26 Feb
2022
26 Feb
'22
12:05 p.m.
-----Original Message-----
From: Paul Koning <paulkoning at comcast.net>
Sent: 26 February 2022 19:21
To: rob at jarratt.me.uk; Robert Jarratt <robert.jarratt at ntlworld.com>;
cctalk at classiccmp.org
Subject: Re: Racking a PDP-11/24
> On Feb 26, 2022, at 3:14 AM, Rob Jarratt via cctalk
<cctalk at
classiccmp.org>
wrote:
cabinet,
I am wondering if I have racked my 11/24 correctly.
As you can see here:
https://robs-old-computers.com/2022/02/10/pdp-11-24-progress/ I have
put the CPU at the top and the two RL02 drives underneath.
That seems fine. Others mentioned having them at the top of a low but the RL02s I used were in H960 (6 foot) racks,
mid-level with stuff
above
them.
I am not in the USA, but I am should be able to look for other screwdrivers
here in the UK. I already have one quite big one, but I think it is still
way too small for this purpose.
The problem is that the CPU enclosure catches on
the RL02 underneath.
There is a bit of play in the mounting bracket:
https://rjarratt.files.wordpress.com/2022/02/cpu-mounting-bracket.jpg.
With a bit of manipulation I can get the CPU to slide in. However, I
am wondering if I have racked it correctly? I don't think there is
room to move the RL02s down and it would presumably leave a bit of a
gap below the CPU. There seems to be very little clearance between the
CPU and the RL02 at the front but more at the back, but I am sure that
the rails are mounted horizontally. Is it just a matter of tightening
the big screws that hold the mounting brackets to stop the play? If so
I am not sure I have a big enough screwdriver!
Hardware stores can fix that. Or Brownells, where you can get really good
screwdrivers that are less likely to damage screw heads than standard
hardware store ones do. 
Something I observed on my H960 that wasn't all that obvious at first: the
holes are NOT evenly spaced. If I remember right, they come in groups of
four where the spacing between groups is something like 1/8th of an inch
more than the spacing within groups. The consequence is that if you
attach
your brackets using the wrong set of holes things may
be 1/4 inch (or
whatever the delta is) closer than they were meant to be.
paul