# How To...with pic



## Robie (Feb 25, 2005)

I have to replicate the arches seen in the picture. The porch has been re-built with new columns, etc. I have made the center, teardrop sections, but am wondering the best way to go about measuring to get the new arches to meet where they should. Any ideas?
Thanks.
View attachment 1573


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## Tom R (Jun 1, 2004)

Hmm, - - I'll give it a shot there, Robie.

How about if you 'clamped' a plywood ripping across any two columns at a time, - - at (any) certain height, - - and perfectly level, - - then measure in (diagonally) from the inside of each upper column corner, - - and mark the 'center' of your plywood, - - then stick a nail in that center mark, - - and pull your tape off of it to any and given points, - - jot down all measurements, - - then transfer to your shop.

You might also want to 'trace' your arch-curves onto a luanne plywood ripping.

Just some food for thought, - - maybe someone knows better.


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## Aceinstaller (Feb 5, 2006)

I like tom's idea. 

My two cents would be to set the teardrop template on the plywood that has been laid out according to tom's advice and find a radiuos that looks most appealing or one that looks the most like the picture to connect the reference points from the post to the teardrop.(different color markers will help to see the different radiouses when trying to find the best one on your plywood)

Good luck, and send us some pics when your finished!


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## Teetorbilt (Feb 12, 2004)

It appears as if each one is different, in regards to spacing. I'd just do the math.


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## Robie (Feb 25, 2005)

Yeah, I'd just do the math too, but it seems I was "smokin' in the boys room" when that class was being taught.
Wanna 'splain a little more about the math?


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## Nick H (Nov 13, 2005)

If those curved pieces are true radius's (or is it radii) then you can work out what the radius is by fixing a straight edge between two pionts that are a known distance apart, say 30" for instance, and then measuring how far the farthest piont on the curve is away from the straight edge, say 5".
With these measurements you can use trigonometry to work out the radius.
I'll try to explain the process !

Distance between two pionts is "A"
Distance from straight edge to furthest piont on curve is "B"

A divided by 2 = "C"

We now work out some angles, (using trig tables)

Tangent of "D" = B divided by C (use tables to find angle (D) which has a tangent = B/C)

90 minus D = E

E minus D = F (these are all angles)

Cosine of F = C divided by R (R=radius of circle)

therefore C divided by Cosine of F = Radius

Couldn't be simpler.


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## Tom R (Jun 1, 2004)

Yeah, I don't really think they're 'radii', though, - - seems to me they would need to be (discontinued) ellipses, bein's they start at the same height, - - yet the posts are different distances apart, - - not really that hard to figure, though, - - just need the height and width of the area in which they sit, - - the 'true' width would be the distance between the posts, minus the width of the 'teardrop'.


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## Nick H (Nov 13, 2005)

I'll work an example,

Distance between pionts is 30", distance to curve is 5".

30/2 = 15

5/15 = .3333 

using trig tables, an angle of 18 deg has a tan of .3333

90 - 18 = 72

72 -18 =54

Cosine 54 = .5878

15/.5878 = 25.5

radius of circle = 25 1/2 inches


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## Joe Carola (Jun 15, 2004)

Robie said:


> Yeah, I'd just do the math too, but it seems I was "smokin' in the boys room" when that class was being taught.
> Wanna 'splain a little more about the math?


Robie,

If you use 30" as the width and 5" as the height you can use this formula.

(Width x²/ 8xH) + (H/2) = Radius


30x² = 900 ÷ 40 = 22.5 + 2.5 = 25" = (Radius)


Or, if you have a Construction Master Calculator, you can do this.


30" [Run]

5" [Rise]

[Conv] [Radius} Returns - 25" = (Radius)


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## JustaFramer (Jan 21, 2005)

Those are quarter rounds on the longer spans. Not full arches. How ever long those seagull looking trim is subtract come the over all run.


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## Nick H (Nov 13, 2005)

I suppose the first question should have been do you have the old sections to copy ?


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## Patty (Jan 21, 2006)

It's moments like this that tell me I should have paid more attention in Trig class!:shutup: 

Sounds like a bunch of Alien Men to me!:laughing: 

Is that what 'speaking in tongues' looks like?:laughing: :blink:


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## Tom R (Jun 1, 2004)

Patty said:


> It's moments like this that tell me I should have paid more attention in Trig class!:shutup:
> 
> Sounds like a bunch of Alien Men to me!:laughing:
> 
> Is that what 'speaking in tongues' looks like?:laughing: :blink:



Yes, Patty, 'ALIEN', - - speaking of which . . . 

Would you like to 'INTERGALACTACIZE' sometime?? :laughing:

Just kiddin', girl, - - take it easy on me now!! :laughing:


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## Robie (Feb 25, 2005)

I have all the old parts, but I'm not sure they will be of any help, except for copying the width and such. 
Seems to me, using Tom's idea of the plywood is the way I will go. Once I have the points referenced, I can make a cardboard cutout of each arch to make sure it fits properly.
Thanks for all the replys. Working on these old places gives you a renewed respect for the craftsman of years gone by. This house was built in 1870. The original middle point in all those "teardrops" are dovetailed into place.


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## Tom R (Jun 1, 2004)

Robie said:


> Working on these old places gives you a renewed respect for the craftsman of years gone by. This house was built in 1870.


You're right, Robie, - - I love gettin' those types of jobs, - - always a fresh challenge, - - good luck with it, - - make sure you post up some pics when it's done!!


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## Tom R (Jun 1, 2004)

Tom R said:


> Yes, Patty, 'ALIEN', - - speaking of which . . .
> 
> Would you like to 'INTERGALACTACIZE' sometime?? :laughing:
> 
> Just kiddin', girl, - - take it easy on me now!! :laughing:



What'sa matta', Patty?? . . . 

'INTERGALACTA-CAT' got your tongue?? :laughing: :shutup: :laughing:


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## tcleve4911 (Mar 26, 2006)

*Tryed & true methods*

Sounds like another situation for the "Tick Stick" method
I like Tom R's method of templating & also using the "tick stick"


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