Saw a picture of a quilt rack with curved sides that are not arcs of a
circle. HOw can I create a fair curve about 36" long that isn't merely
an arc of a circle. I'll post the picture on ABPW in a minute - subject
line: Quilt rack.

dave

"Bay Area Dave" wrote in message
Saw a picture of a quilt rack with curved sides that are not arcs of a
circle. HOw can I create a fair curve about 36" long that isn't merely
an arc of a circle. I'll post the picture on ABPW in a minute - subject
line: Quilt rack.

A large plastic French Curve works well,. Also, at a drafting supply store
you can buy a various lengths of plastic strip that is flexible, but can be
bent in many different positions and will hold its shape. I use one for
non-radius, flowing curves like you mention.

That said, most folks can do a fair job of free handing a non-radiused curve
on a piece of mdf, then using a bandsaw, a pattern maker's rasp, and
finally, a flexible strip with sandpaper attached to fine tune and smooth
out the curve ... the mdf pattern then becomes a template for a pattern bit
and your router so that two or more pieces will have the same curve.

Most of the time it is well worth the effort to make a template with either
of these methods.

For radiused curves, I use a thin strip of wood with a string attached at
either end like an archer's bow, with a piece of wood on the string fastened
in a manner to hold the tension at the desired curve.

--
www.e-woodshop.net
Last update: 2/13/04

thanks! [thinking out loud]I wonder if Office Depot carries any
drafting supplies like the flexible strip you mentioned? (I'm about 5
blocks from OD) I remember using a French Curve in grammar school, but
of course it wasn't near the size that I'd need. I'll definitely take
your advice on making a template. I don't have a pattern maker's rasp,
so I'll look that up to see if I've got anything similar. I DO have a
Surform rasp which is about an inch and a half wide and maybe (going by
memory) about 10 inches long.

For something this long I take it that it wouldn't be a good idea to use
my new handy dandy OSS to smooth out such a gentle curve?

dave

Swingman wrote:

"Bay Area Dave" wrote in message

Saw a picture of a quilt rack with curved sides that are not arcs of a
circle. HOw can I create a fair curve about 36" long that isn't merely
an arc of a circle. I'll post the picture on ABPW in a minute - subject
line: Quilt rack.


A large plastic French Curve works well,. Also, at a drafting supply store
you can buy a various lengths of plastic strip that is flexible, but can be
bent in many different positions and will hold its shape. I use one for
non-radius, flowing curves like you mention.

That said, most folks can do a fair job of free handing a non-radiused curve
on a piece of mdf, then using a bandsaw, a pattern maker's rasp, and
finally, a flexible strip with sandpaper attached to fine tune and smooth
out the curve ... the mdf pattern then becomes a template for a pattern bit
and your router so that two or more pieces will have the same curve.

Most of the time it is well worth the effort to make a template with either
of these methods.

For radiused curves, I use a thin strip of wood with a string attached at
either end like an archer's bow, with a piece of wood on the string fastened
in a manner to hold the tension at the desired curve.

Bay Area Dave writes:
Saw a picture of a quilt rack with curved sides that are not arcs of
a circle. HOw can I create a fair curve about 36" long that isn't
merely an arc of a circle.

Bend a thin strip of wood.
http://www.delorie.com/wood/camber.html

Swingman wrote:

Also, at a drafting supply
store you can buy a various lengths of plastic strip that is
flexible, but can be bent in many different positions and will hold
its shape. I use one for non-radius, flowing curves like you mention.

Solid core electric wire works too. A short piece of 12-2 or 14-2 cable
retains the shape well and lies flat for easy tracing.

-- Mark

Bay Area Dave wrote:

thanks! [thinking out loud]I wonder if Office Depot carries any
drafting supplies like the flexible strip you mentioned? (I'm about 5
blocks from OD) I remember using a French Curve in grammar school, but
of course it wasn't near the size that I'd need. I'll definitely take
your advice on making a template. I don't have a pattern maker's rasp,
so I'll look that up to see if I've got anything similar. I DO have a
Surform rasp which is about an inch and a half wide and maybe (going by
memory) about 10 inches long.

For something this long I take it that it wouldn't be a good idea to use
my new handy dandy OSS to smooth out such a gentle curve?

A thin strip of wood would work well. If you go the Office Depot
route, an inexpensive flexible ruler would probably work as well.

The spindle sander should make the job of smoothing the part
easier. Just remember to take your time (or you'll be re-making
the part.) Plan to do the final shaping by hand with a sanding block.

Woodcraft, Lee Valley, et al carry bendable curves that make this
kind of layout fairly easy. I have one but am usually more
comfortable with the wooden strip approach.

--
Morris Dovey
West Des Moines, Iowa USA
C links at http://www.iedu.com/c
Read my lips: The apple doesn't fall far from the tree.

I get a spool of plumbers solder at the local HW store. That way I can
unroll as much as I need and lay out the curve. It holds it's shape.
Obviously, if you're going to make manyparts, cut a pattern.

HTH,
Vic


"Bay Area Dave" wrote in message
om...
Saw a picture of a quilt rack with curved sides that are not arcs of a
circle. HOw can I create a fair curve about 36" long that isn't merely
an arc of a circle. I'll post the picture on ABPW in a minute - subject
line: Quilt rack.

dave



---
Outgoing mail is certified Virus Free.

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.581 / Virus Database: 368 - Release Date: 02/09/2004

I guess my "thin" strips of wood aren't thin enough! I just ran out to
the shop and tried to bend a piece of oak that is about 1/4" thick. No go.

I ran it through the planer (stuck to a thicker piece with carpet tape)
and promptly "blew" it up on the second pass. Took another strip and
got myself a 1/16+" piece to play with.

I ran screws into a sacrificial assembly table top and played around
with the strip. Seems like that will work. I suppose I can adopt the
same method with the MDF template? Just run some screws in at strategic
locations and bend the wood around them and trace? Am I on the right track?

dave

Morris Dovey wrote:

Bay Area Dave wrote:

thanks! [thinking out loud]I wonder if Office Depot carries any
drafting supplies like the flexible strip you mentioned? (I'm about 5
blocks from OD) I remember using a French Curve in grammar school, but
of course it wasn't near the size that I'd need. I'll definitely take
your advice on making a template. I don't have a pattern maker's
rasp, so I'll look that up to see if I've got anything similar. I DO
have a Surform rasp which is about an inch and a half wide and maybe
(going by memory) about 10 inches long.

For something this long I take it that it wouldn't be a good idea to
use my new handy dandy OSS to smooth out such a gentle curve?


A thin strip of wood would work well. If you go the Office Depot route,
an inexpensive flexible ruler would probably work as well.

The spindle sander should make the job of smoothing the part easier.
Just remember to take your time (or you'll be re-making the part.) Plan
to do the final shaping by hand with a sanding block.

Woodcraft, Lee Valley, et al carry bendable curves that make this kind
of layout fairly easy. I have one but am usually more comfortable with
the wooden strip approach.

"Bay Area Dave" wrote in message

your advice on making a template. I don't have a pattern maker's rasp,
so I'll look that up to see if I've got anything similar.

Very difficult to find tool these days ... and be prepared for sticker
shock:

http://www.leevalley.com/wood/page.a...rency=2&S ID=

Despite the price, it is a much used tool in my shop for curved/rounded
parts.


For something this long I take it that it wouldn't be a good idea to use
my new handy dandy OSS to smooth out such a gentle curve?

I find that I need to use a rasp for roughing out, then the OSS, then
sandpaper on a thin strip of wood that can flex enough to really smooth the
curve without the 'bumps' you tend to get with the OSS.

Just my experience ...

--
www.e-woodshop.net
Last update: 2/13/04

"Bay Area Dave" wrote in message
om...
I guess my "thin" strips of wood aren't thin enough! I just ran out to
the shop and tried to bend a piece of oak that is about 1/4" thick. No
go.

I ran it through the planer (stuck to a thicker piece with carpet tape)
and promptly "blew" it up on the second pass. Took another strip and
got myself a 1/16+" piece to play with.

Why use the planer? That's what a table saw is for!

RIP some 1/8th" strips of oak about 36 - 48" long ... guaranteed to bend and
be flexible enough for a curve, to a point.

I usually have a bucket full of such strips of various lengths left over
after a batch ripping fest. They make great flexible sanding strips for the
final part of the finishing of the curve.

--
www.e-woodshop.net
Last update: 2/13/04

I looked at the link. the price definitely choked me up!

here is a quote from lee valley's page: "These are the traditional rasps
of last-makers"

What is a "last-maker"??

The have some cheaper items on page 215; Microplanes. Ever use those?

dave



Swingman wrote:

"Bay Area Dave" wrote in message


your advice on making a template. I don't have a pattern maker's rasp,
so I'll look that up to see if I've got anything similar.


Very difficult to find tool these days ... and be prepared for sticker
shock:

http://www.leevalley.com/wood/page.a...rency=2&S ID=

Despite the price, it is a much used tool in my shop for curved/rounded
parts.



For something this long I take it that it wouldn't be a good idea to use
my new handy dandy OSS to smooth out such a gentle curve?


I find that I need to use a rasp for roughing out, then the OSS, then
sandpaper on a thin strip of wood that can flex enough to really smooth the
curve without the 'bumps' you tend to get with the OSS.

Just my experience ...

In article ,
Bay Area Dave wrote:

thanks! [thinking out loud]I wonder if Office Depot carries any
drafting supplies like the flexible strip you mentioned?

I've seen that kind of stuff in Staples. I assume O.D. has the same
assortment. It's usually with the art and presentation supplies.

You could certainly find it at any drafting supply place like Charrette (http://www.charrette.com/) or Sam Flax (http://www.samflax.com/). Lee Valley has one too
(http://www.leevalley.com/wood/page.a...1,42936,42958&
ccurrency=2&SID=)

duh, sorry, I DID have an 1/8" piece of oak, but it didn't bend too
well! I see I wrote "1/4". I meant 1/8. my bad.

dave

Swingman wrote:

"Bay Area Dave" wrote in message
om...

I guess my "thin" strips of wood aren't thin enough! I just ran out to
the shop and tried to bend a piece of oak that is about 1/4" thick. No

go.

I ran it through the planer (stuck to a thicker piece with carpet tape)
and promptly "blew" it up on the second pass. Took another strip and
got myself a 1/16+" piece to play with.


Why use the planer? That's what a table saw is for!

RIP some 1/8th" strips of oak about 36 - 48" long ... guaranteed to bend and
be flexible enough for a curve, to a point.

I usually have a bucket full of such strips of various lengths left over
after a batch ripping fest. They make great flexible sanding strips for the
final part of the finishing of the curve.

probably it didn't bend well because it was too wide. I cut it down to a
couple of inches before bringing it down to 1/16. that seems to work
fine. but you are right; if I had realized a narrower piece would
suffice, I could have shaved off a 1/16 piece from a board on the TS.

dave

Bay Area Dave wrote:

duh, sorry, I DID have an 1/8" piece of oak, but it didn't bend too
well! I see I wrote "1/4". I meant 1/8. my bad.

dave

Swingman wrote:

"Bay Area Dave" wrote in message
om...

I guess my "thin" strips of wood aren't thin enough! I just ran out to
the shop and tried to bend a piece of oak that is about 1/4" thick. No


go.

I ran it through the planer (stuck to a thicker piece with carpet tape)
and promptly "blew" it up on the second pass. Took another strip and
got myself a 1/16+" piece to play with.



Why use the planer? That's what a table saw is for!

RIP some 1/8th" strips of oak about 36 - 48" long ... guaranteed to
bend and
be flexible enough for a curve, to a point.

I usually have a bucket full of such strips of various lengths left over
after a batch ripping fest. They make great flexible sanding strips
for the
final part of the finishing of the curve.

In article ,
"Swingman" wrote:

"Bay Area Dave" wrote in message

your advice on making a template. I don't have a pattern maker's rasp,
so I'll look that up to see if I've got anything similar.

Very difficult to find tool these days ... and be prepared for sticker
shock:

http://www.leevalley.com/wood/page.a...24&ccurrency=2
&SID=

Despite the price, it is a much used tool in my shop for curved/rounded
parts.

Wow. You're right about sticker shock. How are those any better than
cheap rasps you can get for under $10? I find a very hand tool to be a
4-in-hand file:

http://www.tools-plus.com/merbsr10.html

For something this long I take it that it wouldn't be a good idea to use
my new handy dandy OSS to smooth out such a gentle curve?

What's an OSS?

In article ,
Bay Area Dave wrote:


here is a quote from lee valley's page: "These are the traditional rasps
of last-makers"

What is a "last-maker"??

I believe a last is the wooden form used by a cobbler to build a shoe on.

Bay Area Dave wrote:

I guess my "thin" strips of wood aren't thin enough! I just ran out to
the shop and tried to bend a piece of oak that is about 1/4" thick. No go.

I ran it through the planer (stuck to a thicker piece with carpet tape)
and promptly "blew" it up on the second pass. Took another strip and
got myself a 1/16+" piece to play with.

I ran screws into a sacrificial assembly table top and played around
with the strip. Seems like that will work. I suppose I can adopt the
same method with the MDF template? Just run some screws in at strategic
locations and bend the wood around them and trace? Am I on the right
track?

Sounds like it. I don't think I'd run (any more) thin strips
through the planer, though. I tend to favor the bandsaw for
ripping thin strips like this because I feel a little more in
control of what's going on. Usually I can rip a nice uniform
strip. If you want one part of the strip to be more "bendy" than
the rest, just plane or sand that part a tad thinner than the rest.

Your screw approach sounds workable. If you're going to do much
of this kind of work, you might want to glue a block to each end
of a strip so you can "freeze" the curve just by clamping the
ends down.

--
Morris Dovey
West Des Moines, Iowa USA
C links at http://www.iedu.com/c
Read my lips: The apple doesn't fall far from the tree.

A "last" is a form piece used by cobblers to make shoes i.e. a dummy foot. A
"last-maker" therefore is the person who makes them.

Also, a while ago on abpw we discussed pilasters and fluting design. I
promised to provide a link to a website of general interest when I found it
again, go to:

http://www.chipstone.org/publications/1993/Miller93/

--

Greg

"Bay Area Dave" wrote in message ...

What is a "last-maker"??

snip

Roy,

oscillating spindle sander. very cool. just got one a couple of weeks
ago; the Ryobi. (Thanks again, Mike for the recommendation)

dave

Roy Smith wrote:


What's an OSS?

yeah, it was a bit of heart lurcher when I heard a chunk tear out. first
time that's ever happened to me, so I was a bit nervous running the next
piece through, but it came out clean and more importantly, uneventfully!

dave

Morris Dovey wrote:

Bay Area Dave wrote:

I guess my "thin" strips of wood aren't thin enough! I just ran out
to the shop and tried to bend a piece of oak that is about 1/4"
thick. No go.

I ran it through the planer (stuck to a thicker piece with carpet
tape) and promptly "blew" it up on the second pass. Took another
strip and got myself a 1/16+" piece to play with.

I ran screws into a sacrificial assembly table top and played around
with the strip. Seems like that will work. I suppose I can adopt
the same method with the MDF template? Just run some screws in at
strategic locations and bend the wood around them and trace? Am I on
the right track?


Sounds like it. I don't think I'd run (any more) thin strips through the
planer, though. I tend to favor the bandsaw for ripping thin strips like
this because I feel a little more in control of what's going on. Usually
I can rip a nice uniform strip. If you want one part of the strip to be
more "bendy" than the rest, just plane or sand that part a tad thinner
than the rest.

Your screw approach sounds workable. If you're going to do much of this
kind of work, you might want to glue a block to each end of a strip so
you can "freeze" the curve just by clamping the ends down.

"Morris Dovey" wrote in message

Sounds like it. I don't think I'd run (any more) thin strips
through the planer, though. I tend to favor the bandsaw for
ripping thin strips like this because I feel a little more in
control of what's going on. Usually I can rip a nice uniform
strip.

Jeeez, you guys sound like you'd walk around the block to go next door. Any
dyed-in-the-wool wooddorker's table saw, with a decent blade, will easily
rip a 1/16th" strip off +/- 4" wide, 3/4" - 1" thick stock safely,
accurately, quickly, and with no need for further fuss or muss ... can't
ask for simpler/better than that.

If you want one part of the strip to be more "bendy" than
the rest, just plane or sand that part a tad thinner than the rest.

That works very well for compound curves.

If you're going to do much of this kind of work, you might want to glue a
block to each end
of a strip so you can "freeze" the curve just by clamping the ends down.

Excellent advice ...unless you have the three hands necessary to hold the
curve AND wield the pencil.

However, providing an extra pair of hands is one of the few things that
SWMBO's are really good for in the shop ... makes them feel like part of the
team and facilitates that warm, fuzzy, harmonious feeling which contributes
directly to loosening of the purse strings.

--
www.e-woodshop.net
Last update: 2/13/04

didn't you notice my post an hour an a half ago where I agreed with you
about using the TS? Or am I not part of "you guys"?

dave

Swingman wrote:

Jeeez, you guys sound like you'd walk around the block to go next door. Any
dyed-in-the-wool wooddorker's table saw, with a decent blade, will easily
rip a 1/16th" strip off +/- 4" wide, 3/4" - 1" thick stock safely,
accurately, quickly, and with no need for further fuss or muss ... can't
ask for simpler/better than that.

"Roy Smith" wrote in message

Wow. You're right about sticker shock. How are those any better than
cheap rasps you can get for under $10? I find a very hand tool to be a
4-in-hand file:

The teeth of a pattern maker's rasp are randomly placed on the surface and
not in rows, like the usual wood rasp. It makes for an exceptionally smooth
cut ... there is no comparison to a cheap rasp for curves and rounding a
plane. I've not used a "micro-plane", simply because I own a couple of
pattern maker's rasps, so I can't vouch for how they work.

IIRC, Highland or Rocklers are more expensive than Lee Valley ... there are
also some European rasps which are very similar, and cheaper, but I have no
idea where to find them.

What's an OSS?

Oscillating Spindle Sander.

--
www.e-woodshop.net
Last update: 2/13/04

On Fri, 13 Feb 2004 21:52:07 GMT, Bay Area Dave wrote:

HOw can I create a fair curve about 36" long that isn't merely
an arc of a circle.

Use a French curve (or a Freedom Curve if you prefer). If you don't
have some, go buy a set of small plastic ones. Then photocopy them at
several enlargements and scroll saw out some big MDF or clear Perspex
versions.

The trick to using a French curve is to remember that every point
where two curves meet should be a smooth join, i.e. their tangents are
on the same line. This implies that the perpendicular to both curves
should be on the same line, which is why some curves have
perpendiculars marked at intervals.

French curves - hard to make your own shape (you can, if you Google)
but useful and worth having around.

--
Smert' spamionam

"Bay Area Dave" wrote in message
didn't you notice my post an hour an a half ago where I agreed with you
about using the TS? Or am I not part of "you guys"?

At ease, Dave ... you were excluded in this one instance, but don't let it
go to your head!

However, I did think it was notable that a table saw would be an
afterthought for the task to more than one woodworker ...

--
www.e-woodshop.net
Last update: 2/13/04

On Fri, 13 Feb 2004 18:22:20 -0500, Roy Smith wrote:

Wow. You're right about sticker shock. How are those any better than
cheap rasps you can get for under $10?

They're worth it, but not needed for last-making.

Rasps all used to be made by hand, but most are now machine-made.
Machine made are definitely not so good - the teeth are formed at a
regular spacing, so they tend to form "tram lines" when you use them.
A hand-cut rasp has randomly spaced teeth, to they don't all fall into
line like this. They're expensive, but definitely worth it if you're
making cabriole legs.

Round here, hand-cut Italian rasps are about $50. I'm no big fan of
buying old files and cleaning of sharpening them, but I do pick up old
rasps when I see them around - and unlike files, you can't easily
chemically sharpen a rasp (the tooth tip rounds off).

$10 rasps are just badly made. They're either not hard, or just
hardened in a very thin skin. They don't last.


There's a description of rasp and file cutting in Bealer
http://www.amazon.com/exec/obidos/AS...55/codesmiths/


--
Socialism: Eric, not Tony

On Fri, 13 Feb 2004 16:31:08 -0600, Morris Dovey
wrote:

A thin strip of wood would work well.

Bent strips are OK for symmetrical curves (I use fibreglass skite
spar), but they don't work so well for an asymmetric curve.

--
Smert' spamionam

"Roy Smith" wrote in message
Wow. You're right about sticker shock. How are those any better than
cheap rasps you can get for under $10? I find a very hand tool to be a
4-in-hand file:

If you can find one in an antique store a float does a nice job of wood
removal as well. Much faster than a rasp and not as groved a surface.
It's like a strip of small plane blades rather than teeth. I love
mine. let me know if you need a pic.
Dave in Fairfax
--
reply-to doesn't work
use:
daveldr at att dot net
American Association of Woodturners
http://www.woodturner.org
Capital Area Woodturners
http://www.capwoodturners.org/

but look at if from my perspective: I had an 1/8" piece that almost fit
the bill. I didn't think of anything more immediate than to plane it
down to to make it more pliable. Had I been staring at a piece of
lumber, then I would have gone over to the TS... see?

dave

Swingman wrote:

"Bay Area Dave" wrote in message

didn't you notice my post an hour an a half ago where I agreed with you
about using the TS? Or am I not part of "you guys"?


At ease, Dave ... you were excluded in this one instance, but don't let it
go to your head!

However, I did think it was notable that a table saw would be an
afterthought for the task to more than one woodworker ...

"Morris Dovey" wrote in message
...

A thin strip of wood would work well. If you go the Office Depot
route, an inexpensive flexible ruler would probably work as well.

The spindle sander should make the job of smoothing the part
easier. Just remember to take your time (or you'll be re-making
the part.) Plan to do the final shaping by hand with a sanding block.

Woodcraft, Lee Valley, et al carry bendable curves that make this
kind of layout fairly easy. I have one but am usually more
comfortable with the wooden strip approach.

--
Morris Dovey
West Des Moines, Iowa USA
C links at http://www.iedu.com/c
Read my lips: The apple doesn't fall far from the tree.

I used this approach to apply a curve to some table base aprons. I bent a
thin (1/8") strip of wood and clamped the ends. I cut it out with a jigsaw
and used the first piece as a pattern for the second. I'm guessing that
doing it the way I did, I ended up with a parabolic curve.

todd

On Sat, 14 Feb 2004 01:12:59 +0000, Andy Dingley
wrote:

The trick to using a French curve is to remember that every point
where two curves meet should be a smooth join, i.e. their tangents are
on the same line. This implies that the perpendicular to both curves
should be on the same line, which is why some curves have
perpendiculars marked at intervals.

Okay Andy, it's my turn to be the village idiot. I must have failed
cut 'n' paste in kindergarten...

I don't "get" French Curves.
Assuming there _is_ something to "get," what do they _do?_

I see the pretty curves, do I just shift it around on the drawing
until I see something I like, or is there more to it than that?
Am I supposed to just pick a section of a curve and use that? Which
one? How do I know?

You're entire statement about perpendiculars and tangents tells me
there's a lot more to this than I see by just looking at one.

Man, I don't even know what I don't know with these things...
"When your only tool's a T-Square, every problem's just another
crooked line." ;

Michael

On Sat, 14 Feb 2004 04:33:55 GMT, Michael Baglio
wrote:

On Sat, 14 Feb 2004 01:12:59 +0000, Andy Dingley
wrote:

The trick to using a French curve is to remember that every point
where two curves meet should be a smooth join, i.e. their tangents are
on the same line. This implies that the perpendicular to both curves
should be on the same line, which is why some curves have
perpendiculars marked at intervals.

Okay Andy, it's my turn to be the village idiot. I must have failed
cut 'n' paste in kindergarten...

I don't "get" French Curves.
Assuming there _is_ something to "get," what do they _do?_

I see the pretty curves, do I just shift it around on the drawing
until I see something I like,

basically, yes.

how I use 'em is first I sketch in freehand with a light loose line
the shape I want. then I shuffle the french curve around on it until I
find a section of it that makes the line (or usually part of it) that
I want. scribe that segment, find the next, repeat.

it can be a bit of a trick to get the segments to fair out right. one
method is to shift it around until you get 3 intersections. pick the
line up from the second.




or is there more to it than that?
Am I supposed to just pick a section of a curve and use that? Which
one? How do I know?

You're entire statement about perpendiculars and tangents tells me
there's a lot more to this than I see by just looking at one.


that stuff is for convenience. it helps, but don't let it run ya.





Man, I don't even know what I don't know with these things...
"When your only tool's a T-Square, every problem's just another
crooked line." ;

Michael

todd wrote:

"Morris Dovey" wrote in message
...

A thin strip of wood would work well. If you go the Office
Depot route, an inexpensive flexible ruler would probably
work as well.

The spindle sander should make the job of smoothing the part
easier. Just remember to take your time (or you'll be
re-making the part.) Plan to do the final shaping by hand
with a sanding block.

Woodcraft, Lee Valley, et al carry bendable curves that make
this kind of layout fairly easy. I have one but am usually
more comfortable with the wooden strip approach.

-- Morris Dovey West Des Moines, Iowa USA C links at
http://www.iedu.com/c Read my lips: The apple doesn't fall
far from the tree.


I used this approach to apply a curve to some table base
aprons. I bent a thin (1/8") strip of wood and clamped the
ends. I cut it out with a jigsaw and used the first piece as
a pattern for the second. I'm guessing that doing it the way
I did, I ended up with a parabolic curve.

If the strip is of uniform width and thickness, I think the curve
is called a catenary. It's the same curve a chain makes when you
suspend it from its ends. It's like a parabola, except that the
apex is flatter.

I don't think you'd really like aprons with a true parabolic curve.

--
Morris Dovey
West Des Moines, Iowa USA
C links at http://www.iedu.com/c
Read my lips: The apple doesn't fall far from the tree.

On Sat, 14 Feb 2004 04:33:55 GMT, Michael Baglio
wrote:

Okay Andy, it's my turn to be the village idiot. I must have failed
cut 'n' paste in kindergarten...

You've already had your chance in the dust collector static thread.

I don't "get" French Curves.
Assuming there _is_ something to "get," what do they _do?_

No problem - two hundred years of draughting just had it wrong. Thanks
for setting them straight.

On Fri, 13 Feb 2004 21:52:07 GMT, Bay Area Dave wrote:

HOw can I create a fair curve about 36" long that isn't merely
an arc of a circle.

Some more comments on smooth curves and French curves.

A "smooth" curve is one that avoids corners. A "corner" is a point
where there's a discontinuity in the tangent - i.e. a tangent drawn
just a tiny fraction to one side of the corner wouldn't line up with a
similar tangent drawn to the curve just the other side of the corner.
By implication, if we can align the tangents of two curves, then we
can avoid the corner.

Now the fun bit - this even works with two different curves. If we can
just get those tangents to line up, then the transition between them
will be smooth - no matter how much of a change in curvature is
involved.

Aligning tangents is one approach. But if tangents align, then so must
the perpendiculars align. Now for a simple arc, the perpendicular is a
radius, which suggests a useful special case.

When joining a circular arc onto a straight line, the centre used by
the compasses to strike the arc must be on a line perpendicular to the
straight line, and crossing it at the point where the curves join.
This sounds awkward, but it's pretty obvious in pictures. It's also
the principle behind constructing the range of Gothic arches:
http://codesmiths.com/shed/workshop/techniques/arches.htm


A French curve is a curved stencil whose shape is a mathematically
somewhat complex curve that changes its radius of curvature along its
length. There are several sorts, and those with access to Mathematica
http://mathworld.wolfram.com/FrenchCurve.html
or other drawing tools can probably generate their own. A useful
source for some basic curves of this family are the Archimedian and
logarithmic spirals, which can be constructed with simple paper and
pencil methods.

A French curve is a curve that changes along its length. So you should
be able to roughly eyeball what you need, then find a curve you
already have that offers roughly the right curvature at two places
roughly the right distance apart (the previous trick about making
enlarged MDF duplicates by photocopying is worth it, if you need big
furnituremaker's curves.)

To use a French curve, first choose the best fit you have. The place
it roughly in place so that it touches the existing curve at the right
places. Now slide it from side to side, keeping it aligned against
those end points, until the tangents are a good fit. You're done !

If it doesn't work, then try different curves. They'll all fit and
give a smooth curve, but they might not offer quite the radius you're
after. _Don't_ use French curve by picking the radii you want,
plonking it down and then trying to "smooth out" the corners. They
just don't work that way. Each given curve will only fit at one place
- if you want different combinations of radii, then you need a
different curve (but photocopiers with fine enlargement control are
your friend).

Avoid Bezier curves (offered by any CAD program) for freehand drawing
work. Although they can be used, it's all too easy to make a spline
curve look ugly in a purely aesthetic sense (and the maths of exactly
_why_ is both horrible, and does actually exist). However today is
Valentine's Day, and I have taken a solemn oath to forswear all
aesthetics.



--
If you can't be good, be weird

On Sat, 14 Feb 2004 04:33:55 GMT, Michael Baglio
wrote:


Okay Andy, it's my turn to be the village idiot. I must have failed
cut 'n' paste in kindergarten...


Speaking of "cut and paste", you will save yourself a lot of trouble
by doing exactly that.

Describe the curved line in a drawing program and print it out full
size.

Spray adhesive.

Bandsaur.



....and it's PURPLE !



Thomas J. Watson-Cabinetmaker (ret)
Real Email is: tjwatson1ATcomcastDOTnet
Website: http://home.comcast.net/~tjwatson1

On Sat, 14 Feb 2004 22:28:49 +0000, Andy Dingley
wrote:

On Sat, 14 Feb 2004 04:33:55 GMT, Michael Baglio
wrote:

Okay Andy, it's my turn to be the village idiot. I must have failed
cut 'n' paste in kindergarten...

You've already had your chance in the dust collector static thread.

I don't "get" French Curves.
Assuming there _is_ something to "get," what do they _do?_

No problem - two hundred years of draughting just had it wrong. Thanks
for setting them straight.

???

Andy, did I **** you off in a previous life or something? You seemed
to know about FCs, so I thought I'd ask. Whatever it was I said that
prompted your last crack, I apologize.

Michael

Better still ,french curves being short, try ships curves instead. Of course
the idea of halving the distance between the length of the curve and drawing
one half freehand and then flipping it and tracing the other has to be way
too simple dunnit. mjh

--




"Andy Dingley" wrote in message
...
On Sat, 14 Feb 2004 04:33:55 GMT, Michael Baglio
wrote:

Okay Andy, it's my turn to be the village idiot. I must have failed
cut 'n' paste in kindergarten...

You've already had your chance in the dust collector static thread.

I don't "get" French Curves.
Assuming there _is_ something to "get," what do they _do?_

No problem - two hundred years of draughting just had it wrong. Thanks
for setting them straight.

On Sat, 14 Feb 2004 19:20:45 -0500, Tom Watson
brought forth from the murky depths:

On Sat, 14 Feb 2004 04:33:55 GMT, Michael Baglio
wrote:

Okay Andy, it's my turn to be the village idiot. I must have failed
cut 'n' paste in kindergarten...

Speaking of "cut and paste", you will save yourself a lot of trouble
by doing exactly that.

Describe the curved line in a drawing program and print it out full
size.

Do you pick up the mouse and speak into it like Scotty
did in "Star Trek IV: The Voyage Home"? Or how does the
computer program understand your description?


Spray adhesive.

Bandsaur.

Poor Mikey prolly didn't "get" Art Nouveau furniture, either.
'Tis a shame, wot?


...and it's PURPLE !

So put a bandage on it and put the Playboys away, silly
savage. It'll be pink again in a week. DAMHIKT blush


--
Impeach 'em ALL!
----------------------------------------------------
http://diversify.com Website Application Programming

In article ,
Andy Dingley wrote:
On Fri, 13 Feb 2004 16:31:08 -0600, Morris Dovey
wrote:

A thin strip of wood would work well.

Bent strips are OK for symmetrical curves (I use fibreglass skite
spar), but they don't work so well for an asymmetric curve.

--
Smert' spamionam

They might if you taper the strip.


--

Larry Wasserman Baltimore, Maryland