Enclosure controller

As mentioned in an earlier post I have a plan to add an Arduino Uno based controller for enclosure. Its responsibility is to monitor temperature, control ventilation fan speed and switch on the main relay. It also has a simple 1602 LCD display shield for temperature and other information. At the moment I haven't planned any use for the keys of the display shield.

So far I have been testing the design on a breadboard in order to get temperature reading and relay control working. I have plenty of 100k Ohm NTC 3950 thermistors so I used one to measure temperature using voltage divider circuit and Steinhart–Hart equation in the Arduino code. There are plenty of examples online how to wire this up.

The main relay is an automotive 40A relay with integrated fuse socket. The funny thing was it actually came with a 30A fuse. That should be enough, though. In order to energise the coil of the relay I used BC548 NPN transistor. I also added 1N4148 as a flyback diode.

Adding a PWM controlled 12V should be straightforward. I will use BC548 or BC639 but I might add a capacitor to smooth out the fan control. After I have that sorted out on the breadboard I'll solder everything together.

Polarity matters

I was reorganising the cabling after I installed the cooling fans next to the hot end. I checked there were no loose ends and everything seemed to be fine. But as soon as I turned the PSU on there was a faint popping sound and no lights on the LCD. I managed to connect wires from PSU to RAMPS wrong way and that instantly fried RAMPS.

Looks like the LCD and MEGA are okay though, I was able to turn them on with USB power and use different features on the controller. However, none of the steppers move and the hot end wont warm up. Just to make sure I decided to order new RAMPS, MEGA and stepper drivers again. This will mean couple weeks pause with printing but I'll use that to design and build an enclosure for the printer.

Toolson improvements

The plastic parts of my P3Steel are quite a mismatch and I have started to print new ones. I chose very nice selection of essential parts and improvements called Toolson edition. It can be found from http://scheuten.me/?cat=9.

So far I have printed parts for Y axis but I haven't installed them yet. I need to wait new bearings to arrive as it uses smaller flanged bearings. I also have bunch of other stuff on the way including cable sleeves, Kapton tape, 40mm fans etc.