How do you countersink for these platenuts?

[alpinelakespilot2000]

I'm stumped. I'm attaching the three inboard tank attach platenuts to the aft side of the spar. However, two of the platenut rivet holes (the top and bottom most) are so close to the spar doubler bars that I can't used my countersink cage to countersink on the forward side for flush rivets. I must be missing something--I just can't figure out what!



Thanks for any help

[N523RV]

Steve,

Many builders grind/cut off a portion of the countersink cage so you can get it to fit. You can also buy CS cages with the foot already modified for just this instance.

The other option is to do it blind without the cage. If you have the hex adapter to screw the cs bit into and chuck it in your drilled. Go slow and keep it level.

[LettersFromFlyoverCountry]

I just took the countersink bit and put it in my deburring tool and gave it a couple of cranks. Simple. Quick. Works.

[alpinelakespilot2000]

Thanks Matt and Bob--

I feel better now. Thought I had the wing spar upside down and backwards or something. (One of those nightmares I periodically wake up in the middle of the night from.)

I'll have to go out and see if I can insert my countersink bit into my hex debur adapter. Not sure if my debur blade screws out or not.

Thanks for the quick response! Back to work!

Steve

[LettersFromFlyoverCountry]

One thing. Be VERY careful when you go to buck those outboard (errr....up and down) rivets. If you're not careful with the bucking bar, you can gouge the doubler bar up something fierce. Lots of duct tape to protect the bar is advisable. It's a real tight fit under there.

[alpinelakespilot2000]

Originally Posted by Bob Collins

One thing. Be VERY careful when you go to buck those outboard (errr....up and down) rivets. If you're not careful with the bucking bar, you can gouge the doubler bar up something fierce. Lots of duct tape to protect the bar is advisable. It's a real tight fit under there.

Thanks for the tip, Bob. I'll remember to tape it up. I'm planning on using my back rivet set, so hopefully the bucking bar (held by my wife) will not be moving at all--it will just serve as the back rivet plate. Insurance in the form of tape is a good investment.

I just did the countersinks on those two holes for each wing. I took my cage off my countersink mechanism (easily removed) and did the first one. My one hole countersink cutter is very aggressive and I took out more than I needed to on that first hole (though not so big that I need to use a 1/8" rivet). For the other three holes, I actually just used my deburring bit (not the countersink cutter at all). That worked the best of all. Three out of four perfect isn't too bad, especially since those rivets only attach the platenuts.

Thanks again for the help.

[Jaypratt]

use reduced head rivits for nutplate attach. 4 turns with a deburr tool and it is ready for the rivit