Drawing Curves?

[Darrin Davis]

I was wondering if anyone had any tips to share on how to draw curves on wood to be cut out on the bandsaw. I'm not looking for perfect arcs, in fact last time I used a fiberglass rod and clamped the ends in place and pulled the middle where I wanted it and drew the line. If you have your way and would like to share it please post it here!

[mark page]

If the radius is going to be perfect arcs or circle segments, I use a draftsman compass to make them. Although in the past I have reverted to using used cd's, coasters, tin cans, etc just for a rough idea of what I am trying to detail out to see what it might look like.

[Darrin Davis]

I should of been more specific. I meant large curves like the coffee table below.

coffee table.jpg

I used an 8 foot long router circle jig made out of a strip of 1/4" ply for the long arc on the underneath sides of the skirts. But sometimes I don't need perfection, I just need an arc that looks good at first glance.

[Mark Singer]

I sometimes cut thin strips of wood...then clamp one side together....then bend and clamp th other side . This makes an adjustable curve. A bar compass with trammels is good if you can locate a center

[Tom Veatch]

...But sometimes I don't need perfection, I just need an arc that looks good at first glance.

Then the technique you're using is fine.

A 'glass rod probably gives you a little smoother curve (which will be closer to a parabolic arc than a circular arc, BTW) than does a strip of wood. Variations in grain direction will cause the stiffness of a wood strip to change along its length. Usually, that's no big deal, but the straighter the grain, the better the results.

[Kurt Strandberg]

I would use my Compucarve to cut a curve an 1/8' or so and then use my band saw to cut it out.

With the computer program that came with Compucarve it would be a perfect curve

[Ray Moser]

For smaller work I have a set of French curves that come in handy. When I built my wife a wall mounted 3 shelf plate holder, I just played with the French curves until I got what I wanted for the sides. Two of the shelves are the same depth and the third at the top is narrower. The curves take care of the transition for the set back. I have also used them to design shelf brackets.

[Joe Pelonio]

I hate to admit it but I have used bender board with a rope around it. Then I realized I can do a curve in the computer and print it out on paper on the vinyl plotter, apply to the wood with artist's spray adhesive.

[Richard Wolf]

I like tremmel points. I use different size beams to layout staircases. I have used some 16 ft. pieces for large radii.
But small ones work just as well.

Richard

[Jeffrey Makiel]

For large curves and complex shapes, I print out a paper template from my computer. However, this means that you are able to draw the part using a CAD program like Sketchup.

When the part is larger than maximum sheet size that my small inkjet printer can handle, I print it out in several full scale sections and then tape the sections together. Using an index, like drawing a ruler on your part, will help you align the sections later.

Here's an example of what I did just a couple of hours ago. This is a part for a curved front medicine cabinet surround. It used three sheets of 'legal' size paper.

-Jeff

[Joe Chritz]

I cheat and have Dad cut me a template on the CNC router.

If I do it by hand it is a thin board or rod. Clamp, bend and draw.

Joe

[Cliff Rohrabacher]

I use my work bench and some scrap wood to make a beam compass. I drive a nail through the beam compass into the bench at the right radius point and clamp the work and then clamp a pencil or scribe to the end of the beam compass and wail away. The work will be positioned according to pencil marks or I've got a lot to do I clamp screw or nail blocks of wood as positive stops against which to clamp the work.

[Ben Grunow]

sometimes, when working without a plan, I draw one side of a curve by eye (freehand) an dkeep re-drawing until I see what I am looking for. Then I make a simple grid (lines perpendicular to eachother with squares about 1/2" x 1/2") and using coordinates, transfer one side to the other for a perfect replica.

I have seen boat builders use heavy weights to hold flexible battens so they can be traced or measured from. THis would be nice because you could adjust (and stand back and look as many times as needed) without ever making a pencil line

[Brian Penning]

A friend has both of these from Lee Valley and they're on my wish list after trying them out.
http://www.leevalley.com/images/item...05n5520s1b.jpg

[Bert Johansen]

Darren, I believe Woodcraft sells a plexiglas curve tool that is similar to what Mark Singer described, except it's made of (drum roll) PLEXIGLAS! I have one, but I'm not in my shop to see what brand it is. Not terribly expensive, as I recall, and I believe mine is 36 inches in length. Very handy.