Set weight of part?

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Hello All,
Is there any way to set the weight of a part, to be used in mass props of an
assembly?
I drew up a right angle gearbox, and would like to set the weight at 4 lbs.
TIA,
Muggs
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To do this in the past, I've adjusted the density of the part. Use mass properties to get the volume, then divide your known weight by that. Use the result as your density.
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Good idea, Thanks Dale!
Muggs
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Same here.
WT
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My collegue once made a 1" cube weigh 300lb because he didn't want to draw a whole engine. Geee what kind of material is 300lb/1in^3. Kryptonite? MyMaterialonite? =^)
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there was a tv advertisment a while back for some science show describing the density of a 1" cube at around a million pounds, material was from a star (best as i can remember).
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I guess that must have been something like a brown drawf or a neutron star. Even Plutonium is only something like .72 lb/cu in. That is, if the info I found with Google is correct.
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not sure ... it may have been as much as 10~15 years ago when this ad aired (PBS only, can't remember). i do remember being baffled as to how something could be that dense. it might have just been speculation (from the astronomers).
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Black hole material?
WT
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My memory has faded some too. Thinking a little more, I think the brown dwarf is a failed star, and therefore composed of ordinary matter. Neutron stars are like a failed black hole, IIRC. A star quite a bit larger than the sun collapses in some sort of nova explosion, leaving a body so dense that the remaining protons and electrons combine to form neutrons. So this thing is all neutrons, not atoms. Something like 1000 km in diameter and spinning up to 30 times per second. Neat stuff.
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There's another trick if the center of gravity needs to be independently located, as in a model of a purchased part (like a motor/gearbox) where the external features are modeled to show appearance and fit, but none of the internal parts are created.
Make the part with a density close to zero. Make a tiny sphere or cube and give it a high density to match the weight of the real part. Put them both into an assembly and mate the high density part so it's at the desired location of the center of gravity. Save the assembly as a 2-body part, which now has the correct weight AND C.G. location.
Art W.
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independently
I should have mentioned that a part made this way still doesn't really duplicate the "real" part. With all the mass concentrated at a point, such things as radii of gyration and moments of inertia will be totally bogus.
AW
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Cute trick! I'll remember that one.
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if you find out the volum of the part. you can reverse from that using 4 lbs to figure out what to set the dencity to.
hope this helps.
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Would be way, way, WAY heavier than than a million pounds per cubic inch. Just for grins . . . the density is theoretically "infinite", but it's actually not even describable in those terms. Since light cannot escape the gravity well Relativity breaks down at the "event horizon" of a black hole and there becomes no meaning to the concept of "infinite". One would need a workable theory of quantum gravity in order to quantify the density, and we don't have one . . . yet (I'm workin' on it 8^P ). SolidWorks is just the means to the end.
'Sporky' "On the foreskin of technology"
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Let me add something to the theoretical "wish list" of stuff for Solidworks (and other CAD packages).
An object called "simple representation" which is drawn using any combination of points, lines, solids, or 3-d faces, which can be assigned a weight and moments of inertia.
This way we can use objects from 3-D model services (normally as meshes) or even 2-D drawings from manufacturers in our designs without all the hassle of re-creating them 3d in solidworks.
Joe

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