Angled Mortise and Tenon, Chairmakers Saw and Tenon Clamp

steve morris

Member
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52
faced with the prospect of making 6 dining chairs with angled M/T joinery, i came up with this jig and saw via a google search
they are called a chairmakers saw and a tenoning clamp

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the clamp is pretty simple, 3/4 plywood, glued and screwed, then a clamping jaw with a bolt, nuts and washers. and a handle

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then the shoulder cutting saw:

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its just a block of white oak scrap, a japanese folding saw blade and an old plane knob and tote, all bolted together

these make cutting the angled shoulders easy and accurate

here's a couple more shots of the saw.

i started with a scrap of white oak, 2" by 10", about 1 1/2" thick

sliced it to give a 5/8 thick bottom, jointed and planed the bottom for a consistent thickness

drilled some holes for 5/16 bolts(be careful drilling the very thin blade)

a junky old hand plane gave up its knob and tote, a couple of squarehead bolts(makes it look old!!) and nuts and washers

this is the saw from lee valley, i always have a couple of these around and a spare blade or two

http://www.leevalley.com/en/Wood/pag...884,42898&ap=1

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the cheek cuts were done on my tablesaw with my shopmade tenoning jig

the angled mortise was cut using my beaver drillpress and hollow chisel mortising attachment. note the angled scrap under the work piece

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and here is my tenoning jig for the tablesaw, nothing fancy, just some scrap 3/4 plywood. note that i added hardwood to the sides of my rather narrow old delta jetlock fence for more stability for the jig. the jig just cuts the cheek cuts, the shoulder cuts are done as above

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im at the "prototype" stage at the moment, practising and setting up with scraps

i'll be building this chair(6 actually): http://www.popularwoodworking.com/oct15/slat-back-chair

the article has some info on the clamp and saw
 
not my idea!! origanally a french design a century ago

ive used a couple of times to get the hang of it, got some improvements to do

the saw registers on the clamp top surface, so the walls need to be thicker. also the saw needs to be longer although the blade is long enough, the saw keeps "falling" over the edges and the knob and tote hit the tenon

so a new and improved version is coming!
 
Steve, just a heads up as I looked into making a set of these chairs a while back. I found a couple of dimensional errors in the article and sketchup file. I asked Jeff and here is the response he sent me:

Bob,

Thanks for pointing out the problems. And my apologies that they crept into the plans.

Most of these problems arose from my less than perfect drawing ability in SketchUp (I submit rough drawings), combined with editor turnover (Bob Land started work on the drawings, then the article sat for a while, and then Donna Hill took over).

The drawing of the chair on p. 28 has the right dimensions: the back leg is 43 1/2” tall and the front legs are 17 1/4”. I don’t really know why the different dimensions showed up, although I suspect it’s because the leg angles back and the measurements may have been generated either on that angle or not.

I didn’t put the grid behind the leg in the back leg pattern, but that is obviously wrong. The leg shape is correct, though.

I usually specify extra length for curved parts that will be bandsawn, so the 46” length in the cut list is about right. They should have put in that those were rough lengths, though.

I hope that this helps.

Best wishes,

Jeff​

God luck with the project. Looking forward to seeing the progress.
 
thanks for that info bob, i did come across that error when drawing out my rear leg pattern, my 48 inch piece of plywood was too short!!
i will post a build thread when i actually get started in a couple of weeks, it will be my first "real" chair project

im still working on perfecting the angled mortise and tenon joinery, just about there

a minor improvement to the chairmakers saw, i made it longer. 18 inches overal actually, now the tote, knob or my hands dont hit the workpiece. also the blade is not bolted in anymore, just clamping the two blocks of oak together is plenty.

also using the wedge for the angle(18 degrees in this case) as additional support, helps hold the workpieces for the side and back cuts

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