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Planning and choice of material

Before I start building, I first think about where the solar panels should be mounted: One on the garden shed, two on the balcony railing and one on the weather station mast.

The garden shed has a straight wooden wall, which makes a flat bracket necessary. The balcony railing and the mast, on the other hand, each have a diameter of 30 mm – a bracket with a rounding is required here. So I currently need two different types of mounting.

I use a monocrystalline 2-watt module with an output voltage of around 6 V as the solar panel (see Figure 1.0.1). For the electrical connection to the panel, I opted for a standard 5.5×2.1 mm hollow socket (see Fig. 1.0.2). Cables and screws are not included in the illustration as they may vary depending on the application. The panels are available in packs of five or ten from various online retailers. Their dimensions are 120 × 110 mm (length × width), whereby the height can vary between 1.3 mm and 1.8 mm.

Construction of the housing

The central component for the solar panel mount is the frame. It provides both the stability and the sealing function of the housing. The frame must be torsion-resistant, be able to accommodate all the necessary threads and still remain compact. The solar panel is pressed into its seat from behind with strips so that it is tightly sealed at the front.
Several screws are required to create an even contact pressure (see Figure 2.0.1).

There is a cover on the back (Fig. 2.0.2), which is reinforced in an X shape for stability. This cover also accommodates the hollow bushing (5.5 × 2.1 mm), which is later attached with a small bridge. One of the four pressure bars that press the panel into the frame can be seen in Figure 2.0.3. The joint holder (Fig. 2.0.4) is used to attach the panel to railings or walls. This serves as a holder for the retaining lever, which holds the housing securely in place and allows flexible alignment.

Figure 2.1.1 shows the holding arm for railing attachment with a 30 mm diameter at the end. The counterpart for the holder can be seen in Fig. 2.1.2. The bridge (Fig. 2.1.3) for attaching the hollow bushing to the cover.

3D printing of the components

For 3D printing, I chose the following print orientations for the Prusa MK4 (see Figures 3.0.1 and 3.0.2).
Particularly important: The bar must of course be printed four times, as it is used on all four sides of the solar panel.

Thread cutting

Now let’s move on to my favorite activity: thread cutting. Admittedly, there is a lot to do in the frame (see Figure 3.1.1): The green markings indicate 12× M3 threads, the yellow ones 4× M3 threads.

There is an alternative version of the frame for those who are not the biggest fans of thread cutting. This is equipped with slots to accommodate normal M3 nuts. The matching file is called: Deckel110x120_V1-2.stl (see Figure 3.1.3).
The recesses for the nuts are also clearly visible in Figures 3.1.4 and 3.1.5.

On the back cover (Figure 3.1.2), however, the cutting of threads can hardly be avoided: 3× M3 threads and 2× M2 threads are required here.
Alternatively, self-tapping screws can also be used – this saves tools and time.

Soldering and assembly

Once all 3D printed parts have been cleaned and threaded, the solar panel can be connected and soldered.

Electrical connections

The first hurdle is to find out where the positive pole is located on the panel.
There are only two soldering lugs on the back of the solar panel, but no labeling – so: plus or minus? To determine this quickly and clearly, we need a multimeter. If we set it to measure direct voltage (DC), it helps us to recognize the polarity.

Figure 4.0.1: The red wire (positive) of the multimeter is connected to one of the soldering lugs, the black wire (negative) to the other. If a minus sign appears in front of the measured value on the display, this means that the red wire is connected to the negative terminal – i.e. the opposite tab is the positive terminal of the solar panel.

Figure 4.0.2 shows the reverse configuration: the red wire is connected to the positive pole of the panel, the black wire to the negative pole. In this case, no minus sign appears in the display – the polarity is correct,
and we now know for sure where the positive pole of the solar panel is.

The hollow socket is now soldered to the solar panel. Figure 4.1.1 clearly shows which connections need to be connected.
Figure 4.1.2 shows the finished soldering in the installed state.

I have also soldered a diode to the positive pole of the hollow socket (see Fig. 4.1.3).
This protects against reverse current: if the connected load does not have its own protective diode, the solar panel would draw energy from the battery in the dark – and unintentionally work as a heater.

A typical example:
If a charge controller does not have an integrated diode, the battery can discharge the panel backwards in the absence of sunlight.

The installation direction of the diode is crucial so that the current can only flow in one direction.

Mounting the hollow bushing and inserting the panel

The installation of the soldered hollow bushing on the retaining bridge is shown in Figure 4.2.1.
The hollow bushing is pushed into the large opening of the retaining bridge until the thread protrudes on the other side. The nut is then placed on the thread and tightened – the result is shown in Figure 4.2.2. The solar panel is now inserted into the retaining seat of the frame (see Figure 4.2.3, red frame).
If you want to increase the tightness, you can apply some elastic adhesive evenly to the seat before inserting the panel. Once the solar panel is correctly seated, the first strip is placed in position and lightly tightened with a screw in the middle (see Figure 4.2.4, magenta circle). A side view is shown in Figure 4.2.5 to illustrate this.

Fastening the slats and screwing

The remaining slats are attached one by one with the screw in the middle (see figure 4.3.1). Then insert the remaining screws, but do not tighten them yet (see figure 4.3.2). When the solar panel is evenly positioned, first tighten the middle screws of each strip.
Then tighten all the remaining screws and retighten them after a short time. If the solar panel still has some play, you can place some shims between the solar panel and the rail until it is firmly in place. Figure 4.3.3 shows how the hollow bushing and retaining bridge are attached to the inside of the back cover.
Finally, the back cover is screwed onto the frame with four screws (see Fig. 4.3.4).

Only a few steps are required to complete the bracket:
First, the M6 nut is pressed into the joint bracket (see figure 4.4.1).
The holder for the railing is then attached to the joint holder with an M6 screw (see Figure 4.4.2).
The joint holder is now screwed to the back cover with three M3 screws.
Do not forget: The M3 nuts must be pressed into the counterholder that will later be used for mounting on the railing (see figure 4.4.4).

Exploded view of the solar panel mount

For a better overview, there is an exploded view of the solar panel holder in Figure 4.5.1.

Note

Of course, there are also alternative mounting options. For instance, in a garden flower bed, plants may grow over time and gradually shade the solar panel. In this case, a holder with an aluminum rod and ground spike can be used (see Fig. 5.0.1).

On a balcony, the panel can be attached via flower boxes that cover the railing; here too, a holder with an aluminum rod is available (see Fig. 5.0.2).

Additionally, a holder designed for mounting on a wall or post is also provided (see Fig. 5.0.3).

Furthermore, I plan to design a solar panel holder with a built-in USB-C output.

The solar panel is an excellent addition for powering my small devices and outdoor sensors – and this holds true even in winter! Depending on your needs, you can either assemble the cables yourself or purchase them ready-made. In any case, the rule of thumb is: the shorter, the better.

Have fun building your own version – or perhaps this project has inspired you to create something entirely new.

Files for Download

• Housing for the solar panel mount

The post DIY solar panel mount for 2W panels appeared first on Nerd Corner.

But wouldn’t it be much more practical to do away with physical keys altogether? Nowadays, there are numerous ways to open a lock: Fingerprint scanners, facial recognition, NFC, numeric codes, dials – or, of course, brute force methods such as explosives and brute force. But if you are looking for an inexpensive, non-violent and simple solution, the keypad lock comes into focus.

Surprisingly, there are hardly any really good DIY solutions for hobbyists on the Internet. So I tackle it myself – my first keypad lock, which I simply call “Version 1”.

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Construction of the housing

The initial focus is on the housing and the keypad holder. The first question that always arises is: How big should it be? The answer depends on several factors:

• Which components are required? Each component takes up space and influences the design.
• How much space do the components take up? A compact design is advantageous, but must not restrict functionality.
• What are the haptics and operability like? The keypad should be comfortable to use without being too cramped or impractical.

These considerations form the basis for the housing design – because good planning saves time and nerves later on.

What will be inside the housing?

The central component is, of course, the membrane keypad (1.0.1). It has the following dimensions:

• Width: 69 mm
• Length: 76 mm
• Thickness: 0.6 mm (or 0.95 mm above the keys)

The keypad also has a ribbon cable with DuPont sockets for connection to a microcontroller. The cable itself is 85 mm long and 17.78 mm wide.

The control center of the lock is the Nano (1.0.2). To accommodate it neatly in the housing and to make the cable connections as convenient as possible, I opted for a Nano expansion board with screw terminals (1.0.4).

A hollow socket (5.5 x 2.1 mm, 1.0.4) is used for the emergency power supply so that the lock continues to function even in the event of a power failure.

The pin and socket connectors (1.1.1) serve as the central power distribution and are later soldered to the breadboard (1.1.2). Jumper cables (1.1.3) are used to ensure that all components are reliably connected. Depending on the position of the components, different lengths are required – in this case 10 cm and 20 cm.

For the status display of the keypad lock, I use Neo Pixel addressable LEDs of type WS2812b (1.2.1). These can be used to control different colors and effects to visually display the current status of the lock.

I will go into the positioning of the screws in more detail later.

Now that the components have been determined, I can think about the size of the housing. This is not only determined by the installed elements, but above all by the usability and feel.

We encounter keypads every day – on ATMs, telephones, door lock systems and, of course, smartphones. The decision for the depth of the housing is based on a positive memory of my penultimate workplace: the keypad lock at the entrance was raised and easily accessible from both sides. You could operate it comfortably with your right or left thumb, and the rounded corners provided a pleasant feel when you put your hand on it.

Keypad lock Housing design

This results in a depth of 45 mm (2.0.3). For better ergonomics, the corners have a radius of 15 mm (R15) and the surrounding upper edges have a radius of 10 mm (R10). I am aware that these roundings slightly reduce the interior space, but the comfort and appearance outweigh this disadvantage.

The width and height of the housing are determined by the components to be installed. The space for the cabling must also be taken into account. Particularly important: When installed, the Nano should still be accessible with a standard USB mini cable, for example to be able to install new programs.

Mounting and fastening

• Four M3 threads (2.0.1) on the inside allow the support plate to be screwed on.
• In addition, there are four mounting points with Ø4.2 mm holes for attaching the housing to a door, cover or wall.
• The housing has a window (2.0.2) measuring 60 × 67 mm, which is intended for the keypad. This is later filled with the carrier plate.
• Retaining columns with M2 threads and the opening for the hollow socket (1.0.4) are marked with orange ellipses (2.0.1, 2.0.3).
• The next picture (2.0.4) shows the external dimensions: 110 mm wide and 117 mm high.
• In addition, an aperture or slot 50 mm long is required for the LED cover (2.0.5).

For the wall thickness of the housing, I have provided 2 mm throughout – stable enough for the intended purpose.

With the housing construction completed, we can now continue with the other components.

The support plate – the central mounting element

The next important component is the carrier plate. The name is self-explanatory: With the exception of the hollow bushing, all components are attached here. This system offers several advantages over direct mounting in the housing:

Easy mounting outside the housing – More space and better handling when wiring.
Modularity – different carrier plates with different components are possible.
Simple enclosure design – The enclosure design remains simpler and more flexible.
Easy replacement – Components can be replaced or extended more easily.

But there is another decisive advantage for the keypad lock in particular:

The keypad is glued directly into a designated recess in the carrier plate (2.1.1). The carrier plate and keypad are then inserted into the housing from behind and fixed in place with M3 screws. The frame of the window in the housing completely covers the edge and the cables.

Safety aspect: The window is dimensioned in such a way that the edge and the cables remain concealed, but the buttons are fully visible and operable. This means that the keypad cannot be removed without destroying it – an important protective mechanism against tampering.

Fastening the components to the carrier plate

There are various mounting options for the electronics on the back (2.1.2) of the carrier plate:

M3 thread for the nano adapter (2.1.3) – As nano adapters on the Internet often have different hole spacings, there is an additional fastening thread on the right-hand side (2.1.2) for flexible adjustment. If the holes still do not fit exactly, they can be carefully widened – but without damaging the adapter’s conductor tracks.

M2 thread for the Nano R3 ATMEGA168P (2.1.4) – An alternative, cost-effective solution instead of a Nano R3 with adapter.

M2 thread for the breadboard (20×80 mm, 1.1.2, 2.1.5) – This is used for power distribution and connects all power supply lines neatly at a central point.

The LED cover and its attachment

The LED cover (2.2.1) has been designed so that it is clicked into the slot (2.0.5) of the housing from the rear. The radius on the outside of the LED cover corresponds to the housing radius, creating a smooth transition and allowing the cover to blend in seamlessly.

I don’t need to redesign the mounting bridge (front 2.2.2, back 2.2.3) as I have already used it successfully in other projects.

Mounting the LEDs

Now it remains to mount the three WS2812b LEDs (1.2.1). I will explain why exactly three LEDs are needed later in the programming section of this article.

The development of the LED holder (SMD50, 2.2.4) was more complex than expected. Of course, you could simply glue, clamp or hot glue the LED strips – but that seemed too unprofessional to me.

I therefore invested a lot of time and effort in designing a perfect holder. The result can be seen in picture 2.2.5.

Further information:

For details on the construction, there is a separate article on NerdCorner.

3D printing of the components

Once the design has been completed, the parts must now be printed.

Material selection for the individual components:

• Housing (3.0.1): Printed with ABS filament, consisting of front and back.
• Carrier plate (3.0.2): made from PLA filament.
• LED cover (3.0.3): produced upright in the printer, printed with PLA+ in the color “natural”.
• LED terminals (3.0.4): also made of PLA+, manufactured in the same process as the LED cover.
• Bridge for the hollow socket: printed from PLA filament, analogous to the carrier plate.

With these materials, the mechanical and thermal properties of the components are optimally matched to their respective applications.

Post-processing of the components

After printing, both the printed parts and some purchased parts need to be processed.

1⃣ Cleaning the 3D printed parts

• Removal of support material and protruding print residues.

2⃣ Cutting the thread
Housing (4.0.1):

• Four M3 threads (Attention: blind holes! Proceed carefully when cutting so as not to push the base outwards).
• Two M2 threads (4.0.2).
• Support plate (4.0.3):
  • The M2 threads marked in blue must be cut in any case.
  • When using a nano adapter with screw terminals (2.1.4), the M2 threads marked in red must also be cut.

3⃣ Shortening the perforated grid plate

• The perforated grid plate (4.0.4) must be shortened to 8 to a maximum of 10 perforated grids.
  Important: The mounting holes should be retained (see 4.0.5).

4⃣ Shortening the pin header

• Shorten the pin header to eight pins using a side cutter (4.0.6).

Soldering the components

Now it’s time to solder the parts. First we concentrate on the power supply board:

1⃣ Soldering the power supply board

• Perforated grid plate (4.0.5): Soldering the base strip (1.1.1) and the pin strip (4.0.6).
• Pin strip (4.1.2): A two-row pin and skirting board is soldered on. We connect the two rows on the back with solder.
• The rows differ in male and female as well as in the colors: red for plus and black for minus. This makes it easier to connect the power supply.

2⃣ Soldering the WS2812B LEDs

• Soldering the connections of the WS2812B LED strip (4.1.3).

3⃣ Soldering the hollow socket

• Finally, the hollow socket (1.0.4) is soldered (4.1.4).
• Detailed instructions on soldering the hollow socket can be found in a separate article. It is important to know the exact procedure in order to avoid mistakes.

Assembling the keypad lock

1⃣ Installing the LED cover

• First click the LED cover (2.2.1) into the housing.
• Glue the LED cover in the intended places as shown in pictures 5.0.1 and 5.0.2.

2⃣ Plug in the Nano R3

• Insert the Nano R3 (1.0.2) into the Nano adapter (5.0.3) of your choice.

3⃣ Installing the Nano adapter

• Screw the Nano adapter (1.0.3) with the inserted Nano R3 (1.0.2) to the back of the carrier plate (4.0.3).
• Use the M3 threads on the carrier plate and the screws (1.2.2), as shown in pictures 5.0.4 and 5.0.5.

4⃣ Attaching the power supply

• Attach the power supply (4.1.2) to the back of the carrier plate (4.0.3) using the screws (1.2.4).
• See figure 5.0.6.

Mounting the keypad on the support plate

1⃣ Selecting the screw length

• Make sure to select the correct screw length as shown in Figure 5.1.1.
• Screws must not be too long, otherwise they will protrude from the adhesive surface when the keypad is attached and the keypad cannot be glued on cleanly.

2⃣ Preparing the keypad

• Remove the protective film from the keypad (1.0.1).
• To remove the film, use a carpet knife to carefully get between the adhesive layer and the protective film at one corner (see 5.1.2).
• Once you have reached the corner, peel off the entire protective film (see 5.1.3).

3⃣ Stick on the keypad

• Insert the keypad (1.0.1) into the recess on the front of the carrier plate (2.1.1) and press it firmly into place.
• The keypad must be completely recessed and must not protrude over the edge (see 5.1.4).
• Make sure that the cables are also in the recess (see 5.1.5).

Wiring the keypad to the Arduino Nano R3

1⃣ Using jumper cables

• Jumper cables (10 cm long, male-male) are used to connect the keypad to the Arduino Nano R3 (see 5.2.1).

2⃣ Connecting the cables

• Make sure that you do not twist the cables, but only bend them.
• The left cable is connected to D2 of the Arduino and the right cable to D8.
• There are seven cables in total, which occupy the connections D2 to D8 (see 5.2.3).

3⃣ Use pin headers

• As the pitch of the Arduino adapter and the keypad do not match, you can use pin strips to make the connection.

4⃣ Fastening the LED terminals

• The clips (3.0.4) for the WS2812B LEDs are clicked onto the LEDs.
• It is best to do this on a flat surface (see 5.2.4).

5⃣ Attaching the LED strip

• The WS2812B strip is now pushed onto the center of the top of the carrier plate (see 5.2.5 Front and 5.2.6 Rear).

Assembling the carrier plate and housing

1⃣ Screwing the support plate to the housing (5.3.1)

• Make sure that you use M3 screws that are not too long. Otherwise, they could push a bump into the front of the housing when tightened.
• The alignment of the carrier plate in the housing is important: the LED strip should be on the same side as the LED cover.
• After screwing, the keypad should be lightly pressed against the inner frame of the housing (see 5.3.2 and 5.3.3).

2⃣ Pre-assembly of the hollow socket for the emergency power supply

• For the emergency power supply, you must pre-assemble the hollow socket and screw it to the housing.
• The hollow socket with bridge and nut is shown in Figure 5.3.4.
• Insert the hollow bush into the round recess of the bridge.
• Lock the hollow bushing with the nut on the other side of the bridge.

3⃣ Fastening the hollow bush in the housing

• The hollow bush with the bridge is then screwed to the retaining pillars provided in the housing using M2 screws (see 5.3.5 and 5.3.6).

Connecting the cables and completing the power supply

1⃣ Connecting the control cable for the servo motor

• The control cable for the servo motor is connected to pin D9 of the Nano R3 (5.4.1).

2⃣ Connecting the power supply for the Nano R3

• The power supply for the Nano R3 is connected to the GND pin and the VIN pin of the Nano R3 (5.4.2).

3⃣ Connecting the control cable for the WS2812B

• The control cable for the WS2812B LED strip is connected to pin D10 of the Nano R3 (5.4.3).

4⃣ Wiring of the power distributor

• All remaining cables must be connected to the power distributor:
  • Servo motor connection
  • Arduino Nano R3
  • WS2812B LED strip
  • Hollow socket All connections are made with plus and minus (see 5.4.4 and 5.4.5).

5⃣ Using different colors and connection types for the wiring

• It helps to use different cable colors:
  • Red for plus
  • Black for minus
• The power distributor has different connection types:
  • Male for plus
  • Female for minus

6⃣ Note on the hollow socket

• There is a separate article on wiring and connecting the hollow socket, which you should definitely read

7⃣ Attaching the connector housings for the servo motor and power supply

• A three-pin plug is required for the servo motor connection.
• A two-pin plug is required for the external power supply.

Further details on the construction process and the download links for connector housings can be found here.

Figure 5.5.1 shows the entire cabling again.

Arduino code

After the intensive work with the hardware and the 3D printer, we now turn our attention to the strategy and programming of the keypad lock. Why is a strategy important for a keypad lock? A well thought-out sequence of actions – i.e. the order in which the keypad lock is operated, which events result from certain actions and which goal is being pursued – forms the basis for functional control. This guideline is therefore also crucial for programming the keypad lock: it determines what should happen when and which hardware is used. The aim is to create a logical and comprehensible sequence of events, which in this case can also be understood visually.

Example 1:
The keypad lock should display how many digits have already been entered. (See Figures 7.0.1 to 7.0.4)

Example 2:
The keypad lock should indicate whether the password entered is correct after pressing a specific key. (See figure 7.0.5)

Example 3:
The keypad lock should indicate if something has been entered incorrectly, such as an incorrect password or too many keystrokes. (See figure 7.0.8)

Example 4:
The keypad lock should display the current status. (See Figures 7.0.5 to 7.0.7)

Now let’s move on to programming the keypad lock, which differs from conventional programs on the Internet in a few respects. To begin with, the three necessary libraries are included: <Keypad.h> for the keypad, <Adafruit_NeoPixel.h> for the WS2812B LEDs and <Servo.h> for the servo motor (Figure 6.0.1). In the following section, the pin assignment for the LEDs is defined, whereby pin D10 is used and the number of LEDs and the color scheme are determined. The brightness of the LEDs is also defined – this value can be adjusted depending on the location, with higher values providing more brightness (values from 0 to 255). (See figure 6.0.2) The third section is dedicated to the description of the keypad used, including the number of rows and columns and the assignment of the buttons. (See figure 6.0.3).

In the fourth section, the servomotor is configured by defining the degree range it can cover and the speed at which it should move (see Figure 6.1.1). This is followed by the section for entering the password. Here you have the option of changing the default password 1516 to set a new four-digit password. The program will only work correctly if a four-digit code is entered. In this section, the control pin for the servo motor is also set to D9 (see Figure 6.1.2). The following section is dedicated to defining the colors for the various events.

The last two sections explain the behavior of the keypad lock during certain actions. This description is of course only a rough overview of the program. In a future article for keypad lock version 2, we will explain the program in more detail and more comprehensively.

//==========================================Librarys==============================================================
#include <Keypad.h>
#include <Adafruit_NeoPixel.h>
#include <Servo.h>
//========================================Neo-Pixel==============================================================
#define LED_PIN 10
#define LED_COUNT 3
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
int led_strength = 75; //controlls Brighttness (0 - 255)
//========================================Keypad=================================================================
const byte rows = 4;
const byte cols = 3;
char keys[rows][cols] = {
 {'1', '2', '3'},
 {'4', '5', '6'},
 {'7', '8', '9'},
 {'*', '0', '#'}
};
byte rowPins[rows] = {8, 7, 6, 5};
byte colPins[cols] = {4, 3, 2};
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, rows, cols );
//=========================================Servo============================================================
Servo lock;
int pos = 0;
int servo_angle = 180;
int servo_speed = 15;
//======================================Password===============================================================
String input;
const String password = "1516"; //Set Password
int n = 1;

 

void setup() {
 input.reserve(password.length() +2);
 strip.begin();
 strip.show();
 lock.attach(9); //motor pin
}

void loop() {
//-------------------colours------------------------------------------------------------------- 
 uint32_t blue = strip.Color(0, 0, led_strength);
 uint32_t green = strip.Color(0, led_strength, 0);
 uint32_t red = strip.Color(led_strength, 0, 0);
 uint32_t orange = strip.Color(led_strength, led_strength/2, 0);

 char key = keypad.getKey();

if (key != NO_KEY) {
//-------------------------End conditions------------------------------------------------------
 if (key == '#') {
 if (input == password) {
 //unlock
 strip.clear();
 strip.fill(green, 0, LED_COUNT);
 strip.show();
 for (pos = 0; pos <= servo_angle; pos += 1) {
 lock.write(pos);
 delay(servo_speed );
 }
 while (1 == 1)
 { char key = keypad.getKey();
 strip.clear();
 strip.fill(orange, 0, LED_COUNT);
 strip.show();
 if (key == '*')
 {
 strip.clear();
 strip.fill(green, 0, LED_COUNT);
 strip.show();
 break;
 }
 }

 for (pos = servo_angle; pos >= 0; pos -= 1) {
 lock.write(pos);
 delay(servo_speed );
 }
 n = 1;
 input = "";
 delay (1000);
 strip.clear();
 strip.show();
 } else {
 //wrong password
 strip.clear();
 strip.fill(red, 0, LED_COUNT);
 strip.show();
 n = 1;
 input = "";
 delay (1000);
 strip.clear();
 strip.show();
 }
 }
 else if (n == password.length() + 1) {
 //Input too long
 strip.clear();
 strip.fill(red, 0, LED_COUNT);
 strip.show();
 n = 1;
 input = "";
 delay (1000);
 strip.clear();
 strip.show();
 }
//----------------------------------Buttons------------------------------------------
 else {
 input += key;
 if (n == password.length() ) {
 strip.clear();
 strip.fill(blue, 0, LED_COUNT); 
 strip.show();
 n++;
 }
 else {

 strip.clear();
 strip.setPixelColor(n-1, blue);
 strip.show();
 n++;
 }
 }
 }

}

Function

Operating the keypad lock is very intuitive. As soon as the first button is pressed, the right-hand LED lights up blue (7.0.1). When the second button is pressed, the middle LED turns blue (7.0.2). After the third button is pressed, the left-hand LED lights up blue (7.0.3). Finally, with the fourth button, all three LEDs light up blue (7.0.4). When these three LEDs light up blue, the user knows that the # button must be pressed.

If the # button is pressed, the password is checked. If the password is correct, all three LEDs light up green at the same time and the servomotor is activated (7.0.5). The green light remains on as long as the servomotor has not yet reached its end position (open). As soon as the servomotor reaches the end position (open), the LEDs change from green to orange (7.0.6). The orange color remains until the user presses the * button.

After pressing the * button, the LEDs change back to green (7.0.7) and remain in this color until the servomotor has reached the end position (closed). If this is the case, the LEDs go out and the keypad lock is ready for new entries.

However, if the password is incorrect after pressing the # button in step 7.0.4, all three LEDs light up red (7.0.8). The red light is also displayed if more than four buttons, apart from the # button, are pressed.

Door mounting

Of course, this variant is not intended for use on an ordinary door, where you simply walk through and the door closes by itself. The reason for this is that the lock remains open until the * button is pressed. But how can you press the * button when you are on the other side of the keypad lock, behind the wall? A delay in the program could help, but who knows how long it takes to pass through the door and close it behind you? A much more sensible solution would be to implement an additional switch that is placed on the other side of the door. When pressed, this switch would lead directly to point 7.0.6 and open the lock so that the door can be opened from the inside without having to enter a password.

But that’s for the future. Now we come to mounting the keypad lock on a door. I have provided four holes on the back of the housing for this purpose. These holes have a recess on the inside for conventional hexagon nuts M4 DIN 934. The corresponding holes can be seen in Figure 8.0.1 (rear view) and Figure 8.0.2 (front view), whereby the housing is shown slightly transparent for better visualization. Installing the nuts is very simple: After ensuring that all support material has been removed, the nut is pressed into the recess provided from behind. Press-in nuts should not be used as they are unnecessarily expensive.

I have developed a drilling template for fixing to the wall or door (Fig. 8.0.3). This template contains a hole with a diameter of 4 mm at each of the four corners. The distance between the holes corresponds to the distance between the holes on the housing. The template can be easily fixed to the surface of the door, for example with adhesive tape (Fig. 8.0.4). This saves you the tedious task of marking out the drill holes and avoids errors.

Figure 8.1.1 shows the drilled mounting holes from the front, marked by magenta-colored circles. Thanks to the drilling template, these holes are the correct distance apart. If the position slips slightly during drilling or is not exactly correct, this is not a problem. In this case, you can simply drill the mounting holes slightly larger to align the keypad lock precisely when screwing it on. In addition, two holes can be seen in yellow circles in this picture, which are unfortunately slightly broken out at the edge. These holes are intended for the servo cable and the power supply. Once the holes had been drilled, I fitted the keypad lock and fed the cables through the holes provided on the back of the door (Fig. 8.1.2).

The entire assembly of the keypad lock is shown on the front side of the door in Image 8.2.1. If you are not satisfied with this mounting solution, don’t worry: As a final step, I have designed a back cover that allows the keypad lock to be mounted on a wall or frame (Image 8.2.2). To do this, simply place the housing of the keypad lock onto the back cover and secure it from behind using M4 countersunk screws (marked by magenta circles in Image 8.2.2). After that, the entire construction is mounted on the wall, for which two tabs with two holes each are available (yellow circles in Image 8.2.2).

It is also important to remember to add one or more openings in the housing for the servo and power supply cables. Additionally, the security risk should be considered, as an unauthorized person could potentially unscrew the keypad lock using the accessible screws.

Locking Mechanism

If you’re still missing a real locking mechanism that goes beyond just a servo connection, you can look forward to the “Locking Unit,” which is already in development and will be featured in future versions of the keypad lock.

The development of the keypad lock was an exciting yet challenging task. Some key features of VERSION 1 of the keypad lock are particularly noteworthy:

• Compatibility with various Arduino Nano models and adapters – Ensures flexibility in hardware selection.
• Visual feedback – Users are directly informed about number input and the status of the keypad lock.
• Emergency power supply via barrel jack – Guarantees reliable operation in case of power failures.
• Stable software – Developed to ensure reliable functionality.
• Optimized ergonomics for both left- and right-handed users – Designed for comfortable use by all users.

Files for Download

• Keypad lock housing

The post DIY keypad lock – 3D printing and code appeared first on Nerd Corner.

You may also be interested in: 3D printed Dupont connector for jumper cables

Implementation of the Dupont connector

As with any new development or modification of an existing part, a number of decisions had to be made, but in this case not many were necessary.

• Number of fixing lugs: two or four
• Diameter of the fixing holes: 2.2 mm
• Cover removable after fastening: yes

With the number of fixing lugs, it is clear that a single lug will cause the housing to rotate around the screw if it is not tightened firmly enough. When the connection is inserted or removed, the housing tries to rotate around the screw. With two or more tabs, insertion and removal can be achieved without any problems, even if the screws are not fully tightened.

The diameter of the fixing holes has been set at 2.2 mm for M2 screws. Larger screws would make the lugs larger than the connector housing itself, and two M2 screws already provide sufficient holding force.

The decision as to whether the cover should still be removable after the connector had been attached was inevitable. As the clamping tabs of the cover protrude from the base of the housing, the fastening tabs had to be raised above the base anyway. If the lugs were flush with the base of the housing, the lid could rise by around 0.3 mm when the screws were tightened. Why were the fixing lugs not attached directly to the lid? The lid is not stable enough to support the side tabs. The distance between the surface and the base of the housing is 1.1 mm when screwed on, which is sufficient to remove the lid without any problems.

Regarding the fixing holes with a diameter of 2.2 mm: The hole spacing is always a multiple of 2.54 mm, which makes sense as the DuPont plugs also have a width and height of 2.54 mm. The hole spacing increases in proportion to the number of pins on the housing. A positive side effect: These distances also match the holes of a breadboard. In Figure 1.0.1 I have mounted two 4-pin connectors on a breadboard. For the attachment, I used the matching holes at the distance of the 4-pin connectors and cut threads with an M2 tap. As you can see, the screws hold perfectly without the need for a nut.

Yes, that’s almost it for this time – we’re actually finished now, but two things are still important to me. Firstly, I would like to talk about the versatility of the connectors. I’ve been using them for four years and am constantly discovering new ways to use them flexibly. Below are some examples with version one, which is identical to version 1.1 except for the screw-on option.

Figure 2.0.1 shows a 10-PIN connector with a 200 mm jumper cable. Figure 2.0.2 shows the difference between a 10-PIN connector with a 100 mm jumper cable and one with a 200 mm jumper cable.

Figure 2.1.1 shows a 9-PIN connector on one side and three different connectors on the opposite side. Figure 2.1.2 shows this side enlarged. Here you can see the three connectors: a 4-PIN connector, next to it a 3-PIN connector and on the far left a 2-PIN connector. If you add up the pins of the three connectors, you get the nine pins as on the other side.

You have probably noticed that the DuPont plugs of the three connections are different. On the 4-PIN connector, all pins are male, i.e. pins. In contrast, all pins on the middle 3-PIN connector are female, i.e. sockets. The 2-PIN connector, which combines a male and a female connector, is particularly interesting. What is it all about? Here I would like to demonstrate the flexibility of Nerd-Corner’s tool-free connector system. As with the 2-PIN plug, these plugs can be used to install reverse polarity protection: The pin is the positive pole, the socket is the negative pole. The reverse is true for the mating connector, which means that the connection cannot be plugged in incorrectly!

The 2-PIN plug is the simplest example, but this principle can be applied to all plugs so that more complex protection systems can also be set up.

The structure in Figure 2.2.1 shows another way of creating a wiring harness. There is a 10-PIN connector on the left-hand side and a 5-PIN connector on the far right, connected by a 200 mm jumper cable. The orange 3-PIN connector is connected to the 10-PIN connector via a 400 mm jumper cable, as is the 2-PIN connector, but with a 500 mm jumper cable. This solution offers unlimited flexibility across the entire connector family and is completely tool-free.

Assembling the Dupont connector

I keep getting requests to build connector housings for 15 or 22 pins. Unfortunately, this is not impossible with this system, but it is a major challenge. The effort involved is disproportionate to the benefit – at least for me. I actually wanted to stop at the 6-PIN version, as the assembly requires a lot of fine motor skills and the holding force of the tabs decreases. I was able to solve the problem of the holding force from the 7-PIN version onwards by using a third tab, but this made assembly very difficult.

However, there is usually a solution, as can be seen in picture series 3.0.

In picture 3.0.1 you can see that a female connector comes into play, as we are using male (pin) cables here. A pin header could be used instead for female cables.

The procedure for assembling with male cables (pins) is as follows:

1. Push the cables into the socket strip.
2. Press the inserted DuPont housings lightly into the base of the connector and press the cables into the recesses provided (see Fig. 3.0.1).
3. Press the DuPont housings fully into the base of the housing and push them towards the internal stop strip. Then pull the cables backwards one by one – the socket strip should not be removed (Fig. 3.0.2).
4. As soon as the DuPont plugs are fixed in the housing, the cover is fitted and snapped into place (Fig. 3.0.3).
5. Finally, the socket strip is removed and the assembly is complete (Fig. 3.0.4).

Files to download

• Dupont Connector 3PIN

The post Dupont Connector V1.1 appeared first on Nerd Corner.

This might also be interesting for you: Magnetic clamp for strong neodym magnets

Production of the LED strips

You also need to know how such LED STRIPS are manufactured, the misconception that the strips are fitted on an endless belt and cut as required is wrong. The strips are stretched 500mm long in a placement machine and fitted with the LEDs. The number of LEDs depends on how many LEDs are needed per metre. There are strips with 30/60/144 LEDs per metre. The 500mm strips are then soldered together at the ends to the required length.

Realisation of the SMD5050 bracket

As always, I first look for all available LED strips from my collection that contain an SMD5050. It was important to have all the variants from the different manufacturers. This way you can find the best possible middle way to apply the function (i.e. the clamping) to as many variants as possible.

The idea was not to glue the strip to the back, but to clamp the LEDs to the outer surfaces. Figure 1.0 shows some of the numerous variants for SMD5050

• 1.0.1 WS2812B strip with 30 LEDs per metre
• 1.0.2 WS2812B strip with 60 LEDs per metre
• 1.0.3 WS2812B strip with 144 LEDs per metre
• 1.0.4 Sk6812 strips with the same subdivisions as above
• 1.0.5 Cold white strip with 60 LEDs per metre

The next step is to measure and compare the outer dimensions of the SMD5050. As the name SMD5050 implies, the numbers 5050 stand for the mass of 5mm on the outer lines (5050 is equal to 5mm long and 5mm wide). To my astonishment, the SMDs are only a hundredth of a millimetre apart. This means that the deviations are marginal (2.0.1, 2.0.2) and negligible for the design.

The situation is different with the height of the LEDs, where the differences are somewhat more striking (2.0.3, 2.0.4 and 2.0.5). But the biggest difference lies in the soldering with more or less solder. The differences are now known and can be taken into account in the design.

The solder joints and external resistors cause the most problems. The solder joints are often very different, sometimes slightly thicker and sometimes protruding beyond the side edge. The resistors are also positioned in different places depending on the strip.

First I draw the retaining clip (3.0.1) to which the LED will later be attached. Next, I design the holding frame for the SMD5050, which will later be used to clamp the LED (3.0.2). In picture 3.0.3 I add so-called recesses. I measured these recesses in the frame for the various LED strips.

After these three main steps, I print the first prototype with my favourite material and favourite printer. After the first attempts to clamp the LED, I was very confident that it would work in the end. Of course, you have to keep an eye on the stability of the clamp when removing the material.

The development is based on my previous experience. It’s a balancing act between holding force, stability and printability. The number of printed prototypes, in this case fifteen, says only a little about the work that has been done. Fifteen attempts is rather few. I was lucky with the basic concept and that the idea was the right one.

In pictures 3.0.4 and 3.0.5 you can see the changes to 3.0.3 in the dimensions and shapes, such as the addition of bevelled edges.

Manufacturing the clamp in the 3D printer

The CAD development is now complete. The next step is the printing process. A number of factors need to be taken into account, such as the correct calibration of the 3D printer. If you print a housing with a lid on a poorly calibrated or uncalibrated 3D printer with the same settings and material, it will always fit together. The dimensions are not correct but the covers of the housing and lid are the same and therefore it still fits.

The situation is different when an externally produced component such as the SMD5050 comes into play. Then the dimensions must match within a certain tolerance range. If you don’t want to calibrate your 3D printer, you can adjust the dimensions using the slicer. Every slicer offers a so-called scaling function. The next factor is related to the size of the clamp, as the clamp is very small, the nozzle cooling must be set to 100%. Nozzle cooling is actually the wrong term, as it is not the nozzle that should be cooled, but the filament that emerges. With small components, the hot nozzle passes the workpiece again more quickly so that it cannot cool down properly. As a result, the filament runs and cannot hold the desired shape.

The printing direction should also not be underestimated. With our clamps, the printing direction should be sideways, i.e. printed horizontally (4.0.1).

Mounting the SMD5050 LED strip bracket

To mount the clip, it is advisable to place the individual LED or strip on a flat surface and then press the clip on from above. The LEDs are very stable and can withstand a lot. If you have any doubts about the holding power of the connection, you can of course add some glue. It is also not necessary to clamp every LED to the strip, it is sufficient to clamp every third or fourth LED.

I have designed different types of clamps that can be screwed, clamped and, of course, glued. However, there is one restriction. The clamp can only be attached in two directions. I had to make the compromise in the design that only two sides are suitable for clipping. This means you can’t turn and attach the clip every 90 degrees, but only 180 degrees. In short, the soldering points must always be to the right and left of the clip and not at the top and bottom. (see pictures 5.0 – 5.1)

Application examples for the LED strip bracket

• 5.0.1, 5.0.2 WS2812B 60 LED/m
• 5.0.3 RGW on circuit board
• 5.0.4 WS2812B 144 LED/m (only every second LED can be clipped)
• 5.1.1 SK6812 soldered to carrier plate clamped
• 5.1.2 WS2812B soldered three pieces
• 5.1.3 RGW
• 5.1.4 CW with side clips right and left

Download files

• Bracket for SMD5050

The post Click and clamp system – SMD5050 bracket appeared first on Nerd Corner.

I do a lot of screwing in my workshop and most often I use Torx, hexagon socket and Phillips bits. I always buy these bits in packs of 10 or 25 because they are cheaper and I like to have a small stock. I feel the same way about tools, so I decided to design a few bit adapters and 3D print them.

You might also be interested in: 3D printed battery container

Procedure

The first thing I did was to tidy up my socket cases to find out which adapters are actually needed. The most common square sizes for sockets are:

• ¼” equals 6,35 mm
• 3/8″ equals 9,52 mm
• ½” equals 12,7 mm

In picture 2.0 I have put together some square photographs. Figure 2.0.1 shows a ¼” hexagonal shaft with three different square sizes. This hexagonal shaft can be easily clamped in a three-jaw chuck which is usually used with a drill or cordless screwdriver. Picture 2.0.2 shows the version with a handle, where the square is at the end of the shaft. In 2.0.3 you can see three joints with different square sizes and picture 2.0.4 shows a so-called “spring pressure piece”. The resilient thrust piece has the task of retracting when inserted into the counterpart and engaging in the intended notch or groove in the counterpart in the final position. This ensures a better hold of both parts in the connection. I have marked the position of the springy pressure piece on the square with red circles on some of the squares as an example. It is important for me to explain the function, because in the construction of the adapter a different solution is realised.

CAD construction of the bit adapter

The realisation on the CAD is actually quite quick. The dimensions for the depth of the square on one side and the insertion depth of the hexagon on the other side of the adapter are measured on the shafts. Picture 3.0.1 shows the surface (red) on the square that is pushed into the adapter, which is the same as the surface on the hexagon (black) in picture 3.0.2. In picture 3.0.3 I made a cut and marked the cut surface in green. The placement of the two shafts is shown by the colours.

Only the square dimensions are decisive for the outer dimensions of the adapters. Since the square shafts are getting bigger and bigger, the outer diameter of the adapter must of course also be adapted. I have therefore added a step to the ½” adapter (4.0.3). After all, there is enough material in the hexagon as it does not change. The recesses or pockets on the lateral surfaces are not for show. On the one hand they serve the stability of the adapter and on the other hand they save material. The two threads are the same on all adapters. The M3 threads are used for optional clamping of the shafts.

I use studs with a hexagon socket, which are flat at the end in order not to damage the surface of the shafts. You can also use normal screws if they don’t bother you. The position of the threads can be seen in the sectional view in figure 3.0.3.

Excursus on spring-loaded pressure pieces: The spring pressure pieces have already been mentioned in picture 2.0.4. I have been trying to use them in plastic for several years and have always found that they do not work. It is easier to design the clamping with screws and it is guaranteed to work!

Finally, the bit adapters are printed and cleaned and the M3 threads are cut. In the pictures under 5.0 you can see some examples for the use of the adapters.

Note

The bit adapters are of course only suitable for use under 15Nm. I easily reached this value with carbon fibre reinforced filament. With higher values there is a risk of breakage and therefore also a risk of injury!

Files for download

• Adapter 3/8″ to  ¼”

The post 3D printed bit adapter square / hexagon appeared first on Nerd Corner.

You might also be interested in: 3D printed battery container

List of components

• LED tealightset
• Button cell CR2032
• Jumper cables
• Screws

Procedure

First, I ordered a set of LED tea lights. I measured it and examined whether it could be connected to a cable. I was quite surprised by the technique of how the LED gets power from the battery. It is simple but well thought out! With the on/off switch, a metal pin is pushed to the edge of the battery. This edge is the positive pole. The other metal pin is fixed in the housing and permanently touches the bottom of the battery. The bottom is the negative pole. The metal pins reminded me of pins on jumper cables. You can see how I connected the cables to the tea lights in the following series of pictures.

First, the cover and contact foil must be removed. Then the battery is removed.

The two current collectors are now visible in the battery compartment. The negative pole is brought into the vertical position using a screwdriver or pliers.

Then remove the black plastic cover (female) from both jumper cables with side cutters. But be careful not to damage or crush the metal clamps!

A jumper cable is pushed over the pin at the positive terminal and at the negative terminal and pressed on. Afterwards, the holding capacity of the press connection should be tested. When the metal clamps are firmly seated on the pin, the function of the LED should be checked. For example, by removing the battery.

The cables are fixed with hot glue. Finally, after checking the function of the LED again, I attach a connector housing to the cables. You can find out how to construct such a connector housing here.

Secondly, I need a holder for my wired tea lights. I want to design the holder myself on the CAD and then print it out on the 3D printer. You can see how to design such a tea light holder in Solidworks in the video below:

After the tealight holder has been designed and printed, it is painted. Then the wired LED tea light can be mounted in the holder. Of course, the holder should be properly deburred beforehand. You can see the procedure in the next picture.

When using the tealight holder shown here, make sure that the cables are fed through the hole provided for this purpose. Please also take care to insert the cables one after the other into the hole in step 6.4.

Power supply

The third step is the power supply for the tea lights. For this I use a USB power supply with 5V and a step down module like the LM2596s. The voltage converter is supposed to provide me with the 3V that the tea lights need. Fortunately, I have constructed some housings for the LM2596 in the past that I can use here.

With the LM2596 used here, I reduce the voltage from the USB charger from 5V to 3V for the LED. You can also apply a voltage of less than 3V, in which case only the luminosity of the LEDs is reduced. The arrangement of the holders in the picture is only an example.

If you need an independent power source, e.g. a power bank, you can use my power bank with 3V output.

Assembly

Different screws can be used for mounting the tea light holders. Depending on the surface, you can use wood screws or cylinder head screws, for example. Alternatively, you can also screw the holder directly to the wall with the help of dowels. The only thing to note is that the screw head must be larger than 7 mm and smaller than 11 mm in diameter. The hole for the screws has a diameter of 5 mm. The hole for the cables lies vertically on the centre line of the screw hole and the centre distance to this is exactly 7 mm. The diameter of the cable hole is 4.5 mm.

Files for download

• Tealight holder

The post 3D Printed Tealight Holder appeared first on Nerd Corner.

To organise the workshop, I have developed a storage box for CR2032 and similar batteries of this type. There are already a few, but they all had the same shortcoming. The battery containers for CR2032 must always be opened with the proper side facing upwards, otherwise everything falls onto the floor. My battery cases for the CR2032 offer safe and clean storage without the cells falling out. In addition, you always have an overview of the number of batteries present.

The container is available in 2 versions, one for 10 and one for 22 button cells. The container consists of a drawer and a cover (container) and is safe against shocks and falls. The batteries are simply clicked into place and hold firmly in their drawer.

You might also be interested in: 3D printed Dupont connector

Construction of battery container CR2032

The container must be stable and durable, but still have handy dimensions. In addition, each individual battery must sit firmly in its compartment and yet be easy to remove. I also asked myself how many batteries the battery container for the 2032 should actually contain. Most sets consist of 5, 6, 8 or 10, sometimes even 20. In any case, the container had to fit in my desk drawer. As I was not sure about the number of batteries to be stored, I decided on two variants, one with 10 pieces and one with 22 pieces.

The construction on the CAD starts with the drawer, i.e. the slide-in part, the long part for 22 pieces. The width of the drawer depends of course on the width of the battery, the battery is 3mm thick, 2.95mm to be exact, and needs enough air between the individual walls. A gap of 0.15-0.2mm for each side is enough to avoid friction. So if we add it all up, we get a shaft width of 3.3-3.4mm. We create the holding force that prevents the battery from falling out of the shaft with the edge trick. We create a circular pocket in the centre of the slot with a larger diameter than the battery. Then we cut off about 1 to 3 mm of the material above the centre point, thus creating an edge. This edge must be slightly smaller in absolute length than the diameter of the battery (in this case smaller than 20mm). If you now push the battery into the shaft, it must overcome the edge, which is also possible due to the elasticity of the material.

Now the battery sits in the shaft and cannot overcome the edge in the other direction with its own weight. This principle is actually quite simple, with the necessary knowledge about material, manufacturing tolerances, forces and holding torques. In the end, it was a mixture of experience and a few test prints until the optimum result was achieved. Now the battery fits neatly into the shaft and holds perfectly. And with gentle pressure, the battery can also be removed from the shaft again.

The next goal was to design the slot so that it holds securely in the case. This is also an interaction of material elasticity and the right diameter at the collar that holds the construction together. After a few test pressings, I was satisfied.

The shell of the CR2032 battery container is quickly constructed. Basically, it is a cylinder with a base. The inner diameter was adapted to the insertion size to ensure locking and the hole in the bottom of the sleeve is for air release, because when the insertion is pushed into the sleeve, the air must be able to escape.

Files for download

• Battery container CR2032

The post 3D printed battery container for CR2032 appeared first on Nerd Corner.

In today’s 3D printing age, it is still the rule to produce threads with a tap, especially since the print quality leaves much to be desired, especially for smaller threads. Printed threads therefore often have to be recut or finished immediately. If you use a steel tap for thread cutting in 3D printing, it is too heavy and the cutting can easily go wrong, since 3D printing requires less force than, for example, steel. The solution is a plastic tap wrench that is light but strong.

You may also be interested in: 3D printed dupont connector

Below is a table of adjustable steel tap wrenches DIN 1814. The table shows in the first column the size, in the second, third and fourth what it is suitable for and in the last column the length in mm:

Construction of the tap wrench

First, the mass of the square and the associated norms must be determined. The square is located at the end of the tap and is used to transmit power from the tap wrench to the tap:

The following table lists different standards for the shank diameter and corresponding mass for the square of the tap. These standards are assigned to the standards of the taps:

• DIN 2184-2 zu DIN 352
• DIN 2184-1 zu DIN 371
• DIN 2184-1 zu DIN 376

After measuring the tap arsenal, it turned out that the tap corresponds to the standard DIN2184-2. With this knowledge, the design in CAD can now begin. Two different shapes are planned, one round with indentations on the edge and one oval smooth shape.

In both variants, the stability and the feel are crucial. Stability is provided by a strong rim with a solid center and supporting ribs. It’s the same principle as a car rim. It is relatively light, yet stable. The indentations on the rim of the round wrench tap also contribute to increased stability. Incidentally, they impart a better grip for the fingers. These indentations are also crucial to transmit the force. This necessity is not given with the oval winch iron, because the position of the fingers is different. Here, the fingers find hold on the straight surfaces of the winch iron. In addition, greater torques are possible with the oval variant because of the longer lever.

At the beginning I had constructed a round variant for M 10, because I was not sure which diameter and which mass the indentations at the edge should have. For this I made two variants, one with diameter 44 mm and large indentations and one with 50 mm diameter and smaller indentations with a higher number. After the test printing of both variants and the first thread cutting came the surprise. It was possible to work very well with both types. The square intake was also fine. The taps went quite strictly and the hold was perfect.

Conclusion about the 3D printed wrench taps

The main positive points are the low weight and the low price of manufacture. I often use hand tap sets, which consist of two or three taps. With these homemade tap wrenches, I can equip my taps each with its own tap wrench. This completely eliminates the need to change taps and saves me a lot of time.

Download files

• Wrench taps round for M5, M6 and M8
• Wrench taps round for M10
• Wrench taps round for M12
• Wrench taps oval for M5, M6 and M8

The post 3D printed tap wrench for tap M5 to M12 appeared first on Nerd Corner.

That’s why I designed a quick connector in CAD that makes it very easy to solder jumper cables. The connector serves as an ideal soldering aid. Of course, the wire diameter must be sufficient for the required number of amperes! On the market there are mainly inferior connectors. My STL file on the other hand is cheap and works perfectly.

This might also be interesting: Universal connector housing!

List of components

• 4 Pin RGB LED Strip
• Jumper cable
• Heat shrink tubing
• Hot Glue

Project application

For a larger project I needed 16 RGB strips with 21 LEDs each. The strips were pushed into a 3D printed socket afterwards. The LED strip was separated directly at the pre-marked point with a standard pair of scissors (usually the RGB strips are divisible after every third LED).

For the jumper cables I chose one side male and the other female. The side with the PINs (male) were soldered to the RGB strip and the socket (female) was used as a plug. It is crucial to use jumper cables with square housing (standard dimension: 2.54 mm). The length of the plastic housing does not matter. Depending on the brand, the plastic housings are 12 mm or 14 mm long.

Procedure

Since no preparatory work on the cables is necessary, soldering can be started directly. I prefer to apply solder to the RGB strip at the soldering points (copper layer) first.  After that I solder the PINs to the soldering points without additional solder. The PINs should not be soldered too deep towards the LED and the alignment must fit.

Then the connector comes into play. This connector is on the RGB side and open at the top. The RGB strip is inserted into the connector so that the solder joints are in the connector. Then the four cables are pressed into the slots and the solder joints are sealed with hot glue if necessary. For safety reasons, I recommend to attach a heat shrink tubing. This way you get a super strong connection!

Steps in pictures

Advantages:

• No cable preparation
• Strong connection
• Easy 3D printing

Disadvantages:

• Requires more space
• STL file only for RGB strips with 10 mm width

Download files

• • STL file of the soldering aid

The post Printed connector as soldering aid for jumper cables and LED strips appeared first on Nerd Corner.

This might also be interesting for you: How to construct a display casing?

List of components:

• 4 x magnet 2x10x30 neodymium nickel plated N42
• 2 x dowel pin dia 4×24

Concept for the development of the magnetic clamp:

• Parts from 3D printer
• Inexpensive neodymium magnets
• Simple to use technology
• No round shape
• Stable and light construction

Implementation of the magnetic angle with 100 mm

STL files are required for the parts from the 3D printer. These can be generated by a CAD program. As always, I use Solidworks as CAD for designing.

The idea was to construct an angle similar to the one that is used as a support or holder when welding. For the magnetic board, of course, magnets are needed. I chose square magnets made of neodymium nickel-plated with dimensions 2 x 10 x 30 mm.

The magnet strength is “N42” and is neither too weak nor too strong. The value “N42” describes the energy density of the neodymium magnet and is mostly divided into N35 to N54.

The higher the number, the stronger the magnet. The nickel coating serves as protection against corrosion. The dimensions of the magnet determine the dimensions at the angle. For simplicity, this was constructed isosceles. A segment with a length of 100 mm and a width of 25 mm should not be a challenge for a small 3D printer.

To improve stability and torsional rigidity, I have constructed 10 mm high walls with a thickness of 3 mm. The magnets are recessed at the bottom with recesses. It should be noted that an oversize of 0.15 mm was planned for the recesses so that the glue has enough space to stick the magnets. A high-quality adhesive should be used if you want to enjoy the magnetic angle for a long time.

To remove the angle from the board, different variants would have been conceivable. One possibility would be a screw that presses the angle from the magnetic board when turning. The advantage would have been that only one thread would have had to be constructed in the angle. The disadvantage would have been that a screw without protection would damage the surface of the board and, in addition, many turns would have been necessary. A better solution was therefore a so-called excenter to be able to loosen the angle without much effort.

A few points had to be taken into account. The excenter could not be placed just anywhere, but had to be attached as close as possible to the magnet. The increase when actuating the excenter should be exponential, since the magnet loses strength with increasing distance. This means that in order to keep the lever length of the eccentric as short as possible, the distance between the magnets and the board was first increased only minimally and then more and more quickly. The fully opened eccentric has 3 mm. With this value, the angle can be easily removed from the board.

One excenter was fixed between the magnets for each leg. A non-hardened dowel pin with a diameter of 4 mm was used for the rotary axis of the eccentric. Alternatively, an M4 screw can be used, but it must be fixed with a nut.

The parts were printed, assembled, glued, and could then be tested. The result was more than satisfactory on various panels and steel sheets. The holding forces are excellent, but it should be fairly mentioned that the angles sometimes slip slightly. Therefore, an anti-slip tape was glued on some angles.

Please note when using the magnetic clamp:

• Attachment only with the open excenter
• Holding force depends mainly on the quality of the magnetic board
• Neodymium magnets are not toys (risk of injury!)
• Use good quality glue

Download files

• STL files for the magnetic clamp and the eccenter
• Alternative STL file for magnetic clamps

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