G

GuppyBob

Member
The only dumb question in aviation is the one not asked so here goes...I am wrapping up my -8 empennage and went to install the hinge bolts in the HS hinge brackets...because of some primer etc. I had to drill the holes out with a #12 bit to get the AN3 bolts to fit. Now, bare steel is exposed on the inside of those holes and I am fearful of leaving thm like that for fear of rust forming on that bare steel. Does anyone use a sealant, or some type of "goo" to keep those bolts from wearing on your primer inside the holes and then exposing the bare steel,( which I've seen will corrode very quickly ) ??
 
bare steel in the holes

guppybob (coolname)
First having bare steel inside the hole should not pose a problem as the hinge will need lubrication which most will displace water anyway. I am generally more concerned about using drill bits to clean out hinges,bellcranks ect... because they can wobble thus oversizing, taking it out of round and can create marring inside the hole which will increase wear of the hinge pin. I would suggest that you purchase some reamers which are perfect for jobs like this. try www.enco.com they have many to choose from you can purchase some cheaper ones which will work fine for shop purposes as opposed to the very expensive which are for industry or built to last longer. hope this helps.
 
I'd bet that the vast majority of builders don't worry about priming the inside of the bolt holes. I certainly don't.

Cheers,
Rusty
 
Thanks for the replies

Yeah...I agree a reamer would be the best tool and I appreciate the link and all of the follow up. I was very careful with the drill bit and the holes still look round and mar-free. I'll get those reamers before hanging the rudder and remember the lesson I've learned....thanks
 
GuppyBob said:
Yeah...I agree a reamer would be the best tool and I appreciate the link and all of the follow up. I was very careful with the drill bit and the holes still look round and mar-free. I'll get those reamers before hanging the rudder and remember the lesson I've learned....thanks
Click to expand...

For our purposes, the reamers from Avery or Cleaveland are cheap and more than adequate. My vote is to buy a couple for the sizes used most often (3/16 and 1/4) right from the start.

Also, re: the primer... probably wouldn't hurt to dab some primer in the steel holes, but I doubt most builders do, especially in this case. Worse case scenario, assuming you do annuals, is that you would see rust developing long before it weakened that hinge bracket sufficiently causing it to fail.

good luck, adn have fun on the rest of the emp.
 
One thing to remember as well: the bolts shouldn't "wear on the primer" as they do not (should not) move relative to the hinge bracket. The hinge movement is in the bearings themselves, not between the bolt and the bearing or the bracket.

Peter Schwarzenbach
RV7 Fuse
 
Reamer Sizes

Reamers come in many sizes, fractions, number sizes and individual decimal sizes.

You might as well buy the most accurate one for your needs.

This old posting of mine explains how to get the size you need...

http://www.vansairforce.com/community/showthread.php?t=5036&page=2&pp=10

Don't just go for the nearest fractional size.... In this case, an accurate 3/16 hole will be too tight if your AN3 bolt is on the high side of it's tolerance...

gil in tucson
 
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