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How is a chair round back joined

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Forum topic by wakinews posted 06-04-2018 10:11 AM 539 views 0 times favorited 8 replies Add to Favorites Watch
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wakinews

16 posts in 300 days


06-04-2018 10:11 AM

Hello team,
I have a project to make a chair with a round back but I have no idea how i can
join the round back to the legs. Should it be one solid wood from the back to the legs or it can be a joint, if joined, how can i join the two? See the image below of what am talking about.


8 replies so far

View ChrisK's profile

ChrisK

1984 posts in 3202 days


#1 posted 06-04-2018 10:42 AM

Mortise and tenon with glue? With a lot of attention to fitting the pieces.

-- Chris K

View Ron Aylor's profile

Ron Aylor

2649 posts in 768 days


#2 posted 06-04-2018 11:14 AM



Mortise and tenon with glue? With a lot of attention to fitting the pieces.

- ChrisK


Ditto… this is where these little devices come in handy… Tenoning Clamp & Chairmaker’s Saw.
 

View msinc's profile

msinc

501 posts in 624 days


#3 posted 06-04-2018 11:15 AM

Wow, good luck doing that!!! The one I saw was similar to your photo on top and had a fairly wide angle where they attached. The maker used dowel rods and drilled clean thru both pieces, he had two at each joint. He was an expert and did a fantastic job of matching the grain because unless you really looked you couldn’t hardly see the dowels.
I don’t see why biscuits wouldn’t work though for the top one, the bottom looks like it would have to be a mortise.

View John Smith's profile

John Smith

1313 posts in 283 days


#4 posted 06-04-2018 12:28 PM

Wakisa – I don’t know how the old artisans did this back in the day,
but, for me, I have a tendency to use steel threaded rod embedded in epoxy
in the joints that will receive a lot of stress – like a chair back or legs.
I have repaired broken furniture with this technique, but never actually built one.
I think I would make the rough frame first with reinforced joints, then carve the detail.
is good to see you again !

.

-- some people are like a Slinky - - - pretty much good for nothing. But still make you smile when you push them down a flight of stairs.

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wakinews

16 posts in 300 days


#5 posted 06-04-2018 01:37 PM

Thanks a lot guys, I think taking the mortise and tenon route will be an uphill task especially the tenon. I will try dowels first. @John, I think a steel threaded rod would be stronger. I might have to try later. its always a pleasure to hear from you John.

View Loren's profile

Loren

10477 posts in 3769 days


#6 posted 06-04-2018 03:16 PM

With the top chair I think the apparent joint is
false and the leg continues upwards by way
of a scarf joint.

You can see the continuity of wood color on
the leg in this chair, with what may be a butt
joint several inches up to join the upper
portion of the back to the lower half. Since
the legs are mounted on a half circle shaped
seat rail, they are not as curved in two
dimensions as they appear. What I think
may be a butt joint may not be. Once
the curve of the leg in one dimension is cut
with can also be added at the top by gluing
a block to the side of the leg. This allows
the upper part of the leg to be shaped in
the other dimension. This sort of chair back
is probably made to hold a curved piece
of laminated plywood inside. In the old days
they may have used something like steam
bent wood strips stuck into mortises on the
insides of the legs.

The second example the whole back assembly,
the legs and back appear to be on a flat plain.
Joinery is likely handled differently.

I don’t recommend this sort of thing for a first
chair build but it can be done. Make mockups
until you figure it out.

You may want to find a busted up old chair of
similar design to take apart and study.

View Loren's profile

Loren

10477 posts in 3769 days


#7 posted 06-04-2018 05:32 PM

If I were going to make a mockup of the chair
in my example or the top one in the OP,
I might take a pine 4×4 and mark out the
curvature I wanted for the legs below the
seat, the seat joint and the angle of the
back. You want to legs swept back a little
so the chair won’t tip over backwards easily.

In the case of the round back chair, add
some thickness near the edge of the shield
to the side profile to allow for a forward
flare when shaping. This is hard to explain
so think about it.

Cut that shape out. You now have a leg
profile the thickness of a 4x piece of lumber.
The taper of the lower leg on this style of
chair is often done on the inside, but it
can be done on the outside, so mark that
out so it widens to about 2” wide at the
juncture with the seat rail. Stand it upright
and try to visualize how it will interact with
the rounded seat rail to create a flare in
the legs below the seat and a flare in the
back above. A plumb line may be useful.
Draw the shape for the shield back above
the seat and cut it out.

Now you have a mockup leg sawn out with
curves in two dimensions. Keep the pieces
you’ve sawn off. You can glue parts back
onto the mockup leg later if you screwed up
or use them to figure out what size hardwood
blank you’ll need for the real chair leg.

Do your best to roughly shape the shield
back above the seat juncture. If it looks
promising, make a seat mockup with some
front legs screwed to it and a rounded back
simulating the curve off the seat rail you’ll
use later. Make a second rear leg and shape
it. Then figure out the curved top rail. It
will be a compound shape curved in two
dimensions and shaped to flow into the
legs.

Here’s a sketch I made of what I think the top
leg profile may resemble. Don’t take my word
for it though, use your head and make mockups
you can change as you learn more.

View wakinews's profile

wakinews

16 posts in 300 days


#8 posted 06-05-2018 03:25 AM

thank you very much Loren for taking your time to give out that detailed info. I have taken note of all the suggestions and i will make up my mind on what to do.

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