DEC PDP-9 fascia panel to PDP-11 H960 rack adapter clip

Having a dozen or so DEC PDP-9 black plastic fascia panels dating from 1968 or so (and no PDP-9 minicomputer to use them on) I designed this clip so they may be used on my DEC H960 PDP-11 racks.

This 5-1/4" high (3RU) panel normally clipped onto the original machine using 3M push-together nylon fasteners (identical to those used in the Apple II lid and case some ten years later) that were on black sheet metal angle pieces. Although I had some of these, some of the 3M fasteners were missing from some panels so I decided to take my own approach.

The clip presented here is a one-piece semi-flexible catch that engages the panel's rectangular cutouts, filling the space. By pressing gently on the exposed clip surfaces each side of the panel it can be removed in seconds.

I'm not expecting anyone here to actually have a use for this unless they had some of these panels, which are probably rather uncommon these days, but have uploaded the model as an example of stepwise refinement. The profile was done in QuickCAD and exported as a DXF. It underwent a few iterations, test printing and fitting, to arrive at the one here. See the relevant image for how it changed. The top-right corner of the angle lines on each version is the origin of the DXF, ie. [0,0,0] when imported into OpenSCAD.

The DXF is simply extruded and three holes punched through for modern 6mm rack mount screws (with the rectangular caged nuts, placed backwards on the screw). I used the centre hole to fasten them to the H960.

I printed the model standing on end. I really wanted to make them from black ABS but had a lot of trouble getting the ABS raft to stick even with high bed temps. I reluctantly switched to black PLA and they printed successfully.

Cura settings were PLA, 212 C hot-end, 60 C bed temp, 20% infill, raft, no support (the holes print fine). The model is symmetrical so I didn't bother to mirror it for the other side.

The results are excellent and now allow me to use the PDP-9 panels instead of trying to chase down more of the normal black/beige PDP-11 fascia panels (with the crappy fastening system - see another of my things).