"Weight" center of an irregular shaped object??

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kristenanne77
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"Weight" center of an irregular shaped object??

Post by kristenanne77 »

I have a long irregular shaped object that I would like to hang on a string in a balanced way. . If I center it, its length from the origin center to either side would be equal, but one side is actually "fatter" than the other. So If I use that origin as center and try and hang it, it will slant down on the heavier side. Is there any way I can determine the center of this shape so that the weight (not length) on either side would be equal? The wood is 1/8 inch plywood with uniform density throughout.

Thanks
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dwilli9013
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Re: "Weight" center of an irregular shaped object??

Post by dwilli9013 »

Well a really trick way I have seen to do this is put the object on edge then place a dowel rod or other round object under the edge approximately where you feel the center may be. Then roll you object back and forth until you find the balance point. Once you have gotten close pencil mark you center point and hang. This obviously is no good if you have no flat edges on your frame.
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Jim_in_PA
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Re: "Weight" center of an irregular shaped object??

Post by Jim_in_PA »

Honestly, the easiest way to calculate this is to cut a sample with a bunch of test holes that you can hang and experiment to find the best balance point...and then finalize your tool path to cut the mounting hole in "the spot".

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scottp55
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Re: "Weight" center of an irregular shaped object??

Post by scottp55 »

Pad smallest suitable clamp, put a piece of cord around clamp in center, and move clamp until it hangs right....mark!
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tomgardiner
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Re: "Weight" center of an irregular shaped object??

Post by tomgardiner »

Wasn't there a gadget at one time that would find the centre of mass? Or I might be dreaming. Autocad?

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Rcnewcomb
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Re: "Weight" center of an irregular shaped object??

Post by Rcnewcomb »

Here are the steps using AutoCAD: ->Link
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adze_cnc
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Re: "Weight" center of an irregular shaped object??

Post by adze_cnc »

If you already have the object: https://youtu.be/HaaL2wucyRE

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mtylerfl
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Re: "Weight" center of an irregular shaped object??

Post by mtylerfl »

tomgardiner wrote:Wasn't there a gadget at one time that would find the centre of mass? Or I might be dreaming. Autocad?
There used to be shortcut keys for calculating volume for 3D models, but was removed. Anyway, I don’t think that would have helped for determining Center of Mass.

An old-school method for finding Center of Mass for planar shapes/objects was to make a cutout version in card stock and balance it or hang it from a string.
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vip-klaus
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Re: "Weight" center of an irregular shaped object??

Post by vip-klaus »

If you are willing to uploade your shape, I can try to find the c.o.g. using a cad software.

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Re: "Weight" center of an irregular shaped object??

Post by ozymax »

The Balance gadget might be of use to you.
http://forum.vectric.com/viewtopic.php? ... et#p194186

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SteveNelson46
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Re: "Weight" center of an irregular shaped object??

Post by SteveNelson46 »

Why not just clamp something relatively sharp or round in a vise (back of a knife, steel rod...) and just hand balance it on the rod or knife. Make a mark on the edge then rotate it 180 degrees and hand balance it again. Draw a line between the two marks. That is your horizontal center of balance.
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mtylerfl
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Re: "Weight" center of an irregular shaped object??

Post by mtylerfl »

mtylerfl wrote:There used to be shortcut keys for calculating volume for 3D models, but was removed...
I stand corrected! There still is a set of shortcut keys for calculating the volume of 3D models (they were changed sometime in 2012)

Here is the shortcut combo: CTRL-ALT-SHIFT-V

This may not help with determining Center of Mass, but I wanted to post the correction to my previous statement. (Volume calculation can be handy for folks making molds for glass, chocolate, wax, etc. so they can get a close estimate of material needed for pouring into the molds.)
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