DIY Mini Metal Brake

Simple metal bending tool that you can build with a drill and an angle grinder, no welding required!

Mini Metal Brake V1

When building my bachelor thesis project – the StarTrckr I noticed limitations of 3D printed parts. I couldn’t design my project how I wanted it to and still make it stiff to handle a DSLR camera. Plastic parts were completely ok for most of the project but 3D-printed arms (similar assemblies are used in camera gimbals) were flexing too much. So I decided that at some point I would upgrade parts for this project with metal parts, preferably laser-cut steel bent to 90 degrees. But the first step is always to make a prototype. I still haven’t tried machining steel with IndyMill so obviously, the prototype shall be made with aluminum, but how to bend it? I tried bending aluminum some time ago just with vice and I know how hard this process is and the results are not satisfactory for me. For that reason, I knew that to create nice prototype parts I need a metal brake (metal bender, bending machine). Tool like this seems easy to build so that’s when I decided to design it, buy the parts and just try to make it as good as I can keeping the budget low and minimal tools required.


One of the challenges was not to use welding in this project and the second one was to use only the parts available at the popular local hardware store in Poland. If you are not familiar with polish hardware stores let me tell you there is not a lot that you can buy there. For that reason project is built with few basic and hopefully easy-to-buy worldwide steel elements. Of course, this instruction is only an example of how I built it and I advise you to use it only as a reference and adjust the project to your needs. If there are other similar components you already have or can buy cheaper, feel free to do that!

L-shaped steel profile 35x35mm 300mm long2
L-shaped steel profile 25x25mm 200mm long1
Steel profile 20x20mm 250mm long2
hinge 40x40mm2
M8x30 screw2
M8 washer2
M5x25 screw4
M5 nut4
M4x6 screw12
M4 nut (optional)12

All elements and the dimensions I have chosen are based on my needs, I know that I am not going to bend some long materials so I preferred to keep the dimensions compact. Here are drawings of the profiles with all the dimensions just to clarify everything:

The M4 nuts mentioned in the table are optional because I tapped the threads in the holes for M4 screws and that way the nuts are not required. Keep in mind that the material that we are using is rather thin (the profiles I have used are just 2mm thick) so the threads are not super strong but so far work great and if there are any problems I can always add nuts later.

It might be hard for you to buy the same hinges that I used in this project so the holes pattern might differ. Make sure to constantly check if everything fits together as you build it and drill the holes for the hinges after checking if they fit. Also, label the holes based on hinges placement and holes pattern. If you use different components do not follow the drawings below very strictly.

Drill press (optional)
Angle grinder
Metric tap set

The tools mentioned above are required for the project, except the drill press it’s very helpful to drill some holes but you can also easily drill them with a cordless drill. As you will see later you can even drill the holes with an old grandpas hand powered drill 🙂

Cut & drill

The drawings presented below should clarify all the holes placement and lengths of the profiles. If the images are too small you can drag and drop them to a new tab and zoom in.

We will need M4 and M8 taps to tap the holes as presented in the diagram below. The rest of the holes are simply drilled.

3 holes on each end of the profile labeled M4 shall be tapped with an M4 tap, that’s where the hinges will attach.
This is the 25x25mm L profile, holes need to be drilled at the corner of the profile. That’s where two M8 screws will be attached to clamp down the material.
5mm holes were drilled in the handles to attach them to the profile.

Unlike most designs of metal brakes, my brake attaches to the vice as it is easier and quicker to set up. For that reason, one of the 35×35 profiles (the one with holes for the handles) needs a cutout. I am using 150mm vice so that’s why my cutout is slightly bigger. Adjust this dimension to your own vice.

Additionally having the brake attached to a vice solves one additional problem and that is all the screws that stick out from the bottom of the other profile that make it impossible to attach to a flat surface. This problem can be solved by adding a piece of wood to the bottom but I am not a fan of this option.

Vice cutout.

After cutting & drilling you might want to check if everything fits together nicely. Before final assembly it’s a good idea to paint your project to give it a professional look 🙂

Painting – powder coating

I like adding a professional touch to my projects and making them as cool as I can. Also, additional protection from corrosion is helpful so that it lasts longer. For that reason, after a test fit I disassembled the whole project including the hinges and powder-coated everything blue and black.

But how did I do that? I have my own cheap and simple powder coating setup. But wait, there is more! You can buy the same powder coating gun that I am using from my store:

This is a very simple-to-use gun perfect for a small project like this one or even small-scale manufacturing because I am also using it to paint parts that I sell for my IndyMill CNC machine. All you need in addition to the powder coating gun is an air compressor and an oven, that’s it. Powder coating is not only simple but also efficient, inexpensive and fast as you don’t have to wait for the paint to dry, it just has to cool down.

That’s me powder coating the parts, the booth is something I have to work on and improve as well as creating a better filtration system.

Your safety is very important when powder coating so you need a filtration system (don’t look at mine, it’s not good enough), a very good mask (I am using a 3M mask and it’s perfect), goggles, and gloves.
Parts drying after powder coating. The whole process takes about 30 minutes. 5 minutes painting, 15 minutes in the oven, and 10 minutes cooling down.
Parts after homemade powder coating.

There is one thing I should mention, tapping the holes and then painting is not the best idea because the paint will get inside the threads and you will need to retap them, otherwise driving screws will be hard. I tapped the holes before painting for a reason – I wanted to assemble everything before painting to test if it works ok or still require some refinement.


Once the MiniMetalBrake was painted to your favorite colors it’s time to assemble it according to the drawings presented below. Those are pretty self-explanatory so I will only point out the most important steps there.

When joining together two L profiles make sure that the top surfaces are perfectly parallel and flat. It’s a good idea to clamp them in a vice together and then join with hinges (actually I used the same technique when drilling holes for the hinges).

Two 35x35mm L profiles.
Hinges attached to the profiles with M4 nuts.

The following step is optional. I tapped the holes with M4 tap and it works ok so I didn’t use nuts but I added it there just to show you that it’s a possibility.

Optional M4 nuts.

Here I want to mention one possible improvement that is super easy to implement. Springs. Adding springs on the screws is a great improvement in user experience as the profile that clamps down the material will rise on its own. I had no such springs around so that’s something I will add in the future.

M8x30 screws are attached with washers through a 25x25mm profile that clamps down the material.
Handles are attached with M5 screws and nuts.
Wireframe view of the completed MiniMetalBrake.
Render view of the MiniMetalBrake.

What can you bend?

There was one goal as I mentioned in the beginning and that was to create metal arms for the star tracker so the first thing I made was exactly that. I designed an arm with sheet metal tools in Fusion360, machined the aluminum piece with IndyMill, and bent it with a MiniMetalBrake. Later the piece was powder-coated black to make it look professional and match with other parts in the StarTrckr.

Unfortunately, I had to cheat a bit when bending this piece and add additional support. The steel profile was bending a lot when I tried to bend this 3mm thick aluminum. So one future upgrade would be to add some flat pieces of steel attached to the handles to support the part more and reduce the flexing in the steel profile.

3mm thick aluminum machine on IndyMill, bent with MiniMetalBrake and powder-coated black. Amazing result and improved stiffness. There are 2 more arms to be replaced in the StarTrckr.

And then I wanted to try something more complicated so I designed a one pice phone holder. It is also made out of aluminum with IndyMill, and the material thickness is 1.5mm.
This time machining was hard, I have no idea what kind of aluminum was that but milling it was almost impossible. At the end after a lof of sanding, I got it to look somehow decent and after powder coating, most imperfections are not visible anymore.

Simple one-piece phone holder.

The small size makes it easy to store for example on your tool wall. Attaches quickly to the vice and hopefully will be often used in future projects. Machining aluminum with DIY CNC is cool but combined with a metal brake it literally adds another dimension to your parts.

MiniMetalBrake is easy to store, for example on your tool wall.

Thanks for reading through the whole project! I hope you liked it and that maybe one-day MiniMetalBrake will show up in your workshop too! I am thinking about redesigning the machine to laser cut the parts out of thicker steel and improve some of its weak points and offer a kit for it in my store. Are you interested? Send me an email:

3D Printed duct fan

This is a 3D printed duct fan that can be used with a 775 motor or a popular BLDC (for example 2212). It can obviously also be adapted to any other motor. It’s an open-source project so below you can find STL files and .F3D files of a project so that you can easily modify and adapt it to your needs.

Consider supporting my work:

Become a Patron!


Below you can download ZIP with all the STL and F3D files of the duct fan, fans, and air filter attachments that I designed. You can also find here the PDF with all of my measurements and plots. Feel free to print, modify and share with others.

Tests and measurments

In the beginning, there was just an idea for a simple duct fan but later I thought that I can optimize it and design a better fan. In order to do that I experimented a lot and measure the performance of each fan while noting everything in a spreadsheet. Later I made a lot of plots to show how each fun perform and you can see all of that here:

You can also find a PDF version of that in the ZIP above.

Here you have 6 most interesting plots where you can observe the difference between performance of each fan and how the measuring method influences the end result.

How to build a robot?

Robots are cool, I think we all agree on that. Right here I would like to give you a short introduction to all the topics that you will most likely face while building your first robot. In the beginning, I just wanted to say no worries, building simple robots is not hard at all, most of it doesn’t even require any soldering (sometimes you may need to solder cables to motors, but for simple robots that’s the only soldering required).

I also wanted to point out the difference between a robot and not a robot. Some tutorials refer to an RC car as a robot but in reality robot is a device that can work on it’s own. At the same time it’s not about fancy futuristic artificial intelligence or humanoid robots, it’s about simple tasks that are solved by the robot completely without human interaction. So a line follower or an obstacle avoiding robot are great examples of ROBOTS while a “robot” and a human with a remote next to it is not a robot.

Keep in mind that this is not a complete tutorial with code, schematic and DIY instruction. It’s meant as introduction to all the topics you should know about in order to even start and understand some of the robotics tutorials so that instead of mindlessly following those you understand what’s going on.

If you want to start easily with a kit, you can check out something like this with all the parts, chassis, motors, sensors, and Arduino. If you prefer to buy components individually check out the list below.

Here you can see a short one minute introduction video, and to learn more about all the topics continue reading:


Microcontroller is a brain of the robot, all the logic, conditions and calculations are performed in here. To simplify it we can say that microcontroller is just a very very simplified computer, the internal structure is more or less similar. There is no screen or keyboard, just a chip with pins. By writing the program you can read pin states set conditions (if statements for example) do some math and set output pins conditions or communicate with other modules, sensors etc.

There are a lot of different types of microcontrollers but if you are just starting you should take a look at Arduino UNO (which is actually more than just a microcontroller, it uses Atmega328 as a microcontroller but Arduino is rather an ecosystem and collection of development boards). Any Arduino board is very easy to start with and Arduino UNO is additionally quite affordable (Original boards start at 23 USD or you can buy a Chinese Arduino clone for 5 USD). With UNO you can build blinking LEDs, learn electronics and programming, simple robots, home automation, measuring devices and even CNC machines! If you need more pins (trust me if you are just starting you don’t need more pins) you can buy Arduino Mega.

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Original Arduino UNO
Clone Arduino UNO
Original Arduino Mega
Clone Arduino Mega

Of course Arduino is not the only way to go. You can read about programming STM microcontrollers, AVR, or lately released Raspberry Pi Pico (programmed with C++ or Python). There are some more advanced boards like Maix Sipeed with an integrated screen and camera programmed with Python. You can also take a look at single-board computers like Raspberry Pi 4B or BeagleBone Black. But all of those examples are probably not the best for beginners.


In order to build a robot (not an RC car) we need sensors. Sensors are devices that measure physical things and transform those readings into electrical signals so that we can read those with microcontroller. For example, to build object avoiding robot we need an ultrasonic sensor that will measure the distance between a robot and an obstacle. This distance or actually two-way time of travel of sound that is processed into the distance can further be processed to decide if the obstacle is close enough to stop the robot or turn. With 2 conditional statements (if(…){}) you can write a simple program for such a robot.

Another popular sensor for simple robots is a line sensor that can be used to build a line follower, that is a robot that follows the black line. By using three of those sensors at the front of the robot you can write a simple program that will drive forward when the line is detected by the sensor in the middle, if the line is detected by the right sensor it should turn right, and if the left sensor detects line you need to turn left. This is a simple example of a not really efficient program for a line follower but it works really well 🙂

There are other types of sensors, there is a sensor to measure everything you can think of air quality, pressure, soil pH sensor, LIDARs, movements sensors etc. Once you get more familiar with basic sensors you can start playing with those a bit more advanced. Ultrasonic sensor and line sensor are probably the easiest to start with and pretty straight forward to use.

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Line Sensor
Ultrasonic Sensor
Sensor Kit


There is many options when it comes to motors for robotics but because this is an introduction I will focus only on simple and cheap motors. You should pay attention to the rated voltage and current of the motors. Usually, you should look for motors with voltage of about 5 to 12V. There should be a way to mount wheels or you will have to look for a DIY solution. In order to increase the torque and lower the RPM motor should have a built-in gearbox. To start I recommend those plastic yellow motors, those are not great and you wouldn’t build the most amazing robot ever with those but to start those are great!

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Yellow Motors
Small Motors
Bigger Motors

Motor driver (H Bridge)

There is no way to drive a motor directly with an Arduino, don’t even try because you will break it. In order to control the motors we need a motor driver also called H bridge. Again there is a lot of options and most of them are very similar. Main differences are max voltage and current that can be handled by a driver or some additional features. Some simple and popular drivers are listed below.

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Cables, Breadboards

Obviously, you will need some cables and a breadboard to connect everything together. They’re nothing complicated, buy some female-female, female-male, male-male cables. When it comes to breadboard use a bigger one for bigger projects and a smaller one for smaller projects, usually power rails on the sides are very useful.

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In order to attach everything together, you will need a chassis. You can buy a set with chassis, motors and wheels or you can try to find your own DIY solution and make a chassis out of plastic or even cardboard (that’s how I built my first robot).

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Chassis 1
Chassis 2


The battery is always a really problematic part of building robots. The most common choice is a LiPo battery but it’s a little bit dangerous, you have to take care of it and be careful because discharging the cells under 3.2V may damage the battery. Those batteries are sold as 1S, 2S, 3S and so on which means one, two or three cells because each cell has a nominal voltage of 3.7V a two-cell battery has a nominal voltage of 7.4V (and a max voltage of 8.4V). Batteries vary with capacity, the bigger the capacity the longer you can power the robot. There is also max current that can be drawn from a battery this is labeled as for example 10C and it means that capacity multiplied by 10 will give the max amperage that you can draw from a battery.

Another (probably safer) way to go is to use protected 18650 batteries. It’s also more complicated because you need to create a battery pack on your own and combine a few of those batteries in parallel or in series. Professionally those batteries are spot welded together but you can just easily use a battery box to keep them together.

I don’t recommend going with AA or AAA batteries as you will need to recharge or replace those very often (it’s not good for the climate and your wallet) and the max current of those isn’t enough for some motors.

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2S LiPo
3S LiPo
4S LiPo
18650 Battery
18650 Box


A lot of people are scarred by programming, I am not really sure why. Programming is easy, you don’t need math to create simple robots! If you have any experience with C++ or similar programming languages you can start programming Arduino right now. If you don’t no worries, there is a lot of great tutorials and examples online. Once you start and try to write your own programs you will realize that it’s not that hard.

You can find some cool tutorials on official arduino website:

Or just type “Arduino tutorial” into YouTube and you will find thousands if videos on this topic!

I hope this article helped you a bit with your robotics journey! If so don’t forget to share with friends and share you progress on Instagram by tagging me: @nikodembartnik and @indystry

Have a nice day!

How to build 3D printed Dremel CNC?

Try typing Dremel CNC to Google or Youtube, the internet is filled with my videos and tutorials about building 3D printed Dremel CNC. I kind of feel just like repeating over and over the same content and that is creatively hard for me because I like creating new stuff the most and not focusing on past projects.

At the same time, I understand that a lot of people want to build DIY Dremel CNC because it’s simple, cheap, and inexpensive, totally understandable! A CNC machine that can be easily 3D printed and assembled with easy to buy components, that was the goal of this project, and looking at reviews of hundreds of makers all around the world I think the project turned out perfectly! I am more than happy that such a simple idea of mine can help so many makers, businesses and people. As you may know, I am working on a new bigger CNC machine called IndyMill, that’s why I created this website to share all the info about this machine, release files, and maybe even create a small business out of that! But I don’t want to forget about Dremel CNC and I know there is still a lot of people that want to build it but don’t know where to start. That’s why I made this post, actually, the first one on, I hope to make some more in the near future 🙂 Let’s start!

Continue reading “How to build 3D printed Dremel CNC?”