[AndyWW]

Hi everyone,

I have a quick question about my RV-7 elevator, but I'm sure it applies to other types so I have put this post in the General section. No success using google to find the answer, so please forgive me if this topic has already been covered.

There is a single hole on each side of each elevator where there are 4 layers fastened together with a flush AD3-4.5 rivet. It is where the skin is on top, the counterbalance skin is next, then the spar and finally a little tab from the counterbalance rib (E-704 on the 7). Obviously the 2 skins should be dimpled; my question is whether to dimple the spar and the rib, or countersink the spar and avoid dimpling the rib. The manual implies that both are permissible but seems to suggest a preference for countersinking the middle layer when 3 or more layers come together. However given that some of my countersunk holes so far have been of dubious quality I would prefer to dimple everything. Also I have read that over time, countersunk holes are more prone to smoking rivets than dimpled ones.

What are the pros and cons? Thanks for any help.

 

[RV6_flyer]

I prefer to dimple everything that can be dimpled and only countersink where I am unable to dimple.

For the 3/32" rivets, the FAA recommends that minimum thickness be 0.032". I typically look at FAA standards to be a minimum and always like to exceed minimum requirements. In other words, the FAA standards are lower than what my personal standards are. For 3/32" rivets, I do not like countersinking anything less than 0.040" (one size larger than what the FAA has for a minimum) but will countersink 0.032" when unable to dimple it.

 

[BillL]

This is going to sound over the top, but I dimple, then use a deburring (guideless countersink) to trim the hole for a better fit. It is in the "middle" enough material for the rivet and fits as well as a countersink.

I stumbled on this for the firewall rivets that I just could not get set flush and all the layers tight. A few turns with light pressure usually does the trick.

YMMV

edit: I have been known to use dimple dies just before riveting to squeeze the parts tightly together.

 

[rzbill]

This is going to sound over the top, but I dimple, then use a deburring (guideless countersink) to trim the hole for a better fit.

You make me smile Bill. Over the top.... Hah! I did this too, in some places. I used the trick when I wanted to dimple really thick material and the die just would not quite do it sharply enough for my likes.

 

[F1Boss]

I would worry a bit about the hole alignment

So, I would drill it to #30 just before riveting, and use a 1097 rivet.

Carry on!
Mark

Hi everyone,

snip

There is a single hole on each side of each elevator where there are 4 layers fastened together with a flush AD3-4.5 rivet. It is where the skin is on top, the counterbalance skin is next, then the spar and finally a little tab from the counterbalance rib (E-704 on the 7). Obviously the 2 skins should be dimpled; my question is whether to dimple the spar and the rib, or countersink the spar and avoid dimpling the rib.

snip

 

[AndyWW]

Thanks everyone. I went ahead and dimpled.