Brodhead Pietenpol Association

Original Posted By: JEFFREY WILCOX
When bending 90 degree fittings out of .090, is it a good idea to play atorch over the bend to relieve the bending stress?Al Swansonswans071(at)tc.umn.edu________________________________________________________________________________Date: 2 Oct 2001 03:30:42 -0700

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Allan,On top of what Craig said, be sure to smooth all the saw cuts on the edgesbefore bending (I use a belt sander and it makes a nice smooth surface). Ifyou leave the rough saw cuts on the edges, the part can crack when you bendit (if you're lucky) or can crack a few years later under load.Check out Tony Bingelis' book "Sportplane Construction Techniques". Ittells all about making fittings.Good Luck,Jack Phillips-----Original Message-----

Original Posted By: "Jack Phillips"
Smoothing the edges of the fittings is important but you must hold the legthwise part of the piece in the same direction as the movement of the belt.This puts the sanding marks legthwise rather than across the metal, creatingstress points. And 4130 will crack at these points.Chris Bobka----- Original Message -----

Original Posted By: mboynton(at)excite.com

Original Posted By: Larry Neal

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Your right, Larry. The lettering on the steel should be perpendicular tothe bend line. And a small sanding drum on a Dremel tool is a must forsmoothing out any inside radius curves before bending.Jack-----Original Message-----

Original Posted By: "Don Emch"

Original Posted By: Larry Neal
Bending the piece WITH the grain would put the letters in the "trough"WRONG!!!Bending ACROSS the grain would be bring the letters closer to eachother, as you put it. If you put the piece in a bending press, have theletters stick out like a tongue!.Be sure to POLISH the edges before bending, No nicks, scrapes, files marks,whatever. I use a dremel tool with a medium rubber wheel to remove all toolmarks, etc., before bending. Of course, since I'm too cheap (poor?) to buya metal cutting bandsaw, I also cut all my pieces with a jewelers saw, 2/0blades. Built four airplanes this way, working on #5 and #6.Craig----- Original Message -----

Original Posted By: "Greg Cardinal"
>> I can't resist:>> Doesn't it depend on the orientation of the growth rings?>> There, I feel better now.>> Mark Boynton>Yes, Mark, but you need my special Xe-Kr-Cd deluxe viewing instrument to seethem. Please send $8,500 in small bills, and wait until you receive theviewer.Craig________________________________________________________________________________Date: Wed, 03 Oct 2001 09:31:54 -0600