Man, this web thing takes the joy out of trying to remember old
HS geometry!
Anyways, came up with the same thing, R = (x^2 + y^2)/(2*y),
where y is half the length of the chord and x is the height above
the chord...
i.
Norm Abrams wrote:
> "Ron Hock" <[email protected]> wrote in message
> news:[email protected]...
>
>>I want to make a table top with a slight arc along the edge. I know
>
> the
>
>>length of the side (the chord) and I know the height of the arc above
>>the chord. Anyone know the formula to calculate the radius of the
>>circle?
>>
>>TIA
>>Ron
>>
>>
>>--
>>Ron Hock
>>HOCK TOOLS -- http://www.hocktools.com
>
>
> I believe this is what you're looking for (bottom)
> http://www.delorie.com/wood/chord-radius.html
>
>
In rec.woodworking
"todd" <[email protected]> wrote:
>You know, I got kind of focused in on the math problem part of this without
>giving a lot of thought to what he would do with it if he had it. So, to
>the OP, what are you going to do if you find out that the radius is 10 feet?
>I'm cutting some aprons for a table base right now that need to have an arc.
>I'm just using a piece of plastic bar stock, clamping it at the appropriate
>places and forcing a bend in the bar and using that to trace an arc.
>Probably closer to a parabola than an arc of a circle, but it works for me.
You could make a string compass and draw that part of the arc on a sheet of
cardboard. Go out on the driveway if you need room. Done.
Yes, the $3400 calculator. You can do better for a lot less money.
"Unisaw A100" <[email protected]> wrote in message
news:[email protected]...
> That's easy. AutoCAD.
>
> UA100
> "todd" <[email protected]> wrote in message
> news:[email protected]...
>
>
> > what are you going to do if you find out that the radius is 10 feet?
"CW" <[email protected]> wrote in message
news:f5d6b.273269$cF.85569@rwcrnsc53...
He would cut a ten foot radius I would assume.
[top-posting fixed]
I was more thinking along the lines of how, but Bruce's suggestion is a good
one.
todd
In article <[email protected]>,
Ron Hock <[email protected]> wrote:
>I want to make a table top with a slight arc along the edge. I know the
>length of the side (the chord) and I know the height of the arc above
>the chord. Anyone know the formula to calculate the radius of the
>circle?
The optimized formula is:
chord squared, divided by 8 times the height, then add half the height.
example:
chord: 10
height: 2
radius = ((10*10)/(8*2)) + 2/2
radius = (100 / 16) + 1
radius = 6.25 + 1
radius = 7.25
The derivation of the above gets messy.
"Iraxl Enb" <[email protected]> wrote in message
news:[email protected]...
> Man, this web thing takes the joy out of trying to remember old
> HS geometry!
>
You think the web's bad? Try AutoCAD. Draw the chord. Draw the
height. Draw a 3 point arc. Select the arc and right click properties.
Gives you the radius, arc length, etc.
> Anyways, came up with the same thing, R = (x^2 + y^2)/(2*y),
> where y is half the length of the chord and x is the height above
> the chord...
>
> i.
>
>
> Norm Abrams wrote:
> > "Ron Hock" <[email protected]> wrote in message
> > news:[email protected]...
> >
> >>I want to make a table top with a slight arc along the edge. I know
> >
> > the
> >
> >>length of the side (the chord) and I know the height of the arc
above
> >>the chord. Anyone know the formula to calculate the radius of the
> >>circle?
> >>
> >>TIA
> >>Ron
> >>
> >>
> >>--
> >>Ron Hock
> >>HOCK TOOLS -- http://www.hocktools.com
> >
> >
> > I believe this is what you're looking for (bottom)
> > http://www.delorie.com/wood/chord-radius.html
> >
> >
>
He would cut a ten foot radius I would assume.
"todd" <[email protected]> wrote in message
news:[email protected]...
> what are you going to do if you find out that the radius is 10 feet?
>>
>
"Ron Hock" <[email protected]> wrote in message
news:[email protected]...
> I want to make a table top with a slight arc along the edge. I know
the
> length of the side (the chord) and I know the height of the arc above
> the chord. Anyone know the formula to calculate the radius of the
> circle?
>
> TIA
> Ron
>
>
> --
> Ron Hock
> HOCK TOOLS -- http://www.hocktools.com
I believe this is what you're looking for (bottom)
http://www.delorie.com/wood/chord-radius.html
On Fri, 05 Sep 2003 09:35:53 -0700, Ron Hock <[email protected]>
wrote:
>I want to make a table top with a slight arc along the edge. I know the
>length of the side (the chord) and I know the height of the arc above
>the chord. Anyone know the formula to calculate the radius of the
>circle?
Let l be the length of the chord
h be the chord-arc height
r the radius
and d the distance from the centre to the chord
Then
r = ( (l^2 / 4) + h^2 ) / 2h
d = ( (l^2 / 4) - h^2 ) / 2h
I had to cut a twenty four foot radius for a template one time. I did it
with a router circle jig.
"todd" <[email protected]> wrote in message
news:[email protected]...
>
> I was more thinking along the lines of how, but Bruce's suggestion is a
good
> one.
>
> todd
>
>
http://mathforum.org/library/drmath/view/55037.html
link to XL spreadsheet (watch out for line wrap)
http://216.239.51.104/search?q=cache:6GIlO2OZGFMJ:www.ukuleles.com/spreadsheets/ArcCalcs.XLS+chord+radius+length+arc&hl=en&ie=UTF-8
--
Ken Vaughn
Visit My Workshop: http://home.earthlink.net/~kvaughn65/
"Ron Hock" <[email protected]> wrote in message
news:[email protected]...
> I want to make a table top with a slight arc along the edge. I know the
> length of the side (the chord) and I know the height of the arc above
> the chord. Anyone know the formula to calculate the radius of the
> circle?
>
> TIA
> Ron
>
>
> --
> Ron Hock
> HOCK TOOLS -- http://www.hocktools.com