pointing out their n00b mistake. It really wasn’t their fault, anyway (it was mine.) They were just doing the natural thing, following the most straightforward path the API made available. So I changed the default, and I think the people I work with must be really smart since they seemed to be able to figure out how to get the missing field values when they really did need them. Even if they had to ask about that, it was much better to field a question like “how do I get the full text of a document in the search result?” than a question like “why do my search results sometimes take 10 seconds to come back?” because often a situation like that would be intermittent, only arising when really large documents made it into the search results, and could persist for a long time with merely mediocre performance before anybody really took note of the egregious outliers.

Apparently I’m not the only one making this mistake. [Safari Flow]( uses [Haystack]( as its internal search API. It’s welcoming words – I just stumbled on this while writing this sentence – “Search doesn’t have to be hard.” We recently found out that Haystack, by way of its defaults, encourages users to make exactly these mistakes. The Solr connector automatically commits after every insert, and I couldn’t even find any way to limit the set of stored fields returned. In both cases we had to fix these serious performance problems by editing Haystack’s Solr “backend” connector source code (in spite of its promise that “\[Haystack\] plays nicely with third-party apps without needing to modify the source…”

OK I’m a bit peeved about Haystack right now, but I truly hope the maintainers will read this and take it as constructive criticism, because their library actually does provide a lot of convenience to Django framework programmers grappling with search. Here’s my advice.

There is a notion gaining currency that programming computers is becoming easier. Sites like codeacademy teach JavaScript using a glossy, game-like spoon-fed interface. “Learn Python The Hard Way” presents Python (and other languages, in spinoff titles) using a baby-step scaffolded teaching approach (the only hard thing about it for me was sticking with it – to be fair, it acknowledges on page 1 that it wasn’t designed for impatient smartypants). There are many other “learn to code in 5 minutes” websites and courses that offer an easy path to software mastery.

This conceit that programming can be easy is partially fueled by the development of software languages and tools. It *is* easier to incorporate other people’s code now using reasily-available libraries and frameworks, and to make use of existing systems, so not every program has to start as a *tabula rasa*. It is *not* necessary to understand computer architecture in a deep way in order to write much useful and/or entertaining code now. In some ways, things have gotten easier.

There is also a cultural component to this new easy-going attitude: it’s a deliberate effort to be more inclusive, to shed the high-priest hacker snobbery that has been the stock-in-trade of software gurus for thirty years and more. “RTFM” with its veiled obscenity was always a little rude, even when uttered in jest, where its moral successor, “lmgtfy,” is simply peevish, but they reflect the same unpleasant underlying attitude of condescension. I’m glad to see some reflection on that negative side of hacker culture and thecorresponding openness to newcomers.

The positive side of the “learn to program” movement is that there are numerous ways to contribute without being a master. More than ever it is possible to go very far with very little. Silicon valley startups no longer sweat hardware: they just rent space with Amazon. This is healthy: it means that the culture as a whole is able to learn and grow, to stand on the shoulders of the previous generation rather than their faces.

I’m sure you saw this coming: yes, Virginia there is a dark side. The thing is, the obnoxious attitude grows out of a hard reality. Expert programming requires knowledge. Mental nimbleness and a problem-solving bent count for a lot, but true mastery of any craft, including programming, is only available to those willing and able to devote years of study, trial, error and correction. And there are still problems to solve that demand mastery, where beginners should be cautioned to read lightly.

So let’s stop saying that search can be easy. We do learners a real disservice by pretending that things are going to be easier than they are. There are complex problems in search, getting them wrong can kill performance (*i.e.* your web site), and our role as guides should be to offer paths to learning that have the right degree of steepness, and to offer warnings about potential pitfalls. If we take you on a mountain-climbing journey, and just tell you everything will be taken care of and there’s nothing to worry about, we’re leading you into a potentially dangerous situation without any preparation: in that setting, this kind of attitude would be criminal. Tell people to bring their helmets, and teach them how to self-arrest! Wat? Metaphor getting out of hand …

At the same time, we don’t want to scare people away. There’s no call to be going all high-priest-in-the-inner-sanctum with acolytes getting in only after years of fasting and prayer. Here’s where I think we can take a cue from video games. I read (this post)[] about luring gamers into playing the video game Devil May Cry. It talks about a game that is notoriously difficult, but also offers an easy way out. The interesting thing is that it challenges the player to try the hard way first, and warns them that there will be no way back if the easy path is chosen. Nethack, an insanely arcane video game, does a similar thing with its wizard mode: players can use it to try out all kinds of stuff, without dying, but it comes with a caveat: this is not for real, and your scores won’t be reported.

Zigzag wrapup

Phew – the polyurethane was drying on my last Zigzag chair while I wrote this post. It’s been a fascinating process, and I’ve learned a lot. Some questions got answered: the chair does not collapse under you when you sit on it, as numerous testers have confirmed, although it does bounce in a way that can be disconcerting if you are expecting it to give way at any moment. I still wondered how the idea for this form arose, and why it had to wait until the Twentieth Century.


My initial thought was that something about the need for bolts to sustain the chair’s joints made it difficult to achieve in older times. However. screws are ancient, were used in furniture production as early as the fifteenth century, and began to be mass produced in the nineteenth century in much the same form as they are today (see Nuts and bolts developed along similar lines, driven by the carriage industry, and widely used in furniture, especially beds, as early as the eighteenth century (when they were hand-forged). In fact nothing obvious about the construction of the chair itself would have made it impossible to achieve in an earlier time. However it certainly would have been more difficult. Highly-precise joinery that is more or less routine today and achievable by workers with a modicum of experience using power tools would have presented a daunting challenge to the master craftsmen of the past working only with hand tools.

The Zigzag exemplified the sleek design aesthetic of the machine age (in particular the De Stijl movement) with its minimal form, simple materials and lack of ornamentation. In previous generations, one could have achieved something similar, but there was simply no reason too: one imagines the idea would have been rejected as a bizarre freakish malformed thing. Acutely angled weight-bearing joints would have been difficult to achieve without machine tools; there was no call for them; they were simply not a part of the design vocabulary.

The chair is the most humane piece of furniture. Its job is to support our bodies, but in its simplest form a chair is a rigid unchanging object, while we remain free to fold and unfold, and we come in many sizes and shapes. Every chair embodies a series of compromises: the height of the seat, the angle of the back, the flexibility of the materials. These, and even carven ornamentations and surface finishes, influence the fitness of a chair for a certain person or activity. The demands placed on a chair by their very nature fuse its appearance and its function into a single inseparable shape, which is why a designer’s chairs often exemplify their aesthetic more than any other work.

I find the Zigzag attractively arresting, and I think it will make excellent chair for working at a desk and for dining, if not for napping. My only regret is not to have made at least a few of them higher, since I like to work at a high drafting chair. A slightly odd feature of the chair that takes some getting used to is its tendency to flex *forwards*, but as my father says, nobody has been pitched across the table yet.

OK I finished the chairs before I finished the blog post; here you see them installed in my dining room.

set of 6 in situ

set of 6 in situ

For comparison, here are some photos of an example from Rietveld’s studio produced in 1938:

1938 example from Rietveld's studio

1938 example from Rietveld’s studio, from the collection of the Carnegie-Mellon Museum of Art, photo: Lauren Hammer


Note the bolt-holes in the seat/back joint. I didn’t find it necessary to bolt this joint since the dovetails seem to be strong enough. On the other hand it took me many weekends over the course of four months to make eight chairs.


Also note that the screws are simply exposed

And some outtakes from the production. I ended up spending an inordinate amount of time finishing off the plywood edges, which is thr process being depicted below. Every chair required 8 pieces of trim that had to be fitted and glued. Because I made these from a standard 3/4-inch fir plank, the thickness matched the plywood’s exactly. Unfortunately this meant a very small tolerance for error during the gluing-up, and when it went wrong, the risk of sanding through the very thin plywood veneer was exacerbated. It would save a lot of time and effort to use solid wood. Still, the nicely-veneered fine-grained plywood surface is attractive and to my eye, enhances the modernist feel. Still, blue paint might be a nice way to go too!








ZigZag fanny test #1

It’s been a while since my last update; I’ve been traveling, and I hit some snags in the production line. It turned out that the clever joint I created just wasn’t going to work, and I decided I really did need to bolt the acutely-angled zigzag joints, as shown in the first fully assembled chair below.

the first chair assembled dry

the first chair assembled dry

In this view the pieces have been trimmed to their final dimensions. Here we can see the chair’s graceful proportions. It spreads out towards the knee and gathers itself in at the waist and heel.

fully assembled and glued, but still unfinished

fully assembled and glued, but still unfinished

Unfortunately, there is just a bit too much spring in the joints, and they creak ominously. I’ll need to brace the zigzags a little more stiffly by increasing the size of the triangle in the joints.

All seated

Finished up the joints for the remaining seats this weekend. Ellen didn’t think I was giving an honest portrayal of the working conditions in my shop, so here’s a full view, showing all eight seats in situ.

what a mess

what a mess

I’m relieved to have finished these joints, probably one of the more exacting tasks in this project. The joints came out pretty well, with only some small gaps (< 1/32") visible on the exterior. I should be able to close most of those up with a little more filing and chiseling, but for now I want to move on to something else. Next up: I have a mind to try a pair of sliding dovetails inside the acute bends.