Deburring After Reaming

While I have been deburring every hole I match drill (using a deburring bit), I have to admit, part of me wonders why I’m doing it half the time. When I use a reamer to match drill, the hole is so clean I really have a hard time making out any kind of a burr on either side of the metal. Using the deburring bit doesn’t seem to make much of an improvement from the reamed hole. The drilled holes have definite burrs, but not the reamed holes. Especially on the skins, I find that running worn out 400 grit sandpaper over the holes very lightly is enough to create a very smooth surface. Talking with someone who retired from a major aircraft manufacturer, he said the spec for deburring was usually to run a flat file over drilled surfaces and that was it. I’ll continue to hit bad holes with a bit, but otherwise the sandpaper approach may get the nod from me. Bad or okay?

I fell in to this trap early on too, de-burring every hole. But I've since learnt that if there is no burr, then the hole doesn't need deburring

My process is to ream holes, quick wipe with scotchbrite, inspect, Done.

Any holes that are drilled, I use the deburr tool.

I think the dangers of over-deburring are bigger than having the occasional tiny burr get missed.

The reason for deburring is increase in useful life.

Metal properties and physics are influenced by surface conditions far smaller than the eye can detect. "Break" all sharp edges. A reamed hole may look smooth to you and appear to lack stress risers.

I microscope would tell you different.

Keep in mind, most all the holes will be dimpled and that stretches the edge of the hole about 18%, Little stress risers become bigger in the process.

FWIW

+1
The goal of ‘de-burring’ is not just to remove burrs. It also puts a very slight radius on the otherwise sharp edge where stress risers live.