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  #11  
Old 10-25-2014, 03:41 PM
chaskuss chaskuss is offline
 
Join Date: Mar 2005
Location: SE Florida
Posts: 1,499
Default NO black Sharpies

Quote:
Originally Posted by 1bigdog View Post
"snipped

So basically what I hear so far is that sharpie will show through some primers but I'm not sure I'm hearing it will survive the alumiprep of the alodine process.
The uniquely drilled out holes sounds good.

Cheers.
I found that depending on the primer, sometimes, the Sharpie will bleed through, so that you can see it. FYI, DO NOT use black Sharpies, as they contain a carbon compound [for pigment], which can cause corrosion down the road. Remember, it's under the primer. Use any other color. I used Sharpies [blue or red], then wiped them off with lacquer thinner and applied the paper tags prior to etch, Alodine and Epoxy priming. After the primer dried, I wrote the ID numbers with a Sharpie and removed the paper tags.
The downside to leaving holes un-drilled, is that you must either deburr the holes later, which removes the Alodine and primer. Or you are riveting parts together with burrs on them. Neither is ideal.

Charlie
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  #12  
Old 10-25-2014, 04:43 PM
60av8tor 60av8tor is offline
 
Join Date: May 2012
Location: Harrisburg, Pa
Posts: 759
Default

Are you positive about the black sharpie. Black came with my Cleaveland tool kit. Seems like they would use a different color...
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RV-7A purchased flying - Sold 6/16
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  #13  
Old 10-25-2014, 06:56 PM
chaskuss chaskuss is offline
 
Join Date: Mar 2005
Location: SE Florida
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Default

Quote:
Originally Posted by 60av8tor View Post
Are you positive about the black sharpie. Black came with my Cleaveland tool kit. Seems like they would use a different color...
Jon,
I have no real proof of this. I was warned not to use black Sharpies by several of my A&P friends. I was told that they used a carbon compound to make the black dye. This can cause a galvanic corrosion issue if left on the aluminum over a period of years.
Probably not an issue for "temporary" marking, assuming you will clean the ink off, prior to priming or final assembly. Red or blue Sharpie lines are also much easier to see, if you are using them to line up a rib or bulkhead flange with a pre-punched skin above it.

Charlie
PS About 8 years ago, I contacted the company to try to verify this. They totally stonewalled me. You'd have thought I was asking to see the budget for the NSA or something.
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  #14  
Old 10-26-2014, 08:15 AM
GeraldC GeraldC is offline
 
Join Date: Sep 2013
Location: Buda, TX
Posts: 56
Talking

I was also looking for an easy way to label parts that would survive the cleaning and priming process and I came up with something that works well for me. I found that I prefer to prime the parts before dimpling them since it makes it a little easier to prime the parts and dimpling doesn't seem to affect the primer at all. But it's really not a big deal one way or another. So I started dimpling a unique pattern on each rib before priming to identify them through the priming process. Dimple the first hole for the first rib, the sixth hole for the sixth rib. One dimple somewhere else to note left or right side. Pick any pattern you want. If you prefer to dimple before priming, then do the opposite and leave a few undimpled holes in a pattern during the priming process. Works great for me and I don't have to worry about keeping track of parts while I'm cleaning and priming.
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  #15  
Old 10-26-2014, 09:28 AM
60av8tor 60av8tor is offline
 
Join Date: May 2012
Location: Harrisburg, Pa
Posts: 759
Default

Quote:
Originally Posted by chaskuss View Post
Jon,
I have no real proof of this. I was warned not to use black Sharpies by several of my A&P friends. I was told that they used a carbon compound to make the black dye. This can cause a galvanic corrosion issue if left on the aluminum over a period of years.
Probably not an issue for "temporary" marking, assuming you will clean the ink off, prior to priming or final assembly. Red or blue Sharpie lines are also much easier to see, if you are using them to line up a rib or bulkhead flange with a pre-punched skin above it.

Charlotte
PS About 8 years ago, I contacted the company to try to verify this. They totally stonewalled me. You'd have thought I was asking to see the budget for the NSA or something.
Thanks for the info, Charlie. I have recently begun using blue, but have quite a bit of my empennage in black.

As for marking, I lay out all parts on the crate packing paper and write the part # on the paper. I then scuff w/ scotchbrite and Prekote, lay back on paper to dry and then remark before priming. Sharpie then shows through for dimpling and final assembly. Think I'll stick with the blue sharpie from here on out
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  #16  
Old 10-26-2014, 10:23 AM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,947
Default Sharpie

Nothing I can do about markings in place but looks like I will go blue as well.
I do know Vans mentions using Sharpies but only recommends blue because they last longer. No mention of not using black.
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  #17  
Old 10-26-2014, 11:03 AM
1bigdog 1bigdog is offline
 
Join Date: Jun 2014
Location: Markham, Ontario, Canada
Posts: 220
Default sorry to get us back on topic

It seems to me for the purpose (surviving alodine prep process)
the discussion is done.

Either the use of pre-numbered metal tags, or blank tags to be numbered, and engraving on the part itself. As to the later, I was a bit concerned that if stamping is seen potentially creating a stress point why using an engraver (I'm assuming electric pencil to be en engraver) would not likewise create stress. Yes, I can see how the stamping itself will deform the part, but likewise with engraving you are removing material. I very much like the engraving idea. Just peel pack the plastic and scribe the part. Done.

As to the black sparpie, I have read the same thing in several places, so I guess I'll go pick up some fine blue's.

Thanks again. Great suggestions about the tags and electric pencil.

Michael B.
(seems every answer has raised more questions - oy )
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  #18  
Old 10-26-2014, 07:29 PM
N427EF N427EF is offline
 
Join Date: Oct 2005
Posts: 1,516
Default Just curious

Now that you have all the answers to your question, allow me to drift off just a bit.
What are you hopping to gain by having your aluminum parts professionally alodined?
I certainly am not criticizing your choice but you are aware that you'll be adding hundreds of hours of delay and work to your project.
I can see a slight weight savings over primer...
Not so much on the wings but the fuselage will be another story.
Do tell.
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  #19  
Old 10-26-2014, 08:39 PM
1bigdog 1bigdog is offline
 
Join Date: Jun 2014
Location: Markham, Ontario, Canada
Posts: 220
Default alodine timing

Hi Earnst

If the question is about why professional, it's to avoid the handling of compounds that should be disposed of properly and the availability of tanks of sufficient size for all the internal parts we would normally prime.

As to the timing, my intent is to take the internal parts from each subset (empennage for now) and have those parts all done up after drill, debur, dimple, countersink, or at least as much as possible given some parts assembly sequencing precludes their complete preparation. So for the parts that have to have touch up I will use something like an alodine touch up pen. They are expensive but should take care of that problem.

Done this way I can't see much time lost, if any, but maybe I'm being naive. And yes, the weight saving was a factor, not wanting build s spray booth ...

I had not anticipate so much delay, so maybe you could expand on that.

Cheers.


Michael B.
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  #20  
Old 10-26-2014, 09:35 PM
N427EF N427EF is offline
 
Join Date: Oct 2005
Posts: 1,516
Default

The question of why "professional alodining", was answered in an earlier post.
I started out alodining parts and made pretty good progress on parts like wing ribs and such. I soon realized that trying to alodine all parts was not going to be possible in my bathtub size tank.
You may have better luck with professional alodine preparation and facilities.
At the end of the wing build I decided to prime instead and made rapid progress vs. what I had learned in the alodining process.
I also understand the toxicity of alodine and the irreversible damage to the environment when improperly disposed.
The work alone is not so much what will slow you down but delivering and picking up parts is what I think will add a great deal of time to your build.
The empenage is a pretty neat little package but once you are on to larger and longer parts, priming out of a rattle can will look pretty attractive.
Later in the build you'll have a couple of brackets ready to rivet before you can move on and with a quick clean up and primer you are ready to move on in less than 30 minutes.
I hope it works for you, good luck.
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