How to lay out a shallow curve?

[Jack Hutchinson]

This is for a headboard for a double mattress bed frame. I plan to make it 1 3/4 inches higher in the center.

What's the best method to draw that curve?

Scribe along a thin, uniform strip of maple bent around three points?

Great forum! I've been lurking and learning for a month.

- Jack

[Ken Werner]

You're close. I'd take a thin strip of plywood the length of your curve and drill a hole near each end. Slip a string through and adjust til you're happy. Eye it carefully, as imperfections in the wood could cause a distortion in your curve. Once you're happy, trace the curve with a pencil.
PS welcome to the creek Jack.
Ken

[John Leslie]

If you want your curve to be part of an ellipse, you can use a piece of string and 2 nails. Place the nails on the axis of the 1/2 ellipse to be drawn and attach the string with some amount of slack. The amount of slack will determine the shape of the curve. Place the pencil inside the string aligned on the axis and take up the slack (such that the pencil will start outside of the nail). Then push the pencil along, keeping tension on the string. I would do this on a piece of hardboard or mdf to make a template that you can then cut and tweak as needed. Then use the template to transfer to your wood. Rough cut to shape and then use a flush trim bit against the template to clean it up.

Cheers,
- John

[Jim Becker]

I generally use the "bent thin strip" method for laying out these gentle curves if they don't have to be a precise radius or perfect side of an ellipse. For the latter, I use the method that John details.

[Norman Hitt]

I use the bent strip method also, except that my bent strip is a long piece of 2" x 3/16" thick aluminum I bought years ago for this because it bends uniformly is smooth and don't rot (or get broken and discarded with the scrap:rolleyes: ).:D Ovals.......same as John & Jim.

[Dave Richards]

You could also take two sticks and attach them in a shallow vee that has the same height as the desired arc. Then put a nail in the end points of the arc and slide the vee over the nails. A pencil at the apex of the vee will scribe the arc.

The sticks each have to be longer than the base of the arc by an inch or so at least.

[glenn bradley]

Ken's got it but I use hardboard as that avoids most of the irregularities in natural woods that cause less uniform curves under tension.

[Alan Turner]

I use the bent strip method also, except that my bent strip is a long piece of 2" x 3/16" thick aluminum I bought years ago for this because it bends uniformly is smooth and don't rot (or get broken and discarded with the scrap:rolleyes: ).:D Ovals.......same as John & Jim.

Great idea. I'll now be looking for a piece of alum. Lee Valley has a drawing bow, of fiberglass, but only 4' long. It won't work on your project, but I use mine when I need a shallow, regualr curve. Wood does not always bend with regularity, I have found.

[Ben Grunow]

The bent stick method is the way to go for arcs but you dont get a radius. I use this method for a eyeing a curve too but I have found that it is good to make a couple of quick checks before cutting because sometimes the eye is hung over or tired.

I draw my curve and then take the stick and place it below the nails and slide it up to touch them. Then measure a couple of even distances from the centerline and record the distance up from the stick to the curved line and then check to make sure the other side is within reason.

Much easier now than later.

[Jack Hutchinson]

for the guidance.

I think I understand how to get a pleasing, regular curve drawn.

This is only my second furniture level project (the first the workbench) - so I'm on that steep early learning slope.

- Jack