Brian, I know someone who is making all of the 4130 fittings which includes wing attach for an aircraft mfg company. All of the parts are being plasma cut by computer and then the parts are being tumbled to deburr. The tumbling process is the normalizing effect. Their engineers think the parts are fine. What do you think about this practice? Larry H.
Brian Kraut <brian.kr...@engalt.com> wrote: Absolutely not. Plasma cutting leaves a very hard edge. I have had several 4130 parts plasma cut including my lower gear attach fittings for the KR and the seatbelt attach fittings and canopy latch parts for the Stang. I did some finish machining on some of the parts and the edges were hard as rocks and needed carbide tools to cut them. Hard edges mean brittle edges. Brittle edges mean the high liklihood of cracks starting. The parts I have plasma cut are sent to a heat treater to be normalized when done, but if you are not getting that done don't do it for structural parts. Same applies for laser cutting. Water jet is O.K. Another problem with plasma and water jet depending on the thickness is that they both cut with a taper and sometimes also a slightly rough edge. If you do water jet and have the bolt holes cut you want to have them done undersized and ream them to finish the holes. Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net]On Behalf Of Chris Johnston Sent: Tuesday, August 22, 2006 6:56 AM To: KRnet Subject: KR> WAF Plasma cutting Can you plasma cut the wafs without affecting the metal?????? Are the tailplane hinge ply backup plates glued in place or just held on by the nuts and aluminium backup plates? The plans state the inner hinges have two bolts, does this mean the outer hinges have only one bolt per hinge half? Can you use two bolts on the outer tailplane and elevator hinge without weakening the spars too much? Chris Johnston North Richmond NSW Australia _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
