Follow by Email

Monday, 29 February 2016

First Milled PCB

This is something I've wanted to do for a very long time. PCB milling. The first attempt has turned out rather well. It's not the most complicated board in the world, none of these milled PCBs will be, but it's turned out nice and clean.

This was with a 1mm D bit, I've ordered some smaller bits to see if I can get to a finer level of detail. Even at this level it's going to be usable for quite a few circuits.

Sunday, 21 February 2016

Compucorp 322G

This calculator, or maybe computer is a long term project. It's quite a bit larger than a handheld calculator, but it was pretty advanced for it's time. It's got scientific functions, memories, and it is programmable.

Mine had a very dodgy keyboard, with lots of key bounce. As the calculator errors if it gets keypresses too quickly for it's liking this was highly irritating. I dismantled the keys and cleaned the metal domes. These provide the click for the key and short out the PCB which registers the key presses:

There were some interesting extra keys under the front panel, I'm not sure what they are:

The PSU needs a rewire, as it wasn't working too well:

The plug needs replacing and probably the socket in the calculator too.

The calculator probably also needs some components replacing, as it seems to be able to eat a set of D cells in about three minutes, this is probably old capacitors or such like. Of course it could be rubbish batteries...

Thursday, 18 February 2016

Pen Set

This is a present, it's all been finished and sent off. Four pens (three pens and a pencil) and a box with space underneath for refills and so on, and a small keyring pen.

The pens are all kit pens and I have used the same acrylic for all of them, so it's a matching set. I matched the kits as well, so there's a definite style to all of the pens.

The blank is a turquoise blue marble and the kits all have a multiple chrome ring in the middle of the pen.

I turned all the pens on the wood lathe:

but I used the metal lathe to make some bushes for the pen making mandrel I use on the wood lathe:

I've done this for almost all the kits I have made. I have also bought some bushes for kits, though.

Polishing of the pens is done using a sequence of abrasive paper grades:

This gives a pretty nice finish to the acrylic, although I sometimes have to run up the grades from rough to super-smooth a few times to remove all the serious scratches.

The pens are mounted in a box on a rack. This was 3D printed and each pen's mounting notch is slightly different to accomodate the different sized pens. It's all covered in black felt paper.

 Underneath the pen rack there's a few compartments for refills and converters and a snug mount for the keyring pen:

I also made a small photobook with some pictures of the pen and box being made and some instructions about how to change refills.

The box is stained and has a brass clasp on the front:

Workshop Pencil/Droplead Pencil

I've been looking at buying a droplead pencil for quite a while now, I almost bought one at the Dulwich Picture Gallery, but didn't. Then I thought Why don't I make one? I had a look at the pencil kits and saw a 'Workshop Pencil' kit. It looked like a droplead pencil, so I ordered one. i had some purple acrylic so I made this:

I really like this pencil, it's smooth to write with and there's plenty of lead laid down when writing (the lead is 5.6mm dia).

Due to thinking I'd lost part of the kit I ordered a second kit, so I can make another one. Hmm. Green?

Portable ZX Spectrum

The venerable Sinclair Spectrum is from the 1980's and it was standard practice then to attach computers to a TV for the video output. This is inconvenient these days as TV's tend to be large and not the sort of thing you can cart about. So I had the idea for a 'portable-iser' which can be used to make a spectrum into a portable setup. Removing the need for a TV is pretty high up the list of things to do. I heard rumours on t'Internet of people using small LCD monitors with single board computers. They are designed for rear view cameras on cars. I ordered a couple, and then modified my spectrum to output composite video instead of modulated RF. This is just a matter of taking the input to the modulator in the Spectrum and connecting it to the RCA output connector (and disconnecting the RF signal to that connector). This gives a signal we can feed straight into the LCD monitor. The LCD requires 12V, apparently, it says so on the box. It turns out that you can use the 12V signal on the edge connector to drive the LCD.

The Spectrum was powered by a mains adapter, that's not very portable, so I wired a battery pack to the same connector the adapter uses and voila! We have a protable spectrum setup:

You can see the video on the LCD monitor works quite well, as the resolution is pretty low. It's colour too.

The only thing missing is some form of non-volatile storage, I tried a minidisc player but it didn't work for some reason I haven';t worked out yet. An SD card or MP3 player device would be good.
For now having a portable setup is good enough.

Saturday, 13 February 2016

ZX Spectrum Edge Connector

Years back I never had a ZX spectrum, but I do now. I fancy some hardware additions to this beastie so I needed some edge connectors. Unfortunately they don't seem to be made and sold anywher ethat is easily findable on websites, so I bought a couple from the retro computer shack. They need a bit of work to make them actually fit the spectrum, so rather than the suggested hacksaw, I used the mill:

Once milled they look quite nice, you'd not know they weren't the correct size to start. Here's the before and after picture:

Friday, 12 February 2016


I've done some more wiring and have run the small spindle up to speed using the controller. I've also got chillipeppr working using the web version, so all should be well once I have the connectors for the stepper motors.
They haven't turned up yet, hopefully they will be here tomorrow.

Tuesday, 9 February 2016

CNC Router

I have just bought the parts for a CNC router, which I hope to use for PCB milling and maybe some other routing type stuff. It's a 3040 type and I have an air cooled 2.2kW spindle (which is admittedly a bit large) and a 400W smaller spindle on order. I'm going to have to make a spindle mount for the larger spindle as the one on the 3040 is a 52mm diameter and I need 80mm.

I have a TinyG controller so I should be able to use USB as a connection to a host PC (which I also have to cobble together), which will be better than a parallel port.

The TinyG controller PCB:

I'm currently mounting the bits and bobs onto a shelf above the cnc. There's quite a few boxes, PSUs, controllers etc.

OLED Watch

The PCBs for the OLED watch have come back. That's the good news. The bad news is that the pinout for the PIC was for the wrong package and the battery holder is missing from the back.
They look nice though:

I've relaid the board out and sent the second set of artwork off.

The old boards might be usable if I solder an 8 pin PIC onto the IC pads. I could then maybe use an OLED display on the PCB.

Saturday, 6 February 2016

Fisher Filament Problems

I've had problems with the filament not extruding on the Fisher 3D printer. Usually it is when starting a print, the extruder motor skips and no filament comes out. Manually turning the filament drive doesn't help much, I have to retract manually and extrude repeatedly and then it's start up.
Anyway I had a bad episode this morning so I dismantled the hot end and screwed the nozzle in further and tried to get the PTFE tube aligned closer to the nozzle. We'll have to see how that goes, but it worked OK after I reassembled the effector.