I am starting a set of 10 dining chairs and have a few questions/problems
regarding complex angles on the tenons.

First a little background: A couple years ago I did a test chair which had
a curved back leg which was then rotated outward by about 15 degrees to
allow the legs to curve outward when viewed from the front and the side. To
get around complex angles on the joinery, I re-cut each face of the leg
such that it was at right angles to the cross rails attached to it. For
example, the inner face of the leg was cut to be at right angles to the back
seat rail and headrail. The back of the leg was square to the inner face.
The front face of the leg was angled out by about 6 degrees to be at right
angles to the side seat rail. The outer face of the leg was square to the
leg front face. This made the mortises and tenons very simple, all square
or only simple angles, but as you might guess, shaping the legs was quite
difficult and would be a problem in making 10 chairs.

For my 10 chairs I wanted to simplify the legs somewhat by not cutting each
face to be perpendicular to the rails. This now makes the mortices and
tenons more difficult. My plan was to still make the mortises perpendicular
to the face of the legs. However the tenons are then more difficult because
the shoulders are not perpendicular to any of the sides of the rails and the
cheeks are not in line with the rails in either plane. For example, on the
headrail, the tenons should be angled forward by about 15% to account for
the rotation of the leg, and downward by a few degrees to account for the
outward curve of the upper part of the leg.

Looking at the standard tenon jigs (Delta, etc), there appear to be some
limitations. If I tilt the blade by about 15 degrees to account for the
rotation of the inner leg face, and lean the rail forward on the face of the
fence by a few degrees to account for the outward angle of the leg, it looks
like I have to change the height of the blade between the two cheek cuts.
In addition, since the jig only allows the work piece to lean away from the
blade, I would need to figure out another way to lean it toward the blade
for the mirror image cut on the other end of the rail.


To do the tenon I am picturing it seems it would be better if the blade were
at 90 degrees and the fence that the rail is clamped to could be tilted away
from the blade at the top by the 15 degrees. I would also need to lean the
rail both toward and away from the blade to account for the mirror image cut
on the opposite end of the headrail. Perhaps wooden wedges at the
appropriate angles would help here? Does anyone have any ideas as to how to
handle this? How do other people handle this problem? Any suggestions will
be appreciated.

I know the above joints are difficult to explain in words. Let me know if i
can explain anything more thoroughly. Thanks in advance for your help.

Thanks,
Bob Abbott

--
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I cut the angled tenons with a back saw after laying them out with a mortise
gauge and a bevel square. :-)
It's much easier than trying to set up a machine to do it. :-)
You may want to view the Frank Klausz video on mortise and tenon joints. He
has a very good segment on this issue.
He uses wedges and a hollow chisel mortise.

"Bob" wrote in message
news:f7vSc.240801$%_6.465@attbi_s01...
I am starting a set of 10 dining chairs and have a few questions/problems
regarding complex angles on the tenons.

snip

On Wed, 11 Aug 2004 20:15:07 GMT, "Bob"
wrote:

I am starting a set of 10 dining chairs and have a few questions/problems
regarding complex angles on the tenons.

First a little background: A couple years ago I did a test chair which had
a curved back leg which was then rotated outward by about 15 degrees to
allow the legs to curve outward when viewed from the front and the side. To
get around complex angles on the joinery, I re-cut each face of the leg
such that it was at right angles to the cross rails attached to it. For
example, the inner face of the leg was cut to be at right angles to the back
seat rail and headrail. The back of the leg was square to the inner face.
The front face of the leg was angled out by about 6 degrees to be at right
angles to the side seat rail. The outer face of the leg was square to the
leg front face. This made the mortises and tenons very simple, all square
or only simple angles, but as you might guess, shaping the legs was quite
difficult and would be a problem in making 10 chairs.

For my 10 chairs I wanted to simplify the legs somewhat by not cutting each
face to be perpendicular to the rails. This now makes the mortices and
tenons more difficult. My plan was to still make the mortises perpendicular
to the face of the legs. However the tenons are then more difficult because
the shoulders are not perpendicular to any of the sides of the rails and the
cheeks are not in line with the rails in either plane. For example, on the
headrail, the tenons should be angled forward by about 15% to account for
the rotation of the leg, and downward by a few degrees to account for the
outward curve of the upper part of the leg.

Looking at the standard tenon jigs (Delta, etc), there appear to be some
limitations. If I tilt the blade by about 15 degrees to account for the
rotation of the inner leg face, and lean the rail forward on the face of the
fence by a few degrees to account for the outward angle of the leg, it looks
like I have to change the height of the blade between the two cheek cuts.
In addition, since the jig only allows the work piece to lean away from the
blade, I would need to figure out another way to lean it toward the blade
for the mirror image cut on the other end of the rail.


To do the tenon I am picturing it seems it would be better if the blade were
at 90 degrees and the fence that the rail is clamped to could be tilted away
from the blade at the top by the 15 degrees. I would also need to lean the
rail both toward and away from the blade to account for the mirror image cut
on the opposite end of the headrail. Perhaps wooden wedges at the
appropriate angles would help here? Does anyone have any ideas as to how to
handle this? How do other people handle this problem? Any suggestions will
be appreciated.

I know the above joints are difficult to explain in words. Let me know if i
can explain anything more thoroughly. Thanks in advance for your help.

Thanks,
Bob Abbott



sounds like a router op.

That would be the approach I would take also. Ten chairs sounds like
about the right number to forego the hand approach and do it by machine.

bob g.


sounds like a router op.

Sounds like loose tenons would be the way to go. With ten
chairs the time used to make fixtures to hold the parts for
mortising would be worth while.

Though the jig shown at the following url is for a horizontal
mortising machine, it may give you some ideas for your jigs.
http://home.comcast.net/~charliebcz/.../RaysJIG1.html
check out the third page to see it set up for a curved chair
leg.

charlie b

I'm not clear on how a router can help me here. Do you have any URL's that
would give me an idea as to how to make the jigs for the complex angle
tenons I need? Bob

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"Robert Galloway" wrote in message
...
That would be the approach I would take also. Ten chairs sounds like
about the right number to forego the hand approach and do it by machine.

bob g.


sounds like a router op.

Charlie,

This looks like it could have some promise. I had planned on mortises
perpendicular to the leg faces, but if I guess I could angle them to make
them in line with the rails. Making jigs for mortises in the legs won't be
so hard. However since I normally make mortises on my bench drill press,
I'm not sure how I can accurately cut the mortises for the loose tenons in
the ends of the rails. It looks like they should be cut prior to angling
the end face of the rails. So do you have a URL for a jig for accurately
drilling mortises in the end of the rails?

Bob
--
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"charlie b" wrote in message
...
Sounds like loose tenons would be the way to go. With ten
chairs the time used to make fixtures to hold the parts for
mortising would be worth while.

Though the jig shown at the following url is for a horizontal
mortising machine, it may give you some ideas for your jigs.
http://home.comcast.net/~charliebcz/.../RaysJIG1.html
check out the third page to see it set up for a curved chair
leg.

charlie b

Get "Chairmaking and Design" by Jeff Miller. It's a very well written book.
Basically the entire book is the answer to your question.

http://www.amazon.com/exec/obidos/tg...glance&s=books

My local library had it, so you might want to check there, also. It is one
of the very few books that I read from the library and has very, very
seriously considered purchasing.

Mark

"Bob" wrote in message
news:f7vSc.240801$%_6.465@attbi_s01...
I am starting a set of 10 dining chairs and have a few questions/problems
regarding complex angles on the tenons.

First a little background: A couple years ago I did a test chair which
had
a curved back leg which was then rotated outward by about 15 degrees to
allow the legs to curve outward when viewed from the front and the side.
To
get around complex angles on the joinery, I re-cut each face of the leg
such that it was at right angles to the cross rails attached to it. For
example, the inner face of the leg was cut to be at right angles to the
back
seat rail and headrail. The back of the leg was square to the inner face.
The front face of the leg was angled out by about 6 degrees to be at right
angles to the side seat rail. The outer face of the leg was square to the
leg front face. This made the mortises and tenons very simple, all square
or only simple angles, but as you might guess, shaping the legs was quite
difficult and would be a problem in making 10 chairs.

For my 10 chairs I wanted to simplify the legs somewhat by not cutting
each
face to be perpendicular to the rails. This now makes the mortices and
tenons more difficult. My plan was to still make the mortises
perpendicular
to the face of the legs. However the tenons are then more difficult
because
the shoulders are not perpendicular to any of the sides of the rails and
the
cheeks are not in line with the rails in either plane. For example, on
the
headrail, the tenons should be angled forward by about 15% to account for
the rotation of the leg, and downward by a few degrees to account for the
outward curve of the upper part of the leg.

Looking at the standard tenon jigs (Delta, etc), there appear to be some
limitations. If I tilt the blade by about 15 degrees to account for the
rotation of the inner leg face, and lean the rail forward on the face of
the
fence by a few degrees to account for the outward angle of the leg, it
looks
like I have to change the height of the blade between the two cheek cuts.
In addition, since the jig only allows the work piece to lean away from
the
blade, I would need to figure out another way to lean it toward the blade
for the mirror image cut on the other end of the rail.


To do the tenon I am picturing it seems it would be better if the blade
were
at 90 degrees and the fence that the rail is clamped to could be tilted
away
from the blade at the top by the 15 degrees. I would also need to lean
the
rail both toward and away from the blade to account for the mirror image
cut
on the opposite end of the headrail. Perhaps wooden wedges at the
appropriate angles would help here? Does anyone have any ideas as to how
to
handle this? How do other people handle this problem? Any suggestions
will
be appreciated.

I know the above joints are difficult to explain in words. Let me know if
i
can explain anything more thoroughly. Thanks in advance for your help.

Thanks,
Bob Abbott

--
Remove NOSPAM from address to reply

On Thu, 12 Aug 2004 15:44:26 GMT, "Bob"
wrote:

Charlie,

This looks like it could have some promise. I had planned on mortises
perpendicular to the leg faces, but if I guess I could angle them to make
them in line with the rails. Making jigs for mortises in the legs won't be
so hard. However since I normally make mortises on my bench drill press,
I'm not sure how I can accurately cut the mortises for the loose tenons in
the ends of the rails. It looks like they should be cut prior to angling
the end face of the rails. So do you have a URL for a jig for accurately
drilling mortises in the end of the rails?

Bob



http://benchmark.20m.com/tools/Littl...eratindex.html

Mark,

Actually I have the Miller book and had referenced it a lot while I made my
test chair. However since I simplified the M/T on the test chair by
angleing the faces of the legs, I didn't have a need for the router jig. I
could easily make simple angle tenons with the table saw/dado. I had
forgotten about the compound angle discussion in the book and the router
jig.

It looks like I now need to decide whether I want to use a router jig for
compound angle tenons into perpendicular leg mortises, or loose tenons into
mortises angled to be in-line with the rails. Any thoughts on the matter?

Thanks,
Bob

--
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"Mark Wells" wrote in message
link.net...
Get "Chairmaking and Design" by Jeff Miller. It's a very well written
book.
Basically the entire book is the answer to your question.


http://www.amazon.com/exec/obidos/tg...glance&s=books

My local library had it, so you might want to check there, also. It is
one
of the very few books that I read from the library and has very, very
seriously considered purchasing.

Mark

I saw the inventor of this build a complete chair at
the 2002 IWF....

It works...

http://www.beadlock.com/projectapplications.html

Poor man's m&t jig....



Bob wrote:

Charlie,

This looks like it could have some promise. I had planned on mortises
perpendicular to the leg faces, but if I guess I could angle them to make
them in line with the rails. Making jigs for mortises in the legs won't be
so hard. However since I normally make mortises on my bench drill press,
I'm not sure how I can accurately cut the mortises for the loose tenons in
the ends of the rails. It looks like they should be cut prior to angling
the end face of the rails. So do you have a URL for a jig for accurately
drilling mortises in the end of the rails?

Bob

Bob wrote:

Mark,

Actually I have the Miller book and had referenced it a lot while I made my
test chair. However since I simplified the M/T on the test chair by
angleing the faces of the legs, I didn't have a need for the router jig. I
could easily make simple angle tenons with the table saw/dado. I had
forgotten about the compound angle discussion in the book and the router
jig.

It looks like I now need to decide whether I want to use a router jig for
compound angle tenons into perpendicular leg mortises, or loose tenons into
mortises angled to be in-line with the rails. Any thoughts on the matter?

Thanks,
Bob


Loose tenon would be the way I'd go. Blow a tenon cut and you may
have
to make another complete part. Blow a loose tenon and you just
make another - much lower risk. And you can use some of those
hardwood scraps you've been saving Two birds - one stone.

charlie b

Oh, you are mistaking me for someone who has actually built a chair. All
I've done is read about it! ;-)

Mark

"Bob" wrote in message
news:YsPSc.137010$eM2.20333@attbi_s51...
Mark,

Actually I have the Miller book and had referenced it a lot while I made
my
test chair. However since I simplified the M/T on the test chair by
angleing the faces of the legs, I didn't have a need for the router jig.
I
could easily make simple angle tenons with the table saw/dado. I had
forgotten about the compound angle discussion in the book and the router
jig.

It looks like I now need to decide whether I want to use a router jig for
compound angle tenons into perpendicular leg mortises, or loose tenons
into
mortises angled to be in-line with the rails. Any thoughts on the matter?

Thanks,
Bob

--
Remove NOSPAM from address to reply
"Mark Wells" wrote in message
link.net...
Get "Chairmaking and Design" by Jeff Miller. It's a very well written
book.
Basically the entire book is the answer to your question.



http://www.amazon.com/exec/obidos/tg...glance&s=books

My local library had it, so you might want to check there, also. It is
one
of the very few books that I read from the library and has very, very
seriously considered purchasing.

Mark

On Fri, 13 Aug 2004 05:04:52 GMT, "Mark Wells"
wrote:

Oh, you are mistaking me for someone who has actually built a chair. All
I've done is read about it! ;-)

Mark


an armchair armchairist?

Jig at the http://www.patwarner.com/tenonmaker.html link will swing
through 30 degrees. To get the compound angle will require a wedge
but not rocket science to produce. Plans avaiable.
************************************************** **************
I am starting a set of 10 dining chairs and have a few questions/problems
regarding complex angles on the tenons.

First a little background: A couple years ago I did a test chair which had
a curved back leg which was then rotated outward by about 15 degrees to
allow the legs to curve outward when viewed from the front and the side. To
get around complex angles on the joinery, I re-cut each face of the leg
such that it was at right angles to the cross rails attached to it. For
example, the inner face of the leg was cut to be at right angles to the back
seat rail and headrail. The back of the leg was square to the inner face.
The front face of the leg was angled out by about 6 degrees to be at right
angles to the side seat rail. The outer face of the leg was square to the
leg front face. This made the mortises and tenons very simple, all square
or only simple angles, but as you might guess, shaping the legs was quite
difficult and would be a problem in making 10 chairs.

For my 10 chairs I wanted to simplify the legs somewhat by not cutting each
face to be perpendicular to the rails. This now makes the mortices and
tenons more difficult. My plan was to still make the mortises perpendicular
to the face of the legs. However the tenons are then more difficult because
the shoulders are not perpendicular to any of the sides of the rails and the
cheeks are not in line with the rails in either plane. For example, on the
headrail, the tenons should be angled forward by about 15% to account for
the rotation of the leg, and downward by a few degrees to account for the
outward curve of the upper part of the leg.

Looking at the standard tenon jigs (Delta, etc), there appear to be some
limitations. If I tilt the blade by about 15 degrees to account for the
rotation of the inner leg face, and lean the rail forward on the face of the
fence by a few degrees to account for the outward angle of the leg, it looks
like I have to change the height of the blade between the two cheek cuts.
In addition, since the jig only allows the work piece to lean away from the
blade, I would need to figure out another way to lean it toward the blade
for the mirror image cut on the other end of the rail.


To do the tenon I am picturing it seems it would be better if the blade were
at 90 degrees and the fence that the rail is clamped to could be tilted away
from the blade at the top by the 15 degrees. I would also need to lean the
rail both toward and away from the blade to account for the mirror image cut
on the opposite end of the headrail. Perhaps wooden wedges at the
appropriate angles would help here? Does anyone have any ideas as to how to
handle this? How do other people handle this problem? Any suggestions will
be appreciated.

I know the above joints are difficult to explain in words. Let me know if i
can explain anything more thoroughly. Thanks in advance for your help.

Thanks,
Bob Abbott

Looking at the site, since the rabbet bit runs on the sides of the rail, it
looks like the size of the tenon is a function of the bearing and the width
of the workpiece. This means that the tenon is not necessarily a fixed size
(ie 1/2"). Do you then cut the mortise to fit the tenon rather than the
other way around? I prefer to fit the tenon to a fixed size mortise.

In addition, if you angle the workpiece in both directions to get a
compound angle tenon, it looks like the shoulders would all be different
sizes. Have I interpreted this properly? How do you account for this?

Bob

--
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"Routerman P. Warner" wrote in message
m...
Jig at the http://www.patwarner.com/tenonmaker.html link will swing
through 30 degrees. To get the compound angle will require a wedge
but not rocket science to produce. Plans avaiable.
************************************************** **************

Understanding correct; to rout compound angles requires an edge guide
and straight bit to get the shoulder in one plane; sides of tenon can
still be cut with rabbet bits, however.
The use of an edge guide (for the 4 faces of the tenon) implies
continuous adjustability so the tenon can be tuned to mortice width.
Using rabbeters will require tuning mortice to tenon width.
******************************************
If rabbet bits
Looking at the site, since the rabbet bit runs on the sides of the rail, it
looks like the size of the tenon is a function of the bearing and the width
of the workpiece. This means that the tenon is not necessarily a fixed size
(ie 1/2"). Do you then cut the mortise to fit the tenon rather than the
other way around? I prefer to fit the tenon to a fixed size mortise.

In addition, if you angle the workpiece in both directions to get a
compound angle tenon, it looks like the shoulders would all be different
sizes. Have I interpreted this properly? How do you account for this?

Bob

--
Remove NOSPAM from address to reply
"Routerman P. Warner" wrote in message
m...
Jig at the http://www.patwarner.com/tenonmaker.html link will swing
through 30 degrees. To get the compound angle will require a wedge
but not rocket science to produce. Plans avaiable.
************************************************** **************