Well, I'm still plodding on and taking 2 steps forward and one backward, but at least it isn't the other way around.
So, I've been thinking that the Pi seems to run very warm, although perceived wisdom ( I use the term loosely) on t'interweb seems to be that fans are not necessary on this model. Nevertheless, I found an Amazon supplier who sells a small fan and selection of heatsinks to fit the various hot bits for £5.99, and I decided that was a small investment compared to trying to buy a new board which are completely unobtainable atm, so I splashed out. That meant that the case I had printed, which didn't have fan mounts, was useless, so I found a different case on Thingy and printed that last night, put it all together this morning, with the fan powered from 5v outputs on the board.
I also bit the bullet a couple of days ago and got the official Raspberry Pi camera, which works fine from just plugging it in, although I'm less than impressed by the ribbon cable which makes it a bit awkward to position. I tried it last night whilst the Pi case was printing and realised that I had probably made a mistake, by buying the 'normal' daylight camera rather than the IR version, because even late afternoon it's difficult to get enough illumination on the head to be able to see a black print on a black build plate!
I also discovered a bit of a procedural issue, which I have solved, pragmatically, but could have done a better job if I'd been aware before.
Basically there are three things to consider; the printer itself, the Raspberry Pi, and the Octoprint software. As we all know, it is not a good idea to simply pull the plug out of a computer except in emergency, but the Pi doesn't have any other built-in way of switching it off, unless it has been rigged up with a keyboard/mouse and monitor and appropriate software. No problem if using Octoprint though, because after a lot of surfing I discovered there is an on/off switch symbol hiding at the top of the Octoprint screen. That has several options, one of which is "Switch system off", click that and the Pi shuts down... Great! Unfortunately, it does not shut down the printer at the same time, not only that, but it subsequently requires a trip the Pi to switch it back on again at the mains.
Now comes the clever bit ( not my idea), but first a short digression: Back just before Christmas SWMBO was given an Amazon Echo Show5. We have it set up to switch the TV on, and a couple of lights, more as a gimic than anything, but they are controlled by "smart plugs" and we have a spare, unused, one of those. So that is now set up with the printer plugged into it, in the spare bedroom which I use as a workshop, and I only have to say " Alexa... printer on" and she duly says "OK" and switches on the printer power, and "printer off" switches it off again, .
Now the forum post that gave me the idea was powering the Raspberry Pi from the printer's power unit ( that does actually seem to be a pretty common thing to do) so that means that the Pi and the printer are powered on /off at the same time. However having bought a proper power unit for the Pi, I didn't want to go poking in the printers innards unneccessarily so I've just plugged the printer and the Pi into a 2-way adaptor and that is plugged into the smart plug which then switches them both at the same time, simples.
So, the procedure is : "Alexa.... printer on", wait a couple of minutes for the Pi to boot up, log in to Octoprint on my laptop.... do whatever printing and watch it on the camera in Octoprint, then close down the system in Octoprint and, on getting the confirmation message, say "Alexa... printer off", all from the comfort of my sofa in front of the TV!
I'm currently working on a housing and mounting system for the camera. There are dozens on Thingy, but none that float my boat
I aslo want to create some sort of filament guide, to line the filament up in a straight line into the extruder. At one point yesterday I had a print fail because it was under extruded which I suspect was due to the angle of the filament at the extruder 'in' side causing it to hang up.