In planning to teach my students how to build circuits and program Arduinos, I decided to mount Arduino UNOs and small breadboards on 6″ long 2×6 blocks.  This should help keep the two together and since they are being used by 5th grade students and younger, having a larger and heavier block should make it easier to plug in jumper wires and small components without knocking anything around.  One issue that cropped up was that once the Arduino was screwed to the board it seemed like the USB cable was going to get jerked around quite a bit.  If you work with students you can probably relate to how rough they can be with classroom supplies!

To solve it I made a two part design that clamps around the USB cable and screws into the board.  Although you can’t unplug it from the Arduino anymore, it makes a huge difference in how much stress is put on the UNO’s USB port.

Assembled board with the strain relief installed

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I set up a FreePBX server for my school and most of it went smoothly.  We have almost 50 Polycom phones and Endpoint Manager made it very easy to assign the phones to the right extensions and put the right BLFs and speed dials on them.  The one issue that I ran into is that I put a Color Expansion Module on our receptionist’s phone, added all the extensions for our school in the right order in Endpoint Manager, left spaces between some BLFs to make it easier to find the right extensions quickly, and updated the phone.  To my surprise the BLFs were all on the phone and Expansion Module but they weren’t spaced correctly and were mashed together starting with the phone and then spilling over onto the Expansion Module.

I did some research and found out that Polycom has a way to space out the Line Keys, but Endpoint Manager doesn’t have that functionality added.  My solution was to make a separate config file with the correct order and spacing per Polycom’s directions and write a Bash script to insert it into the receptionist phone’s features.cfg file.  Although it does work, any changes to the order or spacing must be done by hand and Endpoint Manager will overwrite the changes when it rebuilds the config.  To overcome that, I made a cron job to run the Bash script every five minutes and since it is only one phone, making edits to the config by hand isn’t too tedious.

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I have several Anycubic Kossel 3D Printers that work great for the price ($180-320 depending on the model).  One issue I’ve run into is when a reel of filament gets low, I can’t reliably print with it for fear of running out mid-print and wasting the plastic.  With some changes to the Marlin firmware (version 1.1.8 as of this writing) and adding a sensor for less than $5, I was able to fix this!  The inspiration came from a Thingiverse model by Nenex that mounts this cheap sensor to the 2020 extrusions that make up most of the Anycubic Kossel’s body.

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My older style Anycubic Kossel Pulley didn’t come with a heated bed or a power supply large enough to run it.  Although the newer Kossels Anycubic is making (as of early 2018) come with both, I had to purchase these separately and piece it together.  I spent all of $20 on eBay for the 360W supply and it worked great, until two months later when I smelled some smoke and the printer shut off mid-print.  Opening up the case, I found a NTC 5D-15 thermistor that was ashy and split in two.  This is how I fixed it.

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