To cut the mortises for the stretchers (front/rear lower stretchers and upper rear stretcher), I needed a couple more jigs. In these, I used a combination of the dowels and vertical slabs to center the end of the stretcher over the mortise slot. For the two 3/4" thick stretchers, I ganged both into a single template. The front lower stretcher is 1" thick, so it has its own jig, same idea.
To make this a knock-down chair, the lower stretchers and the upper back stretcher will be fastened to the side assemblies with connector bolts and dowel nuts. To ensure that the bolt holes are exactly centered on the end of the stretchers (two having the bolt hole through the floating tenon), I made a marking jig for each stretcher's tenons. I'll set it in place and tap a 1/4" brad point bit through the center hole to mark the drilling location. I'll use this for both marking the stretcher and the mating side assemblies.
These are the stretcher pieces prior to shaping and cutting to length. The 3/4" stretchers receive a 3/8" radius roundover. The 1" stretcher (under the front of the seat) will just get eased edges later. Its flat top edge will support a spacer between it and the seat frame.
I started with the front stretcher.
Before mortising, I put a clamp around the vertical guides to keep the jig from shifting on the end of the stretcher.
Then I setup for the mortises in the two rear stretchers.
The pressure-treated floating tenon stock is all 3/8" thick.
With some tenons cut to length, I could do a dry fit of the parts made so far.
Thanks, Eric. I think it's multi-purpose as an interesting design element when no arms are attached (they are sold with and without arms), but it's also the mounting hole for the back of the arm. I'm not sure that it would be necessary as a relief hole since there isn't any flex of the inverted 'V' of the uprights.
