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

thingiverse

Having a small collection of DEC PDP-9 black plastic front panels from 1968 or so, but no actual PDP-9 minicomputer to use them on, I designed this clip to allow them to be used on my DEC H960 PDP-11 racks. This 5.25-inch high (3RU) panel normally clipped onto the original machine using 3M push-together nylon fasteners, similar to those found in the Apple II lid and case about a decade later, which were attached to black sheet metal angle pieces. Since I had some of these, but many panels lacked some of the 3M fasteners, I decided to create my own solution. The clip shown here is a one-piece semi-flexible catch that engages the panel's rectangular cutouts, filling the space. By gently pressing on the exposed clip surfaces on each side of the panel, it can be removed in seconds. I'm not expecting anyone to have a use for this unless they possess some of these panels, which are likely rather rare today, but I've uploaded the model as an example of stepwise refinement. The profile was created using QuickCAD and exported as a DXF file. It underwent several iterations, test printing and fitting, before arriving at its current form. A relevant image shows how it evolved over time. The DXF is simply extruded and three holes are punched through for modern 6mm rack mount screws (with rectangular caged nuts, placed backwards on the screw). I used the center hole to secure them to the H960. I printed the model upright. Initially, I wanted to make them from black ABS but encountered issues getting the ABS raft to stick even with high bed temperatures. I reluctantly switched to black PLA and they printed successfully. Cura settings were set for PLA, a 212 C hot-end temperature, a 60 C bed temperature, 20% infill, a raft, and no support (the holes print fine). The model is symmetrical, so I didn't bother mirroring it for the other side. The results are excellent, allowing me to use the PDP-9 panels instead of searching for more normal black/beige PDP-11 fascia panels with their problematic fastening system.