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If ( ) Then {Paint}

create canvas paintings of your favorite digital images

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A cnc painting system that gives artists, crafters, and makers the ability to create canvas paintings of their favorite digital images cheaper and faster than ever before.

Simply upload an image, define the painting parameters, and watch the machine create your custom painting.

The Problem

We can create and share custom digital images at almost no cost, but recreating our favorite digital images in paint on canvas is an expensive service that most cannot afford.

In today's world, if you want a custom canvas painting of a digital image you really only have two options. Either roll up your sleeves and spend the next couple of years learning how to bring your ideas to life on canvas or commission an experienced canvas painter to do it for you. Regardless of which route you go down, its unlikely you will be happy with the results without paying anything less than $300 per painting. Say you want three or four custom paintings for your living room or office - you may end up paying more for the paintings on the wall than you did for all the furniture in the room!

It's not the raw materials that make canvas paintings expensive. It's the time and dedication required to master hand-eye coordination, brush technique, and paint color mixing. But even if you decide to pay the high cost of mastery, there are still no shortcuts to creating canvas paintings. Good paintings simply take hours to create. 

The Solution

A cnc painting system that gives artists, crafters, and makers the ability to create canvas paintings of their favorite digital images cheaper and faster than ever before.

Weigh the high cost of custom canvas paintings against the decreasing costs of cnc machine components and software development and you will find that cnc painting systems can pay for themselves and start adding value in record time. 

Ultimately, the If Then Paint cnc painting system adds value by automating the technical challenges that make custom paintings so expensive and time consuming. It can place paint on canvas with millimeters of precision, be programmed to perform any number of advanced brush stroke techniques, and mix hundreds of paint colors on demand. On top of that, it will perform all of these tasks through day and night without interruption. 

Operating the machine doesn't take years of practice and dedication either. Simply upload an image, define the painting parameters, and watch the machine create your custom painting.

The Potential

  • A canvas painting productivity tool that artists can use to either create originals or replicate their best sellers faster than ever before.
  • A tool for crafters that reduces the amount of time and practiced skill it takes to add personalized painted embelishments to decorations and paper crafts. 
  • An flexible system architecture that gives makers and hackers the ability to make custom enhancements with ease.
  • A platform that artists, crafters, and makers around the world can use to share techniques and recreate each others paintings.
  • A sign making tool for small businesses.
  • A canvas painting learning tool for young artists.
  • A platform for new canvas painting innovations.

The Team

John Opsahl is a hacker and creative. He works as a mechanical design engineer for a lithium battery manufacturer. After hours he develops new cnc art machine technologies and designs laser cut products for his Etsy shop. All of his projects address the challenge of making new technologies and products available to a larger audience.

He is currently looking for a business development partner to help bring the If Then Paint cnc painting system to market. 

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IfThenPaint_cnc_painter.STEP

3D model of the If Then Paint cnc machine

step - 21.67 MB - 08/02/2019 at 02:54

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  • machine control dimensions

    John Opsahl5 days ago 0 comments

    In contrast to 3D printers and cnc mills that only have one or two objects to interact with within the workspace (e.g. bed and stock material), the cnc painting machine interacts with multiple objects like the canvas, towel, water, and paint palette. The tables that follow detail the object dimensional information needed to develop the cnc painting machine control instructions (gcode) for the If Then Paint proof of concept prototype. Most of these dimensions are fixed, but some may need to adjusted as the gcode is developed and tested (z_water_dip for example).

    You will see paint palette object dimensions for both the six axis brush machine and paint management machine because both interact with the paint palette but in their own coordinate systems.

    Six axis brush machine control dimensions (tool docks, brush cleaning water, brush wiping towel, canvas, and paint palette objects):

    DimensionValueUnits
    x_tool_dock_1-88.5mm
    x_tool_dock_2-23.5mm
    x_tool_dock_341.5mm
    x_tool_dock_4106.5mm
    y_tool_dock229.75mm
    z_tool_dock3.5mm
    z_tool_dock_clearance15mm
    x_water109mm
    y_water-61.75mm
    z_water_dip-62mm
    z_water_clearance15mm
    water_dip_radius15mm
    x_towel_start45mm
    x_towel_end-100mm
    y_towel75mm
    z_towel2mm
    z_towel_clearance15mm
    x_home_to_x_canvas_left-253.35mm
    y_home_to_y_canvas_bottom-323.9521mm
    z_canvas2.5mm
    z_canvas_clearance15mm
    x_palette_left-129.0616mm
    y_palette_top189.75mm
    z_palette-7.075mm
    z_palette_clearance15mm

    Paint management system machine control dimensions (paint palette, dispenser, syringe water, and paint objects): 

    DimensionValueUnits
    x_palette_left5mm
    x_palette_right-95mm
    y_palette_top-73mm
    z_palette-173mm
    z_palette_clearance15mm
    x_dispenser-121.6146mm
    x_water-61.6146mm
    y_water-372.9771mm
    z_water2mm
    z_water_clearance15mm
    a_paint_10deg
    a_paint_236deg
    a_paint_372deg
    a_paint_4108deg
    a_paint_5144deg
    a_paint_6180deg
    a_paint_7216deg
    a_paint_8252deg
    a_paint_9288deg
    a_paint_10324deg
    b_push_start13mm

  • origin and axis orientations

    John Opsahl6 days ago 0 comments

    I developed the following graphics to help clarify the location of the origin and orientation of system motor axes. My hope is that these graphics will make it much easier to discuss motion control strategies for the If Then Paint cnc painting machine moving forward. 

    The origin of the six axis cnc brush control machine is located at the bottom left corner of the canvas. The paint management system does not have an absolute origin. Instead, it has a home position at the -x, -y, and -z limits of the paint management system axes.  

    The arrows point in the positive direction of the depicted axis. All axes have the capability to move in both directions.

    The x-axis positive direction is into the paint carousel. When developing the machine movements, it's generally easier to think about machine movements relative to the "tool" (i.e. paint dispenser in this case). Since the bed (i.e. palette) is moving and the tool is stationary, a bed positive movement towards the tool can be thought of instead as a tool positive movement across the bed. 

  • bitmap image to paint stroke examples

    John Opsahl08/07/2019 at 03:35 0 comments

    One of my goals this week was to explore what bitmap image to paint stroke conversions are possible with very simple conversion parameters. In the three image conversion examples below, the original reference image is on the left and paint stroke preview image is on the right. None of the images are a result of being physically painted by a cnc painting machine. The preview images are just approximations of what a final painted image might look like. The longest line algorithm (described in a previous project post) was used to generate paint strokes from the reference image. The generated paint strokes were plotted in their respective colors to construct the preview images. A single round brush size and no more than six paint colors were used to construct each preview image. Even with these simple parameters, the paintings are still fun to look at and given past experience, they will probably look much smoother as actual paintings. The rough and jagged borders between colors shown in the preview images are less striking once physically painted. These conversions get me excited about what might be possible with more complex parameters.

    Another thing I really enjoy about these conversions is that even though I know what the reference image looks like and the painting parameters that the algorithm is using, the result can still be surprising. For example, it's always interesting to me how the algorithm removes detail from the original image, but in some way the message and feeling of the image is not lost. Like the fine details are not what really mattered. 

    This also motivates me to fully develop the paint management system. Without the paint mixing component of the paint management system, I currently have to manually mix paints until the correct color is achieved. Once fully developed, I won't have to mix paints anymore and painting with more than six colors should no longer be much of a challenge.

  • fabrication files posted

    John Opsahl08/01/2019 at 02:03 0 comments

    All fabrication files needed to build the cnc painting machine have been released to the GitHub repository: https://github.com/johnopsahl/If_Then_Paint_CNC_Painting_Machine

    The fabrication files are listed separately for the two cnc subsystems - the six axis cnc and paint management system. Six laser cut 12x24in sheets of 0.175in baltic birch plywood and two 3d printed parts are required for the six axis cnc machine. Ten laser cut 12x24in sheets of 0.175in baltic birch plywood and one 3d printed part are required for the paint management machine. The bills of material include quantities and descriptions of all the purchased components.

    A .step solid model file of the entire machine is included for dimensional reference as well.

  • cnc painting user interface wireframe

    John Opsahl07/30/2019 at 02:19 0 comments

    A few months back I tried to imagine what the cnc painting software user interface might look like. I arrived at the wireframe shown above. The "Feature Tree" box  (left center) includes all high level components that need to be defined to both determine paint strokes from the bitmap image and create the cnc machine gcode painting instructions from the paint strokes. The user works from top to bottom in the feature tree. When the user clicks on and highlights an item in the feature tree, user input parameters unique to the tree item type are listed in the "Details" box (left bottom). In addition, feature tree item actions are accessed by right clicking on the feature tree item. The "Canvas" window (center, depicted as a white square) is where images are displayed. This includes images like the original bitmap image that is being converted to paint strokes, strokes of a specific brush displayed over the original image, strokes generated during a specific iteration of the algorithm, all paint strokes required to create the image, etc. It would be possible to zoom in/zoom out and pan in the canvas window. The "File", "View", and "Help"menu bar headers would contain the standard application features. The "Simulate" menu bar header would run a simulation of the cnc painting operation by showing a moving brush in the canvas window (similar to the simulation feature of a cnc milling CAM software). The simulation feature is somewhat advanced to implement and actually does not add that much value. It's unlikely it will be released in the first version of the software. 

    After completing the wireframe, I began scoping out the UI input fields and actions in a Google doc spreadsheet. The screenshot below is the list of input options that would appear in the details box when a feature tree item is highlighted.

  • cnc painting workflow

    John Opsahl07/27/2019 at 04:19 0 comments

    Once fully developed, I envision cnc painting workflow to be very similar to the workflow used for 3D printing and cnc milling. 

    1. Create a template file with using your preferred software. A bitmap image in the case of cnc painting using an image processing software like GIMP, Adobe Photoshop, Corel Paintshop, etc. A 3D model file in the case of 3D printing and cnc milling using solid modelling software llike Onshape, Autodesk Fusion 360, Solidworks, etc.
    2. Import the template file into the computer aided manufacturing software. The If Then Paint software for cnc painting. Splicing software like Cura or Simplify3D for 3D printing. Software with tool path creation capabilities like Autodesk Fusion 360 or Solidworks for cnc milling. 
    3. Select which machine you are using. The software either loads the predefined machine parameters from a database or asks you to define the parameters for the machine.
    4. Make adjustments to the parameters that effect the tool path operations.
    5. Run a simulation that shows the result of the tool path operations. Observe how adjustments in step 4 affect the final product.
    6. Continue step 4 and 5 until you have a achieved a desirable result.
    7. Export the tool paths from the software as gcode.
    8. Upload the gcode to the cnc machine.
    9. Prep the cnc machine with any raw material needed.
    10. Run the gcode program on the cnc machine.

  • automated paint mixing

    John Opsahl07/26/2019 at 17:57 0 comments

    The automated paint mixing component of this project is essentially a small scale recreation of going into the paint store with a color sample and leaving with a bucket of paint of that color. 

    The main challenge is determining which paints to mix to create the correct color. Paint companies have their own methods for predicting additive color mixing which most likely requires data from expensive photospectrometer equipment. Fortunately, cnc painting probably doesn't require the color matching accuracy that paint companies achieve. 

    I propose using a camera and cnc machine to develop the paint mixing color data needed for cnc painting. The cnc machine would dispense and mix paint color samples in various proportions (e.g. 20% white/80% red, 30% white/70% red, etc.). After those paint samples dry (because some paints change color once dry), the camera would take a picture of the sample in controlled light conditions. Using an image processing tool, an rgb value would be extracted from the picture of each sample. Then it is only a matter of finding the rgb values of the paint sample that are closest  to the rgb values of the desired color, approximate the desired color as the paint sample color, and mix up the paint per the known color proportions of the paint sample to achieve an approximate paint color match. The accuracy of this method can be increased by increasing the number of stock paint colors and using finer increments of mixing proportions.

    The method I am proposing is not a small task, but it should only have to be done once per grade/brand of paints. Whomever designs the paint mixing software would need to create the machine, dispense and mix as many paint samples as needed, and insert the paint mixing color data in the software as a database. The average maker and artist would make use of the database through the software and never need to perform this task.

  • automated paint management

    John Opsahl07/24/2019 at 03:47 0 comments

    "Paint management" refers to the processes involved in dispensing and storing paints during the cnc painting operation. The paint management system developed for the proof of concept prototype is comprised of a three axis positioning system, a syringe carousel and push plate, a paint palette, and a water dish. The three axis positioning system is used to dispensed paint at any location on the palette. The syringe carousel allows up to ten syringes of paint; one per paint color. The syringe carousel rotates to position syringes under the push plate. The push plate presses on the syringe plunger to dispense paint onto the palette. After use, the syringes are returned to the water dish so the paint doesn't dry and clog the tips of the syringes. The palette is made of glass so it can be cleaned easily using a metal scraper.

    In theory, the paint management system will determine how much paint to dispense and where on the palette to put the paint by following this process. After the user has converted a bitmap image to paint strokes, another programming script determines the total paint stroke distance traveled on the canvas for each color of paint and each paint brush. Each paint brush has a predefined (determined through testing) parameter on how far it can travel on the canvas before needing to be reloaded with paint as well as the length of paint bead required to reload the brush. From this information, the length and color of each paint bead that needs to be dispensed on the palette to complete the painting can be found. Another script will map out how to place the variable length beads of paint within the available palette size. This map will be converted to the gcode instructions that get sent to the paint management system microcontroller. 

    Turns out that acrylic paint is thixotropic (viscosity decreases with an increase in shear stress). When I commanded the machine to dispense paint and move all in one single movement there would be a delay before paint would start coming out of the nozzle. After the movement was completed the syringe continued to dispense paint. See the rows of paint at the top of the palette in the images below. I eventually figured out how to create uniform beads of paint by dispensing a little bit at the beginning and including a short delay so the paint could begin to flow before staring the movement. See the rows of paint at the bottom of the palette in the images below. It still needs some work but after a few months of designing and fabricating the paint management system I considered it a victory.

  • load brushes with paint without feedback

    John Opsahl07/23/2019 at 04:36 0 comments

    Imagine you are trying to load a brush with paint with the intent of painting on a canvas. You have a paintbrush in one hand and a cup full of paint in the other. The catch is that you can't see inside the cup. You eventually get good at loading the brush with a known amount of paint by dipping it a distance into the cup. But after a while you've dipped it so many times now that you don't know of how much paint is left in the cup and what side of the cup the majority of the remaining paint is on. This is the challenge of loading brushes with paint without feedback (i.e. The challenge is knowing how much paint is left in the cup and how the paint is distributed within the cup).

    One way to solve this problem is to use paint with low viscosity like tempera or liquid acrylic paints. Low viscosity ensures that the paint always settles to a uniform level in the cup. After that, it only takes some testing to determine how far the paint level in the cup drops each time the brush is dipped into it. Better yet, use a large container of paint so the paint level drops so little after each brush dip that the change in paint level can be neglected.

    Another way would be to use high viscosity paints like oil and acrylic and continuously monitor paint distribution in each cup during the entire painting process. If a brush continues to dip in one location of a cup of high viscosity paint, eventually a well will form. The next time the brush dips into that location for more paint it will just be dipping in air. To combat this, paint needs to be periodically stirred in each cup until wells are gone and all paint locations in the cup are at the same level. Alternatively, the brush could be commanded to dip in the cup of paint at different locations each time. 

    I have used both methods with success but prefer to use high viscosity paints because of the rich color, less risk of dripping on the canvas, and three dimensional texture. At the moment, the cost of using high viscosity paints is being present during every second of the painting operation to make sure there is enough paint in each cup and to stir out any wells when they form. This is in conflict with the unsupervised operation proof of concept design requirement.

    In search of a more complete method to load brushes with high viscosity paint, I stepped back and tried to understand the problem better. I knew that in order to repeatably apply a known amount of paint to a brush without feedback the geometry of the paint that the brush is dipping into has to be predictable. In the case of paint in a cup, the well formation and paint level are not easy to predict because they depend on factors like brush size and type as well as the viscosity specific to each brand of paint. Ultimately it's really just a paint side problem, the cnc machine can position the brush with accuracy and repeatability. 

    I kept digging deeper into the requirements until I realized that canvas painters had already solved half of this problem. The solution is... that simple flat surface called the painters palette. Not only is a good place to mix paints but a flat surface also makes paint easier to control. Think about wiping a brush on the side of a paint can after dipping the brush in the paint. The same concept is at play on a flat palette surface. You press the brush against a hard surface to better control how much paint is loaded into the brush.

    The second part of the solution is my own contribution. To achieve predictable paint geometry, I propose dispensing paint into beads (like a bead of caulk) on the palette. To load brushes with paint, start on one side of the bead and each time that the brush goes back for more paint move a little closer to the other side of the bead. So that every time the brush goes back for more paint it dips into a previously undistributed section of the bead. The brush movement to load paint on the brush can...

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  • automated brush cleaning

    John Opsahl07/21/2019 at 16:55 0 comments

    Currently, the cnc painter uses the same brush cleaning technique that human canvas painters use. Swirl the brush around in a cup of water and wipe it off on a paper towel. This procedure is performed at the start of any painting operation to ensure that the brush bristles are wet enough to accept paint, periodically during the painting process to prevent paint from drying on the brush, between paint colors, and at the end of the painting to clean the paint off the brush in preparation for storage. I would classify this technique as semi-autonomous. You don't have to physically clean the brushes yourself, but you do have to replace the water and paper towel periodically during operation. This technique has worked great so far, but has a few downsides -> the paper towel takes up a large percentage of the workspace (leaving less space for the canvas) and different brush sizes and types require unique water swirling and towel wiping patterns to effectively clean the paint of the brush.

    I tried to come up with a universal mechanical solution. It involved rotating a brush while spraying it with powerful jets of water. I bought a small 12Vdc pump and designed a 3D printed nozzle that would direct two streams of water (90 degrees apart) at the same location. In order to avoid changing water as often, the water used to clean the brushes would be recirculated and a large volume of water would be used to dilute the paint that was washed off the brushes. It turned out working quite well for a variety of brush sizes and types. The water jets were strong enough to deflect the bristles and clean the center of the brush. The only additional design consideration would be to make an enclosure for it. Some of the water was splashing into my face.

    Still looking around for more options I purchased a cheap ultrasonic cleaner bath. Even after one minute there was usually still a little bit of paint left on most brushes. It also gave me a headache if I left it on too long with the lid open.

    Thinking the inverse of the ultrasonic cleaner may be more effective (vibrating the brush instead of the water), I bought a sonicare toothbrush next. It did about as well if not a little worse than the ultrasonic cleaner bath.

    I decided that it was enough of a victory to have found a couple of viable solutions and would worry about how to integrate one of them later. The water swirl and towel wipe technique worked "good enough" at this point and I had bigger challenges to solve with this cnc painter.

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Tom Nardi wrote 08/03/2019 at 04:58 point

Love the use of keyless drill chucks to hold the brushes, brilliant reuse of a common part.

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