Author: opretter

Today we tested the flour dispense mechanism. Since the gears were already mounted on the motor, and we had the code for the motor, we just needed to mount the screw on the shaft. As seen below the motor started, and everything was moving as intended.

Then we tested the setup with with the auger screw inside the flour container to see how the flour would behave. As seen below this went very well, and the flour was successfully dispensed. Next step is weighing the amount of flour dispensed at each turn.

This was also our first test of the wall we put inside the flour container on friday. We learned that the flour is dispensed better with the wall, than with no wall, but it did not move the last bit of flour inside the flour container properly. We want to try and optimise the shape of it, by making a square or a trapez shape instead of a rounded shape.

Node Red progress

Today, we change to layout of Node Red, we keep what we already made and reconfigured some of the elements. The first link you will get to is the page where the user need to input their email. The go back button will take the user back if they came from another dashboard, otherwise the button will not do any thing.

After inputting the email, the use will get to a page where they can name the sourdough and the button will start a new sourdough, and send the user to the main dashboard. The cancel button will send the user back to the dashboard they came from.

In the main dashboard we remove the start a new sourdough, we did this because, the user, will have a smaller chance to start up a new sourdough by mistake. We also add the funktion to create a new user. This will take the user back to the sign up page, it the user regrets the user can use the Go back button to get back to main dashboard.

In the informationen part, we add the name of the sourdough, the baking mode and the travel is not change. The emails for the empty contianers and for the overfilled sour dough contianers is also set up. The Node Red layout is getting finish next thing is to test it together with the Arduino.

The electronics

Aksel has worked on putting all the various electronic together on a few breadboards as this will make prototyping and testing easier when the first chassis/test bench, is done. Besides that is important to test it all set together to verify that there are no conflicts.

The power supply has been ordered, it’s a 12V power supply, therefore we use a voltage regulator to power the Arduino and other 5V components.

The NodeMCU, stepper motors (and their drivers) and the peristaltic pump all run on 12 volts. There is even the option of dosing the flour with a 12v DC motor if the stepper motor isn’t powerful enough. This could also be explored as a mixing option.

The Auger screw for flour dispensing

We finally got our hands on the ~9hour 3D print of our own CAD-design of the auger screw. We got some valuable insights from the moments we had to remove the supports for the structure. Getting the auger screw free from the support was messy – and the rotor pin broke off in the progress. Thus we spend some time drilling a hole through the center, and replacing the PLA pin with a metal pin. This is going to be redesigned in the upcoming version of the auger screw.

Don’t say it with flour

Flour is filled with counterintuitive properties – not entirely easy to dispense precisely. Our first prototype with the small auger screw seemed to let the flour out fine from the bottom. But due to the amazing properties of flour, we would be restricted to a canister with the same diameter as the auger screw, if we were to rely on gravity itself. That would cause the flour-canister to become tremendously tall and slim, which is not quite suitable for the user, when flour is poured up. Therefore we needed a larger auger screw – or another way of dispensing the flour.

One of the issues with our current model of the flour-dispensing mechanism, is that the flour is falling straight down on the stepper motor. We have looked into different kind of bevel gears that would solve this issue by providing an alternative placement of the motor. In the morning we woke up to a team member having provided an alternative to expensive bevel gears, which was fast and easy to prototype on. We laser cut the parts needed, and tried to do a test of the gears and the new auger screw in the flour canister.

The Auger Screw v1.1 failed us

The flour went through the first to slopes seemingly without too much difficulty, however it came to a stop, no matter how many turns we gave it. At one point the flour began spinning on top of the screw, so no flour could be added. We learned that we should implement a wall on the flour canister to ensure it would not follow the spin of the auger screw.

The test gave us following insights:
We need a higher slope and/or fewer threads, which should be included in the next version of the auger screw.
OR we should look back at earlier ideas of dispensing flour.

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Alternative flour dispensing mechanisms

The “classic” or corporate way of dispensing flour, is with flour falling down on an auger screw, which moves sideways. We did a quick test with a flour canister, and it was too narrow to provide a proper slope for the flour to fall. Therefore we try to improve the current auger screw model, while we think of super smart alternatives.

Higher slope & fewer threads for Auger Screw v2.0

We set the new model up for 3D print, and will wait excitedly till tomorrow. The new model will have room for a metal rod to be inserted as a core – to give it the strength needed to dispense the flour.

Container lids

We worked on the lid for the flour container and the water container. The lids need to have holes for the ultrasonic sensor, the sensor is needed to measure how much flour and water is left in the containers. The lids need to hide away the cables and the ultrasonic sensor. We laser cut a part of the lid to see if it fitted the container and that the ultrasonic sensor fitted in the holes. We disused if the lid should be a cylinder, or a cylinder with a sloped top surface. We also played around with a design where the lid had a cylinder shape handle that will hide sensor. For now, we choose the cylinder shape lid. The lid will be made of 2 laser cut acrylic plate with holes for the ultrasonic sensor, a cylinder with holes for the cables and waterpipe and a top plate also made out of acrylic. We made drawing of the lid parts, so that we are ready to laser cut the parts. Because the acrylic is clear we need to paint, so that the sensor will not be visible. We consider, making the lid out of wood, but if we use wood, there is a chance it will reshape or rotten, with contact with water. It is also important that the ultrasonic sensor we stay clear of the water to avoid short circuit.

The mixer motor

So, we have had quite a few struggles with how the motor is going to work together with the dough hooks. The problem is, that the dough hooks should be in a neutral position when they haven’t been turned, and we don’t know if this can be done with a stepper motor without extra logic. A servo would be more suited as it has a rotary encoder to keep track of the position.

After some discussions we decided to mechanically force the dough hooks into a neutral position every time. This is done with a guiding channel where the dough hook axle can only pass through one way, any other way will turn the axle into the correct position.