DEC PDP-11 H960 rack fascia panel clip by 1944GPW

Last crawled date: 3 years ago

Here is my replica of the DEC fascia panel clip for the H960 equipment rack, a common 19" rack frame used for their PDP-11 series of minicomputers. To cover empty spaces in the rack there were two panel sizes, 5-14" high and 10-1/2" high. The panels were affixed to the rack by means of plastic clips with two ball-end posts, these locating in holes in the back of the fascia panel. For a 5-1/4" panel there was one clip each side, and two each side for the larger panel.
Being made of a hard and somewhat brittle plastic, it is quite easy to break the posts off the original clips by involuntarily twisting the panel when removing rather than pulling the panel off the frame perpendicularly. The result is the post snaps with the ball end often needing to be extracted from the panel, not to mention having to then find and fit a replacement. These days they are becoming harder to find butdo appear on eBay from time to time.
There is already an STL file for this clip, see http://so-much-stuff.com/pdp8/cad/3d.php but I thought I'd have a go at it myself. I've included the OpenSCAD source so you can look at it and tweak it if you want. I added the rounded edges to the model after I took the photos, to make it more accurate to the original.
The Customiser should work so you can produce a replica of the original part with the solid posts or you might like to try a modified version. For this one the posts are at the centre of
a few concentric rings, each one allowing a tiny bit of movement. Since there is only a small gap between the ring walls, use an Exacto #11 blade to cut through around the top and bottom walls and ensure the gaps have not printed too closely together. A photo shows close to the maximum amount of post deflection, any more and the post may break.
A second option in the Customiser is that an additional set of countersunk mounting holes at 1RU spacing may be added, allowing more choice in vertical positioning on the H960.
Printing
I printed these from black ABS at 100% infill with no raft and only a small brim.
Updae 2018-05-14
I saw Lou 2NM1Y's ingenious modification on the VCF forum where he drilled out the original clip broken posts and fitted 8-32 steel screws (M4 ought to work as well). I've made that as a small addition (countersunk holes replacing the posts) and updated this script, set STEEL_SCREWS to 1 in the Customizer.