Deburring Rib Flange Reliefs

I have recently started on my RV-14 and am about one fourth the way through the empennage kit. I have a question about the the rather subjective subject of deburring. I tend to be rather anal about things, so I wanted to take a straw pole centering around deburring to make sure my thinking is on track.

Section 5 of the plans gives a good introduction to edge prep:



Recently I have been working on my horizontal stabilizer ribs. My approach was to hit all of the flange outer edges with the 3M wheel on the bench grinder, and that went quickly and worked well. But what about the flange relief cuts? The following pictures detail my current approach:




I start by removing all of the roughness on the straight surfaces left over from stamping with a flat file (RED). Then I do the same on the curved surfaces with a round file (MAGENTA). Then I knock off the edges / round on the straight inside surfaces with a flat file (ORANGE) and then the curved inside surfaces with a round file (CYAN). Finally I deburr (hard to really round) the outside surfaces with a 1" 3M wheel in a die grinder (GREEN).

Some of the more convoluted ribs have ~18 relief cuts and after timing myself at what seems like a pretty good clip on any one operation, it is taking me just under 30mins per rib. Is this the norm? Am I over doing it? Under doing it? Any suggestions? Thanks!

Relief Cuts

Sounds like you are using about the same technique I used early in my build. As my project progressed I switched to emery clothe. I purchased several grades. I think the emery clothe was faster and did a better job. With a little work it is possible to achieve rounded/polished edges, even in those relief cuts.

Deburring: the absolute most frustrating that thing I needed to learn to get going on my kit. Not so much that it is hard - just difficult to judge what is good enough.

Lee Valley sells a blue roll of sand paper made by Hermes. I use 400 grit and it is the absolute best thing that I have found for all those tight spaces. You can cut it into thin strips and use it like dental floss... but not on your teeth Even though it is only 400 grit it is easy to be too aggressive with it and knife edge the aluminum if not careful.

Hope this helps.

Scotchbrite wheels

Get a 90 degree die grinder and a bunch of the 2 and 3 inch diameter red and blue scotchbrite wheels. I cut my mandrel down so it's only an inch in diameter, and you can learn to do the all the deburring on a rib in a couple minutes. Also, the red wheels will really shape quickly and do all the "cutting down" you need to do to prevent silouetting on the skin. I seldom touch a file ever. I do this kind of work for a living in the big jet world..we go through a lot of Scotchbrite!

Ditto Scotch Brite and mini die grinder. Works great on straight edge deburring as well

I just used scotchbrite and files on all the reliefs. If it didn't feel sharp when I moved on.

Debur

AviatorJ said:

I just used scotchbrite and files on all the reliefs. If it didn't feel sharp when I moved on.

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Same here. It was not my favorite part of the build.

When I started I was using the 3M wheel more,
as I got farther into the wings I just used emery cloth 220 grit. It doesn't take much to knock off those sharp corners. Sometimes I quickly go over it with 320 after the 220. I'm sure others would say this is not needed. Then I do one final pass with my hand to check for any spots that I missed.

Thanks for all the good advice. Regarding the mini scotch bright wheels:

fixnflyguy said:

Get a 90 degree die grinder and a bunch of the 2 and 3 inch diameter red and blue scotchbrite wheels. I cut my mandrel down so it's only an inch in diameter, and you can learn to do the all the deburring on a rib in a couple minutes. Also, the red wheels will really shape quickly and do all the "cutting down" you need to do to prevent silouetting on the skin. I seldom touch a file ever. I do this kind of work for a living in the big jet world..we go through a lot of Scotchbrite!

Click to expand...

Could you send a link to the type you are talking about? Also, are you using this to round the inside edges of the notches and corners, or only the outside?

I like to keep the edges flat at the bottoms of those recesses to avoid cracks.



Although I would accept an edge like Van's shows for .040 or thicker material.

Also, I don't allow any burrs.

Dave