Reamer bit vs Drill bit & Deburring questions

I'm working slowly but surely on my RV-10 kit. First part being the Vertical stabilizer it introduces me to a lot of tools I've not used. My question is specifically around match drilling and deburring.

If I understand correctly then when there are prepunched holes, say the skin (VS-1001) against the flanges of the front spar (VS-1002), then I can use the reamer to drill and 'right size' both holes. Do I still need to deburr each hole inside and out or with the reamer does it become more of a spot check thing to where if I see bits and pieces of metal then clear it out.

In the case of match drilling, for example the Read Spar (VS-1003) and the Rear Spar Caps (VS-1014-L & R), where an actual hole needs to be drilled through an actual piece then I use a drill bit to accomplish that. These I assume will always need to be deburred because so far my experience is a lot of material gets thrown around.

Another general deburring question is the plans seem to mention deburring alot. Often it seem like it requests me to deburr the same parts several times even if I hadn't drilled through them. Is the general rule that if you have drilled through a part then you deburr it. For example page 6-3 Step 9 tells you to disassemble the rear spar and deburr all the holes... wouldn't assume that means the web holes that you hadn't touched.

One last question on deburring with regards to the skin sides. On the substructure pieces I use a deburring tool then run them across a 6" Scotch Brite disk at 3 different angles (45 down, straight and up). Do I need to do this on the skin edges as well?

Thanks for any help! Hope it makes sense.

Hi Justin,

I'm just finishing up my tail kit. Here's the conclusion I've come to on deburring...

- Drill bit vs Reamer - You will still need to deburr. Vans prepunched holes have a significant bur on at least one side that needs to come off. It's unlikely that reaming will completely remove this.

- Deburr holes after final drilling them. When in doubt, just follow the plans and do what they say.

- Skin deburring and edge deburring - I typically use a scotch brite wheel or a flat file to knock down any machining leftovers and then use 220 grit sandpaper followed by 400 grit sandpaper to round off the edges. On the inside of the skin, I generally run over it pretty well with a scotchbrite pad to knock down any pre-punch and/or final drilling burrs. I follow up with a single flute deburring tool to get the rest of the burr on the inside. On the outside, I just use a single flute deburring tool.

Be careful about not over-deburring. You're not trying to countersink the hole, just remove the burr. If you can feel a burr catch your fingertip skin while lightly brushing over it, you might need another pass.

I'd highly recommend taking an EAA sheet metal class if you haven't already. It's a great place to get initial experience and ask a bunch of questions!

Maybe just think of it this way - any cut needs deburring. Period. Edges, holes, zigzags, punches; you did it, they did it - doesn't matter. Debur it.

And yeah, don't go crazy. Youre not polishing diamonds here. Knock off the burr, smooth out the cut marks. If you cant cut yourself on it or catch a fingernail, then youre done.

Reaming is a hole tolerance issue, not a burr issue. I guess you could ream every hole you drill for a rivet, but unless its called for, its not necessary. Drill, debur, (paint), rivet. Repeat.

Solid advice, thanks everyone.

Agree with what maniago said.

I use files and sometimes sandpaper to deburr things. For long straight edges, the Vixen file, with the fine teeth, works extremely well to clean up the sheared or cut edges. I use a fine mill file for the corners of the long edges.

I have a variety of smaller files that are handy for the inside curves at the ends of flanges.

Every edge, whether I made it or the factory did, gets deburred. If I pilot-drilled something and need to use that hole in an assembly, I'd deburr it before assembling. After drilling or reaming to final size, I deburr it again.

Dave
RV-3B, where there's LOTS of drilling

What Mani said. Many builders deburr too much material off the mating surfaces. I used a piloted reamer on all of my match drilled holes in my RV8, and the reamer didn't leave much, if any, burr. If you plan on priming this area, you may be able to just remove any burrs in this area with a scotch brite pad. Priming takes care of the missing alclad in this area. Takes a few seconds. Take a close look with a magnifying glass and then feel the holes with your hands to get a 'feel' of what is needed. You don't do this on all holes, just needed to 'calibrate' your feel. Excessive deburring results in too much material removal, and wastes time unnecessarily. Some debarred holes end up looking like they are semi-countersunk.

The theory as it has been explained to me is that a standard twist drill bit will leave a slightly irregular hole and a reamer is much more likely to leave a perfectly round hole. Perfectly round holes are ideal and preferred for any hole getting hardware.
However, and this is where some will scoff, it can be argued that for rivet holes, a slightly irregular hole is better because when the rivet is pounded, it takes on the shape of the hole and locks in. Whereas in a perfectly round hole, there is less torsional lock and over time the rivet can start to spin, wear, and eventually create a "smoking" rivet.

Highly experienced folks have said this theory is nuts whilst others agree and were taught the same. The old guy who told me about it had decades of experience in aircraft factories.

Many high quality RV's have been built without the use of reamers. Another debate for the ages I guess. I bought a couple, but didn't use them on rivet holes. My airplane is fairly new but I've never had a smoking rivet and I've seen quite a few out on flightlines.

I found Scotch Brite discs on an angle die grinder to be the quickest and produced the best quality edge deburring.

brad walton said:

I found Scotch Brite discs on an angle die grinder to be the quickest and produced the best quality edge deburring.

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I have a cheap harbor frieght angle grinder. What kind of disc do you use?

You can get the 1" or 2" scotch brite wheels from Cleaveland tool and others: http://www.cleavelandtool.com/3M-Cut-Polish-Wheel-2/productinfo/3MW7A2S/#.Vfmo3PlVhBc

For skin edges I do not recommend using these wheels as it is real easy to catch the skin with the wheel and end up with a wrinkle in the skin. While replacement skins are available, this adds up pretty fast.

For skin edges I take a few light passes with a vixen file to get rid of the CNC cut remnants, then a V shaped deburring tool to round the edges. Very easy to control and yields good results.

Carl

Carl Froehlich said:

You can get the 1" or 2" scotch brite wheels from Cleaveland tool and others: http://www.cleavelandtool.com/3M-Cut-Polish-Wheel-2/productinfo/3MW7A2S/#.Vfmo3PlVhBc

For skin edges I do not recommend using these wheels as it is real easy to catch the skin with the wheel and end up with a wrinkle in the skin. While replacement skins are available, this adds up pretty fast.

For skin edges I take a few light passes with a vixen file to get rid of the CNC cut remnants, then a V shaped deburring tool to round the edges. Very easy to control and yields good results.

Carl

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I have a few of those, even with the mandrels but not sure how they attach... I have one of the mandrels and a 1" on my cordless drill... so I guess that would work.

I have a vixen file so I can use that on the skin.

I actually went out to the garage a bit ago (I work from home) and spent 30 mins going back over my parts ensuring they're deburred. Mainly was concerned with in between the flanges, used the file where I could and a brite pad where I couldn't get a file in between.

I use the two inch discs on the angle grinder. To avoid catching an edge, rotation should be down on the edge being conditioned. They only catch if the rotation of the disc is obtuse to the edge. Gives the quality of 320 wet/ dry sandpaper with much less labor.

I have used the wheel on both a horizontal shaft (grinder) and a vertical shaft (drill press.) As long as I move the material AGAINST the direction of rotation, and don't start right at a corner, I have never caught an edge or corner. Also, the grooves in the wheel should not be deep enough for the material to bind. I try to have about six grooves on the wheel, use them until they get about .050" deep, and dress the wheel until they just show. A wheel will last for about two planes that way. I do prefer using the drill press as the driving force on most parts. YMMV. I feel reamers are overkill, but that is just me...

Bob

I love my reamers

I know there's a lot of debate on this topic, and many, many RV's have been built without using reamers. But I bought a few, and once I started using them, never went back to drill bits for all the pre-punched holes. They just give a much cleaner hole, less deburring needed (although I still deburred everything), and as far as I'm concerned, it's all more precise and exact. Bolt holes in particular, fit so close and exact. It just seems like the way an airplane should be built. You're removing so little material in a pre-punched hole, a drill bit seems like overkill. This just makes more sense. What's not to like?

I've seen a few examples of micro-cracks appearing around drilled holes over time. Dimpling puts some stress on the metal, after all. For this reason alone, it's cheap insurance. You aren't spending a lot of money. One reamer of each size is plenty. I built my whole airplane with one reamer (of each size). As the old saying goes... "try it; you'll like it!" Just one man's humble opinion... but based on quite a bit of experience.

i have used a reamer on my 12 since early on. the rivets wouldn't go thru 1 hole, let alone 2. a reamer is the perfect tool to take off a minute amount of material cleanly and leave a round hole.

The v-shaped debuting tool is excellent for debuting edges of cut sheet medal. a couple of passes and you have an almost perfectly smooth edge. Acft tool places have them and I think Spruce has them towards the back of the catalogue under "specialty tools" or something like that.