Test data for intonation spreadsheet

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Dominic
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Re: Test data for intonation spreadsheet

Post by Dominic » Tue Sep 11, 2012 8:07 am

I used a wheel assemebly from a rolling cupboard door. I also used T track for the rig so its adjustable for different scales. I take a few pics and post them.
Trevor not many sailing shops in Canberra but there is always something to fit. I like finding stuff from my collection of widgets.

Cheers
Dom
You can bomb the world to pieces,
but you can't bomb the world to peace!

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Dominic
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Re: Test data for intonation spreadsheet

Post by Dominic » Thu Sep 13, 2012 2:26 am

Hey Trevor or Martin (munchkin), in calculating the mass per unit length of a string, eq 4.7-34, is the L variable the L derived from eq 4.7-32?
Or is it just the length of the rig?

Also, what units are all the measurements in? I think I am having issues with putting everything in the right form. I have just been using dummy numbers to get the spreadsheet working but am not sure what sort of numbers I should be getting for K or T.

Should I be converting to Kgms, metres, and Hz? What sort of number should I get for k. As in how many digits, 0.4, 400, 4000, 40000?

This is pretty cool, I am having fun and am nearly there, a few more mods to my rig and a new metric dial gauge with 0.001mm resolution. I made a string height gauge block (al la Stew-Mac) out of some brass off-cuts but need a decent dial. I looked inside an imperial one I have (I hate imperial, mm is so obvious with these small scales) and found it would be simple to remove the return spring so the pin will not depress the string when measuring the action.

I see the bar has really been lifted, with Os nearly finishing the 4DOF model. That was next on my list. But before that, any tips to the above would be very helpful.
Thanks
Dom
You can bomb the world to pieces,
but you can't bomb the world to peace!

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Trevor Gore
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Re: Test data for intonation spreadsheet

Post by Trevor Gore » Sat Sep 15, 2012 12:01 pm

The mass per unit length is the mass per metre of a string. So say a bit of guitar string weighs 5 grams and is half a metre long, the mass per unit length is 0.005/0.5 = 0.01 kg/metre.
Dominic wrote:Should I be converting to Kgms, metres, and Hz? What sort of number should I get for k. As in how many digits, 0.4, 400, 4000, 40000?
Work in SI units. String stiffnesses (for example) are of the order of 40,000 newtons per metre extension per metre length, i.e. N/(m/m), so the final unit turns out to be just newtons, because the metres cancel.

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Dominic
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Re: Test data for intonation spreadsheet

Post by Dominic » Sat Sep 15, 2012 3:16 pm

Thanks Trevor, I'm nearly done but a lot of this stuff is new to me, not the math but the terms and how they compare and how this stuff behaves. But I am close
Cheers
Dom.
You can bomb the world to pieces,
but you can't bomb the world to peace!

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