Pietenpol-List: RIB TEST REPLY/SITKA
Posted: Thu Sep 30, 1999 4:51 pm
Original Posted By: "Davis, Marc"
I was the one who posted the info. on the Western Red Cedar ribs. I made the ribsper Don's full size drawing out of 1/4"x1/2". I used 1/16" Finnish Birch plywood(GL11)and T-88 glue. With 27 ribs finished, they average 201grams (7 oz) and vary only5-6grams. I spent a considerable amount of time building a rib test fixture to testthe ribs.I tested one of my ribs up to 358 pounds at which point my fixture ran out ofspring force.I used engineering grade springs guarenteed to 5% of rated load, so I feel prettygood aboutmy figures. If anyone is intested in pics of the test fixture, e-mail me. Theyrun around200K each. I recently sorted thru McCormick Lumbers sitka for nearly 2 hours tofind(2) 16 footers suitable for spars. I got the impression that the guys in the yarddon't havea clue on grading this stuff. So, be careful if you are ordering sight unseen.They have alot of spruce, but I would say none suitable for solid spars.Mike CushwayMfg. Eng.________________________________________________________________________________
I was the one who posted the info. on the Western Red Cedar ribs. I made the ribsper Don's full size drawing out of 1/4"x1/2". I used 1/16" Finnish Birch plywood(GL11)and T-88 glue. With 27 ribs finished, they average 201grams (7 oz) and vary only5-6grams. I spent a considerable amount of time building a rib test fixture to testthe ribs.I tested one of my ribs up to 358 pounds at which point my fixture ran out ofspring force.I used engineering grade springs guarenteed to 5% of rated load, so I feel prettygood aboutmy figures. If anyone is intested in pics of the test fixture, e-mail me. Theyrun around200K each. I recently sorted thru McCormick Lumbers sitka for nearly 2 hours tofind(2) 16 footers suitable for spars. I got the impression that the guys in the yarddon't havea clue on grading this stuff. So, be careful if you are ordering sight unseen.They have alot of spruce, but I would say none suitable for solid spars.Mike CushwayMfg. Eng.________________________________________________________________________________