- Joined Jun 5, 2020
I want fairly precise distance measurements over a small area, say 200mm x 200mm, accurate to <1mm (ideally ~0.1mm) measured from no more than 10cm away. Non-contact preferred. Grid size no larger than 2mm x 2mm, 1mm x 1mm preferred. I have seen precision contact switches which are threaded housings and claim 3 micron reproducibility, but the width and depth capabilities do not allow the grid precision or depth range capabilities we need. Our Z-axis motion resolution will be orders of magnitude less precise than this, closer to .03mm than the actual resolution of the touch sensor. We also assume that our sample is non-conductive. I am looking to build a 2 1/2D sensor that can measure a z-range of ~5cm with sufficient accuracy to produce a “point cloud” to a CAD system, from a “hand-cut” prototype so we can create casting molds for plastics, or vacuum-forming molds. The goal is to convert a 1-off prototype to produce small quantities of inexpensive research prototypes. We have access to injection molding and vacuum forming equipment but the tedious task of converting a 3D model (which is really a 2 1/2D model) with any precision is challenging. Current 3D scanning technology that is affordable lacks the precision we need. $15,000+ is far outside the research budget of two retired scientists who may have given up our jobs but not our curiosity. Assume that neither of us are intimidated by the idea of building a 2-axis or 3-axis CNC platform or accompanying software, we just are having problems coming up with a reliable sensor mechanism. Triangulation of laser beams has been rejected because shadowing effects of vertical faces would make it difficult to use. Low-resolution non-contact sensors can determine approximate depth, so if we have a physical probe we can back out far enough to keep the probe from scraping the uneven surface. TOF sensors are usually rated for minimum distances that are smaller than our maximum depth needs.