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Should I drill this out again?

J

jwilbur

Well Known Member
I'm looking for advice here. I'm finally riveting my VS together and have run into a hole in the rear spar assembly that I just don't get along with. I've drilled out two rivets so far and am wondering if I need to do it again. I'm still learning some of the basics here, so have mercy if this is obvious to you.

The first time, I drilled it out because the manufactured head was not flush against the web. I think I torqued the squeezer as the rivet was setting. After I drilled it out, I put in another and realized that I put in a rivet that was way too long and as a result the shop head bent over. So, I drilled it out again. The hole did enlarge slightly the second time I drilled it, but not by a huge amount (so I thought) and I felt I could still use a rivet of the original size (AN470AD4-X). This time though, it set a little cockeyed and you can see a little gap next to the shop head. See figure #1 below.

Also, the manufactured head of this rivet seems like it has dug slightly into the web above so that it isn't flush. In the images you can see this along with some bare metal where the primer was worn off during the drilling. I don't think the bare metal is a big deal but what is, I'm guessing, is the fact that the manufactured head is angling into the web along with the gap on the underside. What I want to know is if this has become one of those times where I'm going to do more harm than good in trying to fix the problem (with regard to safety)? Or is it essential that I get this rivet out and something else in its place? If so, what do I put in its place? The biggest rivets I got with the kit are the AN4's.

6sdfgj.jpg

Figure #1 - Gap visible above shop head. You can also see bare metal as a result of deburring after drilling out the old rivet.

ao9ojo.jpg

Figure #2 - manufactured head of rivet in question. Bare metal visible from drilling. Note that the metal is not chipped and there are no gaps on this side.

29pzubm.jpg

Figure #3 - Rivet in question is on bottom next to the spar doubler. You can see it slightly angles into the web as compared to the rivet heads around it.

I appreciate any help.
 
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I would replace it. It's likely to bend over again, though, so I'd probably use one of the 1/64" larger diameter rivets. Something like an NAS1242AD4-(L) where L is the length you need.

I believe GAHCo. sells them.

FYI, when drilling out a rivet, the drill should never actually go through the parts. You just use the drill to pop the head off, then punch out the shank. That avoids enlarging the holes. Rivet drilling tutorial here.

Good luck,
 
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You might find it easier to slightly modify the previous drilling sequence linked in post #2 and drill deeper with the initial small drill.

Borrowed from Vern Little's site, a nice descriptive graphic -

rivet_removal.jpg


Same principle, just a little quicker and easier sequence.

I would just replace the rivet, but slightly pre-squeeze it to fill the slightly enlarged hole.

You might also find that a rivet gun/bucking bar will work better at not clinching over the shop head - a squeezer can easily "tip" on you as you have found out, and is even more likely to tip if the rivet is a loose fit.
 
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Keep some CherryMax rivets of various lengths

in stock. ACS# CR3213-4-1 thru -5. I have used them in places where I know I would have had a hard time bucking. Also keep a few csk versions CR3212-4-2 thru 4-4. Also extra LP4-3(Van's) as you will come up 10 ea short in your wing kit. They come in handy for alot of places later on. I also keep some CCC-32 csk rivets in stock. I have some AN470AD-6-4 rivets for your fuel tank tooling holes when you get there so just check with me. You will need 8 or so.
 
Joe,
I've got plenty of AN470AD5-4 and 5-5's if you want some, and a 5/32 rivet set and #21 drill bit you can borrow.
 
I would suggest a pneumatic squeezer and a longeron yoke, if you can afford one. (It can later be resold to recoup a good portion of your investment.)

For a situation like this I've found that setting the rivet slowly will cause it to swell in the rivet hole before forming a shop head. (You may need to increase the length of the rivet.) Ensure the rivet is fully seated and straight in the hole and that the the rivet (shop head end) is centered on the squeezer set. Set the rivet slowly and with two or more adjustments of the of the height of the sqeezer set.

Good luck.
 
Thank you everybody. As with you all, my goal is to have the safest airplane I can (even if not the prettiest) and your help is clearly helping.

Todd, I'll take you up on the offer for those rivets. I'll give you a call.
 
I caution against drilling through the rivet.

az_gila said:
You might find it easier to slightly modify the previous drilling sequence linked in post #2 and drill deeper with the initial small drill.

Borrowed from Vern Little's site, a nice descriptive graphic -

rivet_removal.jpg


Same principle, just a little quicker and easier sequence.

I would just replace the rivet, but slightly pre-squeeze it to fill the slightly enlarged hole.

You might also find that a rivet gun/bucking bar will work better at not clinching over the shop head - a squeezer can easily "tip" on you as you have found out, and is even more likely to tip if the rivet is a loose fit.
Click to expand...

With all due respect. Except for rare occasions I never drill through deeper than the head of the rivet. If you are slightly off center with your drill you risk hole damage. It is very difficult to drill perfectly through the center even with the proper rivet removal tool (although odds are better). If you drill just deep enough to penetrate the head, it will pop right off just the same.
A punch works ok if your material is thick enough or you back it with something to support it. I prefer to use a squeezer or special pliers that Spruce sells for this task.
To use your sqeezer, after you pop the head off, take your rivet squeezer with an appropriate sized dimple die on one side and nothing or a flat set on the other side. Place a nut or cut yourself a short piece of tubing just big enough to slip over the shop head and squeeze the rivet out with your squeezer.
You will find that this procedure allows you to maintain the hole in near perfect shape making replacement much easier.
I see a lot of posts on this site asking for advice on a repair where more damage was done by removing the rivet than if it was simply left alone.
 
what I have been told

is that drilling out a rivet usually makes things worse than better. I have drilled out some rivets, but before you drill one out think about all the other rivets around it, how bad it really is. The last thing you want to do is have a slightly off rivet turn in to and an3 bolt because you keep messing it up.

Just my take..
 
JonJay said:
With all due respect. Except for rare occasions I never drill through deeper than the head of the rivet. If you are slightly off center with your drill you risk hole damage. It is very difficult to drill perfectly through the center even with the proper rivet removal tool (although odds are better). If you drill just deep enough to penetrate the head, it will pop right off just the same.
A punch works ok if your material is thick enough or you back it with something to support it. I prefer to use a squeezer or special pliers that Spruce sells for this task.
To use your sqeezer, after you pop the head off, take your rivet squeezer with an appropriate sized dimple die on one side and nothing or a flat set on the other side. Place a nut or cut yourself a short piece of tubing just big enough to slip over the shop head and squeeze the rivet out with your squeezer.
You will find that this procedure allows you to maintain the hole in near perfect shape making replacement much easier.
I see a lot of posts on this site asking for advice on a repair where more damage was done by removing the rivet than if it was simply left alone.
Click to expand...

It can be a question of tolerances with a hand held drill.

The first drilling should be quite accurate on the manufactured head - our rivets have a nice dimple to center the drill bit. If the dimple is damaged, then a center punch should be used.

The trouble with the linked sequence in post #2 is that the small drill will tend to center on the "cone" made by the first full size drill, and not where you might want it in the center of the headless rivet. This makes you dependent on the accuracy of the first drilling location, which is exactly the same as the sequence in Vern's diagram, so why bother with a double switching of drill sizes?

The tolerance here is about 0.015 inches if everything is exactly square, care is needed for either process.

I've also had trouble punching out a headless rivet that is fairly long, drilling the "core" of the rivet out makes this much easier, and often the rivet can then be removed with a pair of pliers from the shop side, with less damage to skins than punching it out.

I suggest builders try both ways and see which one they are more comfortable with.

RIVET GUN

Again, no-one has mentioned that a rivet can usually be set much more easily in a slightly worn hole with a rivet gun/bucking bar than with a squeezer. That is how I would repair this particular rivet.
 
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Something that I have done is ream a damaged hole just enough oversize that it is round again. Take a longer rivet than you need and adjust the squeezer so that the closed gap is just a touch smaller than the rivet length. Put the rivet in the squeezer and 'puff' it up by squeezing just slightly (rivet is in mid air, not in the part). Once it is enlarged to the right diameter insert it in the part and check for proper length. Then set as normal. This tends to keep everything straight and controllable and once finished you can't see that there was a mistake.
 
A word of caution!

clevtool said:
Something that I have done is ream a damaged hole just enough oversize that it is round again. Take a longer rivet than you need and adjust the squeezer so that the closed gap is just a touch smaller than the rivet length. Put the rivet in the squeezer and 'puff' it up by squeezing just slightly (rivet is in mid air, not in the part). Once it is enlarged to the right diameter insert it in the part and check for proper length. Then set as normal. This tends to keep everything straight and controllable and once finished you can't see that there was a mistake.
Click to expand...
Please NOT hold the rivet with your fingers while doing this. If the squeezer is miss-adjusted you can mangle your fingers beyond repair.
 
I want to thank everybody for these comments. Since writing this, I've had the "pleasure" of trying out a few of these techniques. Thankfully, I have not mangled anymore holes. And I'm also grateful to Todd Stovall for showing me how to fix the rivet I originally asked about.

The technique I've found very nice and have had great success with is the one where you drill in a small hole first - right up the middle and only slightly deeper than the head. Because it's a bit much smaller than the hole, you've got some room for error on getting it right up the middle. Then I put in the #30 bit and drill very slowly. In almost every case, the slow action of the bit broke the head off for me. Then I applied the punch with a gentle tap and voilla - an unmangled, deriveted hole ready for me to mess it up again!

Thank you everybody for this. Now on to my next question. ...
 
One other thing I'd like to point out that I didn't see mentioned: when punching out a rivet you need to make sure your material is firmly backed with something heavy. The thinner the metal, the more important this becomes.

The tool I find myself using most often for this is the big steel bar that comes in this kit (I've never used this kit for its intended purpose, I picked it up used...):

http://www.averytools.com/prodinfo.asp?number=4500

It is like a bucking bar with holes drilled in it perfectly sized for the manufactured head of a rivet. I clamp this with a hole centered over the rivet I'm punching out, and never have a problem with deformation.

Chris
 
Please NOT hold the rivet with your fingers while doing this
Click to expand...

Sorry I tend to imply things that I think are common sense ;) I hold the rivet in pliers.

Now lets talk about the risk of drilling your wife's finger...

.
 
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