Strikefinder
Member
Hi all,
I worked my way through the tail using the NAPA 7220, and decided pretty early on that to get the best performance of the primer, I would match drill, scuff, dimple, then prime...and for the most part that was achievable with only minor modifications to the order of the steps in assembly. I wasn't very happy with the 7220, so I bought a few cans of SEM, and like its application much better--I find its adhesion and coverage much better, so I decided that I would use that for the wings.
I got as far as the rear spar before it became apparent that, if I was following the directions, I'd have to prime the rear spar components and rivet them together prior to match drilling for skins, which meant I'd be dimpling after priming the rear spar. I prepped the rear spar, primed it with SEM, and let it cure for over a week (not intentionally, just was out of town on a trip).
Just to try it out, I reamed one hole and tried to dimple it using my pneumatic squeezer, and the primer just flaked off around where the dimple die contacted the spar. I can scratch it pretty aggressively on the web without failure, so I was hoping the flange would survive the dimpling process, but it looks like once I get the skins match drilled and I go to dimple them, it's all going to flake off.
So, a few questions:
1. Other than dimpling and then reapplying a coat of SEM afterward, is there anything else I can/should do with the parts that are already primed?
2. It seems like a fair amount of the wing substructure (ribs, etc.) is primed, then dimpled after match drilling the skins. Has anybody changed the order so that dimpling could be done before priming? I'm reluctant to deviate from plans too much--I've tried a few times to do things out of order, and usually after I screw it up I figure out why it was suggested I do it in the order suggested.
3. For prep, I've been doing a pretty good scrub with maroon scotchbrite on all surfaces, followed by an acetone wipe, let it dry for a good 15 minutes, and then spraying the SEM with a few light coats. I use gloves to ensure no contamination occurs after wiping down with the acetone or during the painting process. I hate working with chemicals if I don't have to, so while I've considered doing PreKote or something similar, I would prefer to avoid making the prep any more complicated than it already is.
4. I've thought about switching to EkoPoxy, but I figure I've got about $600 to invest in equipment (paint gun, paint+shipping, mixing cups, etc.), and I'm intimidated by the prep and clean up. With two small kids, most of my work sessions come in 15-45 minute bursts, and so doing something that requires 40 minutes of setup/cleanup (or more) means I lose a lot of opportunities that I can currently use to spray a few parts or drill a few holes. Is it night and day difference to go to a product like this?
Would appreciate any advice!
I worked my way through the tail using the NAPA 7220, and decided pretty early on that to get the best performance of the primer, I would match drill, scuff, dimple, then prime...and for the most part that was achievable with only minor modifications to the order of the steps in assembly. I wasn't very happy with the 7220, so I bought a few cans of SEM, and like its application much better--I find its adhesion and coverage much better, so I decided that I would use that for the wings.
I got as far as the rear spar before it became apparent that, if I was following the directions, I'd have to prime the rear spar components and rivet them together prior to match drilling for skins, which meant I'd be dimpling after priming the rear spar. I prepped the rear spar, primed it with SEM, and let it cure for over a week (not intentionally, just was out of town on a trip).
Just to try it out, I reamed one hole and tried to dimple it using my pneumatic squeezer, and the primer just flaked off around where the dimple die contacted the spar. I can scratch it pretty aggressively on the web without failure, so I was hoping the flange would survive the dimpling process, but it looks like once I get the skins match drilled and I go to dimple them, it's all going to flake off.
So, a few questions:
1. Other than dimpling and then reapplying a coat of SEM afterward, is there anything else I can/should do with the parts that are already primed?
2. It seems like a fair amount of the wing substructure (ribs, etc.) is primed, then dimpled after match drilling the skins. Has anybody changed the order so that dimpling could be done before priming? I'm reluctant to deviate from plans too much--I've tried a few times to do things out of order, and usually after I screw it up I figure out why it was suggested I do it in the order suggested.
3. For prep, I've been doing a pretty good scrub with maroon scotchbrite on all surfaces, followed by an acetone wipe, let it dry for a good 15 minutes, and then spraying the SEM with a few light coats. I use gloves to ensure no contamination occurs after wiping down with the acetone or during the painting process. I hate working with chemicals if I don't have to, so while I've considered doing PreKote or something similar, I would prefer to avoid making the prep any more complicated than it already is.
4. I've thought about switching to EkoPoxy, but I figure I've got about $600 to invest in equipment (paint gun, paint+shipping, mixing cups, etc.), and I'm intimidated by the prep and clean up. With two small kids, most of my work sessions come in 15-45 minute bursts, and so doing something that requires 40 minutes of setup/cleanup (or more) means I lose a lot of opportunities that I can currently use to spray a few parts or drill a few holes. Is it night and day difference to go to a product like this?
Would appreciate any advice!