If you are like me you get annoyed with the constant focus tracking of your webcam in Klipper. This got me wondering if it was possible to turn off the autofocus, and after some research this is the method I came up with. I hope you find it as useful as I did. This worked perfectly for my C920, but it should work on other cameras as well. The method should probably also work on Octoprint, if that is what you are using.  

1. First step is to install putty 51 if you are in windows and this will let you login to the raspberry pi via SSH. If you are on Mac you should use a similar program for that. (I'm no Mac user, so don't have any suggestions at the moment)

3. Username is by default pi, and password raspberry  (If you have changed these, input the values you've changed to)

You have to go to folder "mjpg-streamer", so you enter the command: cd mjpg-streamer/

Now enter sudo v4l2-ctl --set-ctrl=focus_automatic_continuous=0 to disable auto focus

Open a window with your Klipper webcam, preferably with an object in the center of the bed and fine tune the manual focus..
so enter sudo v4l2-ctl --set-ctrl=focus_absolute=70 and change the number until the focus is ok.

In this case, a number of 35, looks to be pretty good, so I'm running with that. 

Now, you have your two commands that fine tune your camera. In order to run them every time you boot up your Raspberry Pi, you have to add them to the rc.local file:
a) enter sudo vi /etc/rc.local, then go to line last line "exit 0"
b) press shift+O and write your two commands (you can copy and paste with left click)..
if you mess up something press esc and :q! to quit
if you are fine press esc and :wq to save
It looks something like this:

Some additional info:
if you set focus_auto to 1 and let the webcam focus an object in the center you can take the "perfect" focus value..and then focus_auto to 0. 

To find the value, You have to run the command sudo v4l2-ctl -l and you will see a list of settings for the webcam, in this case you should be looking for:

"focus_absolute (int) : min=0 max=250 step=5 default=8189 value=*"

The * in this case is your "perfect" value according to the camera. The reason I add this as additional info instead of including it in the main part, is that it didn't work too well for me. It gave me a value of 40 instead of the 35, I got to by looking at the webcam feed. This is probably because some other area of the printer, like my textured sheet kept the focus instead. This might be different for you though, so it's worth a try. 

You can play with the other listed settings also..(like contrast with sudo v4l2-ctl --set-ctrl=contrast=200)

I hope you find this article useful. Have a great day everyone!

Preparing the 3D Print

Before painting your 3D print, it is crucial to prepare the model properly. Here are the recommended steps:

• Remove Supports and Unwanted Parts

  • If your print has 3D printing supports, carefully remove them using a knife or pliers to avoid damaging other parts of the print. Take your time and exercise caution during this process.

• Sanding and Smoothing 

  • If the print has rough surfaces or visible layer lines, use sandpaper or a sanding sponge to smooth them out. Start with coarse-grit sandpaper and gradually move to finer-grit sandpaper for a smoother finish. This step helps the paint adhere better to the surface.

• Cleaning 

  • Thoroughly clean the 3D print to remove any dust, debris, or oils. You can use isopropyl alcohol or a gentle detergent solution. Ensure the print is completely dry before proceeding.

Choosing the Right Paint

Selecting the appropriate paint is essential for achieving high-quality results. Acrylic paints are a popular choice for painting 3D prints due to their versatility, wide range of colors, and compatibility with various materials like PLA and ABS. Look for paints specifically formulated for plastic or multi-surface use.

Painting Techniques

• Priming

  • Applying a primer coat helps the paint adhere better to the 3D print surface and provides a smoother base for further layers of paint. Use a spray primer designed for plastic surfaces and apply it evenly, covering the entire model. Allow the primer to dry completely before proceeding.

• Base Coating

  • Start by applying a base coat of paint that matches your desired color scheme. Thin layers of paint are recommended to avoid obscuring details. Allow each layer to dry before applying additional coats, if needed. Multiple thin layers result in a more professional-looking finish.

• Detailing and Layering

  • After the base coat is dry, use smaller brushes to add details and layers of paint. This step allows you to highlight specific areas, create shading or gradients, and add depth to your model. Take your time and use reference images or sketches for guidance.

• Finishing

  • Once you are satisfied with the paintwork, consider applying a clear protective topcoat to seal the paint and provide additional durability. This step helps prevent chipping and enhances the overall longevity of the painted 3D print.

Tips for Success

• Work in a Well-Ventilated Area

  • It is crucial to have proper ventilation when painting 3D prints to avoid inhaling fumes or harmful particles. Consider working outdoors or in a well-ventilated space and use personal protective equipment such as a respirator and gloves [3].

• Test on Scrap or Similar Material

  • Before painting your actual 3D print, it is wise to practice on a scrap piece or a similar material to ensure you are satisfied with the color, technique, and overall outcome.

• Patience is Key

  • Take your time throughout the painting process. Allow each layer of paint to dry thoroughly before proceeding to the next step. Rushing can lead to smudges, uneven finishes, or accidental runs. 

• Layering and Blending

  • Achieving a professional and realistic look often involves layering and blending different colors on the 3D print. To add depth and dimension to your painted model, consider the following techniques:

• Wet-on-Wet Blending

  • This technique involves applying wet paint onto another wet layer of paint. It allows the colors to blend together smoothly, creating gradients and transitions between shades. Use a soft brush and work quickly to achieve seamless blends.

• Dry Brushing

  • Dry brushing is a technique where you remove most of the paint from the brush, leaving only a small amount. Lightly drag the brush over raised surfaces, such as textures or edges, to add highlights and accentuate details. This technique works well for creating a weathered or worn effect.

• Glazing

  • Glazing involves applying transparent or translucent layers of paint over a base coat to modify the color or add subtle effects. Use thin layers and build up the intensity gradually to avoid overpowering the base coat. Glazing can enhance the realism of your 3D print by adding depth and variations in color.

• Feathering and Smudging

  • These techniques are useful for creating smooth transitions between colors or blending different areas together. Feathering involves lightly brushing one color into another, gradually reducing the intensity. Smudging can be done with a soft cloth or sponge to soften edges and create a more natural appearance.

Remember, practice and experimentation are key to mastering these techniques. Don't be afraid to try different approaches and find what works best for your desired outcome.