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.
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.
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?
Morris Dovey wrote:
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.
Bay Area Dave wrote:
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
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! :)
Morris Dovey 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. :)
That works very well for compound curves.
block to each end
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.
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 ...
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? :)
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.
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 ...
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