What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Best method to match drill a J-Channel stiffener

aeroaddict

Well Known Member
Long story short, I mis-located a top fuselage J-channel stiffener and have decided to replace it. Problem is the top fuselage skin is already dimpled as is the defective J-channel.

With a new, non drilled J-channel, what is the best method to ensure good hole alignment since the dimpled skin holes are slightly enlarged? Im assuming to match up the new J-channel with the skin, as opposed matching it up with the old J-channel, but the same issue exists; ensuring good hole alignment since everything has been dimpled.
 
Drilling holes

I've done similar. I used a piece of brass tubing. 1/16" I think. #41 bit fits perfect inside. Round the end of the tube by putting it in the drill press and using a file. The rounded end sits in the dimple and the #41 drills a holes perfectly centered. Just need someone inside to apply pressure on the stiffener.
Just an idea. YMMV
 
I had to do the same thing. I drew a centerline down length of the flat section of the j channel and held it aligned in place so I could see the line through the dimpled hole. I then drilled each end and clecoed it in place. Then I aligned, drilled and clecoed the center hole. From there, I worked outward from the center repeating the process to ensure the j channel stayed aligned. I didn't have a second set of hands so this method worked well for me.
 
Good ideas

Thanks for the replies, I will definitely centerline the part, as mentioned it is just making sure the holes are accurately positioned as I will have a dimple in dimple when riveted.

I was thinking about using the old J-channel and clamping the two together, then using a deburr bit centered in the old dimple and gently marking the new part. Then using the marks as the hole/drill locations.
 
Might have a method

Just for those that might search in the future.

Spent some time with a piece of left over J-channel and the defective dimpled J-channel. While the above methods are good, I will end up likely using a 7/64 " drill.

Lining up the center line on the scrap with the defective part flipped over (dimples are up so both surfaces sit flat together), the 7/65" drill will just barely ream/remove material from the dimple and with a LITTLE pressure, allow the drill tip to mark the new stiffener. This should allow the matched holes to be aligned.

Using the drill mark on the new J-channel, I can now finish drilling, de-burring and dimpling.
 
Back
Top