On Tuesday 11 February 2020 19:38:01 Bruce Layne wrote: > > On Tue, Feb 11, 2020 at 10:30 AM Gene Heskett <ghesk...@shentel.net> > > > > wrote: > >> Cleaned up with acetone of course. > > Cleaning with acetone will result in a good epoxy bond. Cleaning with > isopropyl alcohol will result in an excellent epoxy bond. Commercial > acetone, at least in the US, is recovered from industrial processes. > It's distilled, but a trace amount of the waste oil remains in the > acetone after the distillation process and will leave a slight oily > film on your parts after the acetone evaporates. It's not enough to > feel or see, but it's enough to prevent the best possible epoxy bond. > > Maybe remove most of the oily gunk with acetone, scrub with 60-100 > grit sandpaper to create a rough surface for the epoxy to grab, then > flood with isopropyl alcohol to thoroughly degrease the part prior to > applying epoxy. I'll sometimes use a clean blue paper shop towel or > toothbrush with the alcohol at first if some physical scrubbing is > still needed. I'll finish the job with a spray bottle with isopropyl > alcohol to blast off the last traces of oil, allowing the alcohol and > suspended oil to drip off the part, and then I don't touch the part > with my bare hands. You've made your own printed circuit boards and > the process is similar to the final step of cleaning the bare copper > board before the etch resist process. When the board is clean of > oxides and oil free, the solvent will uniformly wet the board, drip > off the bottom edge, and the board will dry from the top down leaving > a matte finish. > > Pro Tip: for the very best bond when using a filled epoxy, first > paint the bare surface with a thin layer of raw epoxy (resin and > hardener) before applying the filled epoxy (such as JB Weld). The > unfilled epoxy can more easily penetrate the fine scratches on the > substrate, and the filled epoxy then binds to the unfilled epoxy. > That's a tip from people who build composite fiberglass airplanes. > Too late Bruce, washed with acetone and plumbers purple primer and is under clamps atm, some added scratches with my pocket knife and a wee bit of jbweld. We'll see if its still in time in the morning. I put the first one back in with lots of goop, so if the quadrature's no good, I can cut it loose and shim it one way or the other.
Thanks Bruce. > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
