Thank you for the reply. > -----Original Message----- > From: pbir...@gmail.com <pbir...@gmail.com> > Sent: 26 February 2022 08:48 > To: r...@jarratt.me.uk; 'Rob Jarratt' <robert.jarr...@ntlworld.com>; 'General > Discussion: On-Topic and Off-Topic Posts' <cctalk@classiccmp.org> > Subject: RE: Racking a PDP-11/24 > > The conventional mounting for RL02 drives in a corporate cabinet puts one at > the top with the 6U CPU in the middle *but* that assumes that you have a > corporate cabinet designed for that purpose -- in which case the top is > missing so that the RL02 disk-pack can be directly accessed, and there is a 1U > divider below the top RL02 that reinforces the rack (and in effect replaces the > 1U lip on your rack top).
I saw something somewhere that suggested the RL02 should be at the top with the disk accessible without pulling out the drive. I don't think the cabinet I have was intended to do that, but I will have a closer look. > > AFAIK you should be able to make your rack plan work; it's just the case that > RL02 are always "top snug" (at least in my experience). Have you tried raising > the 6U CPU as high as possible *before* tightening the bolts/screws on the > mounting flanges on the slides (to the rack, not to the chassis)? > There's usually ~1/8" of play there. From your photo perhaps you have > already done that as the CPU-front looks to be snug to the rack-top. If > anything it looks as if your RL02 instead need to move down. > I did try raising the CPU as high as possible. Will have another look to see if the RL02s can be dropped a bit lower, but I don't think they can go lower in terms of using lower slots, not unless I want to leave a gap and possible interfere with the space at the bottom where there will be some cables I think. I would like to avoid filing though! > I would start by moving the bottom RL02 down as far as possible, then repeat > with the second RL02. > > Your observation that there is "very little clearance between the CPU and the > RL02 at the front but more at the back" suggests to me that you need to > fiddle move with the front and /or rear mounting flange positioning on the > various slides. Don't assume that wherever "gravity drops them" is going to > be correct. > > If none of the suggested adjustments are working then I would consider > getting out a rat-tail file and enlarging the slots on the mounting flanges on > the RL02 slides so as to let them drop a little lower (assuming that you have > clearance at the bottom!). > > Regardless you shouldn't need to play with the slide-to-chassis attachment > points -- those are always "just so" and not really free to fiddle with (no > "slop"). There *is* a bit of play in the big black sheet that is screwed onto CPU enclosure. > > In my experience "racking" is a fiddling-time and clearances can be *really* > tight. But ... it can be done :->. Good Luck. > > -----Original Message----- > From: cctalk <cctalk-boun...@classiccmp.org> On Behalf Of Rob Jarratt via > cctalk > Sent: Saturday, February 26, 2022 3:15 AM > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk@classiccmp.org> > Subject: Racking a PDP-11/24 > > 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. > > 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! > > Regards > > Rob
