Raspberry Pi CP Terrarium Controller Using Node-Red

CP Terrarium

My first project was an attempt to learn some programming, some 3D printing, some sensor design, and combine them with a longtime hobby of growing carnivorous plants.

A Raspberry Pi 3B+ is the main control device.

1) It controls turning the lights on and off to match sunrise and sunset anywhere. Mine is set up to match the photo-period of their natural habitat.

2) It monitors the temperature and humidity and displays them on a remote dashboard that can manually override the automatic control.

3) Water level is controlled with a homebrew designed/built sensor. The sensor’s plastic element was drawn on Fusion-360. It was 3D printed at Milwaukee Makerspace. Water level status is also displayed on the dashboard and can be remotely run.

4) Coding is done with Node-Red, a graphical programming tool.

Node-Red Code

The actual terrarium is an uncovered 10 gallon tank. It has two species of Drosera  ( Sundews, a sticky leafed plant) and a Cephalotus. (Albany Pitcher Plant) Lighting is provide by a small LED fixture. Humidity and Temperature monitored with a DHT22 sensor. Water level measured with a CMOS Schmitt Trigger voltage division sensor. Remote viewing and control is done with VNC.

Real world progress is coming along. Code has been finished (until I get a better idea and redo it again) and checked. Temp/Humidity sensor is in place. Right now it’s only monitoring and displaying. Adding a heater and cooling fan is in the future plans. 3D printed sensor has been fabbed. Assembly, electronic circuit building, and testing will be the next phase I approach. Following that will be the addition of a water pump or solenoid to automatically replenish the water level when it drops.

 

TLDR version: Raspberry Pi monitors or controls a CP Terrarium’s lights, temperature, humidity, and water.

Node-Red Dashboard

 

3D printed sensor

Updated Filament Spool Holder for SoM

Big thanks to Tom Klein for a great modification of SoM’s filament spool holder!

The original design used to have a printed ABS top roller and I just pushed the roller against the flanges and finger-tightened the nut.  The problem was people kept taking it apart, so I added rubber bands to pull the roller down, and a nylock nut to prevent tool-free disassembly.  Then the rubber bands kept disappearing, and Tom came up with the idea of making a heavy top roller so the rubber bands wouldn’t be needed.  He cut a new, steel top roller on the lathe and it works great!  The bolt is just loose enough to let the roller slide up and down in the slot in the frame.  The roller is heavy enough that it just falls into position on the spool flanges.

Tangle-free filament spool holder

ShopWare and Markforged

We had a visit from ShopWare during our open night on Tuesday, January 29th, 2019. They thought we might be interested in seeing a Markforged 3D printer capable of printing with nylon, Kevlar, and carbon fiber. And they were right, we were interested!

They showed a few videos that featured the capabilities of very strong 3D printed parts, and then answered questions, and had a number of samples to pass around and show off. They also brought a Mark Two for us to take a look at.

One of the weird things about how the Mark Two functioned was that it homed the x and y after every layer it printed. It also lowered the z just a bit while it homed the x and y, then raised the z back up to meet the extruder (which was dripping a small bit of filament) before then starting a new layer. (None of us could figure out why it was doing that, or what benefit it offered, though we had some guesses.)

These appear to be some sort of brake lever, maybe for a bicycle or motor cycle. They were very strong. There was no flex at all when trying to bend them by hand. Typically parts printed with PLA or ABS feel pretty “breakable” but these seemed like you’d need some tools to break them. (I really wanted to crush one in the hydraulic press when no one was looking!)

Printed threads are no problem, and again, appeared to be very strong, and the ball joint moved pretty good.

The metal part was not printed on the Mark Two, but another Markforged printer. The part gets processed after it’s printed, so it shrinks a bit, but the software deals with sizing up your model before printing so it comes out the correct size when done. We’re pretty sure this part was “finished” a bit after printing as well, perhaps on a lathe, which would explain why the rounded part is polished while the flat hexagonal part is not.

While the extreme cold weather kept some members away, we had a pretty good turnout to welcome ShopWare, and for those who were there, got to see some cool technology we home to someday have a the space.

We have a new Prusa i3 Mk3 3D printer!

This is the printer that we won in the Hack-a-Day contest about 2 months ago.  It arrived at my house last night, so I decided to open it up and inspect the contents.  That’s when I saw it…

Broken upper left Z axis guide rail bracket.

Broken upper left Z axis guide rail bracket!

I lifted it out of the box and discovered that the left Z axis motor mount was also broken:

Broken upper left guide rail clamp and left Z motor mount.

Broken upper left guide rail bracket and left Z motor mount.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A quick trip to the Prusa web site found STL files ready for printing…

 

New motor mount and upper left guide rail clamp printing on UMMD.

New motor mount and upper left guide rail clamp printing on UMMD.

Finally, printed parts installed…

Broken parts replaced.

Broken parts replaced.

 

Alas, it appears that the lead screw is bent- you can see it wobbling when it rotates.  I’ll be contacting Mr. Prusa for a replacement…