Skin rivet question

[wizard]

While making my first match holes through the HS skin into HS-405, I found I was inadvertently using a #30 bit instead of a #40 for the first 6 holes before I caught my mistake. Any suggestions?

 

[RV7ator]

Use an "oops" rivet, sold by Van's. It's a -4 (1/8") body with a head of a -3 rivet. You'll find use for these once in a while beyond your current "opps" if you have to drill out a bad -3 and happen to wallow the hole. That sort of thing.

I live in Boise, also, near Fairview and Cloverdale. Where you?

John Siebold

 

[AltonD]

OOPS rivets are sized such that the head will fit a hole already dimpled for 3/32". If you have got a hole that is undimpled, you would have to center up the 3/32 dimple die and give it a shot. I would just dimple the hole for a regular -4 rivet and put it in. My guess is that nobody will ever notice but the builder.

 

[jcmcdowell]

mark the skin for the #30 dimples or use the oops #40's

OOPS rivets are sized such that the head will fit a hole already dimpled for 3/32". If you have got a hole that is undimpled, you would have to center up the 3/32 dimple die and give it a shot. I would just dimple the hole for a regular -4 rivet and put it in. My guess is that nobody will ever notice but the builder.

The only issue is having to change dimples and remember NOT to dimple the #30's with a #40 dimple.

Aircraft Spruce has the ooops rivets too- they don't call them that though. If you have a source close by- get some, they are handy. Otherwise if you want to keep trucking use a sharpie in big letters on the skin to make sure you remember to switch to a #30 dimple for both skin and rib before you go off into a trance like dimpling mode...

 

[wizard]

OK, great. I have several size oops rivets on order from Vans. Now let me see if I understand the dimpling...I dimple the #30 holes as if I was using a -4 rivet. Wouldn't that make the dimple too big for the oops rivet head (as the oops has the same size head as the -3 rivet)? Why not dimple like the rest of the #40 holes? Wouldn't the dimple set center itself during the process?

Actually, I am in Eagle, but still very close to you.

 

[N674P]

OK, great. I have several size oops rivets on order from Vans. Now let me see if I understand the dimpling...I dimple the #30 holes as if I was using a -4 rivet. Wouldn't that make the dimple too big for the oops rivet head (as the oops has the same size head as the -3 rivet)? Why not dimple like the rest of the #40 holes? Wouldn't the dimple set center itself during the process?

If you're using a C-frame or DRDT-2 and are careful, a #40 dimple die will probably center in a #30 hole ok. I don't know about a pneumatic squeezer though, since you need to smack the trigger to get a good dimple. It could be done, but if you can use -4 rivets, going with the #30 dimples is less nerve wracking.
The usual way you end up using "oops" rivets is when you drill out a rivet (say a -3) and enlarge or bugger up the hole. You clean it up with the next larger drill (say a #30) and use the "oops".

 

[skyyking56]

same thing only three

I did the exact same thing with only three rivets..I ended up dimpling for 1/8 and put 1/8 standard c'sunk heads in there.... no problem...This area will be covered by the fiberglass fairing anyway...
Jim

 

[Kevin Horton]

The NAS 1097 "Oops" rivets are great for fixing the occasional screw up when you can't redimple the hole for a larger size rivet. This happens when you are riveting the skins on, drill out a bad rivet and mess up the hole. Joints made with these rivets aren't as strong in tension as ones made with normal rivets, due to the fact that the outer diameter of the flush head is not that much bigger than the diameter of the body. So, you will have a weaker structure if you use several of them in a row.

In the case in question, you can easily dimple the skins and ribs for 1/8 rivets, so this is the preferred repair, from a structural strength perspective.

 

[sf3543]

Try it out on some scrap before you go to the real piece. That way you'll know which way you want to proceed on the real piece.

 

[FredMagare]

What about...

Where on the emp did you drill those six holes? I've made a similar error (drilled a bolt hole instead of a #30 rivet hole) and it got me thinking about how I would handle it on a visible surface.

The problem with an "oops-rivet", in my opinion, is the decreased shoulder length (and grip) in the dimple. (I'm not an engineer so it may be of little consequence.) I would think your main concern about the larger rivets is the lack of uniformity having six rivets of the next larger size.

Possible suggestions:

1. If it's on the bottom, use the -4 rivets and fuhgedaboudit!

2. If it shows, drill -4 rivet holes in the corresponding locations to provide symetry and uniformity. (If anyone notices, tell them you needed "heftier" rivets to install "safety" equipment in that location. Who's going to know?)

I've been in the position where I wanted to rebuild an ugly, yet airworty part. Fellow builders finally convinced me that should I continue with that line of thinking, I'd never get it flying.

It's been said that all airplanes need a blemish to allow the gremlins to escape. Don't try to cage the gremlins!

Good luck.
Fred
RV-9A (wings)

 

[TShort]

You'll be surprised how little difference there is in the size of the head on the c'sunk -3 and -4 rivets. It really doesn't stand out that much. I screwed up one dimple on the fuel tank stiffeners and had to put in a -4 rivet - even in the line of rivets it is barely noticeable.

I don't see any benefit to using the oops rivets - like Kevin said, the bigger rivets with the standard head will be stronger and likely not that noticeable.

Thomas

 

[wizard]

Hey guys, thanks for all your input. I'm going to dimple #30 and put in 426AD4's. As previously noted, they will be under the fairing anyway.