Photon printing progress

I've finally started using my Anycubic Photon for something after a casual chat with a friend showed they wanted some custom parts made for collectable action figures.

When the thing somebody wants already exists on Thingiverse and you've got an SLA printer this kind of thing becomes an easy favour to do and it has the added benefit of giving you an excuse to get more experience with the printer.

Levelling the bed and slicing with appropriate supports is definitely a learning exercise and I've had a few failed prints, which are annoyingly wasteful of resin.

In the end watching a few YouTube videos got me to this good process for levelling. There seems to be a lot of superstition about the levelling process with vocal adherents for different methods but I'm now getting good prints with this variant.

  • Cut a piece of copier paper so it fits where the vat would go and so you can pull it back/forth from the front.
  • Loosen the hex screw in the middle of the build plate so it can move around on the ball joint.
  • CAREFULLY lower the build plate onto the paper (no vat) until it touches.
  • Lower it slowly, 0.1mm at a time until the paper is firmly held and can't be pulled.
  • Tighten the hex screw while putting light downward pressure on the build plate so it's firmly against the paper and screen.
  • Raise the build plate 0.3mm.
  • Lower the height of the build plate 0.1mm at a time until you can pull the paper out from underneath, but you can't push it back in. You may need to go back and forth a few times.
  • Set this as zero through the menu.
  • You do not need to do this every time, even if you've removed the build plate to extract a print.
Now I'm printing a few of the same thing in different sizes so my friend can try them with the figure, my first guess was perhaps a little oversize but the level of detail is fantastic. It's even better than it looks from the photo.

ESP32-VGA board from Bitluni

There's been a ton of work done by various people to make the ESP32 do things nobody ever really expected. One of those is to output quite decent VGA video.

In principle this is done with just some resistor ladders but building a board to do this is a bit fiddly so I've just picked up one from Bitluni on Tindie.

I don't have an immediate use for this but the vague plan is to use it as some kind of display interface that speaks to my mesh network kit. Connect a PS/2 keyboard and you've got a terminal device based on a microcontroller, rather than using a Raspberry Pi as a bit of middleware and this appeals to me greatly.

YG300 pico projector

I have in mind to build a handheld prop that projects information as you hold it.

What I'm not sure about yet is how this will be implemented but I've been thinking about building a low resolution matrix of lasers and doing something with persistence of vision as you move it.

Which may of course be completely impractical. 
I also saw these pico projectors on sale for only £30 and have picked one up as a more realistic cheap solution. You get what you pay for, they're only a 320x240 resolution, but it does work.

With a Raspberry Pi connected video playback of 4:3 SD content with omxplayer is actually perfectly acceptable for your £30. It's very dim, you have to use it in total darkness but turn the lights off and it's watchable. It'll also play off USB/SD.
To see what's inside I did a teardown. It's all quite predictable, some fresnel elements, a mirror to turn the image through 90 degrees, an LCD shutter and a COB LED illuminator with a big heatsink.

These can take an optional battery pack and there's a space behind the mirror for this. I did a little poking around with a meter and there are three unused connections on the top right of the board.
These connections are labelled B/R/Y

B - Ground
R - Battery positive, it expects a 2S Lipo pack so ~7.2-8.4v
Y - Supply positive which by default is 12V

I assume there's a balance charger built into the battery pack as there seems to be no charging circuit on the board. It runs quite happily off these connections and provides a little battery meter on the menu screens.

Using these connections seems perfectly reasonable although I can see myself making them external rather than squeezing them into the case.

I'd like to run this off a Raspberry Pi Zero, although equally something like an ESP32 can be wired up very easily to generate composite video. At 32x240 it really doesn't need to connect over HDMI.

Space inside is very limited but it would not be impossible to 3D print a replacement case that spaces the elements out like they are in in the original.

It could perhaps make for an interesting "pepper's ghost" setup that emulates a sci-fi hologram projector, just so long as it's in the dark.

EleksLaser end stops

I've had this laser engraver for quite some time but not used it as much as I originally expected.

Lots of that is because it is quite bulky so I can't leave it taking up a table and it's then a bit of a pain in the neck to set up every time, with lots of dangling cables and connections. So over the last couple of evenings I spent a bit of time screwing it down to a mounting board and making it portable.

Once I'd done this I was reminded that it doesn't have any end stops and is prone to hitting the end of travel if you're not careful. This irritates me more than it should as it doesn't actually do any damage, but it can waste loads of time making you set it up afresh with every run and occasionally ruining a job.

I did a little reading round the topic and decided to add end stops and configure it so it will auto-home. This is supported by GRBL but not the controller board supplied, it omits the connectors as well as the limit switches. It is however straightforward to solder the limit switches direct to the bottom of the board.

It was a real surprise to me there was no complete how-to for this even though the information is pretty freely available. So I wrote one and put it up with the designs for the switch holders on Thingiverse.

I'm still using LaserWeb to drive this but thinking about purchasing a copy of  LightBurn as it's quite affordable.

Enigma machine refresh

One of my favourite projects iss my Enigma Machine prop but it had a few shoddy areas. In particular the keys were just hot-glued in place on the end of the brass tubes. This made them prone to damage and they weren't 100% even.

Now my Ender 2 is printing beautifully I made some little cups to hold the keys squarely on the tubes and epoxied them in place. It's more solid and looks better too.
While I was giving it a freshen up I also made some little surrounds for the matrix 'rotor' displays. The Enigma was being made in a hurry and I simply didn't have time to cut neat square holes for the displays so I drilled out some round holes and wedged them in.

This has always annoyed me so I made round spacers to hide this. At some point I'll cut some tinted acrylic to fill the space above each matrix and act as a diffuser.