I’m working on my HS and prepping the front spar. I made a rookie mistake and set my countersink cage for a dimpled skin instead of the flush rivet and now my holes are too deep. Does this mistake require replacement of the front spar or is this salvageable? All 9 holes center holes in both flanges of the spar are the same as the one in the pictures.
Van's Air Force
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Countsink Holes
- Thread starter gbaser47
- Start date
Do not just install the called-out rivets, because they will not be tight into the bottom of the countersinks.
One way to recover in instances when this happens is to make some small circular spacers to place over the manufactured head while setting the rivets.
The punch out disks produced when punching holes in .016 thick aluminum sheet with a Whitney punch work well for this.
What I would do in this case though is to just enlarge the holes to #30 and install AN426-4 rivets of appropriate length. There is no physical reason they are flush rivets. They were spec’s out of convenience because that is what all of the other 3/32 rivets are. So having the manufactured head protruding above the surface of the spar flange a bit won’t cause any issue.
Do not countersink any deeper in an attempt to make the -4 rivets lay flush. Just accept the less than ideal appearance as the price to pay for not having to pay the huge price to have that long part shipped to you.
One way to recover in instances when this happens is to make some small circular spacers to place over the manufactured head while setting the rivets.
The punch out disks produced when punching holes in .016 thick aluminum sheet with a Whitney punch work well for this.
What I would do in this case though is to just enlarge the holes to #30 and install AN426-4 rivets of appropriate length. There is no physical reason they are flush rivets. They were spec’s out of convenience because that is what all of the other 3/32 rivets are. So having the manufactured head protruding above the surface of the spar flange a bit won’t cause any issue.
Do not countersink any deeper in an attempt to make the -4 rivets lay flush. Just accept the less than ideal appearance as the price to pay for not having to pay the huge price to have that long part shipped to you.
I won't weigh in on the solution, since Scott is the man for that. I'm pretty much a rookie myself - the only thing I was going to mention was that you say the countersink cage was set for dimpled skins. Pictures can make things look off, but you might check to make sure what you think is the right depth for a dimple is what it truly should be. Based on the picture and how deep the rivet sets, it looks like it may even be over-countersunk for a dimpled skin. If I remember right, it should only have to be .007" deeper than flush. Just worth checking for the future.
I didn't look that close at the photo, and photos can trick the eye regarding dimensional details, but if the OP is countersinking deeper than the recommended .007", I recommend spending some time looking at this stickied thread and some of the others linked from within it.
https://vansairforce.net/community/showthread.php?t=159343
Allan Stern
Well Known Member
Counter sink
That hole just isn’t for a rivet? Isn’t there a skin that goes on top of that spar? Just curious.
That hole just isn’t for a rivet? Isn’t there a skin that goes on top of that spar? Just curious.
