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Drawing Arcs.
3

Drawing Arcs.

Drawing Arcs.

(OP)
How can I draw an arc? start,center,and lenght of arc. w/out cord lenght or degree.

RE: Drawing Arcs.

2
You can do start, end, radius.  It would take a LISP routine to do start, end, length.  If you can show the math, I can write the code for you.

RE: Drawing Arcs.

(OP)
IFRs; Radis 108" arc lenght 48"

RE: Drawing Arcs.

Since you know the start, end and radius, in AutoCAD, type:
"ARC" [space or enter] then "S" [space or enter]
Now pick or put in the coordinates of the Start point and press space or enter.
Now type "E" [space or enter]
Now pick or put in the coordinates of the End point and press space or enter.
Now type "R" [space or enter]
Now type in the radius and press space or enter.

That should do it !!

RE: Drawing Arcs.

<<How can I draw an arc? start,center,and lenght of arc. <<w/out cord lenght or degree

 You cannot unless you can eyeball the arc length
 with microscopic accuracy. Why make it so hard when
 you can easily get the angle of the arc knowing the
 radius & arc length. Sometimes, software problem comes
 up due to whimsical attitude & plain ignorance.

RE: Drawing Arcs.

"Quick" and dirty method....

1) Draw your arc using Start, End and Centre ensuring that you "overshoot" the arc length required.

2) Check the properties of the arc to determine the actual length drawn.

3) Draw a line from the end of the arc that is long enough to make the total combined length of the arc and line exactly double the required arc length.

4) Combine the arc and line in a Pline

5) Use the DIVIDE command to divide the Pline in 2.

6) Trim the arc off at the point created by the DIVIDE command.

Its not pretty, but it will work

Dave

RE: Drawing Arcs.

This is a 2 part method, but it works...  Start the ARC command > Pick start point > "C" enter > pick center > swing arc to an arbitrary angle.  Next start the LENGTHEN command > "T" enter > enter arc length > pick near the end-point of the angle, not the start point.  

P.S.
"Sometimes, software problem comes up due to whimsical attitude & plain ignorance."
Estassoc, was that really necessary?

Flores

RE: Drawing Arcs.

To find the degree of the arc:
2r*Pi= Circumfrence
Circumfrence/360=inches per degree
Length of required arc/inches per degree = degree of arc

So: Pick arc, then c or center, then pick center, then pick the start point or enter it as a relative cooridinate (@108,0), then enter A or angle to specify the angle, then enter the calculated angle (25.464791 deg).

I hope I made sense here.

RE: Drawing Arcs.

Most draftsmen using Autocad avoid using arc command because we have incountered the same problems you mentioned.  Instead of using arc, use circle command and trim off what you don't need.  The circle command has a lot of options that arc doesn't have.  It is quick and dirty but you don't have to compute degree of arc or try finding where the center of the arc is located in relationship to the drawing. Hope this helps - John.  

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