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Riveting Bottom Skins to F-01442 lower drag fitting - 29-04

avatty

Well Known Member
I am ready to install the CR3213-5-5 CherryMax rivets specified at p. 29-14 step 7 and Fig. 3. Before setting, the hollow portion of the shank only extends about 1/16 inch past the drag fitting, or about as far as the thickness of a properly set 1/8 inch solid rivet.

Has anyone had difficulty setting these properly? Section 5.4, Fig. 2 (blind shop head photo) shows the shank extending significantly farther than what I am seeing.

Thanks!
 
Same here

I recall the same issue and contacted the mothership and was told ?if not long enough - get the correct length?.. I don't have the numbers here now but I bought some of the correct length and built on...
 
From the manufacturer:

"The grip range of all CherryMAX? rivets is in increments of 1/16", with the last dash number indicating the maximum grip length in 16ths.
For example, -04 grip rivet has a grip range of 3/16" (.188) to 1/4" (.250)."

Measure and add up the thickness of the material stack. If not in spec (5/16"), plans and kits would need to be updated. Could it be that you received the wrong length rivets in the bag, or have debris/burrs/excess primer between the parts?

I don't recall having doubts about these -5-5 ones, and they all set perfectly on the first try (not so on some other CherryMax which I remember drilling out--pain). I just went over to the garage and looked. These do look on the short side but not alarming, to me and four other sets of experienced eyes in the past. Keep in mind the aluminum sleeve expands radially and does little work on a CherryMax: the important part is that you hear the double pop of the two steel mandrels which carry all the shear load.
 
I used the depth gauge on my dial caliper and determined the total thickness of the drag fitting and two skins is 0.365-0.370, as nearly as I could tell. This indicates a CR3213-5-6, according to ACS catalog (grip range 0.313-0.375). The -5 rivets provided are for a 0.251-0.312 range.

This a little mystifying - these rivets are specifically used because of the high stress of this joint, but then they are erroneously spec'd? Notwithstanding any mystification on my part, it is hard to see a reason to use the provided -5 rivets in favor of -6. But I will call the mothership first.
 
After recleaning and resecuring, using the long elevator bucking bar to have a flat surface inside the drag fitting, and inserting the depth gauge from the outside, I still come up with a stack thickness of .344. Don't mean to be overthinking this, but that's still slightly beyond the nominal -5 range.
 
Measure and add up the thickness of the material stack. If not in spec (5/16"), plans and kits would need to be updated.
My F-01442 is .196, (2 skins and one doubler @ .040 each) .120 puts my stack at .316. Add .004 +- for primer and you’re at .320. Past the max of the CR3213-5-5. Check your F-01442 thickness and add it up. CR3213-5-6 on order:mad:
 
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