aarvig

aarvig

Well Known Member
I am a newbie learning as I go so I thought I would post a pic of my recent hole deburring. I deburred the horizontal stab spars and double plates as well as all the ribs. I used a single flute, spun by hand with mild pressure (on a scale of 1 to 10 with 1 being no pressure and 10 be everything I have I was at about a 3). Is this good or do I need to change anything or is this too deep and should I start over? Thanks for the help.

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That looks good.. Basicly, you just want knock any rough edges, or burs off. If you can run your finger across the holes and not feel and roughness, you should be fine.
 
plenty good...just need enough pressure to remove any burrs/sharp edges, doesnt take much at all.
 
Rivethead said:
I'm going to disagree here (sorry). it appears to me your being a bit aggressive with the debur to the point of slightly counter sinking the holes. All that's necessary is slight pressure on the tool and once or twice around just to break the sharp edge and remove any chips that can propagate cracks. When done your holes should still have a fairly crisp edge.
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good point...I dont disagree. I dont know if you can do any harm by going that deep, but its not needed. After you do several hundred, the pressure magically seems to lighten up too. :)
 
Rivethead said:
I'm going to disagree here (sorry). it appears to me your being a bit aggressive with the debur to the point of slightly counter sinking the holes. All that's necessary is slight pressure on the tool and once or twice around just to break the sharp edge and remove any chips that can propagate cracks. When done your holes should still have a fairly crisp edge.
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Yeah,
I kind of thought that may be the case which is why I asked the question. Do I need to replace the parts or are we OK?
 
Here is a quote from L. Reithmaier, "Standard Aircraft Handbook", sixth ed. Page 87.

"REmoval of these burrs, called debunking or burring, must be performed if the burrs tend to cause a separation between the parts being riveted. Burrs under either head of a rivet do not, in general, result in unacceptable riveting. .....", "Care must be taken to limit the amount of metal removed when burrs are removed. Removal of any appreciable amount of material from the edge of the rivet hole will result in a riveted joint of lowered strength."
 
Put your rivets in those holes and press on. Don't be so aggressive with your deburring in the future, but don't worry about it on what's been done. All of us have 'over-deburred' a few times. You have strength in numbers.... 18,000+ rivets. It's not coming apart.
 
Certainly good enough to keep going.

The holes in the first picture look fine. That's a thick piece and can accept a heavier hand on the deburring bit. The holes in the middle picture look slightly over deburred. The bottom pic is a mix...the middle hole on the top row looks good, but the other ones look a little too much.

It's clear from the fact that you're asking the question that you're detail oriented. I'm sure your plane will be very nice once it's all done.

Good luck.
 
Build on....Build on....save your money, those parts are fine.

Problem with opinions is that everyone has different standards. You will develop your own as your build moves forward. Just try every work session to do your best and stay within the range of acceptable limits and you will be golden.

Send them pics to Van's and they will tell you that your building an airplane not a watch and to build on.....

I tried to always stay on the conservative side of the Van's standard and that will almost always be good enough. If you have a concern, don't be afraid to keep posting them here as there is a ton of experience on this forum and these guys will call out something that is not safe.

Do you have an EAA tech counselor in your area? Other RV builders that are flying? They can help you with these concerns as they come up...
 
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From a durability and damage tolerance analysis (DATA) standpoint, those holes are a trainwreck. Cracks grow out of imperfections. DATA assumes a .005 manufacturing imperfection, and then grows cracks based on the loading profile, to determine a critical crack growth rate and size. The more and larger imperfections in a bolt hole, the faster cracks will grow, based on loading. If these bolt holes are lightly loaded and not structurally critical, then you are probably fine. If not, plan on alot of future cracks.

Moderators warning about this post:

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S. Buchanan--moderator :)
 
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ferret said:
From a durability and damage tolerance analysis (DATA) standpoint, those holes are a trainwreck. Cracks grow out of imperfections. DATA assumes a .005 manufacturing imperfection, and then grows cracks based on the loading profile, to determine a critical crack growth rate and size. The more and larger imperfections in a bolt hole, the faster cracks will grow, based on loading. If these bolt holes are lightly loaded and not structurally critical, then you are probably fine. If not, plan on alot of future cracks.
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What's that camel smoking?!
 
ferret said:
From a durability and damage tolerance analysis (DATA) standpoint, those holes are a trainwreck. Cracks grow out of imperfections. DATA assumes a .005 manufacturing imperfection, and then grows cracks based on the loading profile, to determine a critical crack growth rate and size. The more and larger imperfections in a bolt hole, the faster cracks will grow, based on loading. If these bolt holes are lightly loaded and not structurally critical, then you are probably fine. If not, plan on alot of future cracks.
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.005 manufacturing tolerance? It will take me 20 years to build and cost me millions to acquire the equipment to produce a homebuilt to that tolerance. It's a good thing Cessna figured out how to manufacture aircraft without that standard...they didn't perform any edge finishing or deburring operations on the 41 year old airplane that I am currently flying...I checked the logs, it hasn't crashed yet either.
 
Good gracious Doug... a trainwreck? Please.

Aaron -

If you're really concerned, email your pic over to Van's so you can give them a call and go over it with them one on one. I don't want to diminish the value of VAF but for questions like this one, you will almost always receive a "yes" and a "no" leaving you wondering even more.

VAF is AWESOME for learning how other builders handled things and debating RV issues but I don't recommend it for getting "Go/No-Go" evaluations on your work. I recommend leaving that to Van's.

So here's my unofficial and unqualified opinion; if those wholes are an actual trainwreck, the -6 should have fallen out of the sky 14 years ago and my -7 will definitely disintegrate on it's first flight. Sheesh!

- Peter
 
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I am sort of surprised no one has asked what tool was used to deburr these holes. I am in the camp that believes these are acceptable, but should be better. Everyone has there own preference in tools, but perhaps your skills are more in line with some other tool. I believe the best deburring tool is the single flute tool tool for a cordless screwdriver (see Cleaveland DB04 or similar) but your mileage may vary. These look to me like they were done with something other than a single flute tool. Something to consider, and certainly cheaper than buying new parts all the time...

Bob Kelly
 
Aarvig,

Another thing to consider, is to double drill your thick pieces (one bit slightly smaller first, then follow up with the final larger drill bit) it will give you a cleaner looking hole. A few of those seemed to show scratches inside the hole. Air drills generally operate at a faster rpm than electric drills, that may give you cleaner holes too. And I assume you are using new drill bits.

I?m currently experimenting around on deburing myself. I?m not happy with the traditional popular tools to do this, but I suppose they are okay. I just find it hard to gauge how much I?m taking off at least on the thinner skins. On thicker pieces, no problem.
 
Well, he states in the original post what tool and what method he was using.....

The other thing to consider is that digital pictures posted on a forum are not the best thing for trying to determine the condition of parts. Especially if they are fuzzy.....

Those that say his work is inferior, take a few pics of your own work and post them on here for comparison. Make sure a few of them are fuzzy and not in the best lighting condition. Flashes tend to highlight defects and make them look worse than they really are.

If these debured holes are bad, the entire fleet of aircraft in the US needs to be grounded as they are sure to fall out of the sky any moment.......

videobobk said:
I am sort of surprised no one has asked what tool was used to deburr these holes. I am in the camp that believes these are acceptable, but should be better. Everyone has there own preference in tools, but perhaps your skills are more in line with some other tool. I believe the best deburring tool is the single flute tool tool for a cordless screwdriver (see Cleaveland DB04 or similar) but your mileage may vary. These look to me like they were done with something other than a single flute tool. Something to consider, and certainly cheaper than buying new parts all the time...

Bob Kelly
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UPDATE!!!!!!!

Thanks for all the advice and for those that offered reasonable constructive criticism. I appreciate it. I always learn.
I sent the pictures to Vans today and told them about all the differing opinions and asked them for theirs. This was the reply:

"I've reviewed your pics and I don't find anything disturbing. The HS-907 spar doubler looks OK as just a bit of material is removed from the edges. You can also use some scotchbrite to polish out any blems on the face, but it really won't affect it much in the end.

The same is true with the HS-902 spar channels. Just polish the edges slightly and remove only the sharp burrs. Any scratches can be polished out with scotchbrite.
Hope this helps you out.... Keep on building!"

Thanks


Vans Aircraft Inc.
 
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I also agree with Van's. They could be better and a light buffing with scotch brite will help. As you continue to build, strive to improve as you get more experience. The fact that you asked for opinions makes me think that you had some doubts. It is good to get a reality check when unsure. Sounds to me like you are a concerned builder who will not settle for mediocrity.

Roberta:)
 
I don't like 100 degree debur tooling

For me, there were two things at work regarding deburring.

One, the standard dingleberry burr was easy to remove without any issue or removal of base material. Piece of cake. The tool didn't really matter.

However, every piece of skin stock had a raised "volcano" edge from the CNC punch. This was large enough not to be removed by match drilling and was as sharp a crack generator as one could make if you tried.
I am planning a polished plane, so scotchbrite (which would work fine otherwise) was not really an option. The trick for me was "flatter" debur bits to take off the edge without countersinking. Specifically, plain old 135 degree drill tips rather than the 100 degree debur cutters sold in the kits. I use a 1/4-28 threaded bit in my debur handle.

YMMV, of course.
 
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