Hi ppl,

I'm getting into curves, not soft & warm (in this group!) but hard,
grainy and flammable.

I'm making a heavy chair I call a "sumo chair" because the overall
dimensions are somewhat larger than the usual chair.

I'm adding curved edges as I go along. A little bit of oriental
feeling

There has to (?) be some way to methodically figure out angles for,
say, a mortise thru a piece curved on both sides, different curves.
Basically, intersections of curved pieces.

Is this always such a PITA involving a lot of fudging and estimating
and jury-rigging?

There's always computer drafting, I do know that, but hell I don't
WANNA use computers except to see prototype ideas.

James

On Thu, 14 Oct 2004 14:48:28 -0400, brocpuffs
wrote:

Hi ppl,

I'm getting into curves, not soft & warm (in this group!) but hard,
grainy and flammable.

I'm making a heavy chair I call a "sumo chair" because the overall
dimensions are somewhat larger than the usual chair.

I'm adding curved edges as I go along. A little bit of oriental
feeling

There has to (?) be some way to methodically figure out angles for,
say, a mortise thru a piece curved on both sides, different curves.
Basically, intersections of curved pieces.

Is this always such a PITA involving a lot of fudging and estimating
and jury-rigging?


chairs are kinda their own thing. people who make lots of custom
chairs generally have an adjustable prototype chair that they use to
fit the chair to the customer- then from that they can pull angles and
dimensions. a lot of knowing what to do comes from experience.




There's always computer drafting, I do know that, but hell I don't
WANNA use computers except to see prototype ideas.

this is an interesting idea for a piece of software- 3d chair design.
it would need size data for the customer- those routines might be able
to be borrowed from some custom tailoring or haberdashery software. it
would need 3d modelling capability- plenty of that around. it would
need to be able to export patterns and cut lists.

I bet there would be a market for it.




James

On Thu, 14 Oct 2004 12:09:28 -0700, wrote:

chairs are kinda their own thing. people who make lots of custom
chairs generally have an adjustable prototype chair that they use to

Makes sense but I do so much like to screw everything around as I go
along. Well, it accounts for my (LOW) production rate :-)


this is an interesting idea for a piece of software- 3d chair design.
it would need size data for the customer- those routines might be able
to be borrowed from some custom tailoring or haberdashery software. it
would need 3d modelling capability- plenty of that around. it would
need to be able to export patterns and cut lists.

I bet there would be a market for it.

All you'd need is a few zillion bucks!!

Since I posted this, I blew the angle on one part of a curved vertical
side rail. I wanted the two straight and horizontal side rails (below
the seat) to go thru the curved piece. This curved piece is to be the
front support for an arm for the chair. The front legs are not long
enough to be the front supports, never mind why.

I can patch it with the usual wedges but I am sooo disappointed at not
being perfect!


James

On Thu, 14 Oct 2004 14:48:28 -0400, brocpuffs
wrote:

Hi ppl,

I'm getting into curves, not soft & warm (in this group!) but hard,
grainy and flammable.

I'm making a heavy chair I call a "sumo chair" because the overall
dimensions are somewhat larger than the usual chair.

I'm adding curved edges as I go along. A little bit of oriental
feeling

There has to (?) be some way to methodically figure out angles for,
say, a mortise thru a piece curved on both sides, different curves.
Basically, intersections of curved pieces.

Is this always such a PITA involving a lot of fudging and estimating
and jury-rigging?

There's always computer drafting, I do know that, but hell I don't
WANNA use computers except to see prototype ideas.

James




Describe the radius of the outer point of the curved section on paper
large enough to draw on at full scale.

Draw a line from the origin of the radius to the outside intersection
of the two curved pieces.

This will give you the line at which the joining cut should be made.

From this point on it is the same as any other mortise and tenon, with
the described line acting as the base from which to begin regular
right angle joinery.


Regards,
Tom.

"People funny. Life a funny thing." Sonny Liston

Thomas J.Watson - Cabinetmaker (ret.)
tjwatson1ATcomcastDOTnet (real email)
http://home.comcast.net/~tjwatson1

brocpuffs wrote in message . ..
Hi ppl,

I'm getting into curves, not soft & warm (in this group!) but hard,
grainy and flammable.

I'm making a heavy chair I call a "sumo chair" because the overall
dimensions are somewhat larger than the usual chair.

I'm adding curved edges as I go along. A little bit of oriental
feeling

There has to (?) be some way to methodically figure out angles for,
say, a mortise thru a piece curved on both sides, different curves.
Basically, intersections of curved pieces.

Is this always such a PITA involving a lot of fudging and estimating
and jury-rigging?

There's always computer drafting, I do know that, but hell I don't
WANNA use computers except to see prototype ideas.

James


Hi James,
You might try to find a book called "Circular Work in Carpentry
and Joinery" by George Collins. 1992, Linden Publishing. Possibly out
of print but a local libary system might have it. I would say this
ranks as one of the best books on the topic I have seen!
Good Luck,
Michael

On Thu, 14 Oct 2004 18:41:55 -0400, Tom Watson
wrote:

Describe the radius of the outer point of the curved section on paper
large enough to draw on at full scale.

Draw a line from the origin of the radius to the outside intersection
of the two curved pieces.

This will give you the line at which the joining cut should be made.

From this point on it is the same as any other mortise and tenon, with
the described line acting as the base from which to begin regular
right angle joinery.

Tom, this just isn't clear enough to do me much good. I'm not even
sure we're talking about the same thing :-)

Lemmie try and make my specific problem as clear as I can without
ASCII mis-art:

On each side of the chair, there are two horizontal side rails front
to back, parallel, both below seat height.

I have a piece meant to serve as a curved, vertical rail. Both
horizontal rails are to pass thru the curved surfaces, which face
front-to-back.The curves are similar in shape and curvature, but
angled re each other so that the bottom of the rail is somewhat
thicker (front-to-back) than the top.

I made a drawing in a graphics program and will post it to
alt.binaries.pictures.woodworking right after this. The filename is
curved joinery.bmp.

The dotted lines (and their perpendiculars) are what I need to get
right.

thanks!

James

On Thu, 14 Oct 2004 23:57:58 -0400, brocpuffs
wrote:



I made a drawing in a graphics program and will post it to
alt.binaries.pictures.woodworking right after this. The filename is
curved joinery.bmp.

The dotted lines (and their perpendiculars) are what I need to get
right.

You know what, I could trace the parts out on paper and go from there!

Always complicating things, that's me-

James

On Fri, 15 Oct 2004 00:29:18 -0400, brocpuffs
wrote:


You know what, I could trace the parts out on paper and go from there!

Sorry, I did misunderstand you, but you seem to have happened onto the
solution.

Good luck.



Regards,
Tom.

"People funny. Life a funny thing." Sonny Liston

Thomas J.Watson - Cabinetmaker (ret.)
tjwatson1ATcomcastDOTnet (real email)
http://home.comcast.net/~tjwatson1