<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 6.00.2800.1264" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face=Arial>Anyone on the list have a little metallurgy/mechanical-engineering background?</FONT></DIV> <DIV><FONT face=Arial></FONT> </DIV> <DIV><FONT face=Arial>I've made myself a little pneumatic contraption = for laminating ribs. I seem to have just about everything worked out for = proper function (actually, works quite a bit better than I had = hoped!) except for some excessive jig flex. I have a 1.5-inch-thick Delignit = pinblock incorporated into the jig for stiffness, but I still seem to be = getting several millimeters of flex in the middle of the 5-foot long jig when I = pressure up. So I think the solution is to put a couple of angle irons, or = steel channels along the length of the jig. This thing is getting VERY heavy, = so I prefer to not use any more steel than needed.</FONT></DIV> <DIV><FONT face=Arial></FONT> </DIV> <DIV><FONT face=Arial>Being that my pinblock stiffener flexes - say - = up to 3 or 4 millimeters over 5 feet, how big a channel (and wall thickness) will I = need to have less than 1 mm flex (zero would be better). I'm figuring maybe = a minimum of 5 to 10 times the current stiffness to get to less than 1 mm = flex. The dimensions I pick out of thin air is to get at least two 2" x = 2" x 1/4"-wall channels. I have proven to myself that I can overbuild just = about any jig, but can anyone help me fine tune these dimensions a little more efficiently - maybe based at least in part on some = science/engineering-related criteria?</FONT></DIV> <DIV><FONT face=Arial></FONT> </DIV> <DIV><FONT face=Arial>Thanks.</FONT></DIV> <DIV><FONT face=Arial></FONT> </DIV> <DIV><FONT face=Arial>Terry Farrell</FONT></DIV></BODY></HTML>