| Author |
Message |
Guest
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 Posted:
Fri Oct 14, 2005 8:10 pm Post subject:
beginner question about entering curve data |
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Hello,
I am doing parcel updates in Autocad. I am able to enter line data
using commands like @150.9<n45d38'22"e. However, I cannot figure out
how to enter curve data using these types of coordinates (especially
considering that I only know the start point of my curve). For
example, I have the following info available for curves:
delta, radius, length, chord bearing, chord
Sorry if this is simple, but my math is rusty and my Autocad skills are
weak. How would I structure this in the command line?
Thank you!
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Michael Bulatovich
Guest
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| Posted:
Sat Oct 15, 2005 12:10 am Post subject:
Re: beginner question about entering curve data |
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Why not just draw the chord, then draw a Point/Point/Radius arc, and then
finally erase the chord?
Why do you have to create the curve from the command line?
--
MichaelB
www.michaelbulatovich.ca
<rioroad@hotmail.com> wrote in message
news:1129308869.074910.212160@g14g2000cwa.googlegroups.com...
| Quote: | Hello,
I am doing parcel updates in Autocad. I am able to enter line data
using commands like @150.9<n45d38'22"e. However, I cannot figure out
how to enter curve data using these types of coordinates (especially
considering that I only know the start point of my curve). For
example, I have the following info available for curves:
delta, radius, length, chord bearing, chord
Sorry if this is simple, but my math is rusty and my Autocad skills are
weak. How would I structure this in the command line?
Thank you!
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R.K. McSwain
Guest
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| Posted:
Sat Oct 15, 2005 8:10 am Post subject:
Re: beginner question about entering curve data |
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rioroad@hotmail.com wrote:
| Quote: | Hello,
I am doing parcel updates in Autocad. I am able to enter line data
using commands like @150.9<n45d38'22"e. However, I cannot figure out
how to enter curve data using these types of coordinates (especially
considering that I only know the start point of my curve). For
example, I have the following info available for curves:
delta, radius, length, chord bearing, chord
Sorry if this is simple, but my math is rusty and my Autocad skills are
weak. How would I structure this in the command line?
Thank you!
|
Draw a line perpendicular to the previous line, the length of the radius.
Move it to the endpoint of the previous line.
Now the endpoint of this new line that is not touching the previous line
is the center point.
Copy this line in place
Rotate this line the delta angle, using the center point as the base for
the rotation.
Now you have the PC, RP, PT
Draw your arc.
You could also use Michael's method, but generally you will find that
the arc is more accurate (or matches all the curve data) if you use the
delta and radius parameters.
--
R.K. McSwain
http://rkmcswain.blogspot.com
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Michael Bulatovich
Guest
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| Posted:
Sat Oct 15, 2005 12:10 pm Post subject:
Re: beginner question about entering curve data |
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Doesn't your method assume that the starting line is a tangent to the curve
the OP's trying to draw? What if it's not?
Also, please eloaborate on the accuracy point. I thought an ARC was an ARC.
What 'curve data' might be different between arcs created using the two
methods?
--
MichaelB
www.michaelbulatovich.ca
"R.K. McSwain" <rkmcswain@yahoo.com> wrote in message
news:vV_3f.2365$BZ5.2201@newssvr13.news.prodigy.com...
| Quote: | rioroad@hotmail.com wrote:
Hello,
I am doing parcel updates in Autocad. I am able to enter line data
using commands like @150.9<n45d38'22"e. However, I cannot figure out
how to enter curve data using these types of coordinates (especially
considering that I only know the start point of my curve). For
example, I have the following info available for curves:
delta, radius, length, chord bearing, chord
Sorry if this is simple, but my math is rusty and my Autocad skills are
weak. How would I structure this in the command line? Thank you!
Draw a line perpendicular to the previous line, the length of the radius.
Move it to the endpoint of the previous line.
Now the endpoint of this new line that is not touching the previous line
is the center point.
Copy this line in place
Rotate this line the delta angle, using the center point as the base for
the rotation.
Now you have the PC, RP, PT
Draw your arc.
You could also use Michael's method, but generally you will find that the
arc is more accurate (or matches all the curve data) if you use the delta
and radius parameters.
--
R.K. McSwain
http://rkmcswain.blogspot.com |
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R.K. McSwain
Guest
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| Posted:
Sun Oct 16, 2005 12:10 pm Post subject:
Re: beginner question about entering curve data |
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Michael Bulatovich wrote:
| Quote: | Doesn't your method assume that the starting line is a tangent to the curve
the OP's trying to draw?
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True.
What if it's not?
Then you construct the starting line the angle of the radial bearing in.
Of course you would need this data. If you don't have it, then you would
have to use the chord data.
| Quote: | Also, please eloaborate on the accuracy point. I thought an ARC was an ARC.
What 'curve data' might be different between arcs created using the two
methods?
|
For example. Given this set of curve data:
R=770.00
A=349.27
D=25°59'22"
CB=N69°08'08"E
CD=346.29
If you layout this arc by using the chord bearing, chord distance, and
the radius, then the arc length turns out to be 349.28 (rounded to 2
decimal places).
If you layout this arc by using the chord bearing, chord distance, and
the delta, then the arc length is 349.28, and the radius is 770.01.
If you layout this arc by using the delta and radius, then the resulting
arc matches all of the data above.
--
R.K. McSwain
http://rkmcswain.blogspot.com |
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