Re: Broken clutch knob


Wiggins, Rick
 

Hi Pete,
I have seen the flurry of posts. Let me offer some simple
suggestions. Don't put any glue or any other stuff down in the hole.
I think that is a low probability of success and higher probability
or making the problem worse.

Next, Are you comfortable with working with the suggested tools? If
so, then take the easy-out screw extractor advice. If not, then have
someone that is comfortable with tools do this or take it to a
machine shop. Of course, you could always mail to AP for repair.

1. First take another stainless steel screw of the same size, put it
in you vise and do a test run of the set punch, drilling, and easy
out insertion. If you can do it in the vise, you can do it in the
mount.
2. If it is too hard to center the dril and not slip, then do this
setup with the drill press and light slow drilling.
3. After you are comfortable with the process, set up your mount so
that you can drill straingth down into the screw.
4. Use a set punch to provide a small starting dimple. This would be
a light tap with the hammer, so you get just a small dimple to
prevent the drill from skating across the screw surface.
5. Drill either with the drill press or very steady and carefully
straight down to make a pilot hole. Use a very small drill bit. Be
careful not to break the bit!
6. Now drill a larger hole to the correct size specified bt the
screw extractor.
7. Slowly and carefully install the easy out.
8. Slowly and steadily back out the screw extractor, making sure to
apply only perpendicular torque. Make sure the wrench is held
perpendicular to the extractor and that the extractor is parallel
with the screw. Dripping a light oil down the hole (only one drop)
may help if you are worried about the screw being struck or cross
threaded. Wait 5 minutes for the oil to soak around the threads.
9. Completely remove the broken screw.
10. Clean the hole of oil and debris.
11. Celebrate with Holiday Drink of choice!

Cheers, Rick



--- In ap-gto@..., "Peter Santangeli" <peter@...> wrote:


I haven't checked yet, but my gut is that the piece that is still
in
there is not extraordinarily tight. I don't think it broke due to
tightening (I don't keep them that tight). I think what happened is
the big knob part got hit at some point, and the shaft broke. I
seem
to remember that at one point this summer I noticed the knob wasn't
square to the mount. Not looking into how it was put together, I
thought to myself "hmmmm. Interesting construction that could let
that
wobble like that but still tighten".

I realize now that what had probably had probably happened is the
aluminum had split but not broken right off. If I had realized the
(somewhat odd) construction of the "bolt" I would have backed it
out
and replaced it right away. Live and learn.

Thanks for all the advice. I'll let you know how it goes. I've
already
had both the Dec section and RA section back to AP at least once,
so
I'd rather avoid another repair visit. I sold my backup G11 last
week,
so it would leave me without a good mount!

Pete


--- In ap-gto@..., "Mark Galiyano Jr" <mgjr@> wrote:

You *cannot* use the broken off piece or any other threaded
extractor. Whatever is glued to the stud must not be threaded. If
you do, there is no way to unsure tha the threads don't jam like a
jam
nut arrangement. If an attempt is made to use glue, I would use a
crayon to wax up the whole inside, then a dremel or small drill
bit to
clean up a spot for the bond, or even drill the size of a heavy
duty
paper clip and glue that inside the hole.
All that said, I still think an easy out is the way to go.
Maybe if
the rest of the clutches are loose, movement of the axis may help
loosen this one.
Mark

----- Original Message -----
From: steve_dashiell
To: ap-gto@...
Sent: Saturday, December 15, 2007 10:56 PM
Subject: [ap-gto] Re: Broken clutch knob


Since the top of the broken stud is 3 mm down in the threaded
hole, if
glue of any sort is put on top of it and the other piece is
threaded
in, any excess glue will be forced out of the space between
the two
broken pieces and into the threads both above and below the
break,
since there will be no where else the excess can go. I
seriously
doubt that there is anything that can be done to seal the
threads
adequately to prevent this, since the glue is relatively
incompressible. If the amount of glue used is so small that
there is
no excess to squeeze out, it might work, but the proper amount
is
probably difficult to estimate.

Steve

--- In ap-gto@..., "Mark Galiyano Jr" <mgjr@>
wrote:
>
> You can protect the threads from the glue by putting wax at
the
interface of the bolt and threads. Most glues will not adhear
to wax
and it forms a fairly good barrier. The thing that troubles me
is that
enough force was present to shear the bolt. I am not sure this
can be
done without an easy out. I do think and easy out will work
though.
Most of us that have had trouble with them were trying to get
out
wrench-tightened bolt remains, not hand tightened.
>
> Best of luck,
> Mark
>
> ----- Original Message -----
> From: steve_dashiell
> To: ap-gto@...
> Sent: Saturday, December 15, 2007 8:17 PM
> Subject: [ap-gto] Re: Broken clutch knob
>
>
> The risk with this approach is that if any of the glue gets
into the
> threads of the broken off stub, it could end up acting like
a thread
> locker, making the broken piece difficult to remove at all,
even
with
> proper equipment.
>
> Steve
>
> --- In ap-gto@..., "Bryon Schwartz"
<bryonnmissy@>
wrote:
> >
> >
> > If the screw part that is still in the mount is not
stripped or
> > jammed into the thread wall maybe try crazy glueing, or
some
other
> > strong epoxy, the knob back onto the bolt and let it set
for
maybe a
> > day and then try twisting it out SLOWLY. This might work
ONLY if
the
> > remaining part of the bolt is not jammed or stripped into
the
screw
> > walls.
> >
> > Just my $.02 and can't hurt to try. The only thing that
could
happen
> > is the bolt will shear again at the point where you glued
it.
> >
> > Bryon
> >
> > --- In ap-gto@..., "Peter Santangeli" <peter@>
wrote:
> > >
> > >
> > > Indeed the problem is bad... that part I'm holding is
supposed
to be
> > > at least 3/4 of an inch long. The rest is in the mount.
> > >
> > > Pete
> > >
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>






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