FR-4 can be purchased in various thicknesses in the fully cured state; Google 'printed circuit laminates' or just 'FR-4 laminate'. Or you might check "printed circuit boards" or "multilayer printed circuits" to see if there is a fabricator near you and they can tell you where you can get it. (They might even be nice and give you a couple of panels after etching the copper foil off. Some of the suppliers used to be GE, Norplex, and Oak laminates.
-----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On Behalf Of Dave_A Sent: Monday, June 25, 2012 11:16 PM To: KRnet Subject: Re: KR> Anyone use FR4 for construction or repairs? Ahh... What I'm looking for (thought this might be it, but I guess it's not) is a pre-laminated fiberglass sheet that can be epoxied in place in leiu of wet-layup... When I first joined the Army, I was an airframe mechanic, and we had this stuff in the shop that we called card-stock or fiberglass laminate. It was used for repair of flat or nearly-flat sandwich-construction panels (essentially similar to most of what the KR's made of) in leiu of wet-layup... Adhesive was put between this stuff & whatever sort of core-patch had been applied, the end result was a nice clean/eaven, very quick patch.... I can't quite put a name on it, and the FR-4 substance seemed right... Guess it's not... If all else fails, I *can* do it the traditional peel-ply way... Will have to come up with a suitably rigid backing board for the underside of the elevator, because this plane is not 'flippable'... One of many times I wish I had access to my old shop on base (and all the whiz-bang composite repair gadgetry - especially the hot-vaccum-bonder)... 'course I'm much happier as a tanker than a REMF, but enough Army talk, anyhow... - Dave On 6/25/2012 7:23 PM, Mark wrote: > More properly FR-4 (fire retardant (e-glass) glass reinforced epoxy > typically used in the manufacture of printed circuit boards (I did > that for about 25 years). The epoxy resin is formulated with a > brominated fire retardant and can be purchased as a "b-staged" > material (partially cured and used to construct rigid PCB's and > Multi-layered PCB's) in 1080 (.0025" cured and pressed thickness) to > 7628 (~0.008" cured and pressed) layed up to produce laminates anywhere from 0.005" thick up to and including 0.125" > thick (typically). Typical lamination pressures are 250 psi at about > 350 degrees F. 25,000 pound shear is common when properly laminated > and cured - post bake is optional. Other resin systems have different > mechanical properties, although the reinforcing material is a > significant contributor to the laminate. > > The b-staged laminate needs to be driven to 300F (minimum to get the > epoxy to flow). You would be better off buying the woven class and > performing the normal epoxy flood/squeegee/peel ply method to get your repairs done. JMHO. > > Vacuum can reduce the net pressure of the process. T sub G's (glass > transition) is typically in excess of 275 degrees F. > > Hope this helps. > > Mark W. > N952MW (res) > > -----Original Message----- > From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On > Behalf Of Tony Wright > Sent: Monday, June 25, 2012 7:23 PM > To: KRnet > Subject: Re: KR> Anyone use FR4 for construction or repairs? > > Dave, > > I have never heard of fr4, but I have used FRP (fibreglass reinforced > plywood) in trailer repairs. think this could be used in > non-structural uses. > > Tony > > -------------------------------------------------- > From: "Dave Acklam"<dave.a.kr...@gmail.com> > Sent: Monday, June 25, 2012 5:51 PM > To: "KRnet"<kr...@mylist.net> > Subject: KR> Anyone use FR4 for construction or repairs? > >> Fr4 is pre-cured fiberglass sheet made with epoxy resin..... Kind of >> like a composite version of 1/16 ply..... It's available in :005in >> and up.... >> >> I'm thinking of using this for some of my larger flat repairs; in >> leiu of laying up glass (eg replacing the pilot side elevator skin)... >> >> Essentially, like an unmoulded version of prefab wingskins.... >> _______________________________________ >> Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. >> 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://tugantek.com/archmailv2-kr/search. > 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://tugantek.com/archmailv2-kr/search. > 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://tugantek.com/archmailv2-kr/search. To UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
