I did a lot of research a while back on cadmium plating 4130. A very knowledegable mil spec plater told me that weather you need to bake them to relieve hydrogen embrittlement or not depends on the hardness of the steel. At the standard hardness of 4130 normalized steel he said it most definitely did need to be baked after plating. He told me how much and I believe it was somewhere around 400 degrees for six hours(don't take this as accurate).
Anyway, the point of this is do not have your local Harley chrome plater that knows nothing about plating high stress aircraft parts plate your attach fittings. You can find a good mil spec plating shop that can do it correctly for probably the same price. Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net]On Behalf Of Mark Langford Sent: Friday, May 13, 2005 3:37 PM To: KRnet Subject: Re: KR> Sanding and painting the WAFs I can tell you for sure that zinc chromate will flake right off the first time the wings are installed. Mine used to be zinc chromated, but it's hard to tell that now! Best thing is to have them plated somehow, like RR does. Hydrogen embrittlement may be a concern though, so check for compatibilty with 4130 first. Here's something I found in a quick search of the web: "One comment is by a guy who overdrilled a spar bolt hole, and then did a D-I-Y plating job on the bolt to bring it back up to size: >Here's what worked for me: I contacted Caswell Plating (www.caswellplating.com) and bought an 8oz. bottle of their CopyChrome nickel plating solution. Following their directions, I plated the bolt up to 0.377" then baked it at 400° F for 4 hours to take care of any hydrogen embrittlement. It worked great. I also plated some 4130 scraps and was pleased with their appearance. The plating looked like it should be pretty durable. I even soaked a 4130 piece in saltwater overnight and saw no effect. It's not quite chrome, but it looks pretty good. " Mark Langford, Huntsville, Alabama see KR2S project N56ML at http://home.hiwaay.net/~langford email to N56ML "at" hiwaay.net --------------------------------------------------------------
