V

VETE76

Well Known Member
what am I supposed to do to the holes in the rear edge of the fuel tank where you screw it to the main spare plate nuts. the main spar at the nut plates is machined countersunk. am I supposed to counter sink the holes in the tank? all I can find in the instructions is to drill them out to #19. later on it says prepare all holes dimple, countersink as required.
if I am to machine countersink, what cntrsnk do I use?
I tried one smaller than #19 with the correct size hole clamped behind it like they had u do on the spar. it removes an awful lot of material. the #19 hole opens way up before the head of the screw fits flush.
or am i supposed to dimple? if yes, is there a #19 dimple?
thanks
Fred
 
Yes - DIMPLE the tank screw attach points! I purchased a hefty little dimple die from Avery to get it done. For the countersink, I think I used #30 countersink cutter in which the pilot centered very nicely in the nutplate. I don't know what plane you're building (I'm working on a -9) but the guidance was provided in my build intructions.

I hope this helps.
 
thanks Fred!
i am building a 7 tail dragger. I currently own a citabria. its nice but i can't wait for my 7 to b a flyin!
Fred
 
Yes, dimple them... do NOT machine countersink the skin holes... ONLY the holes on the main spar.
 
Like this...

I bought a dimple die from AC Spruce for them, I can't recall what size it was, I'll try to look it up in my instructions, it was called out for my 9A.

1001404fv1.jpg
 
You should drill the holes on the tank with a #19 drill bit and dimple them with a dimple die set for #8 screws. Look at this link
 
Tank

Drill with #19, dimple with #8 SCREW dimple set, if necessary to achieve screw depth(head flush with skins) LIGHT countersink dimple with #8 screw countersink.
Mike H 9A/8A
 
Fred-It might be helpful to review Section 5 of your build manual. It provides the basic instructions for when countersinking vs. dimpling is most appropriate or acceptable. It has a wealth of other valuable information as well. Unless specifically stated otherwise in the directions, you should follow the general rules provided in Section 5. Good luck.
 
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