I have been working on a small LinuxCNC companion project called **FabScan**. The basic idea is to create a LinuxCNC-friendly camera tracing utility that can help capture outlines, edges, holes, and reference points from real-world parts, then export usable DXF geometry for cleanup/CAM.
The project was inspired by the general workflow of SheetCam Scanything, to be clear it is not based on Scanything code, reverse engineering, or proprietary information. It is a from-scratch MIT open-source project aimed at LinuxCNC users.
The project can be found here:
github.com/FabLabRacing/FabScan
The documentation is lacking at this point, it is mostly build notes.
The intended workflow is:
1. Mount a USB camera on the Z-Axis.
2. Use LinuxCNC for the actual machine position reference.
3. Use FabScan to view the camera, detect edges/lines, capture points, and build geometry.
4. Export DXF.
5. Use SheetCam or another CAM program for cleanup, tooling, and cutting.
## Current Status
The current working milestone is around **v0.5.10**.
At this point, FabScan can:
* Load an image and detect contours.
* Adjust threshold, blur, minimum area, and simplify settings.
* Select/classify/sort detected contours.
* Export DXF geometry.
* Capture from a USB camera.
* Rotate/flip camera view as needed.
* Calibrate camera scale.
* Capture manual points from LinuxCNC position.
* Continue native DXF geometry using lines, arcs, and circles.
* Perform controlled X/Y motion through LinuxCNC.
* Jog X/Y from inside the app when enabled.
* Use camera center-dot calibration.
* Preview line/edge detection from the live camera.
* Take single-step and multi-step line/edge following moves.
* Export traced/captured geometry to DXF.
The newest work has been focused on camera robustness and line/edge following.
The line-following proof of concept is working well enough to be useful in testing. One important recent improvement was latching the follow direction during multi-step tracing. Before that, the detected edge tangent could occasionally flip direction and cause the machine to step backward. The current logic uses the selected Forward/Reverse direction for the first move, then chooses the next tangent direction closest to the previous successful move. In testing, this fixed the forward/backward flip.
A recent test captured 50 points along a Sharpie line without the direction flipping. The average step was about 0.050", with the largest observed deviation roughly in the .006"-.009" range. That was with the line slightly out of square with machine travel, so I was pretty happy with the result for an early proof of concept.
## Safety Philosophy
FabScan is intentionally limited.
It only moves X and Y.
It does not control:
* Z axis
* Torch firing
* Plasma start
* Cycle start
* Spindle
* Cutting output
* THC
* Any actual machining/cutting process
LinuxCNC still owns the machine. FabScan only talks to LinuxCNC for position/status and controlled X/Y motion. Motion functions require LinuxCNC to be in a safe state, such as machine on, homed, idle, and in manual mode.
The idea is that FabScan should behave more like a camera-assisted measuring/tracing pendant than a machine controller.
## Hardware / Test Setup
My current known-good test setup is:
* Dell OptiPlex 7060
* LinuxCNC / QtPlasmaC
* Mesa Ethernet hardware
* USB microscope/camera
* Camera resolution currently set to 800x600
* LinuxCNC servo period set to 2,000,000 ns
One important lesson from testing: my microscope camera does not support 1280x720. Asking for that resolution caused OpenCV/V4L2 timeouts and made the GUI sluggish. The current version defaults to 800x600 and is being improved to handle unsupported camera modes more gracefully.
## Recent v0.5.10 Camera Work
The latest camera robustness work includes:
* Default camera resolution changed to 800x600.
* Resolution presets added.
* Requested vs actual camera resolution display.
* Explicit V4L2 camera opening on Linux.
* MJPG request where supported.
* Camera frame reads moved off the Tkinter UI thread.
* Better handling of bad camera devices or unsupported modes.
* Safer preview window close handling.
## Current Line / Edge Follow Settings
The current settings that seem reasonable for testing are approximately:
* Mode: line center
* Step: 0.050"
* Max correction: 0.010" to 0.015"
* Minimum confidence: 55-60
* Count: 10-50
* Camera: 800x600
For tight curves or 180-degree bends, the plan is to reduce step size and search area, while keeping correction conservative.
A future safety improvement I am considering is stopping multi-step follow automatically if the heading changes too much in one step, maybe somewhere around 60-75 degrees. That would help prevent the trace from trying to chase a wrong edge or doubling back unexpectedly.
## What It Is Useful For
The project is aimed at things like:
* Tracing a physical part or cardboard template on the table.
* Picking up edges or holes from an existing part.
* Capturing a rough outline for SheetCam cleanup.
* Following a drawn Sharpie/scribe line.
* Getting usable geometry from shop-floor parts without turning the project into a full CAD system.
## Project Direction
The near-term direction is:
1. Keep improving camera reliability.
2. Make camera selection/resolution handling more user friendly.
3. Improve line/edge following confidence and stop conditions.
4. Continue improving DXF export quality.
5. Keep the project focused and safe.
Long term, I would like FabScan to become a practical open-source tracing/scanning helper for LinuxCNC users, especially for plasma/router-style machines where a camera-assisted part tracing workflow can save time.
It is still experimental, but it has reached the point where the core idea is working and the project feels worth continuing.
