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Widget for calculating spine and creep
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There is one thing all of the shingling formulas do not have. That is the use of pi (3.14). Since we are dealing with something that actually curves at the fold, pie should be part of the formula.
Below is the formula using pie. NOTE: the Creep Correction Factor is for paper tolerances/roughness of paper and for how tight or loose a folder is.
Steps to produce good shingling
1.) Total Number of pages (p) divided by 4 is the total number of sheets (n)
2.) Thickness of 1 sheet of paper (t)
3.) n * t * 3.14
4.) Take the value of step 3 and divide by 2
5.) Take the value of step 4 and multiply by the Creep Correction Factor of 1.2
The formula should look like this
(((p/4) * t * 3.14)/2) * 1.2
NOTE: This formula came from Scenic Soft Engineering.Last edited by pcmodem; 09162008, 06:38 AM.
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That's interesting. Does Kodak still make that available, or is it something you got in a tech support call back in the day, or from the old Preps newsgroup?
That seems like just a starting concept for developing a model of the behavior of how sheets wrap around a spine. But the radius of curvature of even a single sheet is not constant, and the variation for each as the number increases is not linear. So a lot more is missing than just Pi and a fudge factor of 1.2.
But before getting carried away with mathematical models, don't lose sight of the real world in which the folding of real sheets of paper has variations of may causes, which lead to errors in predicting the position of the front and back pages of the signature. A slight miss fold causes a shift in one direction for the front pages, and shift in the opposite direction for the back pages.
I use Preps and I also run a Stahl 3 unit folder with addon needle wet scoring. In my opinion, simple creep formulas are as adequate as can realistically be expected.
Al
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I got it back in the day directly from Scenic Soft and heard about it from the Old Preps Newsgroup. I had to sign an NDA that lasted 5 years. A couple days ago I called them up and asked them if I could publish the formula and they said it was possible but I can't publish the document. I am sure if you wanted the document you could email them and ask for the Shingling and Bottling Technical Report.
Brian
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Doesn't do creep but it does do spines. Common American paper weights are loaded, but you can put in your own micrometer settings as well. And it's free.
http://home.comcast.net/~jeff.ulicny...Calculator.zip
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To make the calculations easier for production. I made a Filemaker database where all they have to do is enter the number of pages and select a Stock from the Pull Down. The Stocks are in a related database to make it easy to update. Pretty simple for the users of the system.
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