Need help: get length of arc/spline

thomthom

If you select edges and arches the Entity info will give you the total length.

pilou

You must explode "arc" before else you have only radius

jeff hammond

You must explode "arc" before else you have only radius

no, there's a drop down button in the entitiy info window that you can push which will give more info on the selected entity. i can easily find the length of an unexploded arc.

[this is at least capable on macs though i can't imagine it not working on windows]

pilou

@unknownuser said:

though i can't imagine it not working on windows

Thx! Never used for arcs!
That is the Duhduh of my day! (added to the Duh list

huyvuvn

thanks all , I know this way. But I wanna "GET" the length , not "KNOW" the length. It means have a "dim".

jeff hammond

@huyvuvn said:

thanks all , I know this way. But I wanna "GET" the length , not "KNOW" the length. It means have a "dim".

ok huyvu, you're obviously asking something but it's probably above me..
to me, getting the length means finding out how long the arc is.
maybe "get" is a calculus term that i've never heard of but i really can't figure out what you're wanting to achieve.
the only thing i can think you may be wanting to do is enter a radius and desired length of arc and sketchup will draw it. if that's the case, i personally don't know of any method to achieve this in SU.

do you have a visual example which may show the difference between getting the length and knowing the length?

pilou

before a plug
just use the tape measure tool on a segment of the arc and enter
length of a side / (existing length / length wished) (given by the Info)
Your drawing will be resized with the good length of the arc

Example : you have an arc of 5 sides for a length of 600 cm so a side = 600/5 = 120 cm
you want your arc = 100 cm
you will enter 120 / (600 / 100) = 20 cm

As all will resize, you must export in a new session your arc apply the resize above and import it after the redraw

Seems not many more difficult for a plug

thomthom

@huyvuvn said:

thanks all , I know this way. But I wanna "GET" the length , not "KNOW" the length. It means have a "dim".

Ok, you want a Dimension tool for arches and splines.

pilou

Can anybody can say why the length is false with this big % of error ??? (2.75%)
must be
5 * 120 = 600 and not 616.5...

why.skp

thomthom

@unknownuser said:

Can anybody can say why the length is false with this big % of error ??? (2.75%)
must be
5 * 120 = 600 and not 616.5... [attachment=1:h1pwt2lb]why.jpg[/attachment:h1pwt2lb]

Because SU calculate the length as if it is a perfectly round arch. I bet that it gives the 'correct' length if you explode it.

pilou

@unknownuser said:

if you explode it

Yes but it's dangerous to manipulate TNT