Sketchup question

[Christof Grohs]

I'm curious if there is a function to determine volume of an object. For Example, if I draw a 12" square and pull it up 12" I get a 1 cu.ft cube. Then if I cut, say a 6" dia. hole through the cube, how do I determine the volume of the cube after the hold is made? I could figure the volume of the cube less the volume of the hole, easy enough but my pea brain stops right about there. If I continue to add or subtract things, say I truncate one of the corners I'm pretty much lost with volume.

Below is a pic of a speaker cabinet I build. I'm trying to model it in Sketchup and establish internal volume based on what size I model it at. Any ideas?

Thanks
Chris

[Larry James]

A ruby script may work, if you can install it and make it work.

Try:
http://www.crai.archi.fr/RubyLibraryDepot/Ruby/en_geo_page.htm

[Jesse Kerr]

You have it right volume of a cube - volume of cylinder
volume of a cube = L*W*H, volume of a cylinder = (pi) r^2 h, this will work when you use a cylinder speaker
(I would suggest a calculator for this)
If you use a regular speaker it will be conical in shape.
Letter variable explanation
h1 = imaginary portion of cone
h = height of known portion of cone (rim to back of magnet)
r = radius of magnet
R = radius of rim

This is the equation for a cone with a missing portion
V= (1/3)(pi)R^2(h1+h) - (1/3)(pi)r^2h1

In order to do this you must first set up a ratio and solve to get h1, it is
h1 = h1=h
r R
then simply plug h1 into the formula given

If you really get specific you must compensate for all of the triangle portions of the box and the thickness of the wood, and to do that you need to visualize basic geometric shapes in the box. The cube and the elongated triangles. But in this case I don't think that it will make too much of a difference.

Also check this site out it might have some useful info to it.
http://www.mobileinformationlabs.com/HowTo-1Woofer-Box-CALTriangle%20Volum_1%20.htm

[Jesse Kerr]

ratio will not come up right so here it is
(h1/r)= (h1+h)/R

[Paul Simmel]

Just came across this:

http://www.crai.archi.fr/RubyLibraryDepot/Ruby/em_fil_page.htm

Look for:
VolumeCalculator21.rb