J

jdmunzell

Well Known Member
Hello list:

This issue is related to the recent flurry of riveting posts, but I wanted a new post so as not to get lost on page three of any of the others.

I wished I'd known about the technique of using a #40 bit and punch when drilling out 1/8th inch rivets. That probably would've prevented my current problems. I had almost an entire row (4 out of 5) of 1/8th rivets with unacceptable (to me anyway) smiles on the manufactured heads. This is where one of the main wing ribs attaches to the main wing spar. Location is about mid fuel tank out from the root. A very critical area for wing loading.

Anyway I drilled out these four rivets using a #30 bit and punch as carefully as I possibly could and ...you guessed it, wound up with some oblong holes in 3 out of the 4 holes drilled. The manufactured heads snapped cleanly off when drilling, so the rib flange thankfully is in fine shape. I placed a new 1/8th rivet in the oblong holes to see how they would seat, and all three seated fine in the holes. They obviously have a bit of space around them though in those three holes (top, middle, and bottom).

My question is this: Should I use slightly longer 1/8th rivets to fill these holes and still get enough meat left to get a decent shop head, ...or should I really just go to the next diameter sized rivet (-5) and redrill those holes to round them out. This seems the safest and obvious solution to me, but would like to hear your opinions about this.

Another question is whether using cherry max blind rivets in this particular location even an option or not.
 
jdmunzell said:
Hello list:

This issue is related to the recent flurry of riveting posts, but I wanted a new post so as not to get lost on page three of any of the others.

I wished I'd known about the technique of using a #40 bit and punch when drilling out 1/8th inch rivets. That probably would've prevented my current problems. I had almost an entire row (4 out of 5) of 1/8th rivets with unacceptable (to me anyway) smiles on the manufactured heads. This is where one of the main wing ribs attaches to the main wing spar. Location is about mid fuel tank out from the root. A very critical area for wing loading.

Anyway I drilled out these four rivets using a #30 bit and punch as carefully as I possibly could and ...you guessed it, wound up with some oblong holes in 3 out of the 4 holes drilled. The manufactured heads snapped cleanly off when drilling, so the rib flange thankfully is in fine shape. I placed a new 1/8th rivet in the oblong holes to see how they would seat, and all three seated fine in the holes. They obviously have a bit of space around them though in those three holes (top, middle, and bottom).

My question is this: Should I use slightly longer 1/8th rivets to fill these holes and still get enough meat left to get a decent shop head, ...or should I really just go to the next diameter sized rivet (-5) and redrill those holes to round them out. This seems the safest and obvious solution to me, but would like to hear your opinions about this.

Another question is whether using cherry max blind rivets in this particular location even an option or not.
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Jeff,
One trick for this situation is to take a rivet 1/2 length longer than what is called out. Install it in your hand squeezer and slightly compress it. The idea is to swell the shaft of the rivet so that it will not be so loose in your oversized (drilled out) rivet holes. It may take several iterations of squeeze, check in hole and squeeze again to get a reasonable fit. This is referred to as "swelling" a rivet. A loose fit of the rivet in the hole often will cause you to tip the shop head. Swelling the replacement rivet helps prevent this. The use of 1/2 longer length rivet ensures that you will still have sufficient material to obtain a good shop head.
FYI, most folks want shop heads which are 1.5 D and .5 H They are told that this is the MilSpec. This is the "desired" MilSpec. HOWEVER, the actual MilSpec limits are 1.3D and .33 H. So any shop head which meets these dimensions is acceptable. I use a dial caliper, rather than the rivet gauges sold by Avery for these tests.
If your 2nd attempt using a swelled rivet fails, I would suggest upsizing to a 5/32" rivet.
Charlie Kuss
 
1, Cherrymax have been used before in this area, especialy in the sixes I think. Cherrymax makes an oversize -4 rivet so you would not have to enlarge the hole to the next standard diameter just the diameter of the oversize cherrymax rivet.

2. Vans have said before that the ribs being riveted to the main spar is there only to keep the spar from collapsing, not wing shear.

3. Without a visual of the hole it is hard to say but if it is only slight elongation and the hole is smooth a standard -4 should be ok. Measure the biggest diameter and compare to standard -4, oversize cherrymax, standard -5 shank diameter.
 
Thanks guys for that input. I read somewhere that structural blind rivets could go just about anywhere EXCEPT the main wing spar.

Paul, you are saying that you can, and I also see you're an A&P. You must know for sure!
 
I would go with -5 DIA rivet. Driving a rivet into a oblong hole isn't the perfered method and is viewed as being sloppy. Also if you must use a fastener go with a Hylock instead of a cherry. Hylocks are much better.
 
jdmunzell said:
I read somewhere that structural blind rivets could go just about anywhere EXCEPT the main wing spar.
QUOTE]

This is NOT true, at least for the later RVs. They in fact can be used in some places on the spar. Although I would doubt they could be used for attaching the spar webs to the doublers, Van's does allow the use of LP4 or CherryMax rivets to rivet the spar to the leading edge ribs where the rivets are really hard to buck. This has been confirmed by email from Van's (to me) and I know a lot of other builders have received the same confirmation.

That said... so long as you have edge distance (and easy access) I'd just put a AN470AD5 there and save the pulled rivets for the leading edges if needed. Also, rather than trust me (or anyone else on the web), just email Van's so that you can sleep better at night.

Also, these rivets are much easier to set with "SnapSocs" (from Avery) on your rivet set. They really help to keep the gun on the rivet.

Hope this helps.
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Brockster said:
1, Cherrymax have been used before in this area, especialy in the sixes I think. Cherrymax makes an oversize -4 rivet so you would not have to enlarge the hole to the next standard diameter just the diameter of the oversize cherrymax rivet.
snipped.
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As mentioned above, Cherry Max rivets come is a special 1/64" oversize diameter. This oversize is denoted in the fifth digit of the part number. Normal diameter rivets have a 1 in the fifth digit, while the oversize has a 4.
As an example
Normal CR3213
Oversize CR3243

Charlie
 
#27 drill for a -4 DIA oversize Cherry
#16 Drill for a -5 Dia oversize Cherry

If you look at the pulling anvil on the rivet it is silver. This denotes a oversize rivet. Gold is nominal!
 
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