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  #1  
Old 08-08-2019, 06:22 PM
NotMuchofaStall NotMuchofaStall is offline
 
Join Date: Apr 2018
Location: Seattle, WA
Posts: 8
Default Universal head doesnít snap all the way off

Iím having a time removing AN470 universal head rivets cleanly. I will drill through the head just enough to get a pin punch in there to pop the head off. Usually it works, but every so often the head wonít come off cleanly, and it will leave a little bit of metal around the outside of the hole.

I will try grabbing the little bit of metal with my rivet pliers, or try drilling further down into the rivet, or both (depending on how obstinate it is). The former leads to marring the surface around the hole; the latter seems to lead to damage around the hole because thereís no longer a head to drill into and itís difficult to see where the rivet shank is. Iím currently waiting for Van's to tell me whether I damaged a hole enough to have to updrill to a -5 rivet.

Does anyone else encounter this or know why this happens? What are your techniques for getting a universal head off cleanly the first time?
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Old 08-08-2019, 07:32 PM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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If the drill is not exactly centered and your using a #30 or 40 drill bit this happens. It is almost impossible to get it exactly centered. I work the bit at an angle to get the head off. You must do this before getting to the bottom of the head to avoid hitting the skin. Usually the head stick on the drill bit. I am sure there is more professional trick, but I don't know it. This has worked well for me without any damage, but you need to learn it first with practice. You're basically gouging a larger hole in the head to help it break off the shank. I drill out the shank with a smaller bit and then punch or pull out the shank.

You can also hit the head on it's side with a chisel type too and hammerl. That is more effective than the pin punch when you have a bit too much meat of the shank holding on.

Larry
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Last edited by lr172 : 08-08-2019 at 07:37 PM.
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Old 08-08-2019, 07:37 PM
Bicyclops Bicyclops is offline
 
Join Date: Oct 2012
Location: LA, California
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Need to be in the very center of the rivet. I start out with a small drill, say #40. I start it and assess. If not dead nuts center, angle towards the middle and stand it up straight. I don't go for depth, just center. Once satisfied with that, easy to upsize to #31 to the depth of the head and then go for the snap off. For a #3 rivet, I'll start with about a #55 drill and then on to #41. I'll typically drill 10 or 15 rivets small before going up to a larger drill to get them all ready to be popped off. Every now and then I'll get one or two that don't cooperate and drastic measures will need to be taken - dykes on the back side, chisel - that sort of thing. When I have a problem rivet, it's always an off center problem. When they are painted, it's hard to see where the center is for instance.

Start with a small drill, work slow. Being in a hurry messes em up.

Ed Holyoke
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Old 08-08-2019, 07:45 PM
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N804RV N804RV is offline
 
Join Date: May 2013
Location: Mount Vernon, Wa
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This tool will do a perfect job of this once you get a hang of it. It solves the problem of getting the drill bit started dead center, especially on bucked rivets that have had the dimple worn off.

https://www.aircraftspruce.com/catal...yABEgIFnfD_BwE
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  #5  
Old 08-10-2019, 12:34 PM
NotMuchofaStall NotMuchofaStall is offline
 
Join Date: Apr 2018
Location: Seattle, WA
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Thank you for your replies, everyone! I have one more problem rivet to remove today, then Iíll be ready to reassemble and move on.

I just ordered that rivet removal tool ó should be here next week. I have another joint I need to re-rivet. I noticed one swollen rivet in one joint, and now Iím noticing them in other places as well, so Iím fixing them before the structure is closed. Unfortunately they tend to be deep in the structure, next to ribs where I canít get my normal air drill; Iíve been using a 12Ē #40 bit, but itís so long and bendy that itís probably wandering off-center without me realizing it. If it gets a bit off-center with the #40, I can always use the #30 to recenter it, using the slightly off-center #40 hole as a pilot and drilling slowly at a slight angle.

Incidentally, Eric at Vanís gave me a tip for setting the long rivets in the HS-905-spar-shim-HS-904 joint on the onboard side of the RV-9 horizontal stabilizer with a double-offset cupped set: rather than use the normal spring to hold the cupped set on the rivet gun, use silicone self-fusing tape to hold the set in place. Iíll give that a try when I reinstall those rivets.
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  #6  
Old 08-10-2019, 07:04 PM
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N546RV N546RV is offline
 
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A few people have mentioned the chisel method. I just want to make clear that if you do this, use a dull chisel. Something sharp like a wood chisel will merrily gouge your aluminum parts. I've had good luck using a gasket scraper myself.

As for the rivet removal tool - I just got one, after many years of saying "eh, I can drill em out just fine by hand." I'm in the middle of doing my h-stab SB right now, and looking at those tough-to-access rivets made me change my tune.

After using that tool for the first time, I had a very strong "I should have bought this years ago" reaction. Set up properly, the thing is dang near idiot-proof. It's worth every one of the sixty dollars I paid for it.
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  #7  
Old 08-11-2019, 05:53 AM
BillL BillL is online now
 
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Location: Central IL
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Default I don't need no stinking rivet removal tool . . . . .

Quote:
Originally Posted by N546RV View Post
As for the rivet removal tool - I just got one, after many years of saying "eh, I can drill em out just fine by hand." I'm in the middle of doing my h-stab SB right now, and looking at those tough-to-access rivets made me change my tune.

After using that tool for the first time, I had a very strong "I should have bought this years ago" reaction. Set up properly, the thing is dang near idiot-proof.
+1

Good drill centering is like a good landing, you can't hold the stick/drill in one perfect position. The angle is always changing, although maybe not much. Drill/check, drill/check . . . .

I got pretty good at rivet removal, better than driving. I had this tool and found it is much faster for the universal heads, and very consistent. And in the HS SB work it, was very helpful.

It is still not a substitute for skill, though.
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  #8  
Old 08-11-2019, 07:29 AM
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N546RV N546RV is offline
 
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Quote:
Originally Posted by BillL View Post
+1

Good drill centering is like a good landing, you can't hold the stick/drill in one perfect position. The angle is always changing, although maybe not much. Drill/check, drill/check . . . .

I got pretty good at rivet removal, better than driving. I had this tool and found it is much faster for the universal heads, and very consistent. And in the HS SB work it, was very helpful.

It is still not a substitute for skill, though.
One nice touch is that, thanks to the depth stop, it even works great on rivets that have smeared heads. Those always gave me some anxiety before, since I could no longer trust that a hole centered on the head was centered on the shaft, and so the consequences of drilling too deep were way higher.

The main thing, though, is the efficiency aspect. My hand-drilling procedure for these rivets was to center punch, spin a drill bit by hand to expand the divotand ensure it was centered, center drill #40 kind of deep (intent was to get into the shaft of the rivet - this helps release grip and provides a place for a punch to nest later on), drill up to #30, pop off head.

I spent 3+ hours last weekend super-carefully drilling out the rivets in the accessible portion of the spar/angle junction. I chose to drill out from the shop head side due to accessibility concerns. Every single one felt like surgery.

The tool came in Wednesday night. Thursday I went out and drilled out all 16 of the rivets hiding inside the stab body in 30 minutes. The difference is insane.
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