Racking a PDP-11/24

[Paul Koning]

> On Feb 26, 2022, at 3:14 AM, Rob Jarratt via cctalk <cctalk at classiccmp.org> wrote:
> 
> 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 cabinet, but the RL02s I used were in H960 (6 foot) racks, mid-level with stuff above them.

> 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