Finger Safety Guard for Stationary Sander
A project involving blue-light scanning and 3D printing to address safety concerns.
Preliminary design for Finger Guard overlaid on blue light scan data.
The Challenge
Stationary sanders used in metallurgy tests.
A worker in a metallurgy lab uses a stationary sander to do tests on grain structure of various alloys. A large disk of sandpaper is stuck to the sander. During one test, the edge of the sandpaper disk came unglued and gave the worker an incredibly painful jagged papercut. To prevent this in the future, it was decided that a 3D printed Finger Guard would help prevent this in the future.
The Steps
Scanning process using an ATOS Blue Light Scanner.
The first step was to scan the stationary sander to provide some usable 3D geometry to build from. The general shape of the sander would provide nesting surfaces for the Finger Guard, but several jutting design features of the sander would need to be scanned as well in order to provide proper clearance.
The resident ATOS Scanner expert was called in, and the scanner was set up on an adjustable boom. Target point stickers were applied to surfaces on the sander; these would help the scanner's software accurately render surface detail.
The scan data was then sent to Catia V5 so that I could build usable geometry around it, and eventually a 3D printed part could be made.
Designing the Finger Guard in Catia
Blue light scan data imported to Catia V5.
The first step was to import the raw scan data into Catia, then to use a specialized Catia workbench to extract useful geometric data from the scan data. This workbench helps the user interpret aspects of the scan data as standard geometry such as planes, circles, cylinders, and spheres.
Some preliminary geometry is created from the scan data, such as planes, points, lines, and circles.
Refined geometry is built from preliminary geometry, adding in some offset controls for clearance. The main construction geometry for the finished part was also created at this stage.
I took the preliminary geometry that Catia created and built in some parameterized geometry in order to control offset distances as well as form and fit. Many of these parameters didn't end up being used because the first print fit the sander perfectly, but experience tells me it's good to add parameterized dimensions early in the design process for quick changes throughout the prototyping process.
The preliminary design of the finger guard as seen at the beginning of this article. Clearance geometry for the sander's cylindrical parts is present, as is a "lip" on the underside of the Finger Guard that keeps it locked in place using the sander's oval cutout.
The underside of the preliminary Finger Guard, showing the oval "lip" that keeps it in place on the sander.
The preliminary version of the Finger Guard (above) was printed and sent to the metallurgy lab for testing. The lab suggested adding a "skirt" to the middle cutout of the Finger Guard that would dip down into the sander, decreasing the chances that another paper cut could happen.
Final design for the Finger Guard.
The using shop's suggested skirt was added to the final design, which was printed in polycarbonate due to its strength and durability. Small inner radii were added to every interior corner for the added strength it lends to FDM prints.
The Finger Guard fit the sander perfectly and our customer was very pleased with the final design.
