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  #1  
Old 02-28-2017, 12:34 PM
FL-flyer's Avatar
FL-flyer FL-flyer is offline
 
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Location: Sarasota, FL
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Default Prime before or after match drilling

Hi Everyone,

Quick question. Jason Ellis posted a great video on YouTube (thanks Jason!) and had mentioned if you prime your parts after match drilling / debrrring then you no longer can get the rivets into the holes and they have to be lightly re drilled.

Has anyone ever encountered this problem at all? Or is the consensus that parts should only be primed before match drilling?

Is there any detriment to having primer trapped under the rivet head or other riveted parts?

Thanks!
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Last edited by FL-flyer : 02-28-2017 at 12:44 PM.
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  #2  
Old 02-28-2017, 12:57 PM
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Lemmingman Lemmingman is offline
 
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Default

Everywhere I've primed I have done so after all prep steps are done. After the primer dries I am banging rivets. I've never had an issue with primer causing issues with rivets fitting, and no there is no issue with having a coat of primer under a rivet.
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Gil Brice
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  #3  
Old 02-28-2017, 01:13 PM
PilotjohnS PilotjohnS is offline
 
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Default Huh?

If you cant get the rivets in after priming maybe the primer is too thick?
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  #4  
Old 02-28-2017, 04:55 PM
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agirard7a agirard7a is offline
 
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Default After

You must be using the wrong primer. Try SEM.
Dries fast. Holds up well. Match drill, debur, dimple, prime, rivet.
When you match drill, allclad protection is being removed around the hole.
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  #5  
Old 02-28-2017, 08:57 PM
unitink72 unitink72 is offline
 
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Default No problem here

yea I heard him say that too and was curious if it would affect me. Short answer- it has not at all.

I am priming with akzo. One important piece of info with my data point is that I dimple everything AFTER priming. I think that dimpling enlarges the holes slightly, so that may be why I don't see any issues. Dimpling after priming is easier because scrubbing all those dimples out then making sure they got primer coverage seems like a real pain to me.
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  #6  
Old 02-28-2017, 10:32 PM
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CubedRoot CubedRoot is offline
 
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I am priming after match drilling, but before dimpling. What I found is that the dimple backsides would eat a scotchbrite pad quickly, so now I just matchdrill, then prime. This keeps me from burning through scotchbrite pads.

I am almost done with my empennage, and been doing it this way for about 90% of this kit. I have only had to ream out less than a dozen holes due to the primer causing an issue with the rivet. So, out of the hundreds (thousands?) of holes in the empennage I have drilled, primed and THEN riveted, I have had an incredibly small percentage that I had to ream the primer out of the hole to get a rivet to fit.

I am also using AKZO...love the stuff.
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  #7  
Old 03-01-2017, 07:33 AM
tims88 tims88 is offline
 
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Default

I have encountered this occasionally using Stewart Systems EkoPoxy. Some rivets fit just fine in their holes, some I have to use some force to get them into the hole, and others I have to ream to get the primer out. This isn't a problem with dimpled holes since the dimpling process enlarges the hole slightly.

Since it isn't every hole that has this issue, it probably has more to do with how thick I sprayed the primer, and therefore how much seeped into the rivet holes, than it is the simple fact that I used primer.
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  #8  
Old 03-01-2017, 08:44 AM
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Quote:
Originally Posted by CubedRoot View Post
I am priming after match drilling, but before dimpling. What I found is that the dimple backsides would eat a scotchbrite pad quickly, so now I just matchdrill, then prime. This keeps me from burning through scotchbrite pads.

I am almost done with my empennage, and been doing it this way for about 90% of this kit. I have only had to ream out less than a dozen holes due to the primer causing an issue with the rivet. So, out of the hundreds (thousands?) of holes in the empennage I have drilled, primed and THEN riveted, I have had an incredibly small percentage that I had to ream the primer out of the hole to get a rivet to fit.

I am also using AKZO...love the stuff.
Thanks for the info Lynn!
BTW, when prepping your parts for priming with scotchbrite pads do you also use a cleaner or solvent? If so, may I ask what do you use?
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  #9  
Old 03-01-2017, 08:46 AM
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FL-flyer FL-flyer is offline
 
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Default Thank you!

Thanks so much everyone for your replies. I really appreciate all the good ideas!

I think from the consensus it looks like it should be done in this order:

1. Match drilling (and counter sink drilling if required)
2. Deburring both sides of all skins
3. Prep and clean all surfaces to be primed
4. Prime with AKZO
5. Dimple
6. Final assemble and rivet
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  #10  
Old 03-01-2017, 08:57 AM
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CubedRoot CubedRoot is offline
 
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Quote:
Originally Posted by FL-flyer View Post
Thanks for the info Lynn!
BTW, when prepping your parts for priming with scotchbrite pads do you also use a cleaner or solvent? If so, may I ask what do you use?
I do use acetone as my cleaner. My process goes like this:

1. Assemble parts and match drill or back drill.
2. Deburr all holes and dress all edges with a scotchbrite wheel and/or pad
3. Scuff all my parts for priming using a maroon scotchbrite pad. My goal is to keep as much alclad on the metal as possible (its a good corrosion inhibitor itself), but also clean off any surface corrosion and finish away light scratches from the assembly process. One the parts have nice "satin" finish, thats usually when I call them good to go for the next step.
4. Give the parts a quick wipe down with a dry micro-fiber towel. This takes a few seconds per part, but it gets all the bulky dust off the part and makes the acetone cleaning go quicker.
5. Clean with acetone. I use white, un-dyed paper towels for this. It usually takes a good 3 passes, each time using a clean side of the paper towel (I like to fold in quarters for using the most of the towel). I will wipe the parts with acetone until the paper towel comes up clean, then its good to go! Again, 3 passes is about all it takes.

6. Spray them with primer! AKZO is pretty fool proof and covers very very well with little effort using a cheap Harbor Freight HVLP spray gun. I like to give the parts a day or two to cure. Even though AKZO dries really fast, and can be worked within an hour or so of painting, it does harden very much over a day. So I will let the parts cure at least a day to be safe.

7. Dimple the parts that need it, and then do final assembly and rivet.

The process has worked out pretty good so far for me. I like to dimple AFTER priming because if you try to scuff parts using a scotchbrite pad that has been dimpled, the back side of the dimples will chew up a scotchbrite pad :-)

Also, I will try to "batch" all my priming as much as possible. This is pretty easy to do on the tail kit, you just have to keep up with where you are in the plans. Batching up the priming makes it easier for me personally because I have to wait for good weather since I am spraying outside. AKZO is very nasty, please use a respirator (full face preferable) and a cheap tyvek suit (about $8 on amazon) to protect you. Really, any primer that uses chromates you want to do this, not just AKZO. I think I have around 100 bucks all together in my full face respirator, organic chemical filter cartridges (the pink ones), and a tyvek suit, and its the best money you'll spend if you are spraying chromates.

Hope that helps and happy building!
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Wing Kit Started - June 2017
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Last edited by CubedRoot : 03-01-2017 at 09:03 AM.
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