Laser centre finder with interchangeable collars

thingiverse

Laser Centre Finder for Milling Machine, Drill Press etc. I designed this device to be easily fitted and removed from the machine without disassembling the chuck or tool. The goal was to create a centre finder that can adapt to different-sized spindles. This is achieved through replaceable collars, allowing the same device to work on various spindle sizes. My mill has a 40.6mm diameter spindle, while my drill press features a 36.6mm spindle. The collars simply press onto the spindle from the side, ensuring a secure fit. A DIL/DIP switch is used for control. I employed a 2-way DIL switch, which was then modified by sanding half away to create a single DIP switch (e.g., https://au.rs-online.com/web/p/dip-sip-switches/8772113/). One leg of the DIP switch directly connects to the battery cavity for the negative contact. The other leg is soldered to the negative laser wire. The positive laser wire makes the second contact within the battery cavity. For reliability and high current, I used two SR44 batteries. To operate: 1. Attach the device to the machine spindle. 2. Angle the laser towards the centre of rotation. 3. Turn on the laser. 4. Start the spindle; the laser will draw a circle. 5. Adjust tool height to change the circle's size. 6. Align parts or holes with the circle of light. To centre on a cylinder, project the light onto its side. When centred, the line of light becomes horizontal; if off-centre, it's at an angle. To centre on a point, decrease the circle's size by raising or lowering the spindle until it forms a spot (you may need to adjust the laser's angle). This design surpasses traditional crosshairs laser alignment tools because they can only align with points. My device allows for centreing on holes and cylinders. If you build this device, please share your experience. I appreciate any tips, especially considering how much time and effort went into refining its performance.