When Do You Prime?

If you're priming, at what point in the process do you folks prime the parts?

Reason I'm asking, is that I've got the RV-3 kits on order and that airplane doesn't come pre-drilled or pre-trimmed. I'll be doing all of that.

Thanks!
Dave

I usually finish a section or until I get to a point where I start needing some of the parts to move on. I like to have as much as possible to prime because its kind of a pain for me to set up for painting every time I have a few parts ready.

Just before assembly

Dave,

I do all the fitting, drilling, dimpling etc. of the parts and get them to the point where it's time to rivet. Then I wash with a green scotchbrite sponge and warm soapy water. I found that a light scuff of the surface from the scotchbrite sponge helps a lot with primer adhesion. Rinse well with clear water. I prime the ribs and mating skin surfaces thoroughly. Before I close-up the part, I spray a very light coating of primer on the inside skin surface and touch-up any scratches caused during riveting. I've been pretty happy with NAPA 7220 self etching primer in rattle cans. Can get them on sale for $5.99/can. If not on sale at one store, check another nearby store.

Tom

If you look at a Piper aircraft I believe there is no primer to the interior. I recall Van's only recommends priming mating surfaces. Remimber paint is weight. I prime the visible interior parts with white epoxy primer tinted to the color of Vans powdercoated parts. Holds up well.

I clean and prime after final drilling and deburring, but before dimpling. Not having the dimples makes cleaning MUCH easier. Any good primer on a properly prepared surface will survive the dimpling process.

Good point

Miles, good point - the dimples sure do eat-up the scrubbie pad when you're washing the part. I'll have to see how the primer holds up to the dimpling process - never tried that.

Corrosion

agough277 said:

If you look at a Piper aircraft I believe there is no primer to the interior. I recall Van's only recommends priming mating surfaces. Remimber paint is weight. I prime the visible interior parts with white epoxy primer tinted to the color of Vans powdercoated parts. Holds up well.

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I lost a PA-28 to corrosion because there was no primer used inside. If you're worried about a little extra weight, go on a diet - that's my plan anyway

Please, friends, this discussion is about when to prime, not if to prime.

That has been well-covered elsewhere.

Thanks!
Dave

David Paule said:

Please, friends, this discussion is about when to prime, not if to prime.

That has been well-covered elsewhere.

Thanks!
Dave

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For parts I plan to prime, I do it afer they are "finished" - but before riveting them in assembly.

Paul

I finish all my fitting, drilling, deburring, then I scuff and clean the surface, dimple, wipe with acetone, and then prime.

prime prep

We've been doing the exact same thing as Colin, it's works great. What really cut down on my scuff time was a tip I read on here where right before dimpling with the sheet on the table, flop a Scotchbrite bad on the sheet and put your orbital sander on top. You can scuff a sheet in just a few seconds.
The Acetone is the cat's meow. Amazing how much dirt it picks up off of the surface.
Don