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1. 06:58 PM - Re: a tip ()
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Agreed. Aside from the philosophical "thingy" (that's Socratic talk) of
making the perfect the enemy of the good, we can quote Chris, who said,
"You're making a tractor, not an F-16". I've found the design to be very
forgiving of human error...
Paul R
----- Original Message -----
From: Paul Mulwitz<mailto:psm@att.net>
To: zenith-list@matronics.com<mailto:zenith-list@matronics.com>
Sent: Wednesday, October 02, 2013 7:31 PM
Subject: Re: Zenith-List: a tip
<psm@att.net<mailto:psm@att.net>>
Carlos,
I accept your numbers, but I think you are worrying a little bit too
much about perfection.
Clecos do line up holes pretty well because the back side of the
"head"
is indeed round. This grabs the entire hole on the opposite side of
the
main clamp body. Well . . . it misses the area where the crack
appears
between the fingers, but it does a good job of clamping the sheet
metal
in place.
The more Clecos you use, the more aligned the pieces will be. I like
starting a rivet line with Clecos in every other hole and continue
working on this line by swapping the Cleco points and empty holes as
the
parts are repeatedly drilled to higher and higher sizes. I usually
have
not had any problem getting the holes aligned for final riveting after
deburring. In those cases where I have difficulty inserting the
rivet,
I just run the final dril through the hole again. This may mean the
holes in all the riveted pieces are not precisely the same size but I
don't think this matters. The primary gripping is done by the two
heads
of the final rivet.
It is important to do a good job on your construction, but keep in
mind
you are building a relatively low performance airplane rather than a
space shuttle.
Good luck,
Paul
Camas, WA
Zodiac XL, in phase II
On 10/2/2013 5:13 PM, Carlos Sa wrote:
> I have noticed - through other builders comments, but also through
my
> own experience - that using clecoes to keep parts together sometimes
> does not quite work.
> The parts do remain attached, not doubt, but they can be slightly
> shifted from the original position when they were drilled.
>
> Here's why, in case you don't know:
> The rivet whole is slightly larger than the rivet, and a cleco,
having
> an irregular shape, has plenty of room to move in a rivet hole.
> For instance an A5 Avex rivet has a diameter between 0.140" and
0.155"
> (the rivet has "fins", therefore the diameter varies).
> A solid rivet diameter is 0.155"
> The corresponding drill bit is 0.160".
> A black cleco is 0.149" at its widest point - but it is not round.
> (Note: these are measurements I took from Items I have. You may find
> slightly different measurements.)
>
> In longer parts (more than a foot or two) or assemblies of more than
> two parts, I find that if parts are not perfectly aligned, it's hard
> to insert the rivets. And, worse, parts will be warped or difficult
to
> match as I proceed with construction.
>
> So, instead of simply trusting the clecoes, I started adding spent
> drill bits here and there (a solid rivet is better than a cleco, but
> not as good as a spent drill bit).
>
> I eventually started cutting drill bits and grinding one end to make
> it easier to insert them.
> (The grinding process consists of putting the drill bit in a drill
or
> drill press and grinding it with a dremel tool.).
> The opposite end is covered with masking tape - see attached photo.
>
> I have a bunch of these, A4 and A5, and use them frequently.
>
> Hopefully this can be useful to someone.
>
> Blue skies
>
>
>
> Carlos
> CH601-HD, plans
> (CH650 firewall and canopy)
>
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