Valued Contributor
Posts: 50
Registered: ‎11-08-2007
Message 1 of 6 (240 Views)

# Drawing curves for a sketch & description

240 Views, 5 Replies
08-04-2008 06:04 AM
How do I draw a curve if I only have the direction and length of the previous tangent connecting to the curve, the central angle of the curve, its arclength, and the radius of the curve? I was given the following description but I don't know how to proceed to draw these two curves after the POB:

THENCE CONTINUE N00°24’02”E, A DISTANCE OF 10.39 FEET TO THE POINT OF BEGINNING, SAID POINT ALSO BEING THE POINT OF CURVATURE OF A CURVE TO THE RIGHT HAVING A RADIUS OF 191.85 FEET, A CENTRAL ANGLE OF 18°07’32” AND A CHORD BEARING OF N09°27’48”E; THENCE RUN ALONG SAID CURVE A DISTANCE OF 60.69 FEET TO THE POINT OF REVERSE CURVATURE OF A CURVE TO THE LEFT HAVING A RADIUS OF 133.42 FEET, AND A CENTRAL ANGLE OF 17°03’03”; THENCE RUN ALONG SAID CURVE A DISTANCE OF 39.70 FEET TO THE POINT OF TANGENCY THEREOF;

Any suggestions?
Valued Contributor
Posts: 50
Registered: ‎11-08-2007
Message 2 of 6 (240 Views)

# Re: Drawing curves for a sketch & description

08-04-2008 06:26 AM in reply to: Nostromo2
Just to clarify, I can draw the first curve after using Utilities > Curve Solver to figure out the length of the chord. Problem is, I can't draw the second curve since all I have for its direction is "A CURVE TO THE LEFT" ... (no direction or bearing) ...

I think I am not understanding something about curve geometry. How can I calculate the bearing for the second curve? I always draw a curve based on its radius, chord bearing and chord distance. Help!
Active Member
Posts: 9
Registered: ‎06-19-2008
Message 3 of 6 (240 Views)

# Re: Drawing curves for a sketch & description

08-04-2008 06:41 AM in reply to: Nostromo2
ON YOUR SECOND CURVE SINCE IT IS A POINT OF REVERSE CURVATURE SIMPLY MAKE A LINE FROM THE RADIUS POINT OF YOUR PREVIOUS CURVE TO THE PRC THEN EXTEND THAT LINE OUT THE RADIUS LENGTH OF YOUR SECOND CURVE TO MAKE A RADIUS POINT FOR IT. NOW FROM YOUR NEW RADIUS POINT DO A TURN ANGLE USING THE DELTA GIVING. HOPE THIS HELPS
Valued Contributor
Posts: 50
Registered: ‎11-08-2007
Message 4 of 6 (240 Views)

# Re: Drawing curves for a sketch & description

08-04-2008 07:10 AM in reply to: Nostromo2
Thanks! that helped! but following the second curves comes a tangent, then a third curve:

THENCE RUN N01°28’31”E, A DISTANCE OF 36.63 FEET TO THE POINT OF CURVATURE OF A CURVE TO THE RIGHT HAVING A RADIUS OF 16.48 FEET AND A CENTRAL ANGLE OF 84°36’37”; THENCE RUN ALONG SAID CURVE A DISTANCE OF 24.34 FEET TO THE POINT OF TANGENCY THEREOF;

I know how to draw curves from PRC's. But how do I do this one? I can handle the rest of the description. Thanks again!
Valued Contributor
Posts: 50
Registered: ‎11-08-2007
Message 5 of 6 (240 Views)

# Re: Drawing curves for a sketch & description

08-04-2008 07:19 AM in reply to: Nostromo2
I think I got it... I start by turning my tangent 90 degrees to find the next radius point, right? then draw a line between the PC and the radoud point, then do again the turned angle this time from the radius point and using the delta...

Thanks!!!
Active Member
Posts: 9
Registered: ‎06-19-2008
Message 6 of 6 (240 Views)

# Re: Drawing curves for a sketch & description

08-04-2008 07:40 AM in reply to: Nostromo2
YES - IF A CURVE IS TO BE MATHAMATICALLY CORRECT IT IS TANGENT (90 TO THE RADII) SO ALL YOU DO IS DRAW FROM THE RADIUS TO PC AND TURN YOUR DELTA FOR THE NEXT CURVE OR PUT IN THE NEXT PIECE OF TANGENT (STRAIGHT LINE WITH BEARING AND DISTANCE) FROM THE PC OF THE CURVE. I KNOW THIS EASY ON TO SEE ON THE SCREEN BUT I DO NOT KNOW WHAT AUTOCAD YOU ARE USING THEREFOR I CAN NOT SEND YOU A FILE TO LOOK AT.
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