Previous blogs

Description

#1 - Introduction, the plan and materials preparationIn this blog post we describe the project's main concept and some initial high-level design of it.
#2 - Materials and casing assembly

Our journey with selecting proper materials, cutting and assembling the drawer and its casing!

#3 - Modelling, cutting, planting!The title says it all: this part describes some modelling we did before cutting some holes in the drawer and finally planted some vegetables!
#4 - Plants, harvests, and fertilisers

First harvest, problems with plants and used fertilisers. All that went off-script for our plants in the artificial environment.

#5 - Piping and pumping - water and liquid fertiliser delivery systemDesign and development of water supply system.
#6 - Mix of fixes - various fixes to water supply, lighting and hardwarePolish and fixes of various components of the system, all the small things.
#7 - Ride the lightning - Wiring diagram, pinout and components discussion

Diagram of the circuit, pinout for most components, wire choices and their connections

#8 - Pulling the stringsLED and Fan control circuit, overview of BJTs and MOSFETs with a handful of useful general information

 

 

Next blogsDescription
#10 - Software, architecture and the benefits of good preparationBig explanation of the software and its architecture
#11 - SummaryOur final post before the end of the challenge!

Intro

It is finally time to show off how we utilised the miracle known commonly as 3D printing! I suggest to look through this post if you are interested in 3D printing, as I will be sharing some of my tips and stuff I have learned so far when it comes to printing and modelling things to print! If you are not so keen on it, there is a plenty of nice pictures and renders below, so feel free to look through those . As you might have seen in the previous blogs, many 3D printed parts appear in our project, interacting with each subsystem of it in one way or another. I have learned a lot about 3D modelling and printing throughout this project as you will probably be able to see from the design quality .

 

Meet the printer: Prusa I3 MK3S

This project would definitely have been much more time consuming and some of it maybe impossible if not for this beautiful machine! I am in no way sponsored by Prusa, but I truly must admit that this is a work of art. So if you are ever considering to buy a 3D printer, definitely do check this one out!

 

 

 

3D Model

Since the project is constantly evolving, our 3D model of it is changing as well! All parts used in our project were modelled by us in Fusion 360, so here is a render of the up-to-date version:

 

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View at an angleView at an angle
Front viewFront view of Envidrawer
Bottom view

Bottom view of the envidrawer

The designs

Below each design visible in the render above is displayed with its 3D model and the actual printed part, along with a short history of that particular element . As you will soon find out, I am a huge fan of engravings on 3D prints, which is a neat trick and fairly easy to do! Also they make the prints look much more professional (in my humble opinion at least).

Here is a list of those elements (in chronological order):

  • MDF board clip
  • Outer cover rectangular legs
  • Support wheels
  • Capacitance sensor horizontal holder
  • Capacitance sensor vertical holder
  • Bed clip (Not used)
  • Motor holder + wheels
  • Irrigation hose holder

 

MDF board clip

The clip itself was a very simple design, but necessary as our top part of the Envidrawer's cover is made up of 2 parts. This clip has 2 purposes: the first one is holding those two parts together. The other one is to tie the clips to the bed so that the front part of the cover doesn't dip in the middle. With that in place the Envidrawer can freely move under the cover. The clip simply slides on the cover and the assembly is done!

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MDF board clip model assembly
View at an angle next to the actual 3D print

The clips were printed using Prusa's Gentleman's Grey PLA.

MDF board clip photo

 

Outer cover rectangular legs

The cover legs are a slightly longer story. The first version came out a bit too wide and the screw hole was slightly too big. By version 3 they fit perfectly in place and were extremely easy to install with a single screw each. Because of the nature of 3D printing, The parts were modelled so that the only overhang is very easy to print and generally a semi-complex object was turned into a very simple print! This is something I recommend everyone does when modelling things to be printed - think of the orientation of the print while designing, whether it will need supports, if so maybe it is best to design them yourself.

 

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Rectangular legs model assembly
Legs during print

 

There is a neat trick I used here: The actual 3D model doesn't have a hole in it, or rather it is there, but there is a thin layer

(exactly 1 layer height) of material before the hole. This makes the overhang so easy to print! Instead of working around the hole, the extruder can go over it! Then all you have to do is to puncture the single layer and the print is ready to be used!

 

The legs were printed using Prusa's Gentleman's Grey PLA.

 

For reference, see the 3D models to which I will post a link at the end of this blog.

Legs during print

Leg adapter model

Below is a model for an adapter for version 1&2. With it in place, they can be used as working legs, no need to recycle them just yet!

Adapter

V1 and V2 with adapters installedAdapter installed top viewAdapter installed bottom view
Leg with a screw before installingScrew to be mounted
Envidrawer cover with legs installed

Envidrawer cover with rectangular legs at an angle

 

Support wheels

Since the project itself ways quite a bit, we decided to add some support wheels underneath it so that the full weight won't be supported just by the motors. We found some old skateboard bearings, so we decided to use them here. The caster wheel support along with the axel and the nut were made out of PLA while the tyre itself was printed with filamentum flexfill 98A, a TPU polymer which has a similar hardness to hard rubber. When printing with a flexible material, it is important to run the print slower and loosen the idler which pulls on the filament, to prevent it tangling around it or jamming. Although I never experienced a jam with this material, I always followed those instructions, so keep that in mind . The wheel again went through some changes during the development process, increasing the thickness of some parts, adding the nut and threads to the axel to prevent it falling out.


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Support wheel model assembly
Flexfill tyre with bearing inside

The tyre design actually required some maths in order to be symmetrical, but turned out quite nice

wheel with bearing

Caster assembly

Here are all caster wheels already assembled and  after positioning them and temporarily securing in place with some tape,

they were attached to the drawer with some screws.

casters assembled

Motion subsystem

The Envidrawer is supposed to move on its own from under the bed and hide under it at the end of the day. In order for that to be possible, there needs to be a way for it to know when it is fully under the bed or completely visible. For this purpose we utilise 2 capacitance sensors, but more on that in the motion subsystem blog, to be released soon! The sensor holder designs derived from the simple yet effective MDF board clip design, cause why not reuse what you have already made .

 

Capacitance sensor horizontal holder

This too went through some iterations, Version 1 was a bit too fragile and hard to manipulate, But with a wider gap in the new version and stronger links the holder fit just right! I personally really hate 3D printed supports and removing them, so whenever I can I try to avoid them. A helpful tip is to always consider how you can split the part in order for it to be printed without supports. I then simply add some pegs on one part holes on the other with around 0.5mm of wiggle space and we got a ready part!

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Capacitance sensor horizontal model
Capacitance sensor horizontal holder V1

Here we can see the small "pegs" as they are guided into their holes to secure the part in place.

Horizontal holder v1 pegshorizontal holder v1 on envi

Capacitance sensor horizontal holder final side viewhorizontal holder final
Capacitance sensor horizontal holder final front view + rendered model

The holder was printed using Prusa's Gentleman's Grey PLA.

horizontal holder final frontRendered capacitance sensor holder horizontal

Capacitance sensor vertical holder

 

This design derived from the horizontal holder. The first version unfortunately was too big and did not fit inside of the drawer. The second one was a bit harder to print, with a tough overhang, nevertheless it printed flawlessly . With the modified design it also was easier to assemble

and disassemble (see the animation below). Another friendly 3D printing tip: round holes can be easily printed on a vertical wall, without any supports (nobody likes supports!). Additionally make sure to test your printers bridging capabilities before a print

with big overhangs to avoid failed prints. Luckily for me, Prusa i3 MK3S is an amazing machine and printed it without a sweat . Both V1 and the final version were printed in Prusa's Gentleman's Grey PLA.

 

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Capacitance sensor vertical model assembly
Capacitance sensor vertical holder v1

Version 1 worked similarly to the horizontal holder, with two parts being attached together, this unfortunately proved to be a bit to tall and did not fit under the Envidrawer's cover. The parts were printed at the same time and assembled afterwards

vertical holder afterprintvertical holder v1 assembled

Capacitance sensor holder final side viewvertical holder final side view
Capacitance sensor holder final + rendered modelvertical holder final top view

 

Motor holder + wheels

With support caster wheels in place, capacitance sensors attached it is time to combine it with the motors and print some bigger wheels! The tyres were a remix of the caster wheel tyres with slight improvents and everyting else was designed from scratch.

 

 

 

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Motor + coverr + wheel assembly
3D printing it

The plate connecting the drawer and the motor was printed using PLA, the tyre was printed with Filamentum Flexfill 98A (0.2mm layer height) and the wheel support was printed with black powdered Devil Design PETG (0.3mm layer height).

Plate v1

Nothing goes to waste! I used the failed v1 plates as soldering stands for the motors

 

 

 

 

Summary

Wow! that was long! for those that managed to get through all of this, I am sharing the last video of the day, my second ever 3D printing timelapse! As I already have a ton of embedded videos, this one will be linked to yt: https://youtu.be/FqjGjHK1LWg

All in all, there was a lot of 3D printing and modelling involved in the making of Envidrawer, still some to be made (an electronics box, other smaller designs). This was quite a piece of writing, took me much longer than I anticipated! We finally see the light in the tunnel as we close in on the deadline, stay tuned for an update on the Motion subsystem and more!

 

Szymon, Jakub & MichaƂ

 

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#8 - Pulling the strings#10 - Software detailed discussion