Back Panel Drawings

[Matt W]

Are drawings or schematics available for the PiDP-11 back panel? I would like to customize it for my purposes.

I am trying to solve a number of goals by placing a DC power supply inside the case. To make room I may need to move some of the knockouts. If I'm going to the effort of re-cutting a knockout, I might as well just manufacture a purpose-specific panel from the ground up. This would also let me extend the panel to provide additional room.

For those interested, the goals are:

Provide a power input in the 5.2V - 5.5V range. This would normally mean a pi-specific wall-wart, but I don't want to power the Pi directly. A non-USB wall-wart is almost impossible to find in that voltage range, and with the recommended 2.5A capacity. One option would be to use the Pi-specific supply and a USB breakout board, but I don't like the vendor lock-in, or the additional complexity, and that still includes a wall wart. The more attractive option is to use an IEC inlet to a switching power supply. This hits all the high points as well as includes an input-side fuse.

This means re-drilling the back panel to mount the PSU and inlet, which would occupy the same space as the serial knockouts. Additionally, my panel has the generic rectangular power knockout instead of the circular barrel connector knockout, so I would need to be drilling for power anyway.

I'm pretty sure I can fit everything as-is with just a few mm of standoff, but if I'm manufacturing my own panel, I could rearrange things for a better fit and integrate that offset as well.

[ma...@rsx11m.com]

Matt,

    I got back panel drawings from Oscar some years ago and have made new clear acrylic back panels for each of my three PiDP-11/70s. I've made slight mods to each of them including adding a small digital volt meter so I could keep an eye on the voltage that the Raspberry Pi was getting from the micro USB connector. Below are a few versions of the back panels in a few file formats. I was able to use LibreOffice's drawing program to make changes. I also made a wooden extension to the case to make it easier to connect the RiP3+ sockets to the back panel. This is described in a Dec. 14,  2018 post by me in the "Show us your kit" topic.

    The first two I had made by Pololu but the last one I was able to cut myself with a GlowForge at our local library. The best acrylic thickness is 4mm which is a bit thicker than original acrylic ones. I really like the clear because it is so easy to show people what's "behind the curtain" running the light show.

Best,

Mark

[Steve Platt]

Mark,

Tell me more about the extender for the case.  I (quickly) threw together a 3D-printable extender to fit between the case and back panel.  It allows cables to be installed in the back panel without crunching or carving.  It requires four slightly longer self-tapping 1/4" screws.

If anyone is interested, I can post the STL file.

Steve

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[Matt W]

Thanks, Mark, this is really helpful.

I was also thinking of acrylic as one of the possibilities, but I think that some type of sheet metal will be the easiest to both cut and then bend to get the extension.

[Matt W]

For those interested, I found this design online and it ended up working exactly how I wanted:

https://www.printables.com/model/195214-pidp-11-stable-case-extension

I'm still not used to looking for 3D-printed solutions yet, but Mark's comment, as well as this post from Massimo inspired me to look. The above back is both roomy, and also includes feet so the PiDP is free-standing.

[Steve Platt]

Wow, looks a lot better than the quick extender I made.  Time to fire up my 3D printer.

Any recommendations for colors that would match well?

Steve

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[Matt W]

You can see my print by using the link to the model and then navigating to the "Makes" tab. I think I have the only make listed.

I printed in whatever white was already loaded because I expected it to be a test build. Even though I had to switch brands halfway through, the color seam is barely noticeable. I don't think you're going to hide the physical seam between the chassis and the printed extension, so I would just use whatever white you have enough of. With some tinkering, I think you could merge the parts so the extension prints in two pieces instead of four, which would remove the side seams.

I'm pretty happy with the extension, although I think I will modify the back mounting holes to accept heat inserts. This should also give better access to the chassis-side screws. I'm also considering adding vents for airflow or possibly a fan.

I also pressed some M4 heat inserts into the original chassis to facilitate attaching the extension; I don't like using self-tapping screws in plastic, especially when they are repeatedly removed. As I expect to fiddle with the PiDP and extension quite a bit until I get it nailed down, I went with machine screws. I plan to post some photos of the build process when it's closer to completion. I still have some soldering and flux removal to do, as well as finalizing the back panel.