What should every woodworker know about French curves?

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Forum topic by Rob posted 05-01-2015 05:38 PM 696 views 0 times favorited 3 replies Add to Favorites Watch
View Rob's profile


704 posts in 2491 days

05-01-2015 05:38 PM

I was going to buy a French curve and realized I might not know enough about them to know which one(s) to buy. I just thought a French curve was a French curve, but after looking at them, I see they not only come in different sizes, but also in different shapes. On top of that, they have different internal shapes cut into them…some have circles or ovals while others have more interesting internal shapes. Some even have a ruler or scale.

In high school I learned to just use a French curve to connect 3 points, draw one segment of a line connecting 2 of the points, and move onto setting up and drawing the next segment. Is that pretty much it, or is there something else I should know?

I presume the curves with irregular shapes cut into the inside are more useful than the ones with circles…in any case, I can get a dedicated circle or oval template, or use a compass or trammel or things that I have around the shop to draw circles. Or are the internal shapes somewhat redundant and not as useful?

Is the scale (in particular, the one that bends around a curve) important to have, and if so, how do you use it?

-- Ask an expert or be the expert -

3 replies so far

View Gene Howe's profile

Gene Howe

8098 posts in 2849 days

#1 posted 05-01-2015 05:53 PM

All good questions, Rob.
I’ll be watching this thread because I have the same questions.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View mahdee's profile


3462 posts in 1188 days

#2 posted 05-01-2015 05:54 PM

Hi Rob,
I use them in almost every project I make. From what I understand, the curves were originally created by ship makers a few thousand years back before mathematicalization of such curves. The mathematized version we use today serve functions from creating appealing curves in furniture to determining stock movements based on chart pattern. Normally, the way I use it is to do my drawing first and then conform it to the shape of the ruler. Majority of the time, the hand drawn shape hardly need any major modification. It could be because I love curves and use them often (not sure). Anyways, you can make some interesting shapes by using 2 or three of them at certain increments such as 1/2 of one + 1/3 of another along with a full length of the third.


View SirIrb's profile


1239 posts in 651 days

#3 posted 05-01-2015 06:26 PM

Per the ship builders comment: They called them splines (still used today in CAD) and where the splines today (CAD) have controlling points where the shape changes or inflects, the ship builders had lead “ducks” that held the spline on the floor. When they had the shape the way they liked they would trace it out. Thats all I remember from one of my advanced surfacing classes.

That was just a bit of history 101 and I doubt it will help much. Sorry. Best advice is to freehand and let your eye find what it likes. The natural progression of truing up the edge or shape will turn it into a (God help me) “Happy” shape. I find that the more premade curves I use to try to get a shape the less it fits and the less “happy” it is.


-- Don't blame me, I voted for no one.

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