WIth a Good Hammer It All Looks Like a Nail

I have been down this road before.  I consider the Arduino microprocessor to be a nice hammer and I often find places to use it to solve problems that may or may not exist.  I have also been known to over engineer some of my solutions.  The  Wanhao D7 is giving me the chance to do both!

In a previous post, "Instrumenting a 3D Printer for Heat Testing", I introduced an Arduino based solution to monitor temperatures inside a printer.  I was able to demonstrate that the new 1.3 cooling solution is indeed effective at keeping operating temperatures within a healthy range for the UV LED array.

Since then I went a step further and tied two LED's to the Arduino, a green one, and a red one:

• Solid green - Fans are on and temperature of the UV LED array is optimal
• Flashing green - Temperature has risen above 50c
• Flashing red - Temperature is approaching critical of 60c
• Solid red - Temperature is above 60c

I have now taken my solution one more step and tied the Arduino to a relay that will power down the UV LED if the temperature rises above 65c immediately or after a solid minute above 60c.

Obviously this is pretty drastic but a) I do not see it happening unless something has gone badly wrong, b) RPis do occasionally burp and that burp could be after turning on the UV LED array and before turning it off again, and c) if something has gone badly wrong while a printer is running for a long period of time... I would rather lose a print than have expensive consumable items like my LCD and UV LED array burn out!

Naturally if I am going to these lengths then I am going to have a PCB fabbed!  Here is an image of version 1 which is being produced in China as this is being written:

Note that there are pins on the Arduino that are not being used and are easily accessible for jumpers. NanoDLP has some cool functionality that allows it to react to the state of pins on the RPi GPIO.  An example would be to insert a delay after a layer is cured to allow for cooling when temperatures exceed a certain threshold.  I don't see needing to do that but it is cool!