Yet another math question

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Dave Bagwill
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Re: Yet another math question

Post by Dave Bagwill » Wed Aug 05, 2015 3:59 pm

Thanks Herman. Yeah I know the diff between pressure and force, but in my haste I used them somewhat interchangeably.
So, this is the magic formula????

Yay!!!!!!
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Dave Bagwill
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Re: Yet another math question

Post by Dave Bagwill » Wed Aug 05, 2015 4:21 pm

Ok then, next step.

This is a picture of one of Siminoff's deflection testers. The braced rim is clamped around its perimeter, underneath, to the large plate. This gives open access to the braces for shaving, without having to flip over the assembly, shave, flip again and re-set up. I would like to do this with guitar tops.

He applies the given pressure/force (using H's formula above) from the bottom. That is also what I want to do.

Any ideas on how to apply that upward force??
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ken cierp
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Re: Yet another math question

Post by ken cierp » Wed Aug 05, 2015 4:40 pm

Dave the next pictures show exactly how the device is constructed figs 11-18 thru 11-25 it pushing from the show side of the sound board like you want.

The U channel frame is capturing the bridge plate area inside and out --- slide the weight to match the torque reading -- 4 dial indicators are below in front and behind the bridge, I assume so you shave the X and tone bars evenly.

Dave Bagwill
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Re: Yet another math question

Post by Dave Bagwill » Wed Aug 05, 2015 4:51 pm

I think the remaining photos show the torque (not deflection load) being applied to the bridge plate, not the show side?
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ken cierp
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Re: Yet another math question

Post by ken cierp » Wed Aug 05, 2015 5:11 pm

I like his set up and can see it would not isolate the torque.

But you could just use a small jack and an inexpensive load cell, you'd have to fasten the fixture to a superstructure to keep everything secure.

ken cierp
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Re: Yet another math question

Post by ken cierp » Wed Aug 05, 2015 5:18 pm

More simple yet --- bolt your fixture to a bench, get a small jack and a bath room scale put a board on top the scale, jack on top the --- crank away until you are at the lbs you want. (home made load cell!)

Dave Bagwill
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Re: Yet another math question

Post by Dave Bagwill » Wed Aug 05, 2015 5:25 pm

I see the principle and it makes sense. There must be something more accurate than a bathroom scale though? (Mine weighs 20 lbs heavy when I weigh on it - for some reason it's right on when Ronda weighs herself :-))
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