Initial results from 14 tops and backs

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JamesO
Kauri
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Joined: Wed Sep 09, 2015 12:27 pm
Location: Fresno, CA

Initial results from 14 tops and backs

Post by JamesO » Wed Dec 09, 2015 5:59 am

I'm enjoying the first tastes of freedom as I took my last fall exam last night. This morning I got to work testing 12 top sets and one set of koa with my new found ability to accurate get cross-grain results. I have an LS redwood top on the way that should be here within the next few days. Looking forward to adding that one to the fold of results.

I guessed at the cross-grain for the koa since it's already joined. I'd love to know if my guesstimate is reflective of your experience with it.

The guitars I gravitate towards usually have tops in the .095-.085" range. Likewise, my "best" guitars have been in the low .090's as well. I've wondered if 75 would be too high of a variable for f for the type of sound I enjoy, but it seems like f75 or f75 should do the trick for what I like to get out of the tone.

What was most surprising were the results I got from the cedar. The cedar tops I have are about 30 years old. When I picked them up from a sale on the OLF, I wasn't expecting them to be so extraordinary, but they ring like bells and feel as stiff as can be. The data backs up my intuition.

My next step is to join the sitka tops and thin them down. I want to get deflection results for each f value to see how (if) they correlate. They're lower grade tops I ordered specifically for testing.

Measurements
Measurements.png
Results
Results.png

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kiwigeo
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Re: Initial results from 14 tops and backs

Post by kiwigeo » Wed Dec 09, 2015 9:12 am

James, do you have the Youngs Modulus values? More useful than the raw frequencies. :)
Martin

JamesO
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Joined: Wed Sep 09, 2015 12:27 pm
Location: Fresno, CA

Re: Initial results from 14 tops and backs

Post by JamesO » Wed Dec 09, 2015 2:07 pm

They're display on the calculator I'm using. How would I use them?

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kiwigeo
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Re: Initial results from 14 tops and backs

Post by kiwigeo » Wed Dec 09, 2015 6:25 pm

JamesO wrote:They're display on the calculator I'm using. How would I use them?
The E values are a good indicator of stiffness.....

The density (Kg/m3) values are also useful.
Martin

JamesO
Kauri
Posts: 34
Joined: Wed Sep 09, 2015 12:27 pm
Location: Fresno, CA

Re: Initial results from 14 tops and backs

Post by JamesO » Thu Dec 10, 2015 10:10 am

Actually, I'm sorry, Martin. I don't believe I do have the Youngs values. I thought I did, but they seem quite a bit higher than what you posted in the lutz thread. This is a screenshot of the calculator I'm using.
Screen Shot 2015-12-09 at 3.07.54 PM.png

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