I'd appreciate your advice on how to calculate and/or build a curve of
pickets on a wood gate about 3-1/2 feet wide.
The pointed pickets with spaces between them would begin at their
highest point at each vertical edge and then evenly curve down a few
inches to their lowest point in mid-gate.

Thanks in advance for your help.

Darro

Darro wrote in
:

I'd appreciate your advice on how to calculate and/or build a curve of
pickets on a wood gate about 3-1/2 feet wide.
The pointed pickets with spaces between them would begin at their
highest point at each vertical edge and then evenly curve down a few
inches to their lowest point in mid-gate.

I just built the gate rectangular to the right width, then measure and tie
a string to a pencil that is half the width of the gate. Tack the loose
end of the string down at the halfway point so that the pencil is at the
top of the gate and the tack is directly below, equi-distant from each
side. Then, draw the arc with the pencil, and cut.

Darro wrote:
I'd appreciate your advice on how to calculate and/or build a curve of
pickets on a wood gate about 3-1/2 feet wide.
The pointed pickets with spaces between them would begin at their
highest point at each vertical edge and then evenly curve down a few
inches to their lowest point in mid-gate.

Thanks in advance for your help.

Darro

You didn't say how "deep" you want the distance from end to middle to
be. Say you want a three inch drop, then you have a 6.5 foot radius to
strike an arc to measure each picket against.

If you have other dimensions, use this handy little calculator:
http://www.1728.com/circsect.htm
Your info is the chord and segment height.


--
Grandpa

What is that dripping from my fingers?
Why it looks like time.

Darro wrote:
I'd appreciate your advice on how to calculate and/or build a curve of
pickets on a wood gate about 3-1/2 feet wide.
The pointed pickets with spaces between them would begin at their
highest point at each vertical edge and then evenly curve down a few
inches to their lowest point in mid-gate.

Thanks in advance for your help.

Darro

Others have mentioned the segment of circular arc method. Another
method, also involving string and pencil, is to tack a length of string
to the high points at each end, and let it droop down a little in the
middle. Let it droop down the amount to get the curve you want. Then
pencil in the string position on the pickets. This will give a
parabolic, rather than a circular curve -- matter of taste which you
like better.

Actually with any of these methods, since you want to have your picket
points up, the process is a little more complicated. You could lay out
the pickets on a flat surface in the arrangement they will be in the
gate, then using the arc-circle method mark the bottom ends, then shift
the pickets so the marks all line up (thus shifting the curve to the
top) to see what it looks like. With the droopy string method you
would have to do this with the pickets standing up (perhaps leaning
slightly against a wall) rather than laying flat.

Another method would be to create a template for the curvature by
cutting out a piece of cardboard that is the width of the gate and tall
enough to accommodate the amount of curvature you want, then using the
string and pencil to mark on the cardboard. Then cut the cardboard out
along the pencil marks to make a curve template. The advantage of the
template is greater if you have several gates to make.

Yet another method (saving the simplest for last) would be to lay out
the pickets on a flat surface in the arrangement they will be in the
gate, then just play with them until the top curve is like you want it,
then mark a straight line across them (to define the bottom of the
gate) and cut.

-- H

On 2006-05-05, Heathcliff wrote:

Another method, also involving string and pencil, is to tack a
length of string to the high points at each end, and let it droop
down a little in the middle. Let it droop down the amount to get
the curve you want. Then pencil in the string position on the
pickets. This will give a parabolic, rather than a circular curve --
matter of taste which you like better.

Actually, this gives a curve called a catenary, although it looks a lot
like a parabola. See, e.g., http://en.wikipedia.org/wiki/Catenary.

Cheers, Wayne

Wayne Whitney wrote:
On 2006-05-05, Heathcliff wrote:

Another method, also involving string and pencil, is to tack a
length of string to the high points at each end, and let it droop
down a little in the middle. Let it droop down the amount to get
the curve you want. Then pencil in the string position on the
pickets. This will give a parabolic, rather than a circular curve --
matter of taste which you like better.

Actually, this gives a curve called a catenary, although it looks a lot
like a parabola. See, e.g., http://en.wikipedia.org/wiki/Catenary.

Cheers, Wayne

Oooh, good catch. I was just going by what I was told once in a
ceramics class, where the class was using the hanging-chain technique
to makr out a template for constructing a "parabolic kiln." I guess
the lesson is don't believe everything the art teacher says about
mathematics. -- H