Started by Medeek, March 12, 2013, 03:33:08 AM
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Quote from: Adam Roby on June 28, 2013, 05:27:15 PMNice tool... maybe you could add a scissor truss in there.
Quote from: Alex W on September 17, 2013, 12:06:21 PMI just want to say, first of all, awesome work on the calculator. I recently purchased a property with an existing pole barn, and have been trying to determine if the trusses are sufficient to support a ceiling and insulation. Your calculator has proven incredibly useful in that. I probably could have made the calculations myself by hand, but that would have involved dusting off some skills I have not used since engineering school , plus with my background being in mechanical rather than civil, the application of the basics to wooden trusses is something I do not have experience with.That said, while digging through the calculations on the Fink truss to compare your allowables to the MSR lumber already in my trusses, I came across what appears to be a discrepancy. In the bottom cord design section, you appear to use Fb=2350, and reference table 4A. However, table 4A shows Fb=1250 for spruce-pin-fir select structural. Also, in the top cord section, you use Fb=1500, which while much closer still doesn't match up to table 4A. Am I missing something? As I said before, very impressive work, and very cool of you to make it free for all to use. I look forward to seeing what other features you add in the future.
Quote from: Medeek on September 17, 2013, 05:40:10 PMThank you for using the application, I wasn't really sure who might find it useful, glad to see someone is finding practical uses for it. Can you tell me exactly what span, pitch and loadings you used, as well as overhang and bearing width. To debug and figure this out I need to replicate your settings. I've checked through my Table 4A values and they appear to be correct but I might be missing something or there could be some logic or typo problem in the code. Really appreciate your feedback.
Quote from: Alex W on September 18, 2013, 07:57:47 AMMy inputs are:32' span4/12 pitch48" spacing5.5" bearing12" overhangI have of course been using the Fink truss to get a feel for things, although my exact situation is actually a Modified Queen, as shown here http://www.7dtruss.com/truss_configurations.pdfI have played with the loading a bit, my goal being to verify that I will be OK with 30/5/0/5. At that loading, it puts out a 2x6 top cord, SP SS, and a 2x4 bottom cord, also in SP SS, and the allowables appear to be wrong for both. If I use the default loading of 30/10/0/10 the to cord goes up to a 2x8 HF SS, with the correct allowable, the bottom cord stays 2x4 SP SS with the incorrect allowable. It seems that the questionable number is just in the spruce/pine SS numbers.