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### Author Topic: Calculation for the arc using the height of the arc  (Read 12919 times)

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#### sysKo

• Guest
##### Calculation for the arc using the height of the arc
« on: May 27, 2009, 18:01:16 PM »
I do not know where to put this question, hear or in the CNC? Anyway.

I (re)ask again for this. I have a part of the arc. I want to calculate the radio of the arc. The height of the arc i know it. How to calculate it?

K.

#### kam

• Hero Member
• Posts: 1849
##### Re: Calculation for the arc using the height of the arc
« Reply #1 on: May 27, 2009, 20:13:05 PM »
It's a good board the one you chose to post your question.

So... I think you are missing of something. The given data are not enough. We need either the angle of the arc, or the chord of the arc... Please specify.

My regards

#### sysKo

• Guest
##### Re: Calculation for the arc using the height of the arc
« Reply #2 on: May 28, 2009, 18:19:48 PM »
Chord is the open? You know... The open of the door

#### kam

• Hero Member
• Posts: 1849
##### Re: Calculation for the arc using the height of the arc
« Reply #3 on: May 28, 2009, 20:19:20 PM »
I suppose you want to calculate the radius of the arc, by knowing the arch chord (AKA door width - left space - right space) and by knowing the ark height.

For the people here to understand, because our conversation looks like an encoded signal, i have attached a file...

So, first to calculate the Semi_Chord. That would be the Chord divided by two:

SC = C/2

Then, the radius can be easily calculated using the following formula:

R = H2 + SC2 / 2H

I asked you to write it down not to forget. But now you can find it here whenever you want

#### sysKo

• Guest
##### Re: Calculation for the arc using the height of the arc
« Reply #4 on: May 29, 2009, 18:25:57 PM »
Thanks you Georg. Is this that i am look!!!!!

#### kam

• Hero Member
• Posts: 1849
##### Re: Calculation for the arc using the height of the arc
« Reply #5 on: May 29, 2009, 22:20:39 PM »
Thanks you Georg. Is this that i am look!!!!!

yes is this

I know

#### sysKo

• Guest
##### Re: Calculation for the arc using the height of the arc
« Reply #6 on: June 05, 2009, 22:49:29 PM »
And for the draw with 3 circles? The "perispomenh"? I am sorry i do not know the english name.

#### kam

• Hero Member
• Posts: 1849
##### Re: Calculation for the arc using the height of the arc
« Reply #7 on: June 06, 2009, 00:00:46 AM »
Perpendicular is the name. I told you you should write them down

Rtotal = H2+SC2 / 2*H
Rin = Rtotal * L
Rout = Rtotal-Rin...

#### sysKo

• Guest
##### Re: Calculation for the arc using the height of the arc
« Reply #8 on: June 09, 2009, 16:52:18 PM »
And i understand you think by this?
« Last Edit: June 09, 2009, 16:58:33 PM by sysKo »

#### kam

• Hero Member
• Posts: 1849
##### Re: Calculation for the arc using the height of the arc
« Reply #9 on: June 10, 2009, 23:25:06 PM »
You should!

Anyway.

Consider as it was a single arc (like the first drawing attached).

The radius (that i call Rtotal) should be

Rtotal = H2+SC2 / 2*H

But now you have a parameter L, that is a number from 0 to 1. Use 0.5. You'll get what this is when time comes.

So, the internal arc will have a radius of:

Rin = Rtotal * L

and the external 2 arcs will have rad:

Rext = Rtotal - Rin

Is that clear now?

#### sysKo

• Guest
##### Re: Calculation for the arc using the height of the arc
« Reply #10 on: June 22, 2009, 08:34:55 AM »
I still make china symbols with it

Am i stupid?

#### kam

• Hero Member
• Posts: 1849
##### Re: Calculation for the arc using the height of the arc
« Reply #11 on: June 22, 2009, 16:38:17 PM »
In the name of holy mary madonna

See attached image:

The Semi-cord SC is half the width (left to right) of the drawing.
The Height H is user defined
The proportion L (LOGOS in Greek is also user defined, at about 0.5 or so...)

ROL=(H2 + SC2)/2H
Rin = ROL*L
Rex = ROL-Rin

Ok So far?

Now:

X2 = X1 + H * L
X3 = X1 + L

Y2 = Y1 + SC * L

#### spic0m

• Global Moderator
• Hero Member
• Posts: 841
##### Re: Calculation for the arc using the height of the arc
« Reply #12 on: June 22, 2009, 19:14:15 PM »
That's the problem with CNC, they go along with maths, otherwise is just a big router.

#### kam

• Hero Member
• Posts: 1849
##### Re: Calculation for the arc using the height of the arc
« Reply #13 on: June 22, 2009, 22:07:14 PM »
That's the problem with CNC, they go along with maths, otherwise is just a big router.

That's the problem with operators.... not cnc... You need maths also with the hand routers. If you want to be a good operator, you need maths. Kostas (sysKo) is a "wanna be" good operator, but because of his believes that he needs no maths, he will never be above average.

#### spic0m

• Global Moderator
• Hero Member
• Posts: 841
##### Re: Calculation for the arc using the height of the arc
« Reply #14 on: June 23, 2009, 10:27:00 AM »
Correct, i mean just something to cut straight lines.