The OpenScan is a 3D scanning device designed for hobbyists and makers, enabling the capture of objects for 3D reconstruction. It primarily functions by rotating and tilting an object while a camera (typically a smartphone) captures images from various angles. The system is largely composed of 3D-printed parts and off-the-shelf electronic components, making it an accessible and customizable solution for creating 3D models.
Function Description:
The core function of the OpenScan is to automate the image acquisition process for photogrammetry. It consists of a motorized turntable and a tilting mechanism, both controlled by a central unit. An object is placed on the turntable, and a camera (usually a smartphone mounted on a tripod) is positioned to capture images. The control unit orchestrates a sequence of movements: the turntable rotates the object, and the tilting mechanism adjusts its vertical angle. At each predefined position, the control unit triggers the camera to take a photo. This systematic capture of images from multiple perspectives allows 3D reconstruction software (not part of the OpenScan itself) to generate a 3D model of the scanned object.
The device supports various camera triggering mechanisms, including Bluetooth for Android/iOS smartphones and infrared for a range of DSLR and mirrorless cameras. There's also a "direct" triggering option, which involves shorting two pins on the control unit, suitable for modified remote controls or other custom setups. This flexibility in camera control makes the OpenScan adaptable to a wide array of imaging devices.
The user interacts with the OpenScan through an integrated LCD screen and a set of push buttons. The main menu allows users to load and start predefined scanning programs or modify settings. Programs can be customized to specify the number of photos per rotation, the start and end tilting angles, and the number of vertical positions. This programmability allows users to tailor the scanning routine to the specific geometry and detail requirements of their objects.
Important Technical Specifications:
- Control Unit: Based on an Arduino Nano (or similar microcontroller), integrated with stepper motor drivers and an I2C LCD module.
- Motors: Two Nema 17 stepper motors (minimum 40Ncm torque) are used for the turntable rotation and the tilting mechanism.
- Display: LCD 20x4 with I2C-Module for user interface and program feedback.
- Power Supply: 12V 2A with a 5.5mm-2.5mm barrel connector.
- Connectivity: Jumper wires (10cm m-f) for LCD wiring, stepper motor cables (>70cm JST-XH-4P or 4P DuPont).
- Mechanical Components: Primarily 3D-printed parts (STL files provided), including stands, adapters, gears, and the turntable base. A 6mm diameter, >50mm long steel pin is used for mechanical rotation.
- Camera Triggering:
- Bluetooth: Compatible with Android/iOS smartphones using a modified Bluetooth trigger module ("AB Shutter 3").
- Infrared: Supports various Canon EOS, Minolta, Nikon, Olympus, Pentax, and Sony camera models. The control unit emits short infrared light pulses (<0.1s).
- Direct: Shorting two pins on the control unit for custom remote controls.
- Scanning Volume Adjustment: The height of the tilting mechanism is adjustable to center the object within the rotational axes, optimizing scan quality.
- Mounting: The entire assembly can be mounted on a base plate (min. 600x150mm wood panel) using wood screws or double-sided tape.
Usage Features:
- Programmable Scan Routines: Users can define and store up to twelve different scanning programs. Each program allows customization of:
- Photos per Rotation: Typically 32, but can be adjusted to 16 for simpler objects or higher for very detailed ones.
- Start and Final Tilting Angle: Defines the range of vertical angles the object will be scanned from (e.g., -75° to +75°).
- Number of Vertical Positions: Specifies how many distinct vertical angles the object will be scanned at within the defined tilting range (e.g., 5 positions).
- Home Position Setting: At the start of each program, users can manually set the zero position for both the rotor (tilting mechanism) and the turntable using the up/down buttons.
- Adjustable Time per Photo: A crucial setting that allows users to define the waiting time after each trigger pulse (default 2.5s). This accounts for camera exposure times and processing, preventing blurred images. The range is 0.1s to 20s.
- Minimum Vertical Angle Setting: This parameter helps ensure sufficient overlap between different rotation planes for better reconstruction. The recommended value is 10°, with a range of 2° to 30°. If the angle between rotation planes is too large, additional photos are taken at intermediate angles.
- Interrupt/Stop Routine: A running program can be interrupted by holding down the OK button for at least 1 second, then pressing the UP button to confirm cancellation.
- User-Friendly Interface: The LCD screen displays program progress, settings, and menu options, guided by arrow keys and an OK button.
Maintenance Features:
- Modular Design: The OpenScan's design relies heavily on 3D-printed parts and standard electronic modules (Arduino, stepper drivers, LCD). This modularity simplifies replacement of individual components if they fail or if upgrades become available.
- Open-Source Nature: Being an open-source project, users have access to the STL files for 3D printing, allowing them to print replacement parts or customize existing ones. The documentation also guides users through the assembly process, which inherently provides a deeper understanding of the device's construction for easier troubleshooting.
- Pre-drilling for Accuracy: The manual notes that depending on printing accuracy, it may be necessary to pre-drill screw holes (3mm drill bit) or deburr/enlarge holes for push buttons. This highlights a common maintenance/assembly step for 3D-printed projects.
- Gear Fit Adjustment: The manual advises that if gears do not match well or rotate freely, users might need to replace the small gear with a v2.stl version or adjust printer settings, indicating a potential area for mechanical adjustment or re-printing.
- Superglue for Loose Connections: For mechanical connections that are too loose (e.g., rotary arm to turntable base, or gears to shafts), superglue is recommended for fixation, providing a simple solution for maintaining structural integrity.
- Wiring Precautions: The manual explicitly warns about correct wiring of 12V/5V/Opto connectors to prevent damage to the control board or connected accessories, emphasizing the importance of careful electrical maintenance.
- Firmware Updates: While not explicitly detailed as a "maintenance feature," the use of an Arduino-based control unit implies that firmware updates could be applied to introduce new features, fix bugs, or improve performance, requiring basic Arduino programming knowledge.
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