Arc length??? Any way to draw to an exact length?

[aero_blitz_2216698774]

what's the command for this lisp routine? sorry i'm new to all these. thanks for the reply.

[mlb6d9763438]

The only way I know of is to draw the arc with the radius you want at a random length, then use lengthen to set the exact length.

Or use a lisp routine like

;Written By: derek 'maverick' beals
;Version: a
;Date: 9-26-05
;Description: this lisp routine draws an arc at given length & radius

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Non-Standard Lisp Functions

(defun rtd (r) ; Radians to Degrees
(/ (* r 180.0) pi))

(defun dtr (d) ; Degrees to Radians
(/ (* d pi) 180.0))

(defun tan (a) ; Tangent of variable (a) in Radians
(/ (sin a) (cos a)))

(defun sqr (a) (* a a)) ; Squares the variable (a)

(defun fixx (realnum) ; Rounds the variable (realnum) to the next highest whole integer (opposite of the "fix" function)
(if (> realnum (+ (fix realnum) 0))
(setq realnum (1+ (fix realnum)))
(setq realnum (fix realnum))
)
realnum
)

;(setq variable (ssget)) - allows multiple picks in lisp

;(setq OS (getvar "osmode"))...(setvar "osmode" OS) - gets current O-snap settings @ front of lisp, then reestablishes them at the end

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Lisp Programming starts here


(setq LENG (getdist "\nEnter length of arc: ")
RAD (getdist "\nEnter radius of arc: ")
CEN (getpoint "\nPick center point of arc: ")
ANG (/ LENG RAD)
ANG1 (/ (- PI ANG) 2.0)
ANG2 (/ (+ PI ANG) 2.0)
ARC (entmake (list
(cons 0 "ARC")
(cons 10 CEN)
(cons 40 RAD)
(cons 50 ANG1)
(cons 51 ANG2)))
)
(princ)

Hi Guys - this LISP does exactly what I want it to, but I can't get it to work unless I APPLOAD it every time I need it. If I type 'arc-length' which I assume is the command, it just says 'unkown command.' I'm no LISP expert, what am I doing wrong?

[tedg]

Hi Guys - this LISP does exactly what I want it to, but I can't get it to work unless I APPLOAD it every time I need it. If I type 'arc-length' which I assume is the command, it just says 'unkown command.' I'm no LISP expert, what am I doing wrong?

This lisp didn't have a command function, may have been part of a bigger routine or the author wanted it to run on appload.
Anywho, you still need to appload it per session or add it to your startup suite or acaddoc.lsp, but I added "test" for the command you can change it to whatever you need.

;;;CADALYST Tips & Tools Weekly  05/08/06	arc-length.lsp	(c) 2006 Derek Beals


;File Name: arc-length
;Written By: derek 'maverick' beals
;Version: a
;Date: 9-26-05
;Description:  this lisp routine draws an arc at given length & radius

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Non-Standard Lisp Functions
(defun c:test () ;;<-added command defun
(defun rtd (r) ; Radians to Degrees
  (/ (* r 180.0) pi))

(defun dtr (d) ; Degrees to Radians
  (/ (* d pi) 180.0))

(defun tan (a)  ; Tangent of variable (a) in Radians
  (/ (sin a) (cos a)))

(defun sqr (a) (* a a)) ; Squares the variable (a)

(defun fixx (realnum) ; Rounds the variable (realnum) to the next highest whole integer (opposite of the "fix" function)
(if (> realnum (+ (fix realnum) 0)) 
    (setq realnum (1+ (fix realnum))) 
    (setq realnum  (fix realnum)) 
) 
realnum 
) 

;(setq variable (ssget)) - allows multiple picks in lisp

;(setq OS (getvar "osmode"))...(setvar "osmode" OS) - gets current O-snap settings @ front of lisp, then reestablishes them at the end

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Lisp Programming starts here


(setq LENG (getdist "\nEnter length of arc: ") 
RAD (getdist "\nEnter radius of arc: ") 
CEN (getpoint "\nPick center point of arc: ") 
ANG (/ LENG RAD) 
ANG1 (/ (- PI ANG) 2.0) 
ANG2 (/ (+ PI ANG) 2.0) 
ARC (entmake (list 
(cons 0 "ARC") 
(cons 10 CEN) 
(cons 40 RAD) 
(cons 50 ANG1) 
(cons 51 ANG2))) 
) );;<-added closing parenthesis
(princ)