Tip: A New Take On De Burring

[mike newall]

OK,

We all know that part of the 51% we have to do is the labor intensive, time consuming stuff.

Well, this came via a very experienced Engineer who has worked all sorts of metal for years.

To quickly de burr sheet you have drilled, consider this.

400 grit wrapped round a small tungsten bucking bar - light passes, putting pressure on just rips the paper.

Up and down the line of holes and feel afterwards.

Tried it on my empennage and was impressed. Compared it under a 10x lupe to a standard 3 flute twizzle de burring tool and quite frankly it was a lot better and cleaner !

Discuss

[Mike S]

I wonder if this is an "approved" thing to do to alcald??

[mike newall]

It's only 400 paper - pretty much what you would use for edge prep.

Also, with the backing of the tungsten bar it really only cuts the edges of the holes.

As I say - only light pressure is needed.

You get very slight scruffing at the edges but no more than you would with - say red Scotchbrite.

Having seen the difference under a 10x glass, I am happy this leaves a cleaner edge much quicker.

Mike

[lorne green]

If that technique is faster than conventional, go for it....but. For me; I would like to see all of the swirl marks removed from the surface of the Alclad with a
maroon scotch-brite pad. As you say, these marks are light so five or six passes with the pad should clean these up nicely. We want to leave the surface as "satin" a finish
as possible..stress risers are not our friend!
Regards

[SHIPCHIEF]

I'm worried that too much deburring is going on around here;
My 'Standard Aircraft Handbook' 5th edition, page 54:
...deburring..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. The burrs do not have to be removed if the material is to used immediately; however, sharp burrs must be removed if the material is to be stored or stacked, to prevent scratching adjacent parts or injury to personnel.
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 rivet joint of lowered strength. Deburring shall not be performed on predrilled holes that are to be subsequently form countersunk
For myself, I deburr lightly, or wipe off burrs with leather gloved hand or scotchbrite etc.
The 400 grit - on - bar looks like a safe way, but might not be acceptable if a polished surface is required later?

[mike newall]

I would agree there !

If I let my Bro loose with the de burring tool, we had countersinks !

The old, single hole tool was OK, the 3 flute tends to be a bit harsh.

If you are contemplating polishing - this would be a no no, however I am pleased it is generating some discussion.

[hendrik]

I started with Avery's 3-flute tool, but now I mostly find myself using a scotch brite pad. Much faster and better holes. There is probably little difference between the scotch brite and 400 paper for this application.

[RV7Ron]

Couldn't agree more, deburring is WAY overdone in the RV world.

Originally Posted by SHIPCHIEF

I'm worried that too much deburring is going on around here;
My 'Standard Aircraft Handbook' 5th edition, page 54:
...deburring..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. The burrs do not have to be removed if the material is to used immediately; however, sharp burrs must be removed if the material is to be stored or stacked, to prevent scratching adjacent parts or injury to personnel.
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 rivet joint of lowered strength. Deburring shall not be performed on predrilled holes that are to be subsequently form countersunk
For myself, I deburr lightly, or wipe off burrs with leather gloved hand or scotchbrite etc.
The 400 grit - on - bar looks like a safe way, but might not be acceptable if a polished surface is required later?

[Marc Bourget]

Folks,

Vans Kit builders have the convenience of rivet holes punched by a Trumpmatic CNC machine. AC43-13 references deburring rivet holes with a deburring tool or oversized drill. I believe simply sanding the skin will not achieve the desired results because a perfectly square hole edge still constitutes a stress concentration.

A very slight bevel, even if a few thousanth's is preferable. Having experienced crack formation upon dimpling (guess where my opinion on the necessity of deburring with a drill was reinforced?) with holes I forgot to debur, (and never experienced with holes I did debur), I'm an advocate of deburring with a drill. I use a dedicated, new drill, that I installed in a file handle. No weight, simply the weight of the drill, lightly spun by hand - about 1-1/2 turns.

For holes added by the builder, careful drilling technique is required. Make sure you're "normal" (90 deg) to the skin, Consider using a "spotter" to insure your vertical. Slow down when you're about to "punch through" so as to minimize burr size.

I'll be repeating my Aircraft sheet metal seminars at Sun'nFun and I am scheduled for Airventure if any novices or inexperienced are interested. I won't presume that I can aid, or change the minds of the experienced!

Onward and upward
Marc Bourget
TC#5436

[704CH]

Might work for some, but I will continue to debur the old fashioned way. I like my skins looking clean on the outside surfaces, and then scotch-brite pads before prep and priming on the inside..

I like building and don't mind the extra time involved with a simple single twist of the debur bit in every hole. Tried and true, and looks good.

After two years into this project I don't know what I am going to do with myself when it is finished.. Build another I guess. ;-)

Thx