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#### TechnoPallidin

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My math has totally escaped me... given a curve that I want to replicate, what is the process to determine the bevel dimensions of the overall wood pieces. so lets say I have a panel that has a curve of 1" over a 15-16" length. and I'm cutting 3/4 stock to create the panel. The curve ends at 1" out from the start. so like a very slight convex curve and if I put 2 doors together I would have a full convex curve starting and ending at the same dimension with the "Peak" of the curve being roughly 1" out from the frame. the 3/4 stock I can size down to lets say roughly 2" strips that would be glued together to create the panel.

any thought's / help on this one? I'm guess my angle might be very slight... like maybe a couple degrees, but I'm just guessing. I guess I can always buy a small scrap piece to experiment with, however with wood prices currently I'd rather try to "math" it out first.

Thanks.

#### Rebelwork

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Is this for a cabinet door?

#### TechnoPallidin

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Is this for a cabinet door?
yes. and while I was never bad with math it's been over 20+ years since I had to do anything really beyond what I would call basic math. lol. so all my geometry and such has failed me. these old brain cells.

So yeah, basically think like making a barrel, each board needs to have a, I guess you call it a chamfer maybe, on each length dimension of the board. such that they become a trapazoid vs a rectangle. then by gluing them together it creates the curve. After lots of sanding/planning it becomes a nice smooth door.

Essentially thinking to do this since I have never really done laminates, and not sure how well 3 sheets of 1/4 ply would work in that regard, and then I'd also have to deal with veneer which I haven't really done either.

Thanks.

#### Bob Bengal

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Yeah I'm 63 and a bit dyslexic, my number crunching isn't what it used to be. If I sort of understand your situation the first link @SonnyAgain posted is on the right track but not in the easiest form.

I like this one, you can put in 3 X,Y points on the circle and it will tell you the radius and center of the circle. Say the 2 doors are each 15" wide and in the center where the doors meet they are 1" higher than at the left and right corners. Make the meeting of the doors the Y axis and the corners on the X axis. So the meeting point is 0,1 and the corners are -15,0 and 15,0. Put those coordinates in the calculator, the order of the points doesn't matter, and it will tell you the radius etc.

In what I just said I was thinking of an upward arc at the top of the doors, like the photos @SonnyAgain posted. But you want the doors to bulge outward? As if the doors are cut from a large cylinder? That would be like stave construction, for building drums etc. And you want the face of the doors to be a continuous curve, not with each wood strip still having it's own face? With a radius of 113" not the easiest router jig to make lol. Hand planing maybe? Please post a sketch of what you want to do.

#### woodnthings

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I actually made a router jig for a curved headboard that was 120" from the pivot to the center of the router. I never used it after I looked at the design for a while. Establishing the pivot that far out was not easy, but doable. I spliced two pieces of 1/4" Masonite together to get the 120" distance.

Bob Bengal

#### NoNails

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1" at 16" the angle is a right triangle .. isn't it? That's the worst the curvature I would flex a strip of stock to sketch one side then flip to mirror it.

#### Rebelwork

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Are we making the cathedral/crown parts for doors?

They use to sell per patterns for this. Maybe it was Jesada...

#### DrRobert

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Can you post a sketch? Is this a design feature?

I avoid “math” at all costs and would start by making a full scale drawing and determine the taper angle by trial and error.

Youre still going to have to cut an arch, right? I use templates as Rebel described, or I make my own.

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#### woodnthings

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I used a flexible thin strip between 3 nails to make the curve on top of my fence boards. Start with it under the left and right nails at the terminations and raise it up until you get the curve you like. Put the third nail at the height in the center. Trace the bottom of the strip on your board and that's your curve. Remove the nails and the strip and saw it out..... no Math! The terminations were 10 ft apart on my fence and the height above them is about 12" or so, a very pleasing curve from a distance.
It's also called a "fairing" stick:

#### Rebelwork

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Companies like Jesada will make pattern sets so you just trace, cutout and go. After all said and done you'll have patterns for most sizes..

#### TimPa

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sounds like you want to create a curved panel/door. the math would require more information, like how many "slats" (barrel staves in your comparison) are going to be used, slat width (2"?), etc. the wider the slat, the more segmented it will look.

you can go the non-math route - get the curve you want, either drawn full scale on a piece, or a bent strip of wood. take 2 slats of the width you instend to use. angle your jointer fence (or table saw blade) and run one edge of both slats though, start with say 2 degrees. hold those 2 side adjacent and on top of your curve and see if there is a gap. adjust accordingly.

glue up is a little difficult, as you need a jig to "hold" the curve as you assemble the strips.

#### RBhoffmann

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My math has totally escaped me... given a curve that I want to replicate, what is the process to determine the bevel dimensions of the overall wood pieces. so lets say I have a panel that has a curve of 1" over a 15-16" length. and I'm cutting 3/4 stock to create the panel. The curve ends at 1" out from the start. so like a very slight convex curve and if I put 2 doors together I would have a full convex curve starting and ending at the same dimension with the "Peak" of the curve being roughly 1" out from the frame. the 3/4 stock I can size down to lets say roughly 2" strips that would be glued together to create the panel.

any thought's / help on this one? I'm guess my angle might be very slight... like maybe a couple degrees, but I'm just guessing. I guess I can always buy a small scrap piece to experiment with, however with wood prices currently I'd rather try to "math" it out first.

Thanks.
You'd have to check my math but I get each side would need a bevel of about 1/2 degree. Here is the logic:

I need 'X' to find the angle for one door. Since the door sticks out about one inch I subtract that from X to get the one missing side. Then using the Pythagorean theorem: 15^2 + (X-1)^2 = X^2 I get a radius of 113 inches and then the angle 'a' is 7.6 degrees. Divide that by 8 slates and you get 0.95 degrees which needs divided in half to get the angle for each side of the joints. So, just shy of 0.5 degrees for each slat edge.

Of course, I could load up my cad software and have it measure things for me, but don't have the time to install it now.

#### RBhoffmann

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You'd have to check my math but I get each side would need a bevel of about 1/2 degree. Here is the logic:
View attachment 428309
I need 'X' to find the angle for one door. Since the door sticks out about one inch I subtract that from X to get the one missing side. Then using the Pythagorean theorem: 15^2 + (X-1)^2 = X^2 I get a radius of 113 inches and then the angle 'a' is 7.6 degrees. Divide that by 8 slates and you get 0.95 degrees which needs divided in half to get the angle for each side of the joints. So, just shy of 0.5 degrees for each slat edge.

Of course, I could load up my cad software and have it measure things for me, but don't have the time to install it now.
Ok, I did load LibreCad (free) and confirmed the radius as 113 inches and the angle for one door as 7.6 degrees - so just under 1/2 degree for each bevel on a slat assuming eight 2inch slats.

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