A drawing to hold you over

"I had a perfectly wonderful evening, but this wasn't it"  Groucho Marx

A funny thing happened to me on the way to dusting off my table saw this past week. I ended up cleaning my carport instead. I suppose this isn't all that bad of a thing, really, as it only makes my outdoor work area less cluttered and safer to use power tools in. But it killed off the time I had originally set aside to cutting my beautifully planed and rip cut beech to length.

The good news is that we are currently experiencing our fabulous February desert weather down here (mid 70° F range daytime highs and low 40° F range nighttime lows, as well as no rain in sight.) Better to do all this grunt stuff now that in a few months, when it will start to get painfully hot outside. If all goes well, I'll have the table saw tuned up and cutting wood by the next weekend.

Something that I'll have to pontificate upon here at length fairly soon is the joys of biodiesel. This is transesterified vegetable oil - a petroleum-free "green" alternative fuel - that not only functions beautifully in just about any automotive diesel engine, but is also a fabulous solvent for de-rusting metals. Part of the carport cleanup found me restoring a couple of old, rusted Jorgensen clamps to near-new condition with nothing more than about a cup of biodiesel and a ScotchBrite pad. There are no harmful fumes (it basically smells like corn oil) and you don't have to worry about it attacking most paints or messing up wood parts. In fact, it actually does a fabulous job of cleaning non-finished woods, such as ebony, rosewood and teak. Biodiesel will be certainly be the subject of an entire future post. Marvelous stuff.

Also this week, I managed to find a little time to clean up at least one of my ragtag computer drawings of this chair. The one below isn't dimensioned, but subsequent drawings will have those details. I'll also eventually post a few detailed drawings containing more information regarding the dado and the drilling/doweling process.

I already wrote a bit about blind doweling but, in case you're wondering what, exactly, a Miller dowel is (I'll be using them on the 4 leg-to-cross-brace joints, instead of the carriage bolts found on original examples of this chair,) here's a web link that will clue you in. 

'Til next week . . .

The Cartesian node

"A lot of people are afraid of heights. Not me, I'm afraid of widths."  Stephen Wright

A Cartesian node . . . sounds like some sort of obscure part in the human anatomy, doesn't it? Or maybe some unsavory thing hanging off of said obscure body part that would require the assistance of a surgeon for safe removal? Actually, it's none of that.

Named for the 17th century French mathematician, Rene Descartes  - or, in actuality, for his Latinized name, Cartesius - a Cartesian node can be explained in proper mathematical terminology. But, dear reader, you're going to have to find someone other than me to do that for you. Much like Stephen Wright's aversion to widths, I get more than a bit flustered when letters like X and Y are part of equations that also contain numbers (this was all explained in my one of my junior high geometry classes, but I think I was home sick that day and it never did quite sink in.) So, in the interest of not to making an even bigger fool of myself by trying to communicate in a language I can't fluently speak, I'll simply give you some pretty pictures to look at and elaborate in plainer English from this point forward . . .

OK, that's much better. The 3 dimensional version of a Cartesian node (drawing, left) can be plainly described as a vertical post with couple of overlapping horizontal posts butted up against it (the word "adjacent" would be the more refined one to use here, but there's just something a bit more visceral and earthy about the phrase "butted up against.") One could also take that vertical post, by the way, and just as easily place it behind the two overlapping horizontal ones to get the same effect. Likewise, you can also reverse the order of the two overlapping horizontal posts and still have a Cartesian node.

Examine just about any piece of Gerrit Rietveld furniture from the De Stijl period and you'll see lots of Cartesian nodes. The vertical post ends up becoming one of the chair legs, for instance, and the overlapping horizontal posts  - variously named laths or cross braces - bring the four legs together. The beauty of this thing is that you can come up with a fairly strong wood joint by simply gluing your piece together this way. To get real and usable strength out of it, however, you'll need to also join together the adjacent pieces with dowels while gluing.

Take a look at the second drawing (left) for additional clarity. Well, actually, that drawing is still more grounded in mathematical theory than it is in carpentry reality. Sorry. The carpentry parlance for the technique its attempting to convey is blind doweling: dowels that are present on the inside bridging the two pieces, but which can't be seen after assembly. Unfortunately, the drawing gives the impression that it's possible to blind dowel all three. Not so. In reality, you can blind dowel the two horizontal laths protruding into the vertical leg. But, once that's done, the third dowel vertically tying the two horizontal laths together has to be drilled in such a way as to leave at least one end of that last dowel exposed. No big deal, really, if the resulting work is done cleanly. Rietveld, in fact, wasn't afraid to use rather prosaic looking carriage bolts or machine screws in place of a third dowel in these "gotta drill it all the way through" scenarios.

Back to reality . . . the photo (left) shows a closeup perspective of the rear leg joinery on a 1924 Rietveld "Military" chair, which is very similar to the chair I'm building. In this variation of the basic Cartesian node, there a two smaller laths present to tie the two rear legs together. Two more laths do the same for the front legs. These smaller laths (four in total) also capture the heavier horizontal side braces, which are there to bridge the front and rear leg assemblies. Look into the background of the photo and observe, on this particular Rietveld design, that the front leg is mounted on the outside of the horizontal brace instead of on the inside. Finally, the top laths - both front and rear - also provide a resting platform for the seat plank. This whole business of overlapping wood post Cartesian nodes really defined Rietveld's efficient furniture design philosophy and played into his larger goal of providing labor-saving carpentry techniques that could be accomplished largely with the use of (then) new and inexpensive machine tools.

I'll leave you this week with another unusual word to kick around: dado (pronounced DAY-doh,) which is yet another carpentry term. Imagine, for a moment, that the chair legs in the above photo have slots cut into them - maybe about a quarter or a third depth - that is just wide enough to allow those perpendicularly placed horizontal side braces to snugly rest inside. That's a dado. It considerably strengthens the already very strong doweled/bolted Cartesian node joint . . . and we'll be using this dado technique for our chair building project.

This sort of dado cut can be obtained with the aid of either a table saw or with a router. For reasons that I'll explain later, I'll be using a router on this particular project. Obviously, the width of the slot is critical. No need to be fearful of widths, mind you, but you'll surely want to pay attention as to what you're doing to make them as clean and accurate as possible. Accurate widths - and depths - will involve carefully setting up the router with something called a template collar, or guide collar, which has to be precisely centered around the cutting bit. A template - typically a flat piece of wood, metal or plastic, with a precisely dimensioned rectangular hole cut through it - then needs to be fashioned and securely clamped onto the piece of wood needing to be cut. If all goes well, you get a perfect dado. As to the exact details of how it's all done, with some nice pictures to go with it? Well, that's the subject of another post- or another couple of posts - for another time.

Comfort and ergonomics

"The superior man thinks always of virtue; the common man thinks of comfort."  Confucius

I picked up my planed and width-cut beech from Peter's shop on Friday afternoon and it looks great. Not much time for any real carpentry this past weekend and, as usual, the upcoming work week will probably keep me at bay. But while I'm waiting for some quality time at the table saw, I guess I'll wax on a bit about chair comfort and ergonomics. 

The few people who I've talked to in person thus far in regards to me making copies of Rietveld's 1925 Chair with Spring Seat have all asked "Is it going to be comfortable?" Well, good question! I won't know for sure until I actually build one and sit down in it, I suppose. But I've got an educated guess that it will be. Leading up to choosing this subject to build,  I took careful measurements of just about every chair we have here in the house and compared them with the dimensions outlined in the below two drawings, which I present here courtesy of Wood Magazine and their associated web site.  As the web text there reminds, this is merely a basic set of guidelines and not a precise blueprint for any and all chairs. Dining chairs are going to be fundamentally different than lounge chairs, and so on. But it's a good place to start.

I also found a used copy of a 1997 book titled Chairmaking & Design by Jeff Miller (Taunton Press, ISBN 1-56158-158-5) that is chocked full of good information. Most of what I've picked up there was either previously unknown to me or long forgotten knowledge pertaining to wood shrinkage, joinery techniques and proper grain orientation of the basic components. All in all, it's an excellent overview on the subject and on woodworking in general. Anyone contemplating the construction of any sort of chair should give it a read.

It turns out that the chairs in our household allying closest to the ones matching these hypothetically ideal drawn dimensions and also matching my preliminary dimensional drawings of the 1925 Rietveld chair  - especially when comparing seat and armrest height, back angles, etc. - belong to the rather nondescript metal framed ones that live outside, behind the house on our patio (pictured below, right.) Happily, these rather pedestrian-looking patio chairs are also among the most comfortable ones we own. They're a compromise that function quite nicely as both something you could use to sit at a table while eating a meal and what you might also want to use to casually sit while reading a book . . . probably working slightly more effectively at the latter than the former. Interestingly, though, the upholstery on them is almost nonexistent and, in fact, you hardly miss those cushions when they're removed. They don't look like they would be the most comfortable chairs in the house. But they are.

It should be noted that the most well known Gerrit Rietveld chair - the 1917 Red & Blue - isn't exactly best remembered for being the epitome of comfort in the conventional sense of the word as it is for creating a bold artistic statement, which it certainly did back then and continues to do so even today. In regards to comfort, Rietveld himself was fond of saying "We must remember that 'sit' is a verb, too." Author Paul Overy, further commenting on this in his book, De Stijl, writes "One of the functions of Ritveld's chairs, with their hard seats and backs, is to focus our senses, to make us feel alert and aware. Rietveld was not interested in conventional ideas of comfort (the 19th century armchair that relaxes you so much that you spill your coffee or fall asleep over your book.) He wished to keep the sitter physically and mentally 'toned up'." Hmmm . . .

That said, the Red & Blue (an early version, shown in photo, below, with the designer/builder seated upon it while enjoying a smoke along with his young disciples standing behind him,) with its sloped back Adirondack-like proportions, isn't exactly a medieval torture device either. Yet the lack of opulent upholstered padding and the minimalist stick frame superstructure would probably be off-putting to today's typical American consumer, waltzing through the aisles of the local La-Z-Boy outlet in pursuit of a padded recliner to plonk in front of the widescreen HDTV.

Incidentally, it's worth noting that the Lay-Z-Boy recliner we have in the back room of our house rated rather low in my chair comfort survey. Regardless of seating position selected, it has a nasty tendency to drain the blood out of ones wrists due to the overly high mounted and rearward sloping armrests and, despite all that extra stuffing - or perhaps because of it - lower back support is seriously lacking. Hmmm, indeed. Score one for the Dutch Neoplastisists.

First entry: background and inspiration.

"Don't play what's there, play what's not there."  Miles Davis 

Well, here's where it all starts, I suppose: the first of what I hope will be many posts on this blog. I will have to admit that 2011 was a particularly strange year for me and I generally wrote off most of those 12 months as an ongoing series of mid life crises . . . lots of changes at work and in life; some good, some not so, a few unexpected pleasant diversions and a few blind alleys. Uncharacteristically, not much of anything got built by me that whole year. I vowed that 2012 would be very different in that respect and, thus far, it has been. This project, assuredly, will make it so. 

Over the 2011 Christmas break I decided to get involved in some sort of interesting carpentry project as the new year started. I happened to dust off my copy of Peter Drijver and Johannes Niemeijer's How To Construct Rietveld Furniture for some inspiration. What really got me going, however, was the a photo (left) that I found on the internet in early January. This isn't a design that can be found in the How To . . . book, but it has remarkable similarities to a series of Gerrit Rietveld pieces made in 1923 or 1924 for the Catholic Military Home in Utrecht, Holland. One of these "Military" designs, as they are called , a simple stool, is featured in the aforementioned volume. This gave me some very good technical details and dimensions to get started.

Using the detailed 3-view drawings published there and various photos found online, I drew up what I believe to be a very accurate rendering of the chair in Adobe Illustrator (a program I use for various drafting projects, among other things) and spent most of my free time in January at the computer, working on various 3-views and mapping out the details of individual parts. I'll clean up and consolidate these technical drawings to a more readable form and post them here at a later date. Eventually, a complete and illustrated set of "How To" instructions will be presented here.

Realities dictate that I'm not going to make a hyper-exact clone of this piece of furniture - which, by the way, is simply called "Chair With Spring Seat." For instance, I'm not going to paint my examples in bright primary red or use carriage bolts to attach the legs to the horizontal braces. But I'm willing to bet that my backward engineered drawing is extremely close to the proportions and dimensions of the original . . . allowing for the metric-to-inches conversion, that is. My logic for doing this follows that, since all the raw materials I'm buying (wood and fasteners) and tools that my subcontractors and I are using (width of table saw blades, diameter of router bits, etc.) are calibrated in inches here in the U-S, that's how I will be calibrating dimensions on my copies of this chair. If I was living in Europe or Asia and my materials and power tool settings were calibrated in the Metric System, I would go that route.

I'm completely comfortable "thinking" in both inches and millimeters, but I'm inclined to want to work in just one measurement world on any given project at any given time, if possible. Old habits die hard. When given a choice, I usually choose inches, as this is what I grew up with. But I'm not a slave to the fraction. Since I've become acclimated to drawing my plans on the computer in recent years, I've gotten used to expressing fractional inches numerically, or in decimal "machinist" inches. So . . . 1/16" becomes 0.0625", 1/8" becomes 0.125", 1/4" becomes 0.25", and so on. When it does come time to move back and forth from inches to millimeters (it's bound to happen eventually,) expressing fractional inches in their decimal equivalents makes far more sense.

Some subsequent email communication with Jaap Oosterhoff of the Central Museum in Utrecht gave me a little more of an historic background on this chair than I already had. It turns out that only one of them was made back in 1925 and it currently resides in Rietveld's famed 1924 Schroder house. Subsequent reproductions exist (a photo of one on the left,) but these were made at a far later date. As with most Rietveld furniture designs, this is simple carpentry and half the fun is making it yourself, while adding just a bit of yourself to the project along the way. I'm sure Gerrit would approve.

It just occurred to me that many who are going to read this haven't a clue as to who Gerrit Rietveld was and what's the significance of the Schroder house or the post-WWI De Stijl art and architecture movement. For a good cursory historical background, here is a Wikipedia link that will hopefully give some perspective for the new and uninitiated.

Still with me? Good. I'll just add that Gerrit Rietveld is one of my heroes on so many levels. I'm sure I'll have more to say about him, De Stijl and my take on the aesthetic joy of clean modern design at a later date. For now, though, back to the Chair With Spring Seat . . .

First, I had to decide what I was going to make this thing out of. Birch is the traditional wood for these sort of early to mid 20th century European furniture projects but, as I soon found out, it's VERY difficult to find good birch here in southern Arizona. Part of my dilemma arose because I was dealing with a wood structure made mostly of laths that measure in widths and thicknesses of  2.2cm or multiples thereof. 2.2cm is very close to 0.875" (7/8") and - if you want to be totally precise about the metric-to-inches conversion - 2.2cm is exactly 0.86614173" (yeah, try making a fraction out of THAT!) This was, presumably, a very common thickness for wood stock in Holland in the early 20th century. Most hardwoods here and today, however, are finished milled on both sides to 0.75" (3/4") and this includes all the birch I happened to run across. This is also true in regards to other commonly used American hardwoods, such as maple and red oak. While some of these hardwood varieties might also be available locally in so-called '8/4' thicknesses (realistically, around 1.5" when cured and finish surfaced on both sides,) I was unable to find any birch milled this way.

Fortunately, I happened to locate some particularly nice European beech, which is another sturdy hardwood you might find these sort of modern furniture designs being rendered with. The actual thickness of the finished stock I found was 0.9375" (15/16".) I purchased 10 board feet of this stuff - enough for two chairs - from Woodworker's Source here in Tucson on January 28 for around $67. I had them make cursory cross cuts at lengths I specified (slightly longer than the finished pieces I was going to need) and I was then was able to easily haul it away in the trunk of my car.

A local cabinet maker I met while searching out wood options, Peter Baer, said he would be able to cleanly power plane my beech down to the proper 0.875" thickness and then accurately rip cut the boards to the finished width dimensions of the laths and planks (0.875", 1.75" and 2.625".) I simply don't have the sort of machinery to do these steps cleanly and accurately myself, so I dropped off my stack of beech planks to him on February 3. All I would need to do after he was through would be to do some dado work with my router, make finished cross cuts to precise lengths with my contractor's saw and start gluing/doweling everything together. A pretty simple - yet satisfying - carpentry project, all in all, that would keep me out of trouble for a while. The bent ply seat and back? Well, that's going to be a bit of a challenge, but I've got some good ideas as to how to proceed there. That will be the subject of at least several future posts.

Just today, February 6, I got a phone call at work from Peter's shop, announcing that my wood was ready to pick up. When I get paid on Friday, I'll swing by and grab it. The real fun starts then.