On Tue, Nov 18, 2003 at 10:18:30PM -0500, Ian Primus wrote:
> But, there I face another snag. The Digital rack I am installing this
> in is not threaded.
That is completely ordinary. I have well over a dozen DEC racks... they
have bare holes onto which you Clip tinnerman nuts, except for the really
old racks (pre 1968) that are solid and have to be drilled for rivnuts
(you install them like pop rivets, but there's no central shaft when
you install them, just internal threads).
> Also, the spacing between the front and the back is
> different than the other rack I have, and I noticed that some of the
> rails I had didn't fit as easily as they could have. Are there really
> different depths for racks?
In effect, yes. There is no guarantee that all rails will fit all
racks. DEC rails will fit a DEC rack, though. I might have missed
something, but it's possible that your Eagle came from a generic
rack, not a DEC rack.
In practice, in the past, I've seen systems that had mixed rack styles...
DEC hardware in a DEC rack, and third-party hardware in another rack.
My PDP-8/L + BM08 came in a third-party rack with third-party rails that
just plain don't fit the CPU. Someone before me drilled extra holes
in the CPU case, but that wasn't enough - the width of the CPU itself
is about 2mm narrower than the space enclosed by the rails - I had to
find a way to shim the CPU rails with washers to get a proper fit. When
I got it, it would bind and occasionally hop the tracks. Worst
installation of DEC hardware into a rack I've ever seen. If I had a set
of rails for the -8/L, I'd have moved it all to an H960 long ago, but
all of my -8/Ls came as table-top or rail-less.
Your fit issues are nothing modern.
Personally, I was surprised the first time I ran into "modern" racks
for PeeCee servers. One of the things I like about DEC racks is that
you don't have to worry about stripping out threads in the rack uprights.
I've only ever had to throw away a few Tinnerman nuts, but that's a lot
better than ruining a thread on a rack.
Just this week, we ran into a rack incompatibility at work: we received
rails for some modernish Compaq server that wants to mount into a rack
with square holes that normally accept another style of clip-on nut.
The rack, unfortunately, is of the pre-threaded variety. We ended up
bending back the locking tabs meant to rest in the square holes, and
boring out one of the threaded holes to accept a #12 bolt. For next
year, though, I think we'll bring down a real HP/Compaq rack and
replacement rails.
--
Ethan Dicks, A-130-S Current South Pole Weather at 19-Nov-2003 13:20 Z
South Pole Station
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Ethan.Dicks_at_amanda.spole.gov http://penguincentral.com/penguincentral.html
Received on Wed Nov 19 2003 - 07:34:00 GMT