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Not about Priming

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MauleDriver(at)nc.rr.com
Guest

Posted: Wed Dec 13, 2006 7:34 am Post subject: Not about Priming

I finally primed my first parts (most tail surfaces primed at 

Alexander's Tech Center).  The specs:

- used the Industrial Wash Primer that Vans says they use on the QB. 1:2 

Catalyst mix (should have used 1:1.5 as recommended)

- bought a cheapo 'trim gun' from Harbour Freight - 4oz cup

- Prepped parts by washing down with Coleman fuel and a red scotchbrite 

(thanks all for that discussion)

   - I did scuff the skins after dimpling.  It does destroy the 

scotchbrite especially since I've chosen not to deburr skin holes, but 

the scotchbrite effectively deburrs 3/32 thin skin holes in my estimation

- Did the priming in my hangar, wore a filter mask (no fresh air), ran 

fans, on a 60deg day.  But kept the primer and gun in my 75deg shop 

until shooting.



It all seems to have worked well despite my beginner's spray technique.  

The thin coat I laid on is translucent greenish gold, rather attractive 

but not uniform.  Seems to have bonded tightly with the aluminum.  In a 

strange way it seems tougher than the 2 part epoxy on my other tail 

parts even though it is thinner.  I'm going to go with it.



Just sharing



Bill "I hate all paint, finishes, and primers" Watson - stapling up the 

elevators & trim tabs, ready to dissassemble the tailcone, looking at 

the QB components littering the hangar.

indigoonlatigo(at)msn.com
Guest

Posted: Wed Dec 13, 2006 8:44 am Post subject: Not about Priming

In my estimation, I think the hole deburring is one of the most important 

steps in the longevity of the rivets and the health of the holes they sit 

in. The dimple produces a lot of stress to the aluminum and it should be 

smoothed before it goes into the dimpler...I would reconsider this skipped 

step!



"It does destroy the scotchbrite especially since I've chosen not to deburr 

skin holes, but the scotchbrite effectively deburrs 3/32 thin skin holes in 

my estimation"



The scotchbrite pad or wheel does not spin inside the hole to do an 

effective enough job.



JMOO



JOhn G.



I need to make a deburring tool that is held like a grape before you put it 

in your mouth.

 	  Quote: 	
		  From: MauleDriver <MauleDriver(at)nc.rr.com>

Reply-To: rv10-list(at)matronics.com

To: RV10-List Digest Server <rv10-list(at)matronics.com>

Subject: Not about Priming

Date: Wed, 13 Dec 2006 10:32:53 -0500






I finally primed my first parts (most tail surfaces primed at Alexander's 

Tech Center).  The specs:

- used the Industrial Wash Primer that Vans says they use on the QB. 1:2 

Catalyst mix (should have used 1:1.5 as recommended)

- bought a cheapo 'trim gun' from Harbour Freight - 4oz cup

- Prepped parts by washing down with Coleman fuel and a red scotchbrite 

(thanks all for that discussion)

   - I did scuff the skins after dimpling.  It does destroy the scotchbrite 

especially since I've chosen not to deburr skin holes, but the scotchbrite 

effectively deburrs 3/32 thin skin holes in my estimation

- Did the priming in my hangar, wore a filter mask (no fresh air), ran 

fans, on a 60deg day.  But kept the primer and gun in my 75deg shop until 

shooting.



It all seems to have worked well despite my beginner's spray technique.  

The thin coat I laid on is translucent greenish gold, rather attractive but 

not uniform.  Seems to have bonded tightly with the aluminum.  In a strange 

way it seems tougher than the 2 part epoxy on my other tail parts even 

though it is thinner.  I'm going to go with it.



Just sharing



Bill "I hate all paint, finishes, and primers" Watson - stapling up the 

elevators & trim tabs, ready to dissassemble the tailcone, looking at the 

QB components littering the hangar.

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Wed Dec 13, 2006 9:25 am Post subject: Not about Priming

There's a simple exercise re deburring that provides some visual 

evidence of the differences that I picked up from Dan Checkoway, Take a 

non deburred hole and dimple it then take a magnifying glass and examine 

the edges. I'll bet that with a hole that was drilled with a drill bit, 

you will see cracks around the dimpled perimeter, do the same with a 

properly deburred hole and then compare the difference.

Now with all of that said, I'm not sure deburring will cause your plane 

to fall out of the sky, for me it was a mental peace of mind issue. 

However Ture confessions: there have been times when I forgot to deburr 

a few holes prior to riveting and I didn't drill them out and deburr. 

Some one mentioned that during WWII when they were mass producing P51's 

that they didn't deburr every hole or sheet metal edge in those at the time.

As with everything in an experimental plane you pays your money and 

takes your chances.



Deems Davis # 406

Finishing - ( A Misnomer ! )

http://deemsrv10.com/

John Gonzalez wrote:



 	  Quote: 	
		   



 In my estimation, I think the hole deburring is one of the most 

 important steps in the longevity of the rivets and the health of the 

 holes they sit in. The dimple produces a lot of stress to the aluminum 

 and it should be smoothed before it goes into the dimpler...I would 

 reconsider this skipped step!



 "It does destroy the scotchbrite especially since I've chosen not to 

 deburr skin holes, but the scotchbrite effectively deburrs 3/32 thin 

 skin holes in my estimation"



 The scotchbrite pad or wheel does not spin inside the hole to do an 

 effective enough job.



 JMOO



 JOhn G.



 I need to make a deburring tool that is held like a grape before you 

 put it in your mouth.

> From: MauleDriver <MauleDriver(at)nc.rr.com>

> Reply-To: rv10-list(at)matronics.com

> To: RV10-List Digest Server <rv10-list(at)matronics.com>

> Subject: Not about Priming

> Date: Wed, 13 Dec 2006 10:32:53 -0500

>

> 

>

> I finally primed my first parts (most tail surfaces primed at 

> Alexander's Tech Center).  The specs:

> - used the Industrial Wash Primer that Vans says they use on the QB. 

> 1:2 Catalyst mix (should have used 1:1.5 as recommended)

> - bought a cheapo 'trim gun' from Harbour Freight - 4oz cup

> - Prepped parts by washing down with Coleman fuel and a red 

> scotchbrite (thanks all for that discussion)

>   - I did scuff the skins after dimpling.  It does destroy the 

> scotchbrite especially since I've chosen not to deburr skin holes, 

> but the scotchbrite effectively deburrs 3/32 thin skin holes in my 

> estimation

> - Did the priming in my hangar, wore a filter mask (no fresh air), 

> ran fans, on a 60deg day.  But kept the primer and gun in my 75deg 

> shop until shooting.

>

> It all seems to have worked well despite my beginner's spray 

> technique.  The thin coat I laid on is translucent greenish gold, 

> rather attractive but not uniform.  Seems to have bonded tightly with 

> the aluminum.  In a strange way it seems tougher than the 2 part 

> epoxy on my other tail parts even though it is thinner.  I'm going to 

> go with it.

>

> Just sharing

>

> Bill "I hate all paint, finishes, and primers" Watson - stapling up 

> the elevators & trim tabs, ready to dissassemble the tailcone, 

> looking at the QB components littering the hangar.

>

sstella(at)incisaledge.co
Guest

Posted: Wed Dec 13, 2006 9:55 am Post subject: Not about Priming

If you read the Standard Aircraft Handbook that comes with the kit it tells

not to deburr holes that will be dimpled.



Steve



--

n8vim(at)arrl.net
Guest

Posted: Wed Dec 13, 2006 11:05 am Post subject: Not about Priming

Page 5-2 from Van's (The document called "Useful Information") states:



"All drilled holes should also be deburred ...... Burrs around holes are 

a problem mainly in riveting and dimple countersinking..... "



-Jim 40384

Steve Stella wrote:

 	  Quote: 	
		   



 If you read the Standard Aircraft Handbook that comes with the kit it tells

 not to deburr holes that will be dimpled.



 Steve

LloydDR(at)wernerco.com
Guest

Posted: Wed Dec 13, 2006 11:38 am Post subject: Not about Priming

You are reading from Van's recommendations in the builders manual, if

you go to the aircraft standards book and read about deburring, the only

mention is to deburr for parts storage and to prevent scratches from

material touching, it states nothing about deburring for hole integrity.

Dan 

N289DT

--

sstella(at)incisaledge.co
Guest

Posted: Wed Dec 13, 2006 11:45 am Post subject: Not about Priming

I wonder why the difference of opinion between Vans and the Aircraft

Handbook?



Steve



--

LloydDR(at)wernerco.com
Guest

Posted: Wed Dec 13, 2006 11:45 am Post subject: Not about Priming

Just as a follow up to my last, the primary reason to remove burrs would

to ensure the rivet or dimple set seats correctly and does not get upset

by the burr. 

While I do agree with Dan and Deems, looking at the hole after deburr it

does appear smoother on the lip, but the striations from the drilling

process go all the way through the hole, IE even after deburring they

are still in the interior of the hole, and you can see this after the

dimple is formed because more of the interior of the hole is exposed.

Dan 



--

VHMUM(at)bigpond.com
Guest

Posted: Wed Dec 13, 2006 11:51 am Post subject: Not about Priming

Oh dear....just ask any aircraft engineer!! You should deburr all edges and 

holes to stop cracks.



Chris 388



---

VHMUM(at)bigpond.com
Guest

Posted: Wed Dec 13, 2006 11:51 am Post subject: Not about Priming

Who cares just deburr!!



Chris

---

james.k.hovis(at)gmail.co
Guest

Posted: Wed Dec 13, 2006 12:18 pm Post subject: Not about Priming

Not necessarily. Recent testing shows burrs around fastener holes

don't have significant impact on the strength of structure. Main

driving factor is skin thickness vs burr height. Thicker stock (used

in larger aircraft) can stand larger burrs. Key thing is to prevent

burrs. Keep your bits sharp, don't push hard while drilling, and keep

your parts well cleco'ed together. I don't know what thickness is

typical in the RV-10, I'd assume .032" or .025" stock. If you're

getting .004" or less burrs, then anything other than a quick "hit"

with scotchbrite is probably a waste of time. Typical deburr operation

in the factory is either use as file-like tool (patented by someone I

actually know...) to run across the back sides of skins or use a

drill-motor and sanding disk. For thin sheet stock, I'd prefer doing

it by hand. And if you deburr BEFORE dimpling, you shouldn't have any

need to deburr afterwards. Bottom line, deburr probably makes fastener

installation easier, but may not do much to improve the structural

"soundness" of the airframe.



JKH

PS: BSAE 1989 U of Mo-Rolla

17+ years aircraft design engineer for a "major" midwest aircraft builder.

On 12/13/06, Chris , Susie  Darcy <VHMUM(at)bigpond.com> wrote:

[quote] 



 Oh dear....just ask any aircraft engineer!! You should deburr all edges and

 holes to stop cracks.



 Chris 388



 ---

VHMUM(at)bigpond.com
Guest

Posted: Wed Dec 13, 2006 12:35 pm Post subject: Not about Priming

OK ask Vans!! They say deburr from Ken Kruegar chief engineer Vans!! 



Chris 388

LloydDR(at)wernerco.com
Guest

Posted: Wed Dec 13, 2006 1:53 pm Post subject: Not about Priming

They have not updated that section of the manual in a long time, IE

before the pre-punch days, so in that sense the builders were drilling

thousands of new holes, which had the likely hood of causing large burrs

to form and be trapped between surfaces, but since the advent of the

prepunched kit, there is very little additional metal being remove, thus

there is less likely a burr to form and trap between surfaces.

With that being said, I do deburr everything, but am wondering if I am

just "drinking the kool-aid" as it really adds nothing to the structure,

and if you have a heavy hand might even cause a weaker joint because of

removed material.

Here is another one to stir the pot and a proverbial war, do you always

drill before dimple? If so have you noticed that the hole is actually

larger after the dimple, causing the rivet to be sloppy in the hole,

should you just dimple the punched hole, which then accepts a -3 rivet

without as much slop? I have heard people go both ways on this,

personally I match drill. The reason I was given to match drill was that

the punch does not make a clean hole like a drill will. So with that

being said the reason I ask this is the RV12 will not be match drilled,

IE the rivet will be put directly in a pre-punched hole, and if it is

okay for that structure why not for the previous punched kits? It would

save us a huge amount of time?

Just thinking through out the day.

Dan

N289DT   



--

jesse(at)itecusa.org
Guest

Posted: Wed Dec 13, 2006 2:50 pm Post subject: Not about Priming

This is just my experience, not a technical answer:



I have tried dimpling practice parts without drilling,  I have noticed more

damage to the skin (ie. Tiny cracks) when this is done.  I certainly do not

recommend dimpling without drilling.  For the RV-10, the holes will not be

dimpled.  I don't think the issue is that the holes won't line up well, but

rather that the hole won't handle the dimple die as well without damaging

the skin if you don't drill it out.  It could be that a modified dimple die

could make a difference here, but I couldn’t say for sure.



Do not archive.



Jesse Saint

I-TEC, Inc.

jesse(at)itecusa.org

www.itecusa.org

W: 352-465-4545

C: 352-427-0285



--

armywrights(at)adelphia.n
Guest

Posted: Wed Dec 13, 2006 9:11 pm Post subject: Not about Priming

Yeah, remember the RV-12 is being pre-punched to size, and the RV-10 is

pre-punched undersized, hence our match drilling.  Also, the RV-12 is pop

riveted I believe, which helps take up some builder inexperience.



Rob Wright

#392

Fuse



--

KiloPapa

Joined: 24 May 2006
Posts: 142
Location: Pearblossom, CA

Posted: Wed Dec 13, 2006 9:37 pm Post subject: Not about Priming

We use a #41 drill bit which allows the rivets to fit a little tighter after 

dimpling and non-dimpled holes take the rivet just fine also.

I tip I learned from my mentor, Jack Hakes.



Kevin

40494

tail/empennage



do not archive

---

_________________
Kevin
40494

do not archive

MauleDriver(at)nc.rr.com
Guest

Posted: Thu Dec 14, 2006 6:00 am Post subject: Not about Priming

I'm definitely 'drilling' but actually reaming the pre-punched holes 

where drilling isn't required.  Reams seems to produce a better hole.



Anyway, what I intend to take a critical look at with a my jewelers 

loupe (or whatever those things are called) are prepunched 3/32 holes, 

reamed, dimpled, then deburred with red Scotchbrite -- compared to the 

same holes reamed, deburred with a tool, then dimpled.  It seemed to me 

that reamed dimple holes could be effectively and productively  deburred 

with a vigorous Scotchbrite scrubbing.



Bill "Got my back-rivet plate in place and enjoying some error free 

progress on the elevators" Watson



Lloyd, Daniel R. wrote:

 	  Quote: 	
		   



 They have not updated that section of the manual in a long time, IE

 before the pre-punch days, so in that sense the builders were drilling

 thousands of new holes, which had the likely hood of causing large burrs

 to form and be trapped between surfaces, but since the advent of the

 prepunched kit, there is very little additional metal being remove, thus

 there is less likely a burr to form and trap between surfaces.

 With that being said, I do deburr everything, but am wondering if I am

 just "drinking the kool-aid" as it really adds nothing to the structure,

 and if you have a heavy hand might even cause a weaker joint because of

 removed material.

 Here is another one to stir the pot and a proverbial war, do you always

 drill before dimple? If so have you noticed that the hole is actually

 larger after the dimple, causing the rivet to be sloppy in the hole,

 should you just dimple the punched hole, which then accepts a -3 rivet

 without as much slop? I have heard people go both ways on this,

 personally I match drill. The reason I was given to match drill was that

 the punch does not make a clean hole like a drill will. So with that

 being said the reason I ask this is the RV12 will not be match drilled,

 IE the rivet will be put directly in a pre-punched hole, and if it is

 okay for that structure why not for the previous punched kits? It would

 save us a huge amount of time?

 Just thinking through out the day.

 Dan

 N289DT

MauleDriver(at)nc.rr.com
Guest

Posted: Thu Dec 14, 2006 6:03 am Post subject: Not about Priming

Same here.  Using #41 bits and reamer.



KiloPapa wrote:

 	  Quote: 	
		   



 We use a #41 drill bit which allows the rivets to fit a little tighter 

 after dimpling and non-dimpled holes take the rivet just fine also.

 I tip I learned from my mentor, Jack Hakes.

LloydDR(at)wernerco.com
Guest

Posted: Thu Dec 14, 2006 6:52 am Post subject: Not about Priming

Just so everyone knows, I do not condone nor recommend in any way not

following the builders manual on match drilling and hole prep, and

following the best practices when building an airplane.

Let me stress this, I do match drill, I do de-burr, I do scuff, I do

dimple, I do clean (with Coleman fuel), and I prime (But I am not

telling with what). Then I rivet, and I check every rivet with the

gauge, some people have said that checking everyone is a waste of time,

but as in much of what we do to prep for riveting, it is for our own

piece of mind. I am sure to the best of my ability that it is done

according to acceptable methods and if I have any questions I have a TC,

an A&P, and an IA that come over to verify.



The email about not match drilling was just posting a question, because

I have been told by many different builders there opinion both ways on

this. For me, it was not worth the time savings, much in the same way I

assemble and then match drill, rather than like some that just drill

separate.



Dan

N289DT



--

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