Pen Set and Boxes

What's in the crate?

Well, there's two boxes. A big one:

...and a smaller one:

And what's in the boxes?

Well, the smaller one has some bottles of ink:

The larger one has a set of pens and pencils. There's a fountain pen, a ballpoint pen and a pencil. All from Beaufort Ink.

Under the pen stand there is storage for the bits and bobs that go with pens and pencils.

The bits and bobs are housed in machined aluminium tubes with caps made from the same acrylic that the pens are made from.

Cartridges:

Ballpoint refills:

Pencil leads:

Commodore S61,N60 and M55 Connections

After opening up many old calculators and finding battery leakage has eaten wires and tracks, I thought I'd put up photos of a Commodore S61 (the same internals as the N60 and M55) calculator. Hopefully if anyone needs battery connection positions, this will help.

I've also added some more shots of the PCB just for the record.

This photo shows where the battery connects:

This is the entire PCB. The white taped thing on the right is my battery pack.

Here's the front of each of the three machines in the series:

M55

 N60

 S61

Quick Case for Straws 

We got some stainless steel straws recently and in order to transport them without damage, a case was needed.

A length of plastic pipe and some 3D printing and we have a case:

The bungs in the ends are printed in flexible plastic so fit snugly.

The straws and their cleaning brush fit in the tube and are protectd from bending:

Wooden Pen Box

Another pen kit from Beaufort Ink and a wooden pen box to hold it.

The box retains the bark as a feature (it's special wood...).

The pen is made from the same wood, so it's a good match for the box.
Recesses cut with a CNC router, crushed velvet lining.

Making a Night Light from an IKEA LED Lamp

After a request for some night lights I remembered that I had some IKEA motion sensitive LED lamps that were bought for use in cupboards. One is still in use, the other (they come in packs of 2) was just lying about. They are easy to fix to walls and battery powered, so no trailing cables. I tried one as a night light months ago, but it was very bright and came on during the day as well, so it was removed from duty.

Thinking about the new request, I wondered if the lamp could be modified to add a 'darkness only' feature. Dismantling the lamp revealed a standard PIR chip inside: the BISS0001. Looking at the datasheet revealed even more good news: the chip has a function that  disabled the output from triggering if it detects light. The example circuit has the components for this feature included.

I ordered the parts (100k resistor and an LDR) after working out the values I needed.

I modified one lamp and it didn't work, this was due to the routing of tracks on the PCB, so I lifted the pin on the IC and added the components directly to the pin. SOIC chips don't have robust pins, so bending it up once is about all it can manage. Any more flexing and the pin falls off.

After adding the components correctly, the lamp now only triggers and turns the LEDs on when it is dark. I've also removed three of the four series resistors that current limit the LEDs, as the amount of light given off was too much for a night light.

You also have the option of changing the time that the lamp stays on for, by changing the value of a resistor (or capacitor). This is detailed in the datasheet.

Lift the pin 9 leg:

Then put a 100k resistor from pin 9 to pin 11:

The LDR (light dependent resistor) looks like this:

I used my CNC router to cut a hole that matched the shape of the LDR and glued it in place:

The legs from the LDR wrap around the PCB quite nicely:

One leg can be soldered to the track at the edge of the PCB, the other requires a wire to run to pin 9:

I have modified one of the lamps to have a longer ON time, the rest are as they came. They've been running for a while now and are pretty useful.

These are the LDRs I used:
https://www.ebay.co.uk/itm/192823191519
The resistor was a standard 1206 100k surface mount resistor.

The Failures of 3D Printing

Not 3D printing in general, but the 3D printed parts that were no good, for whatever reason, when I was building my prototype can transformer. The finished article is here:

and makes things like this:

When I was building the prototype I printed many parts, a lot of which didn't work. This is normal for my builds, but this time I kept the failures. It was surprising how many there were:

The histogram of failure

I laid them out grouping the same part, so you can see which bits I had trouble with. The X carriage, for instance, is there as four failed parts, and the Z carriage is there in a form that isn't in the final machine. There are some gears in the picture (a lot of gears, in fact) which are also not in the final machine. I started off driving the Y axis using gears as they 3D print well. They have a lot of backlash, however, and just didn't work well enough. The final machine uses MXL belts.

The biggest failure is the part that engages with the top of the can and has to grab the can well enough to stop it moving as the Y axis rotates. They are the two rows of circular objects just down from the top. I had a lot of trouble with that poart and still don't have it perfect. In the end I made a common base for the part and screw inserts of different shapes in to it. This means I don't waste (any more) plastic and time printing the main body.

Most parts are failures for mechanical design reasons, the printer itself is very reliable now and I only had one or two print failures and they tend to be operator error in some form anyway.

The reason for black and white is that I have two printers, one set up for black and one for white. I found they print slightly different sized objects, so having different colours was useful as I knew which printer had printed what.

Coffee Machine Update

Coffee Machine Update

The coffee machine works. It's good for single cups of coffee, as you don't have to stand there too long pouring water. The old coffee machine is definitely dying, it now takes about an hour to run a pot of water through it.

To investigate how easy it would be to automate the new machine, I set this up:

There's a peristaltic pump:

which pumps water from the kettle to the filter. The power supply is adjustable, which is important to ensure the water flow isn't too fast as it will overflow the filter. For the pump I have the suitable voltage seems to be around 4V, which is pretty low. Usefully the power supply seems to remember its setting when it's off so you don't have to set it up every time you turn it on. A simple voltage regulator circuit and a knob would be equally and probably more suitable.

This arrangement also means you can replace the peristaltic pump pipe if it is dirty or damaged. You can also clean the pipe. We've never cleaned the insides of the old machine.