A couple of days later, I remembered having seen a sketch of a chair in a book titled "Nomadic Furniture" by James Hennessey and Victor Papanek called a "Savonarola Folding Throne". After a quick search on the internet for better pictures of it, I thought I figured out how it was put together. Although I have only seen them in the open chair position and never folded, I could only imagine that the following is a pretty close (albeit very simplified) approximation of how it is done.
Step 1: Materials and tools
-Table saw - for ripping lengths of pieces
-Miter saw with attached jig - the jig makes sure that every piece is exactly the same (and all without measuring)
-Router with 5/16" bit and attached jig - the router makes sure the holes are nice and straight and the jig makes sure the spacing on the holes are exactly the same on each piece (again, no measuring needed once you make the jig)
-Drill with varying bit sizes and a 3/8" boring bit for counter sinking screws
-Sander - this keeps the slivers out of our tender bits
-Philips head screwdriver
-Rack for applying stain and polyurethane, and also for drying
-Foam brushes for apply stain and poly
-Safety goggles and hearing protection
-Square for making sure things are squarish
-Vinyl paper for spacers - I'll explain these later
-Hacksaw - for cutting dowels to length in the finishing stages of the build
-Three 1"x4"x8' boards (actual dimensions 3/4"x3 1/2"x8') - These should be as knot free as possible because we are using such small pieces and if the knots span the width of the piece it will be very weak there (I am using pine for this build, but other woods work very well too, as you will see in later pictures)
-Two 5/16"x3' wooden dowels
-Thirty-four 1" screws (something reasonably appropriate for use with wood)
-Wood stain - optional depending on type of wood used
-Polyurethane - again, optional depending on type of wood used
Step 2: Ripping the Lengths
Now set up the fence to cut all the boards into 3/4" strips. If you get it at just 3/4" and not a hair over (assuming you have a standard blade that gives you a 1/8" kerf) you will be able to get 4 strips from each board without any waste. When you set your blade height, you want the teeth to just clear the top of the board as it comes through. This will give you a nice clean cut as well as keeping the saw from throwing a bunch of sawdust in your face as you cut.
If you've done everything right so far, you should have twelve 3/4"x3/4"x8' lengths of wood. This will actually be more than you need, but some pieces may not be desirable for this project, so you want to have a little extra. If you only ended up with nine of these and three thinner ones, do like the Hitchhiker's Guide says and DON'T PANIC because the nine pieces will be enough if you chose very carefully when you bought your wood. If you don't have any knots or there are only very small ones everything should be fine.
Step 3: Cutting the pieces
The most efficient way of cutting these pieces is to cut two side pieces and two seat pieces from each length. When you're cutting these you want to be aware of a couple of things. First of all, you don't want any potential structural failures due to weaknesses in the wood, so watch out for splits and large knots. Cut your pieces from either side of these types of imperfections. If you cut two long pieces and two short pieces from each length, you will have about 10" or so of scrap left over, so if you have to cut a knot or split out of the middle of your length, you will still have enough to get your four pieces. Don't forget that you also have a few extra lengths to use too, so don't be too stingy and use inadequate pieces.
The second thing you will want to consider is the grain of the wood. I don't think so much about the grain with the long pieces, but you will want to have the most interesting grain showing on the top side of the seat section. With the way I am going to cut these pieces on the miter saw, that means I will be picking my favorite side of the wood and putting that down ( the longer side of the seat pieces is the top side of the seat).
Another thing you will need to be aware of when cutting these pieces is the straightness of all the pieces. Your pieces have to be very close to perfectly straight stock in order for this chair to work well. I have made these out of pine, black walnut and red oak so far. The oak was by far the easiest wood to work for this project. It cuts easily, stays true and finishes easily. The pine usually works well, but can sometimes look good when I buy it and as soon as I rip the 3/4" pieces, the wood starts to warp pretty noticeably. The pine will also tear out on the bottom side of drilled holes and the back side of miter cuts more easily than the other two woods, so a very light touch is needed when drilling and cutting pine.The black walnut was the easiest to cut and is by far the most beautiful wood of all three, but what a pain in the backside it was getting the pieces to remain straight.
With that said, you're ready to start cutting. First cut 17 pieces that are 27" long. I do this by cutting two pieces from each length until I have cut them all. That means you will have cut about 54" from each 8' length leaving you about 42". These long pieces are easy because they are just a nice straight 27" with no angles or anything.
With your miter still set for 90° angles, cut 4 pieces roughly 16" to 18" long. These will be used for the braces on the sides of the chair and will be trimmed up later to the exact length needed.
Next you will want to cut all 17 of your seat pieces from the leftover 42" lengths. First set your miter at 40°. Then you'll want to measure and mark a line 15" from each end of the 42" piece. Then, just go ahead and make all your cuts. What you will have left over will be the middle of the 42" length that is now a trapezoidal shape. Again, once cut, the seat pieces should be 15" on one side and 15 11/16" on the opposite side.
Next you will want to cut the dowels in half. This doesn't have to be exactly in half and most of the time I don't even measure this cut. These get trimmed up later to a more exact length so for now, close enough is close enough.
Step 4: Drilling the Holes
The seat pieces get holes drilled at 7/16" and 8 3/16" from the square end. The jig I use has a moveable stop so that I can drill all 17of the first holes, move the stop, and drill all 17 of the last holes.
Next, drill holes in the long pieces at 5 1/16" and 17 1/16". These measurements are from the same end, so you end up having a hole 5 1/16" down and one a foot away from it.
Step 5: Sanding and Finishing
As far as the finishing, I'll keep that part kind of short. There are sooooo many options for this that I couldn't even begin to talk about them in a single instructable. What I do is choose a stain (some chairs get no stain) and stain it using a foam brush and a rack I built to do the staining. This rack allows me to stain all sides and all pieces at the same time without having to wait for a side to dry so I can lay it on something. Then, once the stain is dry (usually two to three days later) I put a polyurethane on it to protect the wood from weather or coffee spills or oil stains from the skin of people handling the chairs (trust me - people are going to want to play with this chair when you show it to them!). If it's a hard wood, I will usually just put one or two coats of poly on, but with the pine, I will do at least three coats because it is such a soft wood. If you don't know if you're using a hard or soft wood, the easiest way to tell is to scratch it with your thumbnail. If it makes a sizable imprint, it's soft wood. If it leaves a very light or no impression, it's a hard wood.
All seat and side pieces get stained on all sides and ends. The four brace pieces that are cut get stained on just three long sides and you'll see why in the next step. Poly the three stained sides once the stain has dried.
Step 6: Assembly and Final Touches
The first part of the assembly is to attach the dowels to the two outermost pieces of the chair. You do this by choosing one seat piece and one side piece. You will then spread some glue evenly around in the holes drilled in both pieces and stick your four dowels in the four holes. You want them to be nice and flush with the outside edge of the piece. I do this and then slide another corresponding piece on the other end of the dowel without any glue to hold it level while it dries. Use a square to make sure your dowels are coming out of the holes at right angles.
Once the glue has dried, begin assembly by removing the unglued pieces from the dowels and lay the two doweled pieces on your work surface with the dowels pointing up. Orient them so that the seat end hole and the top hole on the long piece are right next to each other with the short side of the seat piece touching the longer piece. This explanation might be a little awkward, so refer to the pictures for a clearer representation. I use spacers in between layers of wood so that I don't get the pieces too tightly packed together. This also gives the wood a little room to shrink and swell (as wood tends to do) without doing damage to the chair. If you push the pieces too tightly together, the chair will either be very hard or impossible to open and close because of all the friction between the pieces. I use spacers made of vinyl printing paper. The thickness is about the thickness of two regular sheets of paper, but because they are made of vinyl, they are very durable and can be used over and over again.
For the next layer you will stack it the opposite of the first layer. The middle seat hole always goes on the same dowel, but the end hole will alternate from left to right dowel. Always put the next seat piece on so that the angled ends form a point with the layer beneath when looked at from above. If it looks like /||\ you are doing it right, if it looks like |\/|, your are doing it wrong. See picture for clarity on this step. Keep doing this - layer - spacer - opposite layer - spacer - layer......etc until you have all 34 pieces stacked up together. Once you have them all on, the two outermost layers should be oriented in the same way. If they are opposite, you either have two layers together facing the same way or you need to look for your lost pieces.
The next thing to do is mark the dowel so that it can be cut flush with the top layer. Just use a pencil or blade to make this mark. Then remove the top layer so the mark you just made is sticking out about 3/4" from the second to the top layer and cut the dowel at this mark using a hacksaw or some other small hand saw. If it's not perfectly flush, don't worry, because we can sand it once the top layer has been glued in place. Now spread glue in all the holes of the top layer pieces and place it back on the dowels and let the glue dry.
Once the glue has had sufficient amount of time to dry, cut the brace pieces to length. We haven't cut them yet, because the width of the chair can vary slightly based on actual width of individual pieces and how tightly we have pressed the pieces together. Lay the chair down with the spacers kept in place as much as possible so that it is resting flat on the work surface and measure across the outermost top and bottom of the side pieces. Again, the picture will probably help make this much more clear. I like to cut and screw on two pieces and then flip the whole thing over and cut and screw the final pieces. (That's right! I said FINAL PIECES! We're so close now....) This step is done with a scrap flat piece of wood under the side pieces I will be screwing the brace to. This makes gaps between the brace and side pieces much less likely and keeps the pieces from moving around while you are drilling and screwing. Start by drilling holes of appropriate size for the screws your are using (slightly smaller than the screw diameter) through the unstained side of the brace into the outermost side pieces keeping the brace flush with the ends of the side pieces. So, just two holes at this point. Then put a screw in each hole to hold the brace in place for the rest of your drilling and screwing. I then go across and first drill countersink holes in the brace at the center point of each side piece (I always just eyeball this instead of doing precise measurements and have always been happy with the outcome). Once all of those are made, I will drill the pilot holes for the screws in the center of the countersink hole, being careful not to go so deep that I come right out the other side of the side pieces. Then I will screw the screws into the holes I made for them, remove the two outer screws, drill countersink holes for the outer screws and put the screws in place. Do this at the top and bottom of both sides and the chair is now a chair.
Go ahead and open it up, you know you want to! Awesome!!
Now we just have to put the finishing touches on. That would be sanding and staining the sides of the braces that were not yet stained and putting polyurethane on to match the rest of the chair. You will also need to do a little sanding on the ends of the dowels so they are flush with the outside of the chair. I like to put a little masking tape on the seat and side pieces before I do this so that I don't ruin the finish with the sanding. Use a fine grain sand paper (150 grit or so) and work very carefully even with the tape in place.
And there you have it.
Step 7: The Finished Chair
The final dimensions of this seat are fairly standard and make it comfortable for a very wide range of body sizes and shapes. The seat height is about 17 1/2", width is 15" and depth is about 13". Depending on the wood this is made from it can support a tremendous amount of weight. I had a gentleman sit one of the pine chairs (the weakest of the three woods I have made this out of) who weighs about 260lbs and it was able to hold him just fine.I am 200lbs and 6' tall and can sit in these for long periods of time and still be comfortable. One of the red oak chairs I made was tested by another gentleman that is about 6'2" and weighs 370lbs and it was a comfortable size for him in all dimensions. It folds to about 3 1/2" thick at it's thickest point and is about 37" tall.
It's such a fun chair to make and show off to people that I would strongly encourage anyone reading this to make one if you have the time and the means. You really won't regret it.