- Thread starter Noel
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Is it the radius of the part circle your trying to work out?

~Nil carborundum illegitemi~

~Nil carborundum illegitemi~

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In essence yes, the arc and chord etc. Various sizes of cathedral doors to make so need something so that they they all blend in. They have to match various sizes of existing doors. I may be able to borrow a door if I need to.deserter":1okw3o64 said:Is it the radius of the part circle your trying to work out?

~Nil carborundum illegitemi~

Assuming the curved edge is part of a circle (it need not be - could be an ellipse or an arbitrary oval)

If you have the length of the chord 2L and the distance D between the chord and the circumference of the circle, then the radius of the circle is given by:-

R=(L^2 +D^2) /2D

hth

Bob

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Thankyou Bob, good on yer.9fingers":1ztwyiuw said:

Assuming the curved edge is part of a circle (it need not be - could be an ellipse or an arbitrary oval)

If you have the length of the chord 2L and the distance D between the chord and the circumference of the circle, then the radius of the circle is given by:-

R=(L^2 +D^2) /2D

hth

Bob

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That's something I hadn't considered Chas and it seems obvious. As long as all the different doors look in proportion I'd be happy. I do have a tendency to over complicate matters.CHJ":2m7grtym said:

Last time I had to do similar I just marked up a series of contours on a sheet of hardboard at the steps required using dividers and used it as a full sized template, starting with the biggest and trimming it down in stages to the smallest.

(A technique borrowed from garment pattern grading where numerous production patterns are cut from a common design sheet.)

Here the radius of each curve equals the width of the opening and the centre of the curve is at the top of each vertical element of the opening.

It might be worth check to see if your pattern complies with this principle and if so scaling other sizes becomes a doddle. Also any trim or moulding radii are readily derived form the basic door.

Bob