I attempted to calculate a meaningful number for the strength of a tabernacle.

I hope this topic is a good place to ask for feedback. If anyone can check my math, in the excel sheet, I would really appreciate it. I taught myself what I could about calculating the section modulus and bending moment and how to use material strengths. This is very different from anything I studied in school. I have no practical experience with structures like this.

From Arne's TCPJR book I determined that it would be reasonable for me to have a mast that supports a bending moment somewhere between 925 kpm and 1826 kpm. I intend to aim for the higher value.

In the attached spreadsheet I did my best to work out this value for a 'C channel' cross section. One tab is for a Douglas Fir tabernacle. The other tab is for a 6061-T6 tabernacle. Both are 'three sided box' sections.

I triple checked my formulas. The results indicate a structure several times stronger than what I expected from the materials. Did I make a mistake?

For a 1.5" (38.1mm) thick Douglas Fir tabernacle surrounding a 7" (177.8 mm) mast I get a maximum bending moment of 7025 kpm

For a 1/8" (3.175 mm) thick 6061-T6 tabernacle surrounding a 7" (177.8 mm) mast I get a maximum bending moment of 2175 kpm

Thank you for taking the time to read my post.

Scott.