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Thanks to the current corona-virus crisis, the parts I ordered for the filament joiner project were taking forever to arrive. But now that they have finally arrived, I can put them to good use.

These were the parts ordered:
0.96" OLED display SSD1306Rotary switch encoder KY-040 Here is the final circuit diagram:
The OLED display is connected to the SCK and SDA pins of the Nano (A2 and A3 respectively), and powered by 5V and GND.

The rotary switch encoder is connected as follows:
VCC => 5VGND = > GNDCLK => D9DT => D8SW => D2 My prototype board now looks like this:


The updated code for driving the knob and display is available in heater-with-display.ino in the Github repository.

We now have a fairly compact (about 7cm x 5cm) and independent filament joiner (no need to connect to PC) that is driven solely by a 12V power supply.

Here's how to use it to join printer filaments.


More usage details in my previous post.

I have been looking at various ways of joining 3D printing filaments.

One method involves running one end of a filament through a short PTFE tubing, melting it with a lighter or candle, retracting it back into the tubing and immediately plunging the filament to be fused into the tubing:


One problem with this method is that you can't really control the temperature at which you melt the filament, so you frequently end up with a brittle joint that breaks upon the slightest bend.

Aliexpress even sells a contraption that works along the same line. As it uses a lighter or candle as well, it suffers from the same weakness. I am not even sure why you need a special contraption when a short PTFE tubing will work just as well.

Another method involves using shrink tubing/aluminium foil, and a heat gun:


But a heat gun is rather expensive, so I wanted to explore other alternatives.

The candle + PTFE tubing method actually works quite well when you happen to melt it at the right temperature. It…

Wife bought a set of anti-fog film for her car and asked me to help her apply them to the side mirrors. Turned out to be a really bad idea.

Firstly, it is difficult to get good clean results. If you have ever tried to apply film-based screen protectors for your smartphones or tablets, you know what I mean. You invariably get smudges or bubbles under the film, and the result does not look quite as nice as what they show in the photos. Furthermore, you are doing this outdoors, where dust is floating everywhere and invariably get caught under the film.

Secondly, and that's the most annoying part about this product, these things stick like crazy! Once they are on, they are impossible to pry off the mirror! I got a fright when I realized the little piece of cardboard that was provided did not make the film budge. Tried a credit card, and that didn't work either. Tried hair dryer on high mode, nothing. At that point, I was extremely frustrated! What kind of product-from-hell was thi…

I threw together a current meter based on the content posted here. It consists on essentially 3 components soldered on a perf board.



The 3 components are:
ESP-12ELTC-41500.96" OLED module SSD1306 (128x64) Here it is, hot-glued into a simple 3D-printed enclosure, and running:



The schematic is as follows: The meter is powered by the micro-USB port on the ESP-12E. I soldered header pins onto the IN and OUT terminals of the LTC-4150. The whole idea is that one could plug the source battery into the IN terminals, and plug the circuit to be tested into the OUT terminals, press the "Reset" (RST) button on the ESP-12E, and it will start measuring the average current draw of the circuit.
The current meter can be easily tested with a passive load like a 100ohm resister, which will simply display a constant current value (V/R). 
But it is really more useful for testing a variable load, like the ESPCLOCK, where running the current meter for a couple of cycles will give you a pretty …

This is an adapter for Ozito 18V battery trimmer (and possibly some Bosch trimmers as well) that uses a plastic blade for cutting.


It lets you insert a 2.4mm trimmer line (about 8cm long) and use that for cutting.


Simply cut a length of trimmer line and briefly heat up one end with a lighter so that a little bulb is formed.


Then insert the trimmer line into the adapter and slot that into the trimmer as per normal. Make sure the trimmer line is not so long that it touches the safety guard. If that is the case, simply trim off any excess with a cutter or scissors.


This part is best printed using PETG, which is a tougher and more flexible material. PLA is more rigid and breaks more easily. However, even with PETG, it will still break when it hits something really hard. Since this takes only 0.5m of material and 15 minutes to print, I will usually print a batch of nine at a time at very little cost. The blades that they sell do not break when it hits a hard object, but it will dislodge an…

Well, you don't really 3D print the entire battery tester. That would be neat though.


This is a actually a 3D-printed casing for the ZB206 battery capacity tester.


What you do print is an integrated battery holder (rubber-band-powered) that can hold an AAA, AA or 18650 battery for testing. So it is easy to pop in any of those batteries and begin testing its capacity immediately.


The ZB206 is mounted to the casing using 4 M3 x 6mm screws. There are 4 bolts that come with the board. I repurposed 2 of them as battery terminals, as shown in the photo.


You can find the OpenSCAD source file and STL file on Thingiverse. 

I have been bitten by this too many times, so note to self: If you are unable to connect to a network share on a new installation of Windows 10, and getting "Unspecified error 0x80004005" with a "net view \\REMOTESHARE" command, but "ping REMOTESHARE" works, then the issue is because the network share is using the ancient SMB1 protocol, and Microsoft has chosen to disable it by default on Windows 10 starting with the April 2018 Update.

There are 2 ways to re-enable SMB1:

1. GUI way
2. PowerShell way

Yes, I know SMB1 is deprecated for security reasons, but when you have working devices at home (eg. memory card on that Epson XP420 printer) that you want to get to over the network, you have very little choice!

Every time I hit this problem, I foolishly spend a few hours testing network connectivity and googling for the solution, which drives me crazy. Hopefully I remember this blog post the next time I inevitably hit the same problem again...