VAF Forums

VAF Forums (http://www.vansairforce.com/community/index.php)
-   RV-14 (http://www.vansairforce.com/community/forumdisplay.php?f=109)
-   -   120 deg dimple die? (http://www.vansairforce.com/community/showthread.php?t=136077)

czechsix 03-25-2016 09:36 AM

120 deg dimple die?
 
Working on the ailerons, the plans call for using a 120 deg dimple die for the 1/8" holes in the main ribs at each end of the aileron. Apparently this is the correct dimple die for the CS4-4 pop rivets used in these holes.

I built my RV-8A years ago and I know it had CS4-4 rivets in some locations, and I've never owned a 120 deg dimple die set...I just used the standard 100 deg set. The rivets looked fine aesthetically and after a decade of flying they are holding up good as new. So I'm wondering if Vans (Scott?) or others have had problems using a 100 deg die with these rivets that I may be unaware of?

I see Cleaveland sells the 120 deg die...it's just another $39 + shipping...

Thanks,

Nova RV 03-25-2016 11:43 AM

Yeah my aileron building came to a screeching halt when I saw the next step needed the 120 degree dies. Ordered from Cleaveland and moved forward. Not sure it it makes any long term difference but I'm trying to follow the plans.

rvbuilder2002 03-25-2016 11:45 AM

The decision is up to each individual builder...

A CS4-4 will fit in a standard dimple but only the very bottom of the rivet head is actually in contact with the skin... there is a slight gap between the perimeter edge of the rivet head and the dimple.

Paint tends to not want to bridge this gap well, and the rivet head will be slightly above the point of being flush compared to using the 120 deg dies.
The rivets do aesthetically look better when the 120 deg dies are used.

There may also be a slight strength difference because of the ability for the rivet head to tilt slightly in the dimple, but I have not done any tests to confirm that.

KeithB 03-26-2016 08:08 AM

I would add that there are countersunk CS4 rivets coming later - one key spot is the Canopy Decks (rails on top of longerons) in the Fuselage kit. I decided these were going to be very visible and went ahead and bought both dimple dies and the countersink for CS4.

SteveT 11-28-2017 03:41 PM

Also called for on page 07-04
 
Dimples for CS4 are also called out earlier, on Page 07-04 (rudder). Based on what Iím seeing as I research it, Iím going to get the 120 deg die from Cleaveland. Is this the one that youíre using?

http://www.cleavelandtool.com/mobile/120-degree-dies-for-1_8-pop-rivets/productinfo/DIECS4-4

KeithB 11-28-2017 07:51 PM

Looks right to me.

Bill Boyd 11-28-2017 08:02 PM

Given how the rivet head angle is measured
 
...I would think the fit of a 120 degree rivet in a 100 degree dimple or CSK would be just the opposite of what Scott describes. As in, the outer edge of the rivet touches the shoulder of the dimpled hole and the part near the shank is not touching.

But I could be wrong - happens often.

I try to picture a flat-head "180 degree rivet" (AN470 if you will), how it would fit in a dimpled hole, and work backwards in my mind from there to 120 degrees. I'm just not seeing the mis-fit in the manner that Scott describes.

vernon smith 11-28-2017 08:36 PM

Quote:

Originally Posted by Bill Boyd (Post 1221959)
...I would think the fit of a 120 degree rivet in a 100 degree dimple or CSK would be just the opposite of what Scott describes. As in, the outer edge of the rivet touches the shoulder of the dimpled hole and the part near the shank is not touching.

I would think so as well, a 100 degree drill point is two 50 degree angles one on either cutting face, a 120 degree is two 60 degree cutting faces so the contact point with the 100 degree dimple would be on it's outer edge unless there is something about all this I don't understand. Seeing I was recently chastised on the forum as a naive newbie, I may be way off base :)

Bill Boyd 11-29-2017 11:52 AM

Quote:

Originally Posted by vernon smith (Post 1221967)
I would think so as well, a 100 degree drill point is two 50 degree angles one on either cutting face, a 120 degree is two 60 degree cutting faces so the contact point with the 100 degree dimple would be on it's outer edge unless there is something about all this I don't understand. Seeing I was recently chastised on the forum as a naive newbie, I may be way off base :)

Vern, we can at least go off to a corner and hallucinate together :(

So if we're right, why does the paint not want to lay right on these pulled rivets in 100 degree dimples? Or is that not a thing, either??

mturnerb 11-29-2017 12:04 PM

Quote:

Originally Posted by Bill Boyd (Post 1222089)
Vern, we can at least go off to a corner and hallucinate together :(

So if we're right, why does the paint not want to lay right on these pulled rivets in 100 degree dimples? Or is that not a thing, either??

Wouldn't it be pretty easy to just fill the gap with some kind of epoxy or body filler and paint over it?


All times are GMT -6. The time now is 03:31 AM.