The back assembly is broken down into five slats, the foundation and one support piece. The center slat is 7” x 33” and has a radius of 3.5”. The radius is easy to make with just a compass. Extend the compass on a ruler until it spans 3.5”. Mark your slat down 3.5 from the top and 3.5 from the side. This gives you your center point. Place the metal tip of the compass on this point and swing the business end in an arc creating your half circle/radius across the top of the board. You now have your radius.
The 4 other slats all have identical radii (2 15/16”) and differ only in length. The inside slat is 29” long and the outside slat is 26.5” long. I cross cut and rip these from two 1×4’s. Because the board is already ripped to the correct width your radius is easy to make. Open your compass to 2 15/16” and place the business end of the compass at the very corner of the board and the metal tip on the edge, the rotate the compass in a half-circle to get your radius. (Hopefully I explained this ok since I can’t find my compass to take a picture of the process. I am using templates that I’ve had for a long time and so I don’t need to do the compass thing again.)
Once all 5 boards have the proper radius drawn on it, take the pieces to the band saw and rough cut the shapes. Try to get close to your pencil lines but not right on the line, you’ll clean up the edges in the next step. I stack cut two of the slats at once by using carpet tape to secure them together.
When the boards are rough cut you can decide how you want to get the slats down to the line. You can use a power sander, a router using your template or you can file them down. If you choose to sand or use a file – it’s a good idea to put several pieces together so that as you shape one you shape two to be identical. I simply leave the stacks I made to band saw the shape together and shape them as one. I’ve done a lot of these and I generally sand or route. However, as most of you know, I’m on a hand tool quest trying to make my woodworking a bit quieter and comfortable. I’ve discovered the Microplane system of files/rasps. Let me put this simply. I will never, ever, never sand these shapes again. With the fine Microplane I was able to final shape all the slats in less than 10 minutes tops. Sanding would have taken considerably longer and would have created a large amount of dust. The Microplane does not create the dust and was actually enjoyable to use. With very little effort they all turned out great. The other nice thing is the Microplane is not expensive. $16 for the handle and one file and $9.99 for the other inserts (At Woodcraft – the prices are about $2 higher than the Website.)
If you choose to use the router to final shape your slats. Be careful. You are trimming off end grain and it can split in a great big hurry. I used to do it this way on a regular basis. If I got a split, I lived with it. I probably will not revisit this method.
Next crosscut a 1×4 to 19.5”. This is the foundation for the backrest. This needs to be as close to 19.5 as you can. This particular project is not fine woodworking and most measurements can be fudged a bit here and there. This is one that is pretty important to be 19.5” If you already have your seat assembly done you can measure between the back to get an exact measurement needed, but it should be 19.5”
Out of some scrap you need to cross cut and rip a piece 1.5” x 18.5”. This piece will be your upper support.
I put my back support together using the Kreg Pocket Hole system. It’s quick, simple and strong.
To assemble the backrest start by laying out the slats in the correct order (good faces down) and place dividers between each slat. Once laid out the whole back should measure 19.5” to correspond to the support piece you cut earlier. If your assembly is not 19.5” across you need to figure out why at this point. If it’s a bit to wide, then decide if your spacing is off (check your spacers to be sure they are all the same thickness) or if you may have cut your slats to wide. You need to fix this problem before you move forward.
I actually ended up being just a smidge over 19.5” and decided to trim half a smidge off each of the two outside slats. If you end up doing this you need to be careful how you run the slat through the saw. You need to run the side through that does not have the curve – this will keep your radius the same as the other slats. Also, be sure to push the slat through the saw by using a push stick on the square edge not the curved edge. Safety first.
The two photos show the wrong way to cut.
This is the better way:
Once you are satisfied that your slats are correctly spaced, place them all on the worktable so that the bottom edges are even and place the support piece on the end. Make marks on the support piece for one screw (centered on each slat) for each slat and two for the middle slat. Use the Kreg jig to cut these 6 holes.
Before I screw the support piece on, I generally use clamps to keep all the pieces together. This keeps me from having to wrestle with a piece that wants to slip around once I get glue on them.
Once that piece is secured, measure up from the bottom 23 1/8” on each of the outside slats. At that point measure in from the edge ½”. This is the position of the upper support piece. I secure this piece with one screw in each of the small slats and two in the large middle slat. I countersink these. Glue and screw this piece on an your are done with your backrest.
Now would be a good time to slip the back rest into the seat assembly to be sure it fits.
Next is the arm assembly. As always, your thoughts are welcome.
-- Like a bad penny, I keep coming back!