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Gear Tower Cherry Max Rivets

T

tinman

Well Known Member
I have given up on trying to buck solid rivets along the top of the gear towers. I went to Genuine Aircraft Hardware and found the 3214-4-4 Cherry Max rivets. They were offered in packs of 100...not so good for our needs since we need around 20 or so...
After explaining the need for smaller quantites for the RV-8 to them, they have agreed to offer the rivets in packs of 10. Go to the website here and you can locate them:
part # CR3214-4-4PKG/10
http://www.gen-aircraft-hardware.com/store.asp?alternate=CR3214-4-4
If you order the PB REF BOOK (Cliff Notes for hardware) they will throw it in for free if you plug in the promotion code GEARBOX

Regards,
Don Alexander
 
RV505 said:
Hyloks would be a much better choice..
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Hyloks are great but are usually used in thicker materials than what we use in our RV's and require precision reamed holes. If the holes are not specifically reamed for Hyloks than rivets are probably better.
 
Walt said:
Hyloks are great but are usually used in thicker materials than what we use in our RV's and require precision reamed holes. If the holes are not specifically reamed for Hyloks than rivets are probably better.
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You are thinking of interference fit holes that are reamed to attach all aluminum l stuff like eng pylons vert stabs, primary structure. . You can install Hy-loks using Clearnce fit ( Rivit hole sizes ) The smallest Cherry is 1/8 or a #30 drill bit. The smallest Hi-lok starts at a 5/32 or # 20 dril so they arn't that much bigger. Plus the Hy-loks won't work like a cherry and looks really trick. Anyway Don if you want some Cherrys PM and I'll send you some. I have tons of them.
 
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The problems I foresee trying to use hyloks in this application are threefold. First the skins are dimpled and can't take very much remachining, especially to accept 5/32" hyloks. Even if the dimples could be reworked, the flush hylok heads would stick out "like a sore thumb" compared to the rivets in the surrounding area. Also, you would have to bring up a series of holes to approx. .160 in the (very structural) longeron which is a consideraby larger dia. than the design call out for AD3 rivets through the longeron in that area. Finally, even if you could accomplish all that satisfactorily, I have to wonder this. If you can't access the very limited area inside the towers with a small bucking bar, trying to reach inside them with your fingers to thread the individual collars onto the hylok threads and follow that up with a wrench or ratchet setup to set them with would seem.......well, difficult.
 
I didn't know the skin was already dimpled.. Suppose if you did accomplish the first to hurdels would hi lites work? They have a smaller collar?
 
Thanks for that Don!
I went ahead and ordered the 100 pack because of the price break. They offered the Hardware manual like you said they would.
We have a lot of RV's being built @ EAA326 Puyallup WA, so I'm sure none of the extras will go to waste.
 
Rick6a said:
The problems I foresee trying to use hyloks in this application are threefold. First the skins are dimpled and can't take very much remachining, especially to accept 5/32" hyloks.
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Rick-

I am working on this area now. I've got 2 of the rivets in the gear tower done with much frustration. I have the Cherry Max rivets, but the skin is already dimpled for 3/32 rivets per the plans. When you say remachining...what do you mean. Would you countersink the skin to accept the larger Cherry Max rivets?
 
That's what I did.
The Fuse skin is pretty thick, so I drilled the holes out to #30, and reset my machine countersink to a very shallow cut. All of them came out perfect but one where I machine countersunk a tiny bit too much.
It wouldn't look horrible if you didn't machine countersink at all, but if you do, it looks just like a driven rivet with a dot in the center.
I think it will be invisible when you paint it.
 
jmbrwn said:
Rick-

I am working on this area now. I've got 2 of the rivets in the gear tower done with much frustration. I have the Cherry Max rivets, but the skin is already dimpled for 3/32 rivets per the plans. When you say remachining...what do you mean. Would you countersink the skin to accept the larger Cherry Max rivets?
Click to expand...
Yes, I slightly reamed the holes and then remachined the dimpled 3/32 countersinks to a slightly larger depth to accept the 1/8 Cherry flush rivets. In reality, you are removing very little material because the dimple itself already accomodates most of the head of the cherry rivet. I not only used CR3212-4 rivets for the gear towers but also in hard to reach areas of the forward upper skin on both my -6A and 8. In fact, if I had to (although I have not) I would not hesitate to use a CR3212 to replace a weeping rivet on a fuel tank.

2zzuxkx.jpg
 
I used the CR3214-4-4 which has the -3 size rivet head. It was mentioned earlier in this thread. The CR3212-4-4 has the -4 rivet sized head, and would require a deeper countersink. It would look larger, but might also be stronger.
It also might be easier to find, as a more common rivet.
 
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