uneven-shaped box volume formulas needed....asap!!!!

[buchi 10+ year member]

its been a long time since i have entered the forum. too long that my IP is no longer recognized by OUR site that i needed to log in and type my password.

anyway, my problem is about how to compute volume for uneven-shaped sub enclosures. im into fiberglassing enclosures and i usually dont place mdf boxes inside my fiberglass enclosures. i simply mold or cast the sides or the surfaces of the enclosure directly with resin then fiberclass. i usually estimate the volume and so far, it proves to be okay with sealed enclosures. but i just want everything to be exact.

is there a program that i can couple with AutoCAD that automatically computes the enclusure volumes after it is drawn in AutoCAD? ive checked with Linear X systems and all that the software could do is compute simple geographical shapes. polygons (like heptagons which i assume is simple enough to compute the volume) have formulas but not uneven shaped enclosures. i need a software here. surely, with the use of calculus with analytyic geometry, one could eke out any volume but hey, who would dare do the computation by hand?

hope someone could help me out.

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[_PuNiShEr_ 10+ year member]

The best way i have heard is to use packing peanuts fill the enclosure with them and then messure how many ft^3 you used.

But im guessing you are wanting to design your box to a specific volume and then build it. If that is the case your best bet would be to design it in a 3D modeling software. Such as Pro/E, SolidWorks, Solid Edge, Inventer something to that affect.

If you need i can use solidworks at work (which is where i am now shhhh) if you could get me some general shape and dimension i could throw something together.

 

[GCAdidas13 10+ year member]

you could also estimate if the figure has at least some straight edges. give a little here, take some there, take some measurements and then fiberglass what you need to.

actually, i was considering the following:

when it comes time to fiberglass, do way more than you think you might need to do, and then mount your MDF ring. when you go to attach the fleece, only hotglue the baffle, and when that dries, cut out the fleece of the baffle so you can see inside your box. pack lightly with packin' peanuts, and then you can make adjustments to your baffle as necessary to get the appropriate volume.

i think.

 

[swimfreak26 10+ year member]

Calculus is the only real way to do it...the problem is that you'll need to create a formula that depicts the upper (z-axis) boundries of the enclosure. Also, it sounds as though you know what you're doing, but if not...you'll need a triple integral underneath this surface to determine the volume.

Sad thing is, this takes WAY too much time, and is not worth it. Give yourself a rough estimate by breaking the desired enclosure into simple geometrical figures and just be sure to underestimate. Then, you can fill your enclosure with packing peanuts as was stated above and figure out the actual volume...then just fill with wood the space you don't need.

 

[GCAdidas13 10+ year member]

Give yourself a rough estimate by breaking the desired enclosure into simple geometrical figures and just be sure to underestimate. Then, you can fill your enclosure with packing peanuts as was stated above and figure out the actual volume...then just fill with wood the space you don't need.

Best idea ever. Make it 20% too big, then fill the rest with port area and/or wood.

 

[buchi 10+ year member]

thanks guys!!!! though crude the methodology that you have presented...who would think packing peanets is the answer!!!!....it kinda give me the whole picture on what to do. but at least i know there isnt any software that is in the market to help me out with this problem.