Intro: Neutra Boomerang Chair
I was looking around an expensive designer shop one day and came across boomerang shaped chair that looked really cool. What wasn't cool for me was the price, the one I saw was about £1600 ($2200 USD), I'm sure a designer chair is worth that amount but not something I could afford, but I was sure I could make it!
When I returned home I searched for the chair on the internet and found out it was a Richard Neutra Boomerang Chair. Richard Neutra was an Austrian architect born in 1892 and the chair was designed in the 1940's when he intended it to be a do-it-yourself design. He also published a plan of the chair in the Women's Day Magazine.
You can find the magazine plan with an internet search which was my starting point.
I should also say that I did just make this one chair for my own use and don't intend for the following Instructable to be an aide to anybody's capitalistic tendencies to make and sell for their own profit!!! Rather a brief explanation of how to go about making such a chair.
Step 1: Planning
The chair that I saw and most of the commercial ones I've seen online use high quality plywood to make the chair sides but I didn't have any ply hanging around and oak faced ply was rather expensive. The plan in the Women's Day Magazine was made of two bits of hardwood doweled together and shaped. I had a couple of long planks of brown oak which had a lovely strip going down the middle of the plank and though it would be a good idea to try and make the stripe continuous along the boomerang shape.
The hardest thing was planning the cuts to create a continuous stripe and to make the shape out of 200mm (8") wide planks. I started off by getting rough dimensions of the chair from the Women's Day Magazine plan and sketched it in a 2D CAD software package. To get the missing dimensions I imported a photo of the chair and scaled it in CAD so I could measure the parts I needed.
Once it was sketched out I drew boxes of 200mm (8") over the boomerang shape to work out how I could use as little wood as possible and still sticking to the width of the planks. I worked out that I need to add a smaller bit of wood to one of the planks for the internal corner of the boomerang.
I have attached a pdf so you can see the layout.
Step 2: Chair Sides
I started off by cutting the first angle on the vertictal part with a circular saw on a homemade track.
I then layered this on top of horizontal part prior to cutting it so I could visualize and get the angle right on this second piece. I also layered these on top of the additional wood I'd need for the corner. Once I knew how everything was going to be put together I glued the small bit on the horizontal part and then cut the other angle once it was completely dry.
I then sketched the boomerang shape on the two bits of wood and cut the shape out on the parts with a band saw followed by planing the outside edges flat and sanding the internal edges smooth. To fix the parts together I used a glued butt joint using three pocket hole screws temporary clamps. Once it was all dried I removed the screws and filled the holes later with oak plugs. I did do both side at the same time so once I had the shape finalized on the first side I clamped them together and used a flush pattern bit on the router to make both sides the same.
Step 3: Cross Bars
The sides are fixed together using pegged through mortise and tenon joints. I started by marking the mortise with a pencil and drilled out the majority of the waste on a pillar drill finished by pairing the sides square with a chisel. I then cut the cross members to size and created the tenons on the bandsaw with a fence.
I could then fix the chair together and mark the positions for the peg holes which I then cut will a drill bit and chisel as before.
To make the pegs I constructed a jig for the bandsaw to cut small angles on small bits of wood. The photos explain the jig better than I can describe here!
The lower cross piece would be fixed to the sides later with pocket hole screws.
Step 4: Huge Dowel
The whole chair is supported on two 40mm (1.5") diameter oak dowels. I haven't made dowels this long or wide before so I needed to make a new jig. To make the jig you need to drill two different size holes halfway though a bit of wood. Where they join you need to cut a vertical hole with a router bit (see photos). You then attached a bit of wood to a drill with the router on and push it through the jig which essentially removes the edges of the wood to create a cylinder.
To work out the required size of holes required a little maths. The diameter of the larger entrance hole needs to be the same as the diagonal dimension of the square bit of wood that you're going to cut. The diameter of the smaller hole needs to be, at most, the dimension of the side of the square bit of wood.
Say you had a 40mm x 40mm hole the larger hole would need to be sqrt(40^2 + 40^2) = 56.6mm and the smaller hole would be 40mm. You do have to adjust these dimensions according to the size if drill bits you have though.
Once the jig is made you need to size the wood so it just fits in to the larger hole. I then put a fixing in the end of the wood so I could screw in some threaded rod to mount in to a hand drill. I then turned everything on and pushed the wood through the jig to make the dowel. I then sanded it while it was still attached to the drill for ease.
To determine the cutting angle of the dowels I clamped the dowels to the side of the chair and clamped a piece of mdf to the dowels. By drawing a line along the dowel length you get the cutting angle, which I then cut on the bandsaw with an angle cutting jig I made. The dowels are fixed to the chair with bolts and insert nuts with brass olives (used in plumbing) to create a gap between the dowel and sides. Once I had installed the insert nuts I used some pointed dowel bar to mark the position of the bolt holes I needed to drill in the sides of the chair. I then added a chamfer to the end of the dowel on the router table with a 45 degree cutting bit.
Step 5: Router Slots for Straps
The main body holding is done with webbing. Having never used webbing before I needed to research how-too's on the internet. I didn't quite find what I was looking for but ended up using a system where you have two different sized slots, halfway through the depth of the cross pieces, to each side. The webbing is then doubled over and pushed through the smaller width slot, a dowel inserted in to the loop and the webbing pulled back tight so the dowel 'locks' the webbing in to place. I marked all the positions of the slots and used a router with fences to cut them.
You can see on the photos that I initially used some blue webbing but this ended up being far to elastic and couldn't get a good, comfortable shape so I switched to a much more inelastic webbing in the end.
The photos show quite well the method I used on the chair.
Step 6: Finishing
Now I had all the parts I plugged the pocket hole holes and sanded the entire thing to 320 grit. I then added a couple of coats of hard wax oil. All that was left was to put it all together and have a lovely sit down!