Deburr both sides?

Hey builders,

I am wondering do you deburr both sides of match punched holes in the aluminium sheets?
To me the edges of one side feel super smooth while the edges of the other side feel quite rough.
I guess the smooth side is the top side during the punch process. I am about to skip deburring this side as the edges don't feel smoother after I have deburred them - quite the opposite.
I am explicitly talking about matched punched holes here - not holes you have to final drill! So lots of the RV-14's skin and rib holes for example.

How do you handle this?

Malte

Hi Malte,
You may get other opinions here (deburring is one those topics like priming), but the point of deburring is to remove burs. If there are no burs then there is nothing to remove so in my opinion, your intuition is correct that you should only debur when you can feel that there is something there.
I'm about 2 years into my build and have almost completed the wings. As much labor as is required on one of these projects, any time savings I can find that does not affect the quality of the build I take advantage of. I do the same thing on the skins-if there is no bur on one side of the skin, then only debur the side that has them.
My two cents, YMMV

Here?s a quote from Section 5.2 of the instructions that may answer your question:

All drilled holes, or prepunched holes that have been final-drilled to a larger size, should also be deburred. Holes that were factory punched to final size can be inspected and only deburred if needed (with the exception of large holes to be dimpled for screws).

If you question it and want to be sure, take 400 grit wet/dry sandpaper and make a quick pass on the back side. That?s all it takes if it takes anything.
This also works for holes that you can?t get a debur tool on. Might need more than one pass depending.

I have seen quite a few aircraft that had very poor edge finishing and I suspect those builders also had very poor hole deburring, but have yet to see a crack even in the poorest quality build. So, yes, debur, but don?t make yourself crazy.