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From: "C&P Kucera" <cpkucera@idirect.com>
To: "Murphy Rebel" <murphy-rebel@dcsol.com>
Subject: Re: bolt holes
Date: Mon, 29 Mar 1999 22:23:20 -0500
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Hi Neil. I drilled and reamed my bolt holes using "under" reamers. One place
to get them is www.kbctools.com. They will supply a huge tool catalog free
of charge.
The bolts went in snug, some needed a light tap with a plastic mallet. I
found slight variation in the bolt diameters which is to be expected from
plated parts.
Paul Kucera, 453R


-----Original Message-----
From: Neil F Humphrey <neil@uwyo.edu>
To: Murphy Rebel <murphy-rebel@dcsol.com>
Date: Sunday, March 28, 1999 3:28 PM
Subject: Re: another question on epoxy etc.

Thanks for the comments, but I guess I didn't make myself clear. My
handbook of standard aircraft practise says that for a 1/4 inch bolt, the
hole can be up to 6 thousands oversize! In addition if you micrometer the
AN bolts you will find they have considerable slop, and average about 4
thousands undersize. As a result, a hole that is to be drilled to
1/4inch, micrometers at (say) .251 thousands... and the bolt that goes in
it is 4 thou under.. hence 5 thou of slop even in a close tolerance 1/4
inch hole. And my query was whether others had worried about this..
But I expect I am just being overly anal,... since the only solution is to
go to close tolerance bolts and reamed holes.
Oh, well, I will just go back to deburring.

Neil Humphrey

On Sat, 27 Mar 1999, Bob Patterson wrote:

Several thou. of slop sounds serious to me - it might be better to ream
to allow the next size larger bolt !

Any slop can cause greatly increased wear rates, and create major
safety problems quickly. I have seen flutter problems on gliders caused
by barely perceptible movement on control surface attachments !

Useing Epoxy on bolts is not a good idea, in any case, as the

adhesive

effect will make it difficult or impossible to remove the bolt -
which you will want to do for service !!

Best to talk to Kerry, at Murphy, about these sorts of problems -
a little time on questions now could save a lot of grief later !!

.....bobp

-----------------------------orig.----------------------------------
At 03:35 PM 3/26/99 -0700, you wrote:

By the time you have drilled through several layers of material, and

used

the resulting holes for drill guides for other holes, I sometimes find
that the resulting bolt holes are a couple of thousandths oversize.

This

isn't a problem for rivets, but there is sometimes a barely perceptible
slop on the inserted bolts. Anybody else worried about this enought to

do

something about it? Is the epoxy chromate strong enough as a gap filler
to fill a couple of thousandths of an inch... anybody out there with
thoughts? since I am sure others have worried about this.

Neil Humphrey
#371