topic Re: Length of arc? in Modeling

Length of arc?

Anonymous — Tue, 04 Jan 2011 19:53:47 GMT

Can't remember how to do this in trig, been way too many years.
And can't seem to figure out how to get AC to measure the length
of this arc. either with spline or polyline.

I'm sure I missing the obvious but have run out of ideas.
I've tried holding down ctr/alt keys etc,etc to get it to add all together but each point I click resets length to zero again.
And bending straight line so far gives no joy.
help would be great.

Re: Length of arc?

Anonymous — Tue, 04 Jan 2011 20:29:15 GMT

Select the arc then go to
Window->Pallets->Element Information
and click on the second icon from the left.
Peter Devlin

Re: Length of arc?

Anonymous — Tue, 04 Jan 2011 22:25:10 GMT

I found on the web an equation for arc length
that does not involve trig or calculus.

C is the central angle
R is the radius
∏ is Ludolph's constant
(3.1415926....)
Peter Devlin

Re: Length of arc?

Anonymous — Wed, 05 Jan 2011 00:05:26 GMT

The dimensioning tool has an arc-length geometry style for measuring arcs.

Re: Length of arc?

David Maudlin — Wed, 05 Jan 2011 13:50:22 GMT

Peter wrote:
Select the arc then go to Window->Pallets->Element Information and click on the second icon from the left.

Be sure to draw the arc counter-clockwise, or the angle and length will be wrong. Looks like a bug.

David

Re: Length of arc?

Anonymous — Wed, 05 Jan 2011 16:54:05 GMT

Hello David,
I could not reproduce the clockwise counterclockwise bug
in either AC 10 or AC 12.
Could it be that what works correctly in AC 10 or AC 12 got busted in AC 14 ?
If you still have an AC version earlier than AC 14, see if it works correctly in that version.
Thanks,
Peter Devlin

Re: Length of arc?

Anonymous — Wed, 05 Jan 2011 18:27:33 GMT

Thanks all for the replies.

David, I tried both directions with the spline tool (14) and Element Info gave me the same length.

zpf, Could not get dimension tool to measure arc, my ignorance there I suppose.

Peter, thanks for the formula, took me a minute, but I got it.

Thanks again everyone.

Re: Length of arc?

Anonymous — Wed, 05 Jan 2011 18:42:52 GMT

Select the tool, then select the arc geometry method like in the attached pic, click on the edge of the arc you want to dimension, click twice outside (or inside) of the arc to generate the dimension, click once more to place it. That should be it.

Re: Length of arc?

Anonymous — Wed, 05 Jan 2011 19:18:52 GMT

Duh, I was trying to make it work on a spline "arc".
Thanks zpr

Re: Length of arc?

Laszlo Nagy — Wed, 05 Jan 2011 21:10:38 GMT

David wrote:
Peter wrote:
Select the arc then go to Window->Pallets->Element Information and click on the second icon from the left.
Be sure to draw the arc counter-clockwise, or the angle and length will be wrong. Looks like a bug.

David

I get this bug too.
I also get it if I draw counterclockwise, then mirror it. The angle of the mirrored arc will be incorrectly reported.
So I send this to GS.

Re: Length of arc?

Anonymous — Wed, 05 Jan 2011 21:20:32 GMT

Since I did not get error(win7-64), is it only a mac thing on 14?
Or am I just lucky?

Re: Length of arc?

Anonymous — Wed, 05 Jan 2011 21:20:45 GMT

Hello Laszlo,
I notice that you have AC 12 and AC 13.
Does this bug happen in either of those versions ?
Thanks,
Peter Devlin

Re: Length of arc?

Laszlo Nagy — Wed, 05 Jan 2011 21:34:31 GMT

Hi Peter,
No, it does not happen in AC12 or AC13.
Works well both when created clockwise and when an arc created counterclockwise is mirrored.
Must be a AC14 specific thing.

Re: Length of arc?

Anonymous — Wed, 05 Jan 2011 22:19:05 GMT

Hello Laszlo,
Thank you for checking and posting back.
Peter Devlin

Re: Length of arc?

Barry Kelly — Thu, 06 Jan 2011 02:08:20 GMT

laszlonagy wrote:
Hi Peter,
No, it does not happen in AC12 or AC13.
Works well both when created clockwise and when an arc created counterclockwise is mirrored.
Must be a AC14 specific thing.

Maybe this problem is related to why mirrored elipses (basin objects for example) don't print to PDF in 14.
All the geometry is getting screwed up behind the scenes although it still appears correct on screen.
Barry.