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Deburr using drill and 400 grit sandpaper?

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I am just getting started, and I have some sheet metal of a CH 750 rudder kit that I was preparing. I found that many (if not almost all) holes in the sheet metal had burrs, so I gently used a large drill bit to get rid of the worst of it, and then used 400 grit sandpaper to level the remainder. This process seems to keep me safe from countersinking, but causes some pretty ugly scuffing/scratching on the sheet metal. I guess I would see the same results if I used a smooth file.

First, am I causing any damage to the skin by doing this? I think not, as I have seen others use files. But worth asking.

Second, any thoughts or suggestions on what to do about the scuffing/scratches? Can I buff out the scuffing/scratching before riveting? If so how?

Any advice would be most appreciated. Rather try to understand now before I make mistakes down the line that would be more expensive. Thanks.
 

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Victor Bravo

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That's pretty much show quality for the Zenith 750. It was designed as a simple and not-fancy rough and tumble machine. The worst thing that could happen is that you'd have to prime and paint the rudder. Very very very few CH STOL airplanes are polished aluminum.

When you start building your own assemblies instead of repairing someone else's, just use sharp, new drill bits. And figure out the correct pressure and speed that gives you the best results.

There are special hole deburring bits sold by Aircraft Spruce. They are sharp little hooks that you swirl around the edge of the hole. Work pretty good.

Another thing you can try if you want to is called a drill-reamer or "dreamer". They are used in aerospace mfg. all the time. The end of the bit is a little smaller drill, and then the next section is a final size reamer... all in one bit. That should create a pretty good hole by itself.
 
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Thanks. I was surprised at the amount of burring for some of the parts, but I think I will get the hang of it for future parts.

Any ideas how to remove the scuffs there? I guess going up in grit could make the things a bit better.
 

cvairwerks

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In production, we generally deburred using a piece of a vixen or bastard file glued to a wood block. Occasionally we would use IN and OUT deburr tools on structure greater than .063" thick. We would then use red scotchbrite to polish up the area a little. Most of the time, for aluminum parts, we then cleaned, alodined and primed the area, including the holes. Engineering called out things different for some locations.

For quick, power deburring, use a 2" roloc wheel with red scotchbrite and touch it just enough to smooth the area. It doesn't take much pressure or time to do it, but you do need to practice a little on some scrap until you get the feel for it. All you want to do is make the area around the hole smooth and not remove material.
 

TFF

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Buy the tool. It will save your hands. It’s not perfect but it’s cheap enough to be worth it. If you are really bothered, aluminum polish and some artificial elbows will make it look better.
 

Victor Bravo

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There is also a fantastic tool called the Cogsdill Deburring Tool. Probably goes back to WW2 aircraft manufacturing. It can de-burr both sides of a drilled hole in under five seconds. After a very short amount of practice to develop the technique, you can make great speed with it.

But Heintz himself advocates the use of a coarse file, carefully slid across the surface. As CV Airwerks mentioned, a chunk of a coarse file, glued to a block of wood, is an indispensable thing to have on the bench while you are working with sheet metal. It's a perfect use for an inexpensive HF brand vixen file that has been broken, dropped and shattered, etc. Especially since you can put one in a vise, whack it with a mallet, and have your hot glue gun heating up at the same time.

The (small wood block with the short file piece glued on) tool is also a fantastic tool for deburring edges of sheared sheets.
 

Angusnofangus

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But Heintz himself advocates the use of a coarse file, carefully slid across the surface. As CV Airwerks mentioned, a chunk of a coarse file, glued to a block of wood, is an indispensable thing to have on the bench while you are working with sheet metal. It's a perfect use for an inexpensive HF brand vixen file that has been broken, dropped and shattered, etc. Especially since you can put one in a vise, whack it with a mallet, and have your hot glue gun heating up at the same time.

The (small wood block with the short file piece glued on) tool is also a fantastic tool for deburring edges of sheared sheets.
This method, using a vixen file, is exactly what the aircraft manufacturer that I retired from specified for deburring. But only on the exit side of the hole. Common practice elsewhere is Roloc disc, as per CV Airwerks.
 

BBerson

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I think an abrasive spot facer with a pilot would be elegant. Should be smaller than the rivet so nothing would show.
 

cvairwerks

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Hot Wings's photo is a piece of vixen file on a wood block. As others have said, you can make your own rather quickly, just don't use double cut file pieces, as they will clog quickly.

BTW....a full flexible type vixen makes one of the best edge trimming tools there is. The trick to using one, is to not push the file, but use it in a draw motion. With a little practice and guidance, I could get the new kids working for me on the production line, trimming and cleaning skin edges so well, they looked like they had been milled and polished......Was a blast to see them get the hang of it and realize the new skill they had.
 

Wayne

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With thousands of holes ahead of you (don't ask me how I know :D) I would say get good with a large sharp drill spun quickly and lightly between the fingers or a deburring tool and just go with it.

Your perception of a properly deburred hole will change from "every hole has to be 1,000,000% perfect to "that will do it" very soon :)

When my Dad was working on our Zenith 750 Cruzer (painted and going together now) with his older hands (lost him at 88 last year) he used a deburring bit (it looks like a little drill with a hole in the end and it scoops the burr off) in one of those dollar store rechargeable screwdrivers. The thing was cheap and perfect for the job as it was too anemic to do any real damage. Just learn the reason you are deburring and let that guide your efforts.
 

narfi

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if using a large drill bit, find a piece of thick walled rubber hose that fits tight over the back end of it to give you a better grip and more use time before your fingers start blistering.
 

Daleandee

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I used one of these.
1600203690116.png
Had an adapter where I could put it into a a cordless screwdriver. Don't need much pressure and only a few turns.

Also had a yellow handled one similar to this:
1600203908969.png
There are a number of ways to skin a cat ...
 

bmcj

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I used one of these.
View attachment 101731
Had an adapter where I could put it into a a cordless screwdriver. Don't need much pressure and only a few turns.
I had one of those (the blue handled So shaft) and it worked great. Quick and easy. Of course, if you’re working with a closed structure, you can’t always get to the back of the hole.
 

rv7charlie

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FWIW, on the VAF forum a Van's Aircraft employee has repeatedly advised builders to just hit the burrs with maroon Scotchbrite. This is to avoid removing excess material from the hole. Now I'd agree that some burrs don't yield to Scotchbrite. The Van's skins are 2024, and harder than 6061, and 6061 can be worse to machine because it's...gummier, for lack of a better term.

I've used a small dia Scotchbrite *wheel* in a cordless drill; I've used that blue handled deburr tool; I've used a standard 135 degree twist drill (needs to be new/sharp); I've used a *sharp* 1/4" wood chisel, with the corners rounded, to slice off the burr. In soft aluminum, I'd worry that the deburr tool would countersink the hole before the burr yields; in 6061 it tends to roll out of the way. I've been known to do that. The SB wheel is hard to land on top of the burr every time.

I'd consider the ideal to be one turn with a *sharp* 150 degree deburring bit in the blue handle, but that's unobtainium. The standard 135 degree drill bit 'works', but is hard on your hands when doing hundreds of holes. Maybe a threaded bit, made for a right angle drill? With (relatively) soft 6061, I'd at least consider sacrificing a cheap wood chisel to the cause. I'd round the corners to avoid gouging the sheet, sharpen it well, and use it to shave off the burr.

I'm certainly no expert; just sharing my experience.

Charlie
 

Victor Bravo

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One more idea to try. I have not tried this myself, but just brainstorming.

Get a pin punch or piece of music wire the diameter of your rivet hole. Round the end so it doesn't damage the aluminum. Put it in the cordless drill chuck.

Put a set screw style drill stop (that's a "wheel collar" for us model airplane builders) on the wire about 3/8 or 1/2 inch from the rounded end.

Cut a very small round piece of Scorchbrite, maybe 3/8 of an inch diameter. Just larger than the head of the rivet.

Pierce the wire through this small Scotchbrite disk in the middle.

EDIT: Put a drop of hot glue on the Scotchbrite and stick it to the wheel collar

Put the round end of the wire in the rivet hole as a pilot, and turn the small Scotchbrite as you push the tool down onto the aluminum sheet.

This should minimize the scratching and scuffing of the aluminum to a small area around the hole itself.
 
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MadRocketScientist

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A trick I used was to leave the protective plastic on until after the holes were drillled, lightly sand off the burrs with sandpaper, then remove the plastic. The outer skins on my build are polished and I needed them to stay as pristine as possible. I was also dimpling a lot of the holes and needed the neat holes. The insides of skins didn't matter so much so I either lightly sanded or scotch padded the burrs away.
 
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