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Order of Steps in Plans--just getting started

Basic question here--the answer seems obvious, but I want to make sure I'm not missing something.

In Scn. 6, working with the vertical stab components after disassembly and de-burring, the manual suggests to "Prime as applicable..." before the dimpling and countersinking steps for the spar, doubler, ribs, and skin.

Seems to me that the prime step would ideally be done after dimpling and countersinking, basically as the last step before reassembly and riveting.

Am I missing something? Or do they call out priming before dimpling throughout the process?
 
Before or After

Basic question here--the answer seems obvious, but I want to make sure I'm not missing something.

In Scn. 6, working with the vertical stab components after disassembly and de-burring, the manual suggests to "Prime as applicable..." before the dimpling and countersinking steps for the spar, doubler, ribs, and skin.

Seems to me that the prime step would ideally be done after dimpling and countersinking, basically as the last step before reassembly and riveting.

Am I missing something? Or do they call out priming before dimpling throughout the process?

Almost as much debate as the Primer War. Builder preference. Personally, I scuff before and prime after dimpling.
 
Interesting Larry, thanks.
As a newbie, I certainly don't wanna find myself in the middle of one of those "Ford vs. Chevy" debates or 'Primer Wars' discussions.
I can't help but be curious though, from the prime before dimpling perspective, what would be the advantage? Seems like any metal work after priming would almost have to at least run the chance of damaging the primer coating. What is the upside?
 
The benefits of priming before you dimple is that the scotchbrite pads last longer and you don?t get shadows around your dimples. Some primers may chip or crack if you prime then dimple if the aluminum isn?t prepped well enough. Another compromise may be to scuff, then dimple, then prime, but I scuff, prime then dimple after the akzo cures for several days..
 
Order of operation

The benefits of priming before you dimple is that the scotchbrite pads last longer and you don?t get shadows around your dimples. Some primers may chip or crack if you prime then dimple if the aluminum isn?t prepped well enough. Another compromise may be to scuff, then dimple, then prime, but I scuff, prime then dimple after the akzo cures for several days..

What he said. Advantage of priming before dimpling? None that I can think of.
If the primer will stand up to the dimpling, go for it. I think it's builder preference.
 
The benefits of priming before you dimple is that the scotchbrite pads last longer and you don?t get shadows around your dimples. Some primers may chip or crack if you prime then dimple if the aluminum isn?t prepped well enough. Another compromise may be to scuff, then dimple, then prime, but I scuff, prime then dimple after the akzo cures for several days..

I've tended to complete all steps before priming, so there's just the riveting / assembly to be done.

Scuffing skins before dimpling is a lot easier I find, and I also pay a bit more attention to the rivet lines when priming.
 
For those parts which I've elected to prime, that's always the final step prior to reassembly and riveting. That is, all drilling, deburring, and dimpling/countersinking operations are completed prior to priming.
 
What Ken said. I do all the prep work, and right before riveting is priming.

As the build continues you'll notice the instruction for priming coming up less frequently and by the time you get to the finishing kit instructions like debur, final drill, etc are mostly non existent for routine building steps as by then you should have that in muscle memory.
 
Lots of opinions as would be expected.....

The logic behind the recommendation in the plans is this -

- It is much easier to do a good job of scuffing and properly cleaning parts and skins if there are no dimples (it is very tedious to actually get parts clean within the dimples).

- Besides abrading the surface of the parts to promote adhesion, scuffing removes surface oxidation.
The oxidation effects primer adhesion. The oxidation begins to reform the instant you stop scuffing.
Primers that are self etching seem less effected by the how well the surface is scuffed or what the level of oxidation is, but not all primers are self etching.

So, as you can see there is a number of variables involved.

The recommendation give in the build manual is to try and remove the influence of these variables as much as possible by making it easier to scuff (no dimples to deal with) and making it possible to prime as soon after scuffing as possible so that oxidation is not an issue. Once that has been completed, there is zero time sensitivity for when the dimpling gets completed (on very large skins this can be a factor if a bunch of parts are being worked on at the same time).

All of the protective primers I have ever used have had no issues with dimple countersinking after they have been applied but it would always be a good idea to do a test with what you have chosen, before doing so.
 
I used the Sherwin Williams P60G2 wash primer (same stuff Van?s uses) and that stuff is very durable. I dimpled after applying that primer with absolutely no issues.
 
I'm only slightly ahead of you finishing up the rudder right now. What seems to work for me is
1) Edge trimming/shaping/deburring
2) Assembling/match drilling
3) Countersinking (not dimpling)
4) Deburring
5) Scrub the bejeezus with Bon Ami in bathtub. Dry with compressed air. Wipe with acetone.
6) Prime with Akzo
7) Re-label everything with Sharpie since I erased all marks in step 5.
8) Dimple
9) Spot prime the places I missed in 6 with SEM rattle-can primer.
10) Final assembly

I'm sure this flow will get streamlined as I go. So far the hardest thing to keep track of is when the order-of-assembly in the plans doesn't jive with this flow. I don't want to do more than one priming session per section if I can avoid it, so I wind up delaying some of the initial riveting later than the plans call for. I'm working on streamlining my setup for cleaning and priming to make it a little less labor intensive too. It's the part of building I enjoy the least but a nicely primed part just feels nice - like you're building a real aeroplane!
 
Thanks to all for the info and explanations. Now I understand how the steps are ordered and why.
As always, final decision rests with the 'BIC' (Builder in Command). :)
 
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