The two side frames are now complete. Now comes the last joinery step of routing the three spline slots in each of the 6 miter joints. This is done on the Multi Router of course. The machine table has a center line that I use to line up the joint. I marked the first joint for the slot locations, then set the two stops on the z axis for the two outside slots. I machined these first two, then reset the height for the center. The results were good.
I unclamped the assembly and continued on with the other joints. Next I milled a piece of ash to fit the slots. I inserted the piece, then traced the shape. I cut out three of these triangles right next to each other. The result is grain that lines up across the three splines. These are cut so the long grain spans the two halves of the miter, making a strong reinforced joint.
With all the splines glued in, I'll be flushing them up and continuing on with the shaping of the two assemblies. I also need to make a bent, laminated plywood shell for the back upholstery panel. This is a change from the prototype, but it will be a better chair. That's why we build prototypes, right?
I had been thinking the side assembly would have to be done all in one shot with the three miter joints and the three mortise and tenon joints. Fortunately this was not the case. After doing a dry run, I decided to do it in three steps, each being very low stress. First I glued the side rail to the front and back leg. The clamping was made easy by the little extra nub I left on the angled end of the back rail. This will now get a radius cut to flow into the rear leg.
To glue the two miters on the rocker, I could have glued some blocks on to each side of the joint to allow me to clamp in the right direction, similar to what I did for the back leg joint. That was quite time consuming, and I came up with a better way. Since there will be spline slots cut across the miter later, I took advantage of the situation and used strategically located trim head screws to act as my clamps. It worked great, was quick, and it will be gone once I remove the screw and cut the slots.
All these joints came together very well, without a second set of hands, and no swearing.
The final step of the sub assembly is the arm. This one was a little bit trickier, involving three clamps. The miter wanted to slide past where I wanted it to be, and getting it back the other direction caused some gaposis in the mortise and tenon joint on the back of the arm. I had to leave well enough alone, the arm still needs some final shaping so it will be fine.
So here is the first assembled side, ready for final shaping. The mortises for the back rails are done, so the final glue up will be a piece of cake once the other side is all together tomorrow.
Wow! I had a very productive day today. I fit the tenons for the side rails and dry assembled the rail to the legs. I put this sub assembly on top of my full size drawing to work on the layout of the miter joints. I set the rocker on top of the legs and marked the intersections. I then bisected these layout lines to get the angle.
I used my new Veritas sliding bevel gauge (Thanks Mom!) to set the angle on the miter gauge on the Felder.
I cut the angle on the bottoms of both rear legs, then both front legs. Then I scribed the rocker to each leg.
Here is the set up I used for cutting the miters on the ends of the rocker. There's a pneumatic clamp (not in the frame) holding down the far end while I make the cut. This worked really well, I crept up on the mark by advancing the black stop on the miter gauge. If you just slid the rocker on the cradle, the angle would change.
Next I cut the angle and the triple mortises on the end of the arm blanks. I'm using the Festool Domino for this operation. For multiple small tenons, its the way to go and can be set up and executed faster than the Multi Router. Those three mortises are cut off one layout center line, and the machine has indexed height stops so its perfectly repeatable.
Now that all the joints are cut for the side assembly, I can go ahead an put it together. I'll do some preliminary shaping of the arm before I glue it up, but here it is! Hope to glue up tomorrow. Looks like I'm going to have to do it in one shot though. I hope Laurie can help.
Today I continued with the final smoothing and shaping of parts for the chair. This work is done with a small arsenal of tools, from planes, spoke shaves, scrapers, and the good old edge sander. Here's one of the back legs getting refined.
Next I continued on with the joinery. All of the mortise and tenon work is done now with the exception of the two back rails. All of these joints were cut on the Multi Router. For those of you who do not know what that is, have a look here http://jdstools.com/multi-router.aspx. It is essentially a 3 axis milling machine, manually controlled rather than CNC. It is the fastest, most accurate way to do a great many operations on the shop, joinery and otherwise. Here's a mortise being cut in the front leg.
The side rails have a pretty sever miter on the back end. Because of this angle, it will make clamping that joint difficult. The rail will also have a curve at the intersection to make it flow together with the leg. I opted to leave an extra chunk of wood there, with the right angle to aid in clamping. This piece will get cut and shaped to create that curve after glue up. Here's that rail getting mortised.
Tomorrow I will be fitting tenons, mortising the back rails, and starting the arms. I will also start building the fixture to hold the assembled sides while I cut the spline slots in all the miter joints.
So I haven't been blogging for a while, but I have another long distance customer and its a good way to keep them up to date. This project is a Mid Century inspired rocking chair for Anna and her new arrival Matilda. This has been going on for quite some time with design work, fitting, and a full size prototype. That first version is at the upholsterer right now and should be done soon! My upholsterer David at http://www.remnantsdesign.com/ is the best. He specializes in exactly what we're doing here.
Here is a photo of version 1, sans upholstery.
The final version of the chair will have splined miter joints where the arm legs meet the rocker and the arm. The back leg will also kick out a bit further toward the rear.
The rockers are the first thing, since the 7 layer lamination takes 24 hours to dry for each. I rip 1/4" strips off a board, keeping them in order the way they came off. Next I run the strips through the wide belt sander, removing the bandsaw marks. I put the stack back together, and prepare my glue. I use Unibond 800 for laminations because of its very rigid glue line. I roll glue on with a foam paint roller, stack them up in order. I finally found a perfect use for these goofy clamps I bought on auction a while back. They don't slide off when used on a curved surface!
Once the glue is cured, I joint one edge, then run the other side through the planer. I'll set these aside till I'm ready to cut the miters on the ends.
Next, I started milling the 3 rift ash boards, then used my patterns to select the grain I want for each part. I rough cut each part on the bandsaw. Then its on to joinery.
I'm going to do the bridle joints on the back legs first. I cut the angle on the ends of the four parts on the sliding table saw. Next I machine the mortise on the Multirouter. I make test cuts so I get it perfectly centered. Then I use mortise to set the cutter height for the tenon. Once I cut one cheek away, I've lost the reference to the fence on the machine for the other side. I milled up a piece the exact same size as the length of the tenon to use to set the piece up for the other side. Forgot to get a picture of that. It worked great though. I dry fit the joint, and its a bit tight. Couple swipes with the Clifton plane and its right where I want it. This is a difficult joint to glue up, like a boomerang in two parts. I've decided to add glue blocks to each face so I can clamp in the right direction.
Once that glue has set up about half an hour, I go ahead and glue up the leg joint. Awesome, squeeze out all around.
I leave that clamped for an hour or so. Then I have to cut and plane off those glue blocks. It was a pain, but the result was worth it. Perfect joints. Next I'll be cutting and smoothing the leg to final shape.
