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Countersinking R-916 Rudder TE

KC10FE

Member
Help, I have already destroyed one part, and not looking forward to another. Any advice on how to countersink both sides of the trailing edge wedge without the bit chattering or oversizing the inner diameter of the hole....Help!

My current setup: Countersink cage set with #40 3 flute bit.

I keep on enlarging the inner diameter hole before the skin will lay flush to the wedge.
 
Get a piece of 1/4" x 1" angle iron to use as both a back riveting bar and pre-drill it for a guide for your counter sink bit. I set mine up for every other hole and shifted it to do the other holes. Be careful countersinking and not get too deep. Remember you are filling one side of the countersink with the shop head and the other side with the MFG head. Alternate these rivets and work slowly so as not to create a curve or hook in the TE when riveting the skins on. This is one area to use patience and finesse.

Roberta
 
I used the trailing edge wedge to predrill an angle piece as well and used that angle as a backup while countersinking, this prevents the countersink from wobbling.
 
Thank you

Thank you gentlemen! It makes perfect sense how you accomplished this task....great advice! When I receive the new part I will definitely be using your guys techniques.

P.S. I also talked to Vans, they advised me that it is acceptable for the inner diameter of the hole to be enlarged, however....try to keep it as small as possible ( just enough to make the skin sit flush )
 
Angle

I used the trailing edge wedge to predrill an angle piece as well and used that angle as a backup while countersinking, this prevents the countersink from wobbling.

If you decide to Proseal the edge, this angle Jereme mentions is perfect to cleko the edge and hold it perfectly straight till it cures.
 
Same here, , I was very happy with side "A" (the first side that I did) however, when I flipped to the other side the nightmare started. I had few oblong holes right from the get go. I used search function here and found an interesting and unscientific advice:
Use cordless drill to control your speed and establish the tilt (edge angle) by hand.
Do not push too hard to prevent countersink chatter.

Worked really well for me, however, original two holes are little funny looking, but according to vans are fine.
 
I had one or two oblong / oversize too . Take it slowly/gently with the rivet when you come to set them so that it has time to expand into the hole fully. It ended up a neat job first time.
I used the VHB tape method as well - cleaner and cheaper than proseal. It worked ok but needed a warm workshop and second attempt to bond.
 
Proseal

I used a wood jig to hold the angle in the drill press duting counter sinking. And. Then I used the proseal to help fill in any oblong holes. Worked out fine. When I got to the ailerons and flaps, did the same thing and the T edges came out perfectly straight.
 
I haven?t actually tried to countersink my trailing edge yet, knowing full well that it holds a lot of potential to scrap an otherwise nice bit of aluminium!

Having studied the wedge, the pre-drilled hole is parallel to the ?leading edge? of the wedge, rather than perpendicular to the sides of the wedge that will offer up to the skin. I think this will cause problems when I put the piloted tip of the countersink into the hole, because it will naturally want to turn the countersink away from the perpendicular to the wedge and instead line it up with the pre-drilled hole..

Is it ok to countersink with the pilot perpendicular into the hole (rather than the wedge), or will that cause one side of the countersink to be deeper than the other? In that case, should I use a countersink without a pilot or should I drill into each hole perpendicular to the skin from both sides to allow the piloted countersink to go in perpendicular to the wedge?

Thanks....! Maybe I am over complicating this!
 
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