[Michael Burbidge]

I'm deburring my first holes on the horizontal spar doubler. I using the deburr bit that came in my Cleveland kit.

(http://www.cleavelandtoolstore.com/prodinfo.asp?number=DBB30)

It is giving me less than satisfying results. I've finally figure out what the problem is. As the bit goes around, it shaves off little pieces of aluminum which continue to rotate for a little while with the bit. As these pieces of aluminum shaving rotate they leave little scratches on the alclad around the hole. I'm sure these scratches a purely cosmetic. On the first side I did, I buffed the whole side of the doubler with maroon scotch-brite, to get rid of these little scratches. But it appears that I buffed through the alclad, not sure though. I don't have a feel yet for what the alloy looks like vs. the alclad. It didn't take much. That really defeats the purpose of the alclad.

I don't understand why anyone would ever scuff the alclad to apply a primer. Isn't the alclad a better protectant than any primer?

 

[Transporter]

Deburring

I have a collection of deburring tools, and my Cleaveland hex deburring bit is a favorite. I use it in an electric driver at very slow speed; see http://www.cleavelandtoolstore.com/prodinfo.asp?number=DB04

Lest we start a tool war, I also own the Avery dogleg tool, which also works fine. You just need to find a combination that works well for you.

Deburring takes a light touch, regardless of the style of tool/deburring bit. Just one or two turns gets it done...

Don't think your spar doublers are 2024-T3 Alclad; the skins and some of the thinner parts are Alclad but the thick pieces are generally made from 2024-T4. These are not corrosion treated in any way and should be primed (see section 5 of the plans).

For parts you intend to prime, scuffing the aluminum helps ensure a good bond with the primer. See the "Primer Wars" section for additional info. Some primers require acid etching and alodine treatment prior to primer application-in addition to a good scuffing!

Hope this helps,

Mike

 

[cnpeters]

Michael - Can you post a pic of an example? Tiny scratches right around the hole sound trivial. May be covered by the rivet heads depending on how much. You will get many more. And, the Alclad is very thin - the Scotchbrite pad can rub it off in a few passes, so you should prime these areas. I decided not to prime Alclad coated pieces except mating surfaces. Do recall the whole exterior Alclad will be rubbed off when paint prep is done (unless you intend to go bare metal). Of course, non-Alclad aluminum should be primed.

 

[RV7]

Deburring bit

FWIW, I once used the deburring bit that you mentioned for all of the #30 and #40 holes, but I've found that using a larger size drill bit is easier and it helps to prevent deburring too much. However, I still use the deburring bit on some of the larger holes.

 

[wingtime]

love it

I have that Cleavland bit and I love it. I use it in a slow turning electric screw driver (not a screw gun). It sounds like you might be using a tad to much pressure and maybe spinning it too many times. On thin material only one to two revolutions are required to debur a hole. Remember you just have to knock off the burr. Not countersink the hole.

 

[SvingenB]

I'm deburring my first holes on the horizontal spar doubler. I using the deburr bit that came in my Cleveland kit.

(http://www.cleavelandtoolstore.com/prodinfo.asp?number=DBB30)

It is giving me less than satisfying results. I've finally figure out what the problem is. As the bit goes around, it shaves off little pieces of aluminum which continue to rotate for a little while with the bit. As these pieces of aluminum shaving rotate they leave little scratches on the alclad around the hole. I'm sure these scratches a purely cosmetic. On the first side I did, I buffed the whole side of the doubler with maroon scotch-brite, to get rid of these little scratches. But it appears that I buffed through the alclad, not sure though. I don't have a feel yet for what the alloy looks like vs. the alclad. It didn't take much. That really defeats the purpose of the alclad.

I don't understand why anyone would ever scuff the alclad to apply a primer. Isn't the alclad a better protectant than any primer?

I just use a large (12mm) drill bit that I twist lightly a couple of rotations between my fingers, after recommendation from proffesionals. The idea is just to remove loose chips and get an even edge (not countersink).

Regarding the priming, I have been (and still is) wondering about the same thing. The whole idea of alclad is to electrochemically protect the core with a more anodic material. Priming that material surely will throw away all protection. On the other hand, uncladded 2024 would probably start to corrode long? before the aircraft is finished, so the purpose is more of a shop primer to protect the core metal during storage and while building. The plastic wrapping will probably also prevent much of the protection.

The galvanic potential in 2024 alclad is about 150 mV between the core and the cladding (1230). When in a corrosive environment, the cladding will corrode first even though the core material is much more likely to corrode in general, but the electric potential also means that corrosion is more likely to occur. It is therefore probably very important to prime the edges and holes if no other priming is done.

I have decided to follow the industry standard regarding priming. This basically means using the approach recommended by manufacturers of aircraft paint used by large aerospace companies. This will not be the easiest way (spray gun, large cans, messy, poisenous), but surpricingly probably one of the cheapest ways. I am also sure that I actually do protect my aircraft from corrosion, instead of applying something that has no other purpose than to prevent the corrosion protection properties of bare alclad.

Another point worth considering is the climate. Living in a very humid environment close to the sea, like I do, the corrosion rate of aluminium is a factor of 100-1000 larger than the corrosion rate inland. The corrosion I see in one year, typically takes 100 years in dry sunny places.

 

[777Dave]

deburring?

Here's a comment from a professional sheet metal worker regarding deburring...
http://planetools.blogspot.com/2006_01_01_archive.html

I guess the least you can take from this is that you should not remove much, if any material when deburring...

 

[airguy]

I've been wondering about this as well - I'm just starting to figure out the whole deburr idea, I've used the Avery dogleg tool and a larger drill bit spun in my fingers, I have not yet tried the hex deburr tool. It seems to me that I would get very tired (not to mention sore) trying to deburr all the holes with a drill bit in my fingers, so I'm looking for a reproducible method that gives good results other than that one. I suppose I should buy a cheap cordless low-rpm screwdriver and try the hex deburr tool next, eh?

I bought the Vans practice kit, and I'm using that as my "trainer" piece to figure out my techniques and tool selection - I've already massacred it pretty well and learned quite a bit.

 

[N131RV]

Heresy from N131RV

This applies mostly to .020 and up to about .040 sheet metal:

After doing a couple thousand holes the old fashioned way, my brother and I hit on this:

If the hole is to be dimpled, we did not deburr before dimpling. After dimpling, we lightly deburred the convex side of the hole. My favorite deburring tool is a large drill bit with some tape wrapped around it for a good grip. Two light twists is just about all it takes. If the part was difficult to reach into (ribs come to mind), a quick pass with a scotch brite pad also removed the imperfections.

This presupposes that you are using high quality drill bits, good technique and BOELUBE every so often to get pretty smooth holes. If your bit is leaving jagged edges on your drilled holes, it's time to get another.

If I ever build another one, I'll use chucked reamers on all the predrilled holes.

Just MHO.

JP

I'm deburring my first holes on the horizontal spar doubler. I using the deburr bit that came in my Cleveland kit.

(http://www.cleavelandtoolstore.com/prodinfo.asp?number=DBB30)

It is giving me less than satisfying results. I've finally figure out what the problem is. As the bit goes around, it shaves off little pieces of aluminum which continue to rotate for a little while with the bit. As these pieces of aluminum shaving rotate they leave little scratches on the alclad around the hole. I'm sure these scratches a purely cosmetic. On the first side I did, I buffed the whole side of the doubler with maroon scotch-brite, to get rid of these little scratches. But it appears that I buffed through the alclad, not sure though. I don't have a feel yet for what the alloy looks like vs. the alclad. It didn't take much. That really defeats the purpose of the alclad.

I don't understand why anyone would ever scuff the alclad to apply a primer. Isn't the alclad a better protectant than any primer?

 

[wv4i]

Before/after debur and online wars

If you look at hole before/after debur with a magnifying glass, you'll see results, and will see if you're overdoing it with whatever debur bit/method you're using. Idea is to get rid of radial cracks and burrs of course. How long would it take to crack without debur? Who knows, if ever? I just followed Van's instructions on my RV10 tail/emp kit re deburring and priming. My fmr airplane restorer neighbor says they found most corrosion between joints, on warbirds (salt water ops?), hard to prime a rivet hole. I've owned two RV6's, live 15 miles off the beach in South FL, 1st one was not primed, no corrosion after 4 years, this one is primed, but is a LOT heavier.

I'm sure the primer/debur/etc wars are still alive and well on Matronics List and perhaps here, but I have better things to do. Guess the question becomes, if you don't want to follow Van's/mfgr's recommendations, should you even be building their product?

 

[airguy]

Guess the question becomes, if you don't want to follow Van's/mfgr's recommendations, should you even be building their product?

Oh come on now - you don't want to try the whole "square peg, round hole thing"? Where's your experimental spirit?

 

[Sam Buchanan]

Here's a comment from a professional sheet metal worker regarding deburring...
http://planetools.blogspot.com/2006_01_01_archive.html

I guess the least you can take from this is that you should not remove much, if any material when deburring...

After getting a good ways into my project, I came to the same conclusion as the individual quoted in the link above. I found a couple of swipes with a ScotchBrite pad did a great job of knocking the burrs off a row of freshly drilled holes in skin stock. This was much quicker/easier than individually deburring each hole and didn't remove material from the edges of the hole.

 

[Michael Burbidge]

Thanks for the great advice

I think I was indeed using too much pressure to deburr. I bought a slow speed electric screw driver and am using that with very little pressure. The temptation surely is to remove too much. I still have to fight the urge to make it look slightly countersunk.