Project development

Neil said something on the recitation which I really liked which was: “Propose a final project masterpiece that integrates the range of units covered” referring to masterpiece as showing mastery. I understand my path in the Fab Academy as a time to learn different skills, resources, techniques and machines which I will later apply in different future projects, giving the real importance to how good we have learned those skills and not the project itself. Regardless of this for my first spiral I will be designing part of the future kitchen of my van so I better master it!!!

For this week’s assignment I had to answer the following questions:

What will it do?

I will be designing a kitchen module that incorporates:

• a sink with the water jerrycans, water pump and faucet where water runs.

• storage for tableware, pots and pans. I want them to be as fixed as possible to avoid movement when on the road.

• propane canister storage and gas stove to cook food

• structure of the module and countertop

• drawers and sliding doors

I will also design some waterproof and lightweight tiles to avoid wood walls to get wet from cooking and washing.

I will also design a gas sensor that measures the gas in the van and alerts if it gets too high by turning on a red light and a buzzer.

I will also connect the gas sensor to an interface on my phone to regulate all this from an app.

Who’s done what beforehand?

• I know Andrew after Fab Academy he also made his van and in this link he explains how he did the gas installation, etc. So I will look at this for reference. There are also a lot of references online which I am already looking into.

What will you design?

• Kitchen module as seen in the sketch above taking into account lightweight materials, the total weight, openings, doors, secure closing, secure storage, measurements regarding the rest of the van, etc.

• Wall hexagon tiles by creating moulds which I have some tests done from wildcard week.

• Gas sensor with corresponding security box, I have been working in this in my input device and interface programming week already.

• Interface which connects to gas sensor (I have decided that I do not want to do this step anymore as I want the camper van to work totally offline).

What materials and components will be used? Where will come from? How much will they cost?

For kitchen module:

Material	Description	Where will it be used	Where to get it	Units	Price per unit	Total price
Wooden sheets	Plywood sheets	Kitchen module	Fijnhout Amsterdam	?	?	?
Wood treatment	to protect the wood	Kitchen module		?	?	?
Rails for drawers	?	Kitchen module		8	?	?
Magnets	to secure close cabinets and drawers	Kitchen module		7-8	?	?
Door hinge	to open gas canister cabinet and also water module	Kitchen module		4	?	?
Sink Enamel	Secondhand sink	Kitchen module	Facebook Marketplace	1	5.00€	5.00€
Faucet	Extendable faucet	Kitchen module	?	1	?€	?€
Drain hole	Fixed into sink manually	Kitchen module	?	1	?	?
Water pump	20V	Kitchen module	Wagenplatz	1	63.50€	63.50€
Tubes	Tube system connecting tap to jerrycan	Kitchen module	?	?	?	?
Jerrycan	20L cans for cleanwater and greywater	Kitchen module	?	2	?	?
Gas Stove	Dometic HB 2370	Kitchen module	Wagenplatz	1	129.00€	129.00€
Propane gas canister	10kg refillable	Kitchen module		1	?	?
Gas tubes	?	Kitchen module		?	?	?
Gas valves	?	Kitchen module		?	?	?

For kitchen tiles:

Material	Description	Where will it be used	Where to get it	Units	Price per unit	Total price
Epoxy	Bio-based epoxy	Kitchen tiles	Entropy Resins is an option.	?	?	?
Micro - plastics	to create tiles from them	Kitchen tiles	Precious Plastic stations	2	10.00€/kilo	20.00€

For gas sensor and interface:

Material	Description	Where will it be used	Where to get it	Units	Price per unit	Total price
Copper board	to mill	Gas sensor	Fab Lab Waag	1	?	?
Gas Sensor MQ-2	to detect propane	Gas sensor	Fab Lab Waag	1	?	?
Buzzer	to alert from high gas concentration	Gas sensor	Fab Lab Waag	1	?	?
UPDI connections male	to add buzzer and resistor to circuit	Gas sensor	Fab Lab Waag	2	?	?
UPDI connections female	to connect UPDI	Gas sensor	Fab Lab Waag	1	?	?
FTDI connections female	to connect FTDI	Gas sensor	Fab Lab Waag	1	?	?
LED	red	Gas sensor	Fab Lab Waag	1	?	?
Resitor	300Ω	Gas sensor	Fab Lab Waag	1	?	?
Capacitor		Gas sensor	Fab Lab Waag	1	?	?
ATtiny chip	ATtiny412	Gas sensor	Fab Lab Waag	1	?	?
ESP32?	wifi/bluetooth component to connect to interface	Gas sensor	Fab Lab Waag	1	?	?
Acrylic	to create a box to secure the gas sensor	Gas sensor	Fab Lab Waag	1	?	?

What parts and systems will be made?

• From the kitchen module I will design and create the structure of the 3 cabinets taking into account the incorporation of the different components after: water pump, sink, jerrycans, water system, gas stove, openings, gas canister. I have read the gas installation has to be done by a professional.

• I will also make the tiles myself with moulds and different materials. Still not sure if I would use epoxy or if I would make tiles from just plastic using the different machines from the precious plastic org at one of their stations.

• I will do the gas sensor by milling it with the Roland CNC machine, solder it and program it.

What processes will be used?

• For the kitchen modules I will first design them parametric using Fusion 360. I will do some tests with the laser cutter specially to test the openings. I will then cut the final pieces with the CNC and sand it manually (this will take a long time :) )

• For the tiles I will use moulding and casting techniques.

• For the gas sensor I will use electronics design, production and embedded programming.

What questions need to be answered?

• Is the design parametric?

• Do the kitchen modules work with the rest of the components which I will not make?

• Are the materials used lightweight, waterproof, and suitable to use on a moving space?

• Is everything I have done suitable to run a legal check?

How will it be evaluated? how do you tell if you succeeded or failed? VERY important!!!!

• If it works: drawers and cabinets open correctly

• If it fits in the space I have it planned within the van.

• If when connected to power source everything works fine: water pump, water running, nothing filters out, all the components fit in perfectly.

Your project should incorporate 2D and 3D design, additive and subtractive fabrication processes, electronics design and production, embedded microcontroller interfacing and programming, system integration and packaging It does!

Where possible, you should make rather than buy the parts of your project It does, I will try to also buy as much second hand as possible too.

I have also worked out how the rest of the modules will work to see how they would fit with the kitchen module of spiral 1:

Organising my time left

To organise my remaining left I used the Gantt App which Ferdi showed in one of our regional meetings. This came very handy! I downloaded the app from here.

Before designing the cabinet in Fusion 360

To start the design I had to understand and define some aspects first. To start with this is the van the cabinet will be placed in:

And this is a small sketch to start with, showing how everything could be stored and placed:

I started the difference between Face Frame cabinets and Frameless cabinets.

• Face-frame cabinets incorporate a frame that is attached to the front edges, or face, of the cabinet. Hinges mount to this face frame (typical in American cabinetry).

• Frameless cabinets are essentially box with an open front. The exposed front edges of the plywood or material used are covered with edgebanding. In this style of cabinets, hinges are mounted to the cabinet interior (typical in European cabinetry).

I also read some blogs which explained pros and cons from both: Copeland and Cabinets.com. Pictures below are from this pages.

Personally I think I prefer face-frame cabinets because I prefer the look it has but functionality wise and taking into account this is a campervan and space should be maximised I will be designing frameless cabinets. I would love to leave the box-frame exposed and paint the doors another colour to play with this so I am thinking of fitting the door within the box shape and use specific hinges to create this effect.

I also had some doubts on where to place the hob to cook. Could I place it on top of the opening door for the gas?

After trying different designs I decided that it was not possible to place the hobs on top of the right opening as it was a bit not very intelligent-comfortable idea and also not very safe. If I had to change the gas tank while cooking or if I had to remove the gas tank in case of fire quickly placing the hob here would be a problem and always in the way. After rethinking the whole design I decided that I would put the hob to the left and under the gas tank, the sink on the middle cabinet with the storage below and the gas tanks on the right accesing them with the upper opening (option shown on the tracing paper).

I also checked the regional requirements in order for my van to be passed as a campervan. The following will be very important when designing:

• at least 2 fixed seats.

• a fixed table: the table may be attached in such a way that you can easily remove it (this is what I had in mind with the second kitchen module).

• sleeping places for at least 2 persons, these may be sleeping places that you create using the seats. But not with the seats for the driver and co-driver. The minimum dimensions of the sleeping places are:

• with 1 double berth: at least 180 cm long and at least 110 cm wide

• with 2 or more separate berths: at least 2 berths are at least 180 cm long and at least 60 cm wide

• at least 2 fixed and lockable storage facilities

• a fixed kitchen unit intended for use in the interior.

• The worktop is at least 60 cm high, equipped with a built-in (removable) water supply with a sink, a tap and a drain.

• a permanently built-in cooking facility intended for use in the interior.

Another thing I had to look into was how to make drawers. I found this very helpful blog which explained it and this one. I bought 2 runners of 45kg in Gamma. I also learned that I had to leave some clearance at the back just in case, more a less 25mm.

I also learned about the different types of hinges to use within the doors of the cabinet. Finally I went for the european concealed hinges.

Understanding better how gas sensor MQ-2 works

In this blog they explain safety measures when installing a gas sensor in your van, the main concern is gas leakage, this is why you would want to have a gas sensor. If you combine a gas leakage with a spark you could have an explosion. Propane is highly flammable.

• the cabinet where you keep the gas cylinders needs to be ventilated to the outside of the van, this will be done with a gas vent.

• gas installation (valves, pipes, stove… etc) should be done by a professional.

• there needs to be a safety shut off valve on the gas bottle, this valve closes the gas in a case of a crash and prevents the gas from escaping from the bottle. Better to shut them off while driving.

• Propane and butane are non-toxic so LPG gas leak is not a problem health wise. Propane and butane are heavier that air so they accumulate near the floor. If you sleep on the floor this could lead so asphyxiation. Gas is also odorless so odor is artificially added so we can smell if there is a leak.

• You can get a 12V camper van gas sensor that detects really low gas concentrations.

Meanwhile I was looking into the design of my cabinet I was also researching further into the MQ-2 sensor for the gas sensor board. In my input devices week and my interface and programming week I worked a lot with my gas sensor board. This sensor board has a MQ-2 which is able to detect propane and CO2. I will use this to see if there are any leakages of propane or CO2 coming from the gas canister into the campervan. If there is, a buzzer and red light will turn on to alert me. I wanted to also have an alert on my phone via wifi using an ESP-32 but I will no longer incorporate this.

Quoted from last minute engineers “MQ2 Gas sensor works on 5V DC and draws around 800mW. It can detect LPG, Smoke, Alcohol, Propane, Hydrogen, Methane and Carbon Monoxide concentrations anywhere from 200 to 10000ppm.” Specification table shown below:

How will I measure the concentration?

What is 1 ppm equal to?
When measuring gases like carbon dioxide, oxygen, or methane, the term concentration is used to describe the amount of gas by volume in the air. The 2 most common units of measurement are parts-per-million, and percent concentration.

Parts-per-million (abbreviated ppm) is the ratio of one gas to another. For example, 1,000ppm of CO means that if you could count a million gas molecules, 1,000 of them would be of carbon monoxide and 999,000 molecules would be some other gases.

The sensor is actually enclosed in two layers of fine stainless steel mesh called Anti-explosion network. It ensures that heater element inside the sensor will not cause an explosion, as we are sensing flammable gases.

It also provides protection for the sensor and filters out suspended particles so that only gaseous elements are able to pass inside the chamber. The mesh is bound to rest of the body via a copper plated clamping ring.

To calibrate it I have to leave it 24h heating up only once, after this I only need to heat it up for a short time but I can’t do this through the ATtiny412, the one I was using, because this does not deliver enough current for the heater! Lucia is also working with gas sensor boards and she explained that the sensor uses 5 volts but it has a heater inside (H+ and H-) that uses a lot more current. The microprocessor cannot deliver enough current for the heater, so I will need direct current from the source. I will need to incorporate a mosfet because it is a type of transistor that will get the smaller amount of current from the microprocessor pin and turn into bigger current directly from the source on to turn the heater on on the short heating and off. She also shared this diagram to understand it better:

The mosfet would act as a switch but with electricity passing by, it will work like: if it is on HIGH = send signal.

So I will have to add a mosfet in my design, mosfet ssm3k336r LF/MOSFET_N-CH_30V_1.7A

I also changed the ATtiny 412 for the ATtiny1614 as it had more legs to attach the mosfet.

Water system installation:

After looking into different water systems for the campervan I came across with a very helpful video which illustrates a very good example for a water system. I would only want cold water so I do not have to take into account the hot water part of the system. The system would look something like this:

Starting from left to right the system holds an opening and closing valve for water to come from tank to system and then to faucet. Then a piece of water pipe (make sure this is suitable for drinking water and it is not made from a toxic material) connected to a filter which takes all little particles like sand or dust that may be in the water to avoid taking them to the motor(it might damage it) then it has the water pump motor, it runs on 12V and it pumps water 2.5 meters so it is more than enough for what I need, then it comes the expansion tank (internal pressurized diaphragm) which is optional but very recommended because it makes a constant and smooth supply of water and extends the life of the pump. After this there is another closing and opening valve (both should be off when not using the system) and this goes with the water pipe to the faucet. There are also female connectors to connect the different components together.

This video of how to silence your water pump may also be helpful in the future

Choosing and ordering the right material

There are still some things I don’t have ready and I have to order. I will re-do my checking list with more details and order everything to have everything ready for when I need to put everything together. Below you can find checking list.

For kitchen module:

• Wooden sheets to make kitchen cabinet. What materials are more suitable to make the kitchen cabinet for the van? After researching and reading different campervan blogs like this spanish one I finally decided to go for plywood sheets but what type? There are so many!! And so many different thicknesses. “Plywood boards are made of natural overlapping sheets or veneers of wood. They are placed alternating the direction of the wood grain, glued and subjected to pressure. It is a light wood and resistant to weight and movement.”

There are different types of plywood depending on its origin: the most common is poplar (the lightest and most flexible of all, but if we are using it for surfaces that will have to support weight we have to choose a plywood of at least 2 cm. It is the cheapest). Pine is the most resistant so it is ideal for furniture that will withstand a lot of pressure, but it is also the heaviest. Birch is halfway between the two, it is the balance point between weight and resistance. It’s the most expensive. Most people recommend birch plywood to make van furniture.

Also there is the possibility that a plywood board can be mixed. For example, they can sell us a birch board where the internal veneers are poplar and only the external ones are birch. That is why we have to make sure that the description says “100% birch” or ask to make sure.

There is also phenolic plywood which means that during the manufacturing process the sheets have been glued with phenolic glues, which are resistant to humidity. So our board will resist moisture and water without the sheets coming off. Any plywood from above can be phenolic, so a good board for the furniture of my van could be: 100% Birch phenolic plywood.

Regarding the thickness of the plywood the best I have read is 15mm, (also used this type of thickness for the bed).

I could cut costs by using phenolic plywood in the humid areas of the living room, such as the floor and the kitchen cabinet. We can make all the other furniture in Birch plywood, without being phenolic, but this is another spiral…

So … having read all this I think I will be using 100% birch plywood of 15mm. I could not find phenolic birch plywood in the Netherlands.

I also checked the grades of wood here as my final design would be made of BB/CP birch plywood.

After this some more questions appeared:

How will I securely attach the kitchen cabinet to the wall and floor to make it as sturdy as possible? Some people attach the furniture to the car’s chassis. I don’t know if by attaching it to the wall and floor wooden plates will it be enough? Or should I think in making it to attach it to the chassis (I’ve read that they do this with metric threaded fasteners and rivets 5).

How will I securely close all doors and drawers to avoid them opening when on the road? Ferdi recommended me the push button system. I was thinking in magnets but this also works and it comes integrated in the rails so it is less pieces to think about. As I read in some forums the push openers installed in the rails are not tightly shut (needs a little gap for it to be pushed & spring release). Another option is to install them on the front of the drawer. I found this blog on different ways to secure doors. Finally I think I will be using magnetic latches as I want the drawers and doors to have handles and with the push system there is no need for them.

What material to use on the countertop? For the counter top I will need a thicker piece of wood. As I will be using a 15mm thickness for the rest of the cabinet I think a piece of wood between 20-25mm would be ideal. This piece of wood would have to be properly treated. Reading through blogs most recommended using Butcher blocks of wood. This type of wood is both beautiful and practical: if it becomes too scratched or nicked, you can just sand it down and re-stain it. The one I linked is not butcher block but it is wood veneer from Ikea which are less expensive.

Another option is to buy a thicker piece of wood and treat it with Tung Oil/Citrus Finish. Tung oil is pressed oil from the nut of the tung tree and boiled. This type of treatment is recommended for tops used as cutting surfaces. Quoted from DeVosWoodworking. “Pure tung oil is FDA approved and non-toxic by nature. Citrus solvent, which is 98% orange peel oil and 2% water, is added to tung oil to hasten the drying process and deepen the penetration of the oil into the wood. The oil penetrating into the wood makes the surface resistant to water, heat and stain damage. Surfaces treated with the Tung Oil/Citrus finish have an overall matte quality while still retaining their natural appearance.” In this blog they explain how to properly buy a tung oil as “a lot of the “tung oil finishes” you’ll find at the hardware store aren’t pure tung oil. In fact, lots of companies use tung oil as a bit of generic term – as in any finish that includes some tung oil or even has a similar finish. Many are filled with mystery ingredients. But when I’m talking about tung oil here, I’m talking about pure, 100 percent tung oil.”

• I would have to oil it every 4 months.

• It takes a week to cure.

In the last page it explains the whole process of doing this. In this spanish blog also. This friendly man from Spain explains it very good in this video.

How to make it sturdy enough The way to make it sturdy enough is to calculate very well how the pockets and joints will be fit together to make a perfect press fit.

How to avoid vibrations or reduce them? I also read that to mitigate vibrations on the road we can use a strip on the joints.

With what type of material will I finish the wood - structural part of cabinet? There is the option of lacquer or the option of varnish. In this blog they explain the difference. My plan is to cut the pieces in the CNC, sand them and them apply the product. From the pros and cons I read I think I will apply varnish especially “Water-based varnishes form yet another group which are low on toxicity and easy to maintain. This type of varnish dries quickly, within 15 to 30 minutes, and does not crack or form bubbles. It also exhibits a fair degree of resistance to water and volatile substances. Water-based varnish does not become yellow with age but tends to become cloudy with multiple applications on certain woods.”

How will I attach the kitchen cabinet to the campervan? I was thinking of attaching the kitchen cabinet to the van with L-brackets. This way I don’t have to think about incorporating these in the design process. There is also the option of adding wooden studs to the chassis of the car and drilling the cabinets to it to hold it in place. Probably I will go for this last option. See how to do it here and here.

What colour to paint the cabinet doors?

I looked into different colours from Gamma (local hardware store)

And tested them all in fusion 360. In the end I went for the one which is to the left as I was looking for this type of intense colour.

So what do I need to make the kitchen cabinet?

Material	Description	Where will it be used	Where to get it	Where does it come from	Units	Price per unit	Total price
Plywood sheets for structure	birch plywood wisa twin 2440x1220x15mm BB/CP	kitchen module	Houtwerf	Russia	4	71.50€/sheet with 21% TAX	328.35€ including transport costs
Wood piece for countertop	okoume 40mm	kitchen module	reused it from one I found at home	-	1	0€	0€
Wood varnish	water-based varnish matte effect with a bit of colour	kitchen module	Gamma	Netherland/Belgium	1	8.74€	8.74€
Wood treatment to protect countertop	Tung oil	kitchen module	Amazon	China	1	14.99€	14.99€
Wood paint	colour green type customed “Boogschieter”	kitchen module	Gamma	Netherland/Belgium	1	10.00€	10.00€
Wood primer	white primer Histor	kitchen module	Gamma	Netherland/Belgium	1	6.49€	6.49€
Drawer runner	Steel side-mounted (leave 3cm of clearance at the back) 400mm 45 kg	kitchen module	Gamma	Germany	Need 4, comes in pack of 2	24,95€	24,95€
Drawer runner	Steel side-mounted (leave 3cm of clearance at the back) 400mm 12kg kg	kitchen module	Gamma	Germany	Need 2, comes in pack of 2	14.95€	14.95€
Magnetic closure	to securely close doors and drawers XXL brown (max. 10 kg), width: 19mm, heigh: 17mm, length: 75mm	kitchen module	Gamma	Netherland	pack of 6	5.99€	5.99€
Cabinet door hinges	drill-in hinge with spring type B 35 mm to open water module	kitchen module	Gamma	Netherlands	2 (comes in pack of 2)	6.49€	6.49€
Cabinet door hinges	hinges to open gas canister upwards	kitchen module	Gamma	Netherlands	2	9.99€	9.99€
Glue for wood	to make everything stay in place	kitchen module	Gamma	?	1	6.99€	6.99€
Metal screw	4.2 x 13mm (30 pieces)	kitchen module	Gamma	Netherlands	1	2.39€	2.39€
Metal screw	3.5 x 19mm (30 pieces)	kitchen module	Gamma	Netherlands	1	2.29€	2.29€
Hinges to attach cabinet to countertop	Seat corner Galvanized 40x40 mm - 4 Pieces	kitchen module	Gamma	Netherlands	1	3.39€	3.39€

So what do I need in terms of components for the system of the kitchen cabinet?

Material	Description	Where will it be used	Where to get it	Where does it come from	Units	Price per unit	Total price
Sink	secondhand sink	kitchen module	Facebook marketplace ad	Netherlands	1	5.00€	5.00€
Faucet	GIMILI Black faucet kitchen faucet with shower 360° extendable single lever mixer tap basin fixture	kitchen module	Amazon	America	1	84.99€	84.99€
Water pump	20V shurflo 7L/min comes with filter module	kitchen module	CampingSport	EEUU	1	87.99€	87.99€
Water filter	filters sand or dust from water	kitchen module	CampingSport	EEUU	1	8.95€	8.95€
Drain plug	drain plug with plug PVC for sink 1/2 “x32 mm	kitchen module	Gamma	?	1	6.29€	6.29€
Siphon flexible	Sanivesk flexible siphon moduflex 35-80 cm white 5/4” x 32 mm	kitchen module	Gamma	Netherlands	1	9.19€	9.19€
Universal expansion Fiamma A20 Fiamma A20	connection for pvc pipes 10-12mm	kitchen module	CampingSport	Italy	1	25.45€	25.45€
White 15mm pipe	John Guest LDPE with Wras symbol (not toxic) 1.5m	kitchen module	Camping Sport Amsterdam	United Kingdom	1	3€	3€
Push fit fittings with valve	John Guest push fit fittings 15mm	kitchen module	Tool Station Amsterdam	United Kingdom	2	9€	18€
Push fit fittings	John Guest push fit fittings female 15mm	kitchen module	Camping Sport Amsterdam	United Kingdom	2	4€	8€
Jerry-can for clean water and for grey water	20L FDA approved	kitchen module	Gamma	Netherlands	1	11.98€	23.98€

For kitchen tiles:

For the kitchen tiles I am doubting in how to do it. Either with bio-based epoxy or making tiles in a precious plastic station. These would look something like this. To do this I asked various precious plastic organisations in the netherlands: VanPlestik, Polimeer, ReMake, Pluspunt, Shred&Mold

Good afternoon, 

At the moment I am in the final two weeks of my final project for the Fab Academy in Amsterdam Waag. One of the aspects of the final project I'm making is making tiles out of recycled plastic. I am writing to you to know if it is possible to make this with you. I don't know if you have the machinery needed to make this. The process is something like the one shown in this Precious Plastic sample video: https://www.youtube.com/watch?v=dYG7qcGp5mc&ab_channel=OneArmy. I would hugely appreciate if you could help me to make this using your workspace. 

Thank you very much, 

Best, 
Paula Alonso

Finally the material I will be using is:

Material	Description	Where will it be used	Where to get it	Where it comes from	Units	Price per unit	Total price
Epoxy	Bio-based epoxy	Kitchen tiles	Entropy Resins is an option.	?	?	?	?
Micro - plastics	to create tiles from them	Kitchen tiles	Precious Plastic stations	HDPE plastic shreded by a precious plastic station	2	10.00€/kilo	20.00€

For gas sensor:

These were the final materials I used for the gas sensor:

Material	Description	Where will it be used	Where to get it	Units	Price per unit	Total price
Copper board	to mill the pcb board onto	Gas sensor	Fab Lab Waag	1	0.90€	0.90€
Gas Sensor MQ-2 SEN-17049	to detect propane	Gas sensor	DigiKey	1	4.04€
4.04€
8 ohm speaker CLS0201MA-L152	to alert from high gas concentration	Gas sensor	DigiKey	1	2.78€	2.78€
UPDI female connector	to add buzzer and resistor to circuit	Gas sensor	DigiKey	2	0.40€	0.80€
UPDI male connector	to connect UPDI	Gas sensor	DigiKey	2	3.45€	6.90€
FTDI male connector	to connect FTDI	Gas sensor	DigiKey	6	3.45€	20.70€
LED	red	Gas sensor	DigiKey	1	0.06€	0.06€
Resitor for LED	300Ω	Gas sensor	DigiKey	1	0.08€	0.08€
Resitor for gas sensor	5K	Gas sensor	DigiKey	1	0,17676€	0,17676€
Capacitor C3216X7R1H105K160AB		Gas sensor	DigiKey	2	0,23€	0,23€
ATtiny chip	ATtiny1614	Gas sensor	DigiKey	1	0.64€	0.64€
Mosfet SSM3K336R,LF	to control current going to the gas sensor	Gas sensor	DigiKey	1	0.42€	0.42€
Acrylic	to create a box to secure the gas sensor	Gas sensor	Fab Lab Waag	1	25€/100gr	3€

Designing the cabinet in Fusion 360

I want the cabinet to work with finger joints and pockets. Probably for security reasons I will later on also glue it as it will be in a moving vehicle and I want it to be as sturdy as possible. I also will have to attach it to the van as I explained before.

I first started deciding on the space I had for the cabinet. It could be around 1.40m to 1.50 long and between 0.5m and 0.55m of width. The cabinet will hold a:

• Module 1: the first cabinet starting from the left will store a gas locker and above it will be connected to the gas stove, in this cabinet I will also place the gas sensor screwing it to the wall.

• Module 2: the second cabinet will hold 2 drawers for storage and above it will have the sink.

• Module 3: the third cabinet will have a door which will open upwards and there I will store the gas tanks (fresh water and grey water).

I defined the length for each module depending on the things I would put inside (the gas tank, the water tanks, the size of the sink, the gas of the stove). This took quite a long time because I also changed my minds several times on where it was best to fit everything but finally I decided to put the water tanks on the right because the gas stove would not be safe to be placed on top of the upwards opening door. After deciding on this I started making the parameters I needed to make the cabinet parametric:

I started to make the modules with their corresponding parameters:

And started to extrude the walls:

I also decided to add a toe kick to my design as this would make it much more comfortable when cooking and also taking into account I had limited space it would ergonomically fit better within the kitchen space. This space could also become drawers in the future:

I joined the pieces with finger joints and pockets. Pockets will be 11mm deep from the 15mm wood thickness.

When there is double walls together I alternated the joints as you can see below:

I also had doubts with the clearance of the doors and drawers doors and also with the offset I would need to put on the offset from the Shopbot(as we did in the Make Something Big week) to double check the pockets fit precisely. To solve this I made a small replica that would test this before milling the whole thing:

I also tested with different types of colours of paints I got from my local store Gamma to see which colour I would prefer to paint the doors and drawers:

Finally I added the countertop (this would be a separate block of wood of 40mm) and decided to use L hinges and glue to attach the countertop instead of putting pockets as I did not want to mill screws onto the the countertop (these would be visible). I also added a replica of the vintage sink I had bought to see how it would look with the cabinet:

Milling and soldering

The schematic and pcb design was quite similar than the previous ones but I changed the chip and the mosfet. I also added a capacitor to reduce noise on the board. The mosfet has 3 pins:

• One pin is for the powersupply (S) which is the power source of 5V going directly to the mosfet called in my schematic “”

• One pin is the Gate (G) which comes from a pin of the microchip which says something like now give power to the gas sensor. (There is also a pin connected to the chip which says now get analogue output from the sensor).

• One pin is the Drain (D) which is the direct voltage coming from power source going to the sensor

This is how my final schematic looked like:

I milled and soldered the board but had to repeat it because Lucia figured out the footprint of the Mosfet was the wrong way around, so the source and gate were the wrong around as you can see below:

This is how the final correct schematic looks like:

The final files that I milled in the corresponding order:

This is how the final board looks like:

Using the ShopBot to cut the cabinet:

To start with I did a first test with the small replica of the cabinet. Remember to leave a bit more than 5mm from the screw to the actual milling. Don’t forget the dogbones!! For this I used all the steps from my Making Something Big Week.

The sheets were 15mm but I first measured different parts of the sheet. For example 15.20 would not cut it through in some parts. After cutting the first test the clearance test I did worked okay with the 2mm I had done in the Fusion parameter for the opening clearance of doors and drawers but the pockets did not fit. I measured the depth of the pocket and instead of 11mm it was 10,70mm. The cut overall looked also very rough. Something was not quite right.

I will do a second test where I will:

• change milling bit for a new one
• changed feed rate of tool in VCarve to 80
• change thickness depth for outside and inside milling to 15.40
• leveled again z axis (after having made the screws)
• changed offset allowance to -0.4mm instead of -0.3mm which is what I had done for the Something Big Week.

The results after the test were:

• the cut is not rough anymore so that means changing the milling bit was the right thing to do
• the allowance offset is too big now (it becomes loose, there is no press fit)

I will do a third test where I will:

• change the offset allowance to -0.2mm

The results after the test were:

• Pockets worked very good.

When I milled the first sheet I made an error because VCarve interprets pockets on the sides as complete through finger joint:

So it cutted the whole piece through. After doing this (which I did this to make hided finger joints) I decided that I would not repeat the piece again and changed the design in Fusion so all the pieces fitted as finger joints:

The final outcome of the pieces was very good! Everything fitted together although I did A LOT of sanding to make this work. After having put all the pieces together it looked like this:

I would have left the allowance offset of -0.3mm in the end because although it was more a less loose it would have made things easier in the end.

Contacting precious plastic companies

I contacted different precious plastic stations and even visited one more place of Precious Plastic in Rotterdam but due to the small time I had left and their availability I am not able to develop the tiles anymore for this assignment, this will have to be done after Fab Academy!

Developing the code for the gas sensor:

• I checked the board by uploading the hello echo code and this worked:

• I then checked the gas sensor by using the same code as in the interface programming week:

#define MQ2pin (11)

float sensorValue;  //variable to store sensor value

void setup()
{
  Serial.begin(9600); // sets the serial port to 9600
 // Serial.println("Gas sensor warming up!");
  delay(20000); // allow the MQ-6 to warm up
}

void loop()
{
    sensorValue = analogRead(MQ2pin); // read analog input pin 0

 // Serial.print("Sensor Value: ");
  Serial.print(sensorValue);

 // if(sensorValue > 300)
 // {
 //   Serial.print(" | Smoke detected!");
  //}

  Serial.println("");
  delay(2000); // wait 2s for next reading
}

• But I now had to incorporate the buzzer and the red light. I first tested the red light of the board and it worked:

// Blink the LED on and off every two seconds

#define led_pin PIN_PA4 // This uses the ATtiny pin number
//const int led_pin = 0; // This uses the Arduino pin number instead

// The setup function only runs once when you press reset or power the board
void setup() {
  // Use the alternate pin positions due to swapped TX&RX pins
  Serial.swap(1); 
  // Initialize digital pin led_pin as an output
  pinMode(led_pin, OUTPUT);
}

// The loop function runs over and over again forever
void loop() {
  digitalWrite(led_pin, HIGH);   // Turn the LED on (HIGH is the voltage level)
  delay(1000);                   // Wait for a second (= 1000 microseconds)
  digitalWrite(led_pin, LOW);    // Turn the LED off by making the voltage LOW
  delay(1000);                   // Wait for a second
}

• I then checked the speaker. I saw a video which uses this speaker to make the happy birthday song. I also checked this reference and this one. You can make different types of tones if you incorporate the file with the notes. I used this same code with my board. For this code you need to incorporate the file pitches as following, it will be incorporated to the code as a new tab:

/*
  Melody

 Plays a melody

 circuit:
 * 8-ohm speaker on digital pin 3

 created 21 Jan 2010
 modified 30 Aug 2011
 by Tom Igoe

This example code is in the public domain.

 http://www.arduino.cc/en/Tutorial/Tone

 */
#include "pitches.h"

// notes in the melody:
int melody[] = {
  NOTE_C4, NOTE_C4, NOTE_D4, NOTE_C4, NOTE_F4, NOTE_E4,
  NOTE_C4, NOTE_C4, NOTE_D4, NOTE_C4,NOTE_G4,NOTE_F4,
  NOTE_C4, NOTE_C4,NOTE_C5,NOTE_A4,NOTE_F4, NOTE_E4,NOTE_D4,
  NOTE_AS4,NOTE_AS4,NOTE_A4,NOTE_F4,NOTE_G4,NOTE_F4,
   NOTE_C4, NOTE_C4, NOTE_D4, NOTE_C4, NOTE_F4, NOTE_E4,
  NOTE_C4, NOTE_C4, NOTE_D4, NOTE_C4,NOTE_G4,NOTE_F4,
  NOTE_C4, NOTE_C4,NOTE_C5,NOTE_A4,NOTE_F4, NOTE_E4,NOTE_D4,
  NOTE_AS4,NOTE_AS4,NOTE_A4,NOTE_F4,NOTE_G4,NOTE_F4
};

// note durations: 4 = quarter note, 8 = eighth note, etc.:
int noteDurations[] = {
  4, 4,2,2,2,2,
   4, 4,2,2,2,2,
    4, 4,2,2,2,2,2,
     4, 4,2,2,2,2,
     4, 4,2,2,2,2,
   4, 4,2,2,2,2,
    4, 4,2,2,2,2,2,
     4, 4,2,2,2,2
};

void setup() {
  // iterate over the notes of the melody:
  for (int thisNote = 0; thisNote < 52; thisNote++) {

    // to calculate the note duration, take one second
    // divided by the note type.
    //e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.
    int noteDuration = 1000 / noteDurations[thisNote];
    tone(A5, melody[thisNote], noteDuration);

    // to distinguish the notes, set a minimum time between them.
    // the note's duration + 30% seems to work well:
    int pauseBetweenNotes = noteDuration +50;
    delay(pauseBetweenNotes);
    // stop the tone playing:
    noTone(A5);
  }
}

void loop() {
  // no need to repeat the melody.
}

• I then modified the notes in order to have the same notes beeping continously and it also worked.

• Then what I did was make a code which combines all this together plus the old code that I had. I made a loop of “if gas concentration higher than..” then make speaker beep and red light turn on. This also worked after trying different things:

// Gas Sensor detecting CO2 and Propane for campervan
// If gas concentration higher than _?_ red light will turn on and alarm will start beeping
// Charge 24h the sensor board to calibrate it
// Board working on 5V

#define MQ2pin (11)
#define led_pin PIN_PA4
#include "pitches.h"

float sensorValue;  //variable to store sensor value

// notes in the alarm:
int melody[] = {
  NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4,
  NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, 
  NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4,
  NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, 
};

// note durations: 4 = quarter note, 8 = eighth note, etc.:
int noteDurations[] = {
   2,2,2,2,2,2,2,2,
  2,2,2,2,2,2,2,2

};


void setup()
{
  Serial.begin(9600); // sets the serial port to 9600
  Serial.println("Gas sensor warming up!");
  delay(20000); // allow the MQ-2 to warm up
  pinMode(led_pin, OUTPUT); // initializes digital pin led_pin as an output
}

void loop()
{
    sensorValue = analogRead(MQ2pin); // read analog input pin 0

  Serial.print("Sensor Value: ");
  Serial.print(sensorValue);

  if (sensorValue > 710)
 { 
   // iterate over the notes of the alarm:
  for (int thisNote = 0; thisNote < 52; NOTE_C4) {

    // to calculate the note duration, take one second
    // divided by the note type.
    //e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.
    int noteDuration = 1000 / noteDurations[thisNote];
    tone(A5, NOTE_C4, noteDuration); // A5 is the pin number of my speaker

    // to distinguish the notes, set a minimum time between them.
    // the note's duration + 30% seems to work well:
    int pauseBetweenNotes = noteDuration + 100;
    delay(pauseBetweenNotes);

   digitalWrite(led_pin, HIGH);   // Turn the LED on (HIGH is the voltage level)
   delay(1000);                   // Wait for a second (= 1000 microseconds)
   digitalWrite(led_pin, LOW);    // Turn the LED off by making the voltage LOW
   delay(1000);                   // Wait for a second

    Serial.print(" | Smoke detected!");
    Serial.print(sensorValue);
    delay(2000); // wait 2s for next reading
 }
  } else {

  Serial.print("Sensor Value: ");
  Serial.print(sensorValue);
  delay(1000); // wait 2s for next reading
 }

}

A video showing how the sensor is working:

Laser cutting acrylic box for pcb board:

I then laser cutted a box on acrylic to encapsulate the sensor board and screw the box to the same cabinet (within the space for the gas tank). I put special attention to making it pressfit (had to repeat it 3 times trying different thicknesses) and left some holes at the back to be able to screw it. I also made a hole for the diameter of the gas sensor to be able to sense the air and a hole for the FTDI to be able to be connected, as well as for the speaker. This was the result:

3D printing pipe holders:

I could not do the tiles so I decided to make some pipe holders to screw to the cabinet and secure the pipe in place. I did the design in Fusion 360:

I measured the diameter of the screws I would be using and made a hole on the piece

I prepared the gcode files in Prusa Slicer and printed them out with the Prusa with the settings I used in Output week

I did three tryouts:

• The first one was too thick and the screw hole too small so I made the piece shorter to see if it would be sturdy enough with less material (less material being used) I also made a bit bigger the size of the diameter of the hole.

• The result was good, the piece was strong enough to hold a pipe but still the hole was a bit too tight so I did a third version with the hole a bit bigger (after measuring the screw again).

• The third version was the good one, worked very good! You can check how I screwed it in my final presentation video

To paint plywood doors:

I sanded all the pieces from the cabinet for them to fit smoothly but I also wanted to paint the door and drawer from the cabinet green. As it is plywood I researched online that the best way to do this would be to:

• Sand the pieces with very fine grit sanding paper so that it absorbs better the paint.

• Apply 2 coats of primer using a paint sprayer (or manually). Allow to dry 3-6 hours and sand between each coat of paint.

• Apply 2 coats of paint using a paint sprayer or manually. Sand lightly between each coat with super-fine grit and wipe off all the dust.

• Apply a couple of coats of polyacrylic - in matte or gloss - depending on your preference and you’re done.

I did all this except the coats of polyacrylic.

Making presentation video and slide

To make the presentation video of my project I used kdenlive. I really enjoy working with this program, I think it is quite complete and intuitive. I did not really see any tutorial I just looked for things. It was not a really complex video, I just placed the clips and put a fading effect as well as subtitles. You can check the final video here

I made the slide in Illustrator also. I had already done a template for it on week 17 so this went really straightforward. You can check the final slide here

After presentation feedback

Neil said I should show more how the gas sensor works. Show how you test the gas sensor.

Managing time

Overall, after the Gantt chart I followed, I think I did quite good managing time, the only thing I did not manage on time from my whole planning was the tiles and contacting different companies to make this (as I did not wanted to make this with epoxy). This would have needed to be planned more in advance to take into account the availability of the different companies.

Files from final project:

• This is the .stl file for the kitchen cabinet | stlkitchencabinet

• This is the Ki-CAD schematic file in PDF | kicadschematicgassensor

• This is the Gas sensor holes PNG | holespng

• This is the Traces PNG | tracespng

• This is the Interior PNG | interiorpng

• This is the .stl file for the acrylic box | stlacrylicbox

• This is the .stl file for the pipe holder | stlpipeholder

• This is the g-code file for the pipe holder | gcodepipeholder

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Last update: July 2, 2021