Arduino Kitchen Scale

In this project I will show you how to build a simple kitchen weight scale with a custom 3D printed enclosure!

Step 1: Intro

I have been getting into meal prepping lately to save time and attempt to eat healthier. I was missing a kitchen scale to verify all of my food portions were split evenly so I decided to make a simple kitchen scale. I am still learning Fusion 360 so I decided to design a custom enclosure to house the electronics, load cell, oled screen, and battery.

It is a simple project and could be used as a great introduction into load cells, 3D design/printing, electronics, and programming.

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Step 2: Components Needed

The components needed for this project are below:

1. Arduino Nano Amazon Link

2. Load Cell (5 kg) Amazon Link

3. 0.96 inch IIC Serial White OLED Display Module 128X64 I2C SSD1306 Amazon Link

4. On/Off Button Amazon Link

5. 9V Battery Amazon Link

6. 3D Printed Components (I use this filament Amazon)

7. M4 x 45 mm (2)

8. M4 Nuts (4)

9. M4 x 20 mm (2)

10. 10K Ohm Resistor Amazon Link

11. Push Button Amazon Link

12. HX711

Disclosure: The amazon links above are affiliate links, meaning, at no additional cost to you, I will earn a commission if you click through and make a purchase.

Step 3: Electronics

Now that you have gathered all of the required components, it is time to start assembling everything together. I would recommend wiring up everything on a breadboard first and then once everything is functioning properly go ahead and solder everything up on a perf board.

I used a common load cell that you can find on Aliexpress, Ebay, or Amazon. That is then wired into an HX711 breakout board for the HX711 IC that allows you to easily read load cells to measure weight. I used a push button with a 10k pulldown resistor to tare out the scale. I used a simple switch to apply power to the arduino nano from a 9V supply. The .96 OLED display is used to display the current weight on the scale.

Step 4: Programming

The programming of this relies on the installation of the following libraries:

HX711 Library

OLED Library

In order to get the scales calibration factor I would use the guide below:

https://learn.sparkfun.com/tutorials/load-cell-amp...

After you get your calibration factor enter it in the code posted below. Once everything is wired up correctly, the weight will be displayed on the OLED display. In order to tare the scale simply hold the button down until the scale reads 0 grams.

Step 5: 3D Design/Print

I designed the scale in Fusion 360. The load cell goes on the top portion with a slot for the load cell wires to be routed into the base of the scale. I left plenty of room in the base for a tare button, on/off button, arduino nano, hx711, and a 9V battery. The OLED display can be taped and placed in the front area so the display can easily be seen.

The files can be found below:

https://www.thingiverse.com/thing:3864061

Step 6: Test It Out!

Now that you have the kitchen weight scale all assembled and programmed, it is time to test it out!

Push the power button, wait for the oled display to load up, and enjoy your new kitchen scale.

Please consider subscribing to my youtube channel to support me and see more projects/videos. Thank you for reading!

Comments

[MahdiN11]

3D File dose not exist!

[ohiogigolo56]

Problem?

I receive a error when trying to upload code into Arduino
Line 74 in code ... current_Weight = scale.get_units(10);

This is the error ... "current_weight was not declared in this scope"
Any idea what it means?

Thanks

Edited: I found the problem :)

[AnnaMai]

nice design

[wisteria113]

I'm new to this so please be patient with my confusion (I'm quite old !). "OldSkiBurn"'s comment doesn't make sense to me taken in conjunction with the current circuit diagram.

Pressing SW2 will only connect VCC to GND via the 10k resistor R1 so has the diagram been changed ?

Staying with this diagram and with SW2 released, it is not clear to me what is happening to D4. Is it close to 0V because the internal resistance associated with D4 is much greater than 10k ? Obviously when SW2 is pressed D4 rises to close to 5V.

But this seems to conflict with OSB's suggestion which would drop D4 to near 0V when the SW2 is pressed.

Thanks in advance for any clarifications.

[kcassella]

Hello,
Just wondering where is the stl file for the bottom cover? I downloaded the files from thingiverse and there is no bottom cover for the base.

Thanks,
Kerry

[kcassella]

Ok, I got it. Thanks to posting the file.

[TedB62]

Ok, a little confused here.
First off, thanks for the wonderful project!
Sent for most of the parts and now waiting to receive them to start the build.
In the circuit diagram, the buttons are listed as SW1(2)EVQ22705R.
Looking them up they come back as momentary switches, in the parts list links it shows them as on/off switches.
Please confirm.

Thanks HerrBall

[MnMakerMan]

Yup, the tare feature was a last minute addition so I used a momentary push button. The part numbers are just the default that EasyEda uses when making schematics, sorry! The on/off switch is a standard switch (Not momentary) that you can get on amazon. The YouTube video should show you how to install it. Let me know if you have any other questions and have fun building!

[Alex in NZ]

Nice! Thank you for sharing :-)

[ralfsteck]

Any idea how precise this scale is?

[MnMakerMan]

It's been accurate for me well below a gram. You can also swap out the 5kg load cell with a 1kg or 500g load cell for more accurate measurements. The type of load cell I used can be bought in different configurations.

[ccooksey1]

The schematic has a 1k resistor but the text talks about a 10k resistor. Which one is correct? It would also be nice if the electronics parts especially had links to purchase via Amazon, Ebay, etc.

[MnMakerMan]

I used a 10k resistor. Maybe I will add links on my next instructable!

[wcmiller5]

I don't have a 3D printer and I checked on thingeverse and it is priced at around $150 to $200? I'm thinking of making this but will have to make my own base out of wood.

[MnMakerMan]

A wood one would look really cool but difficult without a CNC. If you are thinking about getting into 3D printing I would recommend checking out your local library or makerspace. That way you can try it out without investing too much money in a printer.

[OldSkiBum]

I think there is a small problem with the schematic. Pressing SW2 will connect VCC to GND - DEAD SHORT! Instead, configure D4 as INPUT_PULLUP, then wire SW2 between D4 and GND? R1 no longer needed.

[MnMakerMan]

Good catch! I'll fix the schematic when I get time.