Finding Center of Uneven Object for Hanging Keyhole

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WaltS
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Finding Center of Uneven Object for Hanging Keyhole

Post by WaltS »

So I've looked all this up online and since I'm not an engineer I can't comprehend the math so cutting it out and playing with it may be the only trial and answer method for me.

That said, anyone care to tell me where to put the keyhole on this fish shape so it hangs evenly?
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4DThinker
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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by 4DThinker »

Vertical centerline of mass is where the keyhole should be lined up. Hard to find on an odd shape. I usually lay down two dowels of the same diameter (1/4" or smaller), lay the shape on top, then start pulling the dowels closer together. If you can get them all the way together and the shape is still balanced then the centerline of mass will be the line between where the two dowels meet. Not much help until you've cut the shape out though.

I've played around with your drawing and using the measure tool if you draw a vertical line 0.4886" left of the center of the plate then that will be very close to where each half will have the same area.

If you can put two keyholes on the back level to each other as you want the shape to hang, then so long as they are on opposite sides of the mass center they'll work to keep the shape level on the wall.

4D

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by 4DThinker »

Here is the file I ended up with. V9.010.
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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by WaltS »

Thanks 4D. I can't open your file, I only have VCP and 8.5xx at that. I looked at all the "centerline mass" stuff online. I actually printed and cut out the fish to play with but didn't get close enough for me.

Funny enough my daughter and her boyfriend just stopped by. He recently graduated from engineering school. I was holding my paper fish in my hand when they came in. So I put him on the job. We played with it for a short bit and his "very rough" calculations put the centerline mass approx 3/8" to the left of center, which is somewhat close (within a tenth or so) to your 0.4886. He thinks he can figure it out on the dot with one of his software programs but not sure he can open any of the files VCP let me export. Have sent him all four file types so now waiting to see. I plotted your figure on my file and I'll see what he comes up with if he can open and use any of the files.

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by 4DThinker »

Just for you I exported my 9.01 file as a DXF file, then imported into 8.5.

4D
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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by lsvien »

This thread and others brings me to a conclusion that Vectric needs to bring in some way to save files in backward compatible formats. When I save a file in Word I have the option to save in an older version format. It will warn me that some features are going to be lost but I'm then able to save files in older formats. That way I can share files with other folks who have either decided to not upgrade or are financially unable to upgrade for various reasons. There are many different software packages that have this feature including many different CAD programs. This is a feature that I feel Vectric should be working on. Instead of a pull down that says save in .crv format it should offer up save as ver.8, ver. 7, etc. Yes some features are lost but not every project is bleeding edge technology with the most current wiz-bang features. I would probably use that way more than some of the current improvement that I just had to pay for in the upgrade to v9

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by ozymax »

I haven't had any time to play with it, but would the Balancing Gadget be of any help.
http://forum.vectric.com/viewtopic.php? ... et#p194186

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by cac67 »

You could just put in two and not worry about it.

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by WaltS »

4D - Thank you!!

Isvien - I agree 100%, however your post should probably be a new thread since it will be lost in here.

ozymax - Thanks for that! I had not seen that thread and I am going to look at it right now.

cac67 - Thanks, yes, that's an easy way out, but I prefer one. Many people are challenged when it comes to hanging things, easy things, let alone trying to hang something level that has two hanging points.

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by garylyb »

I make all my keyholes horizontal instead of vertical. There is never an issue this way.

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by 4DThinker »

garylyb wrote:I make all my keyholes horizontal instead of vertical. There is never an issue this way.
Unless you want to mount the shape at a specific location on the wall. Centered between windows for example.

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by WaltS »

ozymax wrote:I haven't had any time to play with it, but would the Balancing Gadget be of any help.
http://forum.vectric.com/viewtopic.php? ... et#p194186
After experimenting with this gadget it looks like it is telling me that the center is off by -3.808 (at least I think that is what it is telling me, but I know it's not off by almost 4" so I'm guessing there is something with where the decimal is placed that I'm not getting). But anyway that is close to what 4D came up with. However if I move the vector over 0.3808 it then tells me it is off by +7.142. So I'm not sure what this gadget is really telling me. I'm waiting for the daughter's boyfriend to come up with his numbers and then I think I'm going to test cut a piece with 4D's numbers and his numbers and see how things look. Hopefully both numbers will be the same. Really appreciate all the help.

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by PaulRowntree »

You could just trace it on cardboard, cut it out, and find the CoM of it. As long as as you are not cutting much out of the fish itself by v-carving etc.
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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by lfinsr57 »

Interesting problem...

It appears the Balance Gadget result is the difference between the right and left torque. Move the object right about .130", rerun the gadget, and it's close to balanced, at least according to the gadget.

Another option is here.

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Re: Finding Center of Uneven Object for Hanging Keyhole

Post by WaltS »

lfinsr57 wrote:Interesting problem...

It appears the Balance Gadget result is the difference between the right and left torque. Move the object right about .130", rerun the gadget, and it's close to balanced, at least according to the gadget.

Another option is here.
Yes, thank you, I just now got done moving it around by small increments and came up with 0.1324 as perfect, according to the gadget. However that doesn't jive with what others have come up with by a close margin.

I had read the SA article yesterday, before posting. And as I stated above, I did print and cut out the shape. One problem is the shape is almost 12" in length and my paper and printer only go up to 11", so even if I managed to come close with that method I'd still have to refigure everything for the correct dimensions. And hanging an object from a string is only going to come so close. That's why I was looking to see if there was a math option, which there seems to be.

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