> > I accidentally read this, despite my non-ownership of an A20M, and thought
> > I'd expand the discussion a bit. The 560 series maintenance manuals also
> > say to use the screws just once. I can't see any evidence that these
> > screws have suffered any when I remove them, but I *have* lost a few after
> > reinstalling them, so now you have me wondering: (a) which machines use
> > "use-once" screws, and does this include the 560 line?
I don't think the 560s should be included, but YMMV. I have 3 dead 560s,
and after swapping parts on all 3 I mix and matched screws from all 3 to
assemble a working machine. After using that machine for travel for 2
weeks I went through the screwholes again and adjusted the screws. They
seem tight enough for me so I did not need to re-tighten them.
In any case, it's usually not the screws that I usually worry about in the
assembly process. The problem is the often stressed plastic casters that
the screws are usually attached to on the chassis mount points.
While working on the Dell Latitude CP lines I often have instances where
the casters cracks and breaks under the torque of the screw turning, so it
becomes almost impossible to tighten them. I have no idea how prevalent
this problem could be in other Thinkpads (Especially the taller ones like
the big 770Z that I used to have). I suspect that newbies might crack
them more often than they would like to admit.
(b) is there any
> > harm in reusing them other than the fact that they might fall out again?
Probably not. However, during the disassembly process I noticed that some
of the screwheads are pretty soft and are vulnerable to "balding" and
stripping. I fixed that little problem by trading the bad screws
for the good ones and getting a more suitable screwdriver. (I got rid of
some cheap screwdrivers for better ones from Radio Shack. Their #1 size
screwdrivers have a more blunt surface so it "cuts" the groove better and
prevents stripping near the center. Oh, and watch out for
chassis/mountpoint stress deformation. That problem caused one of the
560s to develop solder joint failures in the motherboard/DC board
junction.
> > (c) where does one get replacements? (Used to be Boulder, I think, but my
> > bookmark for that website doesn't work any more...)
>
eBay is a good bet, but no guarantees on their progeny.
> You can't see the deformations with the naked eye, but I'll bet you
> could detect it with a micrometer.
>
Compared to the stresses and deflections that the machines undergoes
during operation I will have to say that the deformations in screws are
somewhat insignificant.
> As for which ones are use once, you'd have to look in the specific
> manual. No, no "harm" in using them -- they will still hold things
> together, but not as well under long term vibration as they originally
> did. If I had to go inside a ThinkPad without them I'd do it, but I'd
> remember that I did that and try to get replacements for them,
> especially if the unit travelled a lot.
I'm sure there are chemicals that can help adhere the screwheads to their
mounting surface better.
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Received on Wed Apr 30 13:40:34 2003
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