Another new PiDP-11...and yet another case extension!

[Marco]

When I finished building my Gigatron TTL computer, some two-and-a-half years ago, I finally had blinkenlights...sort off. There were only four, and not doing much more than just blink. Very happily, that must be said. But still. It's like an addiction, so I had to find more blinkenlighs! Enter the PiDP-11.

Enough has already been said and written about building a PiDP-11, apparently in the past many people have done the effort to film their builds on Youtube. Well, at least watching these gives you something to do whilst waiting for the mailman to finally ring your doorbell.

It's been almost two weeks since my doorbell rang, and I have been busy. I am a careful and nit-picky builder, but still had blinkenlights in no-time. But there was much work to do still. Enough said, some pictures:

It's probably heretic not to use the wooded stand, but I wanted something more stable and roomy. Long story short: it took me a full week of 3D printing and fitting, but I am now happy with the result. And needing to print the case extension in parts anyway, why not use some nice matching colours?

Some explaining is probably in order here...

• I have covered the insides of the original frame, and the newly printed back cover, with self-adhesive aluminium tape, to block any light showing through.
• I have added two LED's on the back cover: a red power LED (permanently on the 5V rail with a 2k2 transistor to dim it sufficiently) and a green LED attached to the free GPIO pin 19 for Raspberry Pi activity, with a 22 ohm transistor. Adding the line 'dtoverlay=act-led,gpio=19' to /boot/config.txt on the Pi will 'move' the green activity LED on the Pi to an external LED on GPIO pin 19. I believe this will only work with Pi 3 and 4's.
• I had a spare Vonets VAR-11N mini-router lying about, which I here use as a WiFi to Ethernet bridge. They are quite cheap and work very well. So I now have WiFi but the Pi (and thus simh and all simulated OS'es) are Eth0 connected. I have found this makes life on the connectivity front much simpler, in the case of the PiDP-11 at least. It is powered by one of the USB ports on the Pi, and enclosed in a black box because it is otherwise very bright.
• Just for fun: I added a small switch to the prototyping area which can bypass the LED-dimming diode. Not needed really, but it was little effort.
• To give the whole assembly "a bit" more weight, a stone bar is fixed to the bottom of the case extension. But that still wasn't sufficient when toggling the switches. So I printed two subtle feet which I attached with very sticky tape to the bottom of the original frame. Then I also added rubber pads on them, and on the case extension. Now it actually is rock solid! 

And now I have come to the conclusion that I need a 6/10th scale fancy desk lamp...

Should anyone be interested in 3D printing the case extension, I have added it on Thingiverse.

Marco

[Brian Denley]

Outstanding job!  Looks great too!  What is the biggest dimension?  Looking to see if my printer can do it!

Brian

Brian Denley

KB1VBF

Sent from my iPad

On Apr 25, 2022, at 2:41 PM, Marco <crou...@gmail.com> wrote:



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[Marco]

Brian,

As sliced, you will need 160mm x 100mm x 170mm (width x depth x height), to print the four large parts of the case extension separately.  Printing them separately is advised anyway. By rotating the two upper parts you could reduce the print area to 170mm x 100mm x 130mm, or even 160mm xx 100mm x 130mm by omitting the connecting tab.

I have a Prusa Mk3S, nothing special,  and it fits spaciously.

Op dinsdag 26 april 2022 om 00:03:14 UTC+2 schreef b.de...@comcast.net:

[Neil Higgins]

Very swish. Well done!

[Bill Backstrom]

Hi Marco,

I love your case extension, it pushed me into buying a printer. On thingiverse you mention minimal build supports. Since I'm new to 3d printing, could you elaborate on what support was needed?

Thanks,

Bill

[Marco]

Hi Bill,

Only overhanging parts need support, 3D printers usually have a hard time printing a layer on top of thin air... Slicing software (needed to turn STL files into the G-code 3D printers can understand) will show where overhangs occur and can automatically add supports.

This is PrusaSlicer:

The green bit is the overhang support. After the print it can be easily trimmed off and discarded.

Printing large parts as a "beginner" can be daunting, but why not. You'll learn along the way. 3D printing however is not always as straightforward as, say, your office laserjet printer. Things will go wrong now and then, and it's a learning curve. One tip: never underestimate the importance of proper first layer ("Z layer") calibration! All said, 3D printing is also very satisfying.

Good luck!

Marco

Op woensdag 4 mei 2022 om 17:46:50 UTC+2 schreef Bill Backstrom:

[Bill Backstrom]

Hi Marco,

Thanks for the explanation and advice, that helped a lot. It led me right to the support settings in Cura. I'll probably try some test prints just to get an idea of how they work. I've only had the printer for a few days and, yeah, there is a learning curve, but it has been a blast so far.

Thanks again,

Bill

[Marco]

In the mean time, I have added a second version (V2) of the upper parts, with the top sloping back in line with the PiDP-11 case, instead of being horizontal. The original rear cover won't fit V2, so you will need V2 of the 3D printed rear cover instead. I haven't actually printed it (yet?), so no photo's unfortunately.

Updated on Thingiverse, and now also on Printables.

Op donderdag 5 mei 2022 om 01:11:45 UTC+2 schreef Bill Backstrom:

[Marco]

As a kind of add-on, here's a Programming Card holder, to be attached to the case extension. The upper  clip is optional.

It's also on Thingiverse.

[Heinz-Bernd Eggenstein]

Just wanted to add a big "Thank you" here, I just built most of the V2 version of the case extension as a test project for my new 3D printer. It is marvelous and finally I can get rid of that piece of wood for a stand. It wasn't even looking that bad in my IKEA "rack" and next to teh PiDP-8i, but still, this is much, much  better. I haven't printed the back-panel yet, I would like to modify it to insert grille-style openings for a (fake or real, not decided yet) cooling fan, but I first have to learn the basics of (Free)CAD to cut some holes into the existing 3D model. Rather decent & fast 3D printers are getting really affordable these days, I got myself an Anycubic Kobra 2 Pro for just 240€ which took between 1:20 and 1:40 hours for each of the 4 big parts of the sides and top/button. 

Thanks again for sharing the model on Thingyverse!

HB

[Marco]

You're very welcome! It is always satisfying to hear other people enjoy the work I basically just did for myself too ;-)

Do post a picture of the end result if you want, I'm curious.

Cheers,

Marco

Op zaterdag 31 augustus 2024 om 13:11:43 UTC+2 schreef hbep...@googlemail.com: