Countersinking with a Drill Press

[attackpilot]

I was wondering if anyone has countersunk spars, stringers, whatever using the micro-stop in a drill press? My countersinking craftmanship is just not developing like I wish it would after countersinking the VS and one of the HS spars. My idea is that if i put the micro-stop in the drill press, I could control the process better and ensure that the holes are not getting "oval." I go slow with the air drill and 95% come out fine, but that 5% that I mess up seem to happen despite going slow and taking my time. It is almost luck, or lack there of whether or not the countersink is acceptable.

Also, what do I do with "oval" and countersinks that are too deep. My thought is to do nothing or put an "oops" rivet in there. The only problem with the "oops" rivet is that it is going through the skin so I don't know how that would look or work. I would greatly appreciate any thoughts.

Joe Hutchison
RV-10 Tail Kit

[Mel]

The drill press is always preferred over hand drilling and countersinking. Anytime you can use the drill press, do so. It provides much more precise control.

[rmcgann]

G'day Joe,

Use the drill press for any drilling/countersinking wherever possible. For items too big to take to the drill press, try a battery powered or normal electric drill that spins at a slower speed than the air drill.

If the countersinks are too deep, it is probably not adjusted correctly - I assume you are using a microstop cage? An oops rivet won't help much if the countersink is too deep - it has (almost) the same size head as a -3 rivet.

The oval hole is probably due to chatter. Try placing the part to be countersunk over a plate with a 3/32 hole (assuming -3 rivet hole), so the countersink pilot can track through the hole in the part and into the hole in the plate.

cheers,
Ron
-10 finishing

[N674P]

Originally Posted by attackpilot

what do I do with ... countersinks that are too deep.
Joe Hutchison
RV-10 Tail Kit

This is just a thought, and if you think of trying it, please check with your DAR or Vans first!
How about pro-sealing (gluing) a tinnerman type washer in the countersink to fill in where the c-sink is too deep?
I was thinking about this when I thought the first countersink on my main spar was too deep , but turned out it wasn't. I actually had to go back and countersink all the rest of the holes more...

[rv9builder]

Originally Posted by attackpilot

What do I do with "oval" and countersinks that are too deep.
Joe Hutchison
RV-10 Tail Kit

Joe,

I over-countersunk the holes in one of my flap spars. Van's tech support suggested that I make a doubler out of a thin strip of .025 and put it behind the flange of the spar. I then riveted through the skin, the spar and the doubler. From what I can tell, the flap came out fine.

[rickmellor]

Anytime I've hosed a part I just order a replacement. Most parts in the kit can be had for less than $20 so it's no big deal, and it provides a nice incentive to not screw things up. Maybe it's just me, but I want my plane built as close to spec as possible. Work arounds would cause me more grief in the long run (aka, paranoia). You can order most parts for the plane online through Van's so you don't even have to worry about admitting to someone you trashed a part.

For your question though ... yes, use the drill press. It'll prevent ovals and rough cuts due to chatter. And ... for tight spots where you can't fit the cage on the countersink ... it provides you with much greater control so you don't cut too deep.

-Rick