PiDP-11

It's been a good few months without an update. Real Life interfered, as it does. But also, I had lots of trouble getting the CAD design ready for injection molding. Stuff you don't think about: selecting brass inserts for screws, and how they should fit in the plastic. Controlling cost by ensuring a hobbyist can mount the inserts himself...

Hopefully, a professional checkup on the CAD file means it is now good to go. One more 3D printed prototype to check these inserts, and then the case should be done.

About time, the rest of the project was done 6 months ago. I'm curious if at the end of this I feel injection molding is just a horrible idea for hobbyists, or whether I just was slow climbing the learning curve. We'll see.

Today was a great day - after 10 months, all the parts were fitted together for the first time. As a 3D printed prototype of the case just arrived.

Excuse the bad photo quality, late at night again and I still have a low-tech camera that can't deal with dim lighting conditions. But actually, grainy pictures are a Good Thing because there's a lot of finer detail still to be done. The new case is just dropped over my prototype like a hood - not even screwed together yet.

Still, a fiiiiine day for the project. The PiDP-11 will be pretty, now I know for sure :)

Well, it took months but today I got a batch of switches from the factory. Yay!

That leaves the injection-molded case still to do... Hopefully more progress on that in two weeks' time :)

The PDP-11 uses a very peculiar colour scheme. Getting the colours right is crucial to get that early '70s feeling across. Unfortunately, getting colour exactly right is much, much harder than you'd think. The problem starts with computer screens, which unless they are professionally calibrated do not show colours faithfully *at all*. Then, the manufacturer of my acrylic panels has the same problem, so I had to make a special acrylic bar with all possible colours to pick the right one.

And now, I have to make sure the switch manufacturer delivers the exact right colour. Today I went to a local specialist shop, and identified the near-perfect Pantone colours for the switch manufacturer.

That is, if anyone is ever interested, Pantone numbers 222 and 187. For fun or otherwise, below are colour sets I got off high-quality photos of the PDP-11. Even good cameras are off no matter what you do. Seriously, that is how far off you get without 'professional' colour calibration. It illustrates the misery of colour matching:

After 4 months of waiting, the pre-production samples of the switches came from the factory! Yay! They look exactly as I had intended, so that is a relief. Having to change the mold is an expensive thing to do. Now, all that's left is to ensure they are produced in the right colours - as is obvious from the picture, these samples are in black.

Now, back to making a CAD design that works for the case...

It will be horribly expensive to make, but this is the case for which I'll ask quotes from a few manufacturers, using different techniques. Just to see what's feasible:

It's been a month or so since my last post, but progress has been made. Samples of the replica switches will arrive on Friday. And thanks to Henk of pdp-11.nl, I started in earnest on case design. He let me borrow one of his original bezels/frames - thank you, I'll be careful with it!

It would have been impossible, with hindsight, to exactly replicate the bezel without having the real one at my desk.

I started the CAD work yesterday, and followed the path of least resistance by doing it in Sketchup. Which, maybe, will not be the best idea in the end but I will see. At least I've got all the measurements done for a mostly-finished v0.1 version:

Next version should be good enough to go to a plastics manufacturer for evaluation and testing. Hopefully in the next two weeks, as I visited two of them recently to learn more about the whole process.

A blinkenlight movie means progress. Not there yet, but here's the PiDP-11 doing the '11's signature pattern:

To be continued. As in, tomorrow night.

Not in the right case, not with the right switches, with an imperfect acrylic panel and most certainly not in the right colours. But it seems to work with initial tests...

Magically, the encoder switches turned up this morning just when I needed them. So they are in! Tomorrow I'll start adapting the BlinkenBone server. Five days left before I leave for VCF SE.

...so after four days, I've only just got the PCB finished. But testing will have to wait till tomorrow. Still, it's (almost) all there: the temporary switches painted to match the panel, the PCB... now it'll be a matter of putting it all in its case, and focusing on the software. Oh - and the rotary encoders are still missing. Two months shipping time is not enough?

Again, the final form factor will be different. Different case, different switches. But this prototype will help me drive the bugs out.