Author Topic: The length of a scroll arc  (Read 7986 times)

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Offline mike2334Topic starter

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The length of a scroll arc
« on: May 22, 2020, 19:31:12 PM »
I have drawn the top of a impeller scroll for a cyclone using AutoLisp.
Now using AutoLisp I have to find the length of this scroll so I can make the side.
How can I get this length, I have use pedit to make it all one line but with entget I can't find the length?
Is there a way to use list in Autolisp and pull out the length?

Thanks Mike

Offline Steadtler

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Re: The length of a scroll arc
« Reply #1 on: May 24, 2020, 16:53:04 PM »
I don't know how accurate you need to be but a very good result can be achieved by doing the following:

Using the offset command, offset the spline say 1".
Move the resulting spline off to the side.
Repeat the offset 1" but in the opposite direction (this will result in a "copy" of the original spline but will include control points along the spline).
Type "List" at the command line to see the length and a list of control point coordinates to replicate the spline using straight line segments.

No information on whether this is a one time or production situation. If production, just run a test side a little long and trim the excess off  - measure the length of scrap.  If a one time, well, you're already done.