DEC VAXstation VSXXX-AA puck mouse roller wheel replacement

thingiverse

The DEC VAXstation VSXXX-AA mouse designed by Hawley utilized an XY tracking arrangement featuring two roller wheels, one dedicated to vertical and the other to horizontal movement, with axes canted at approximately a 10-degree angle. This design was first pioneered by the original Xerox mouse, showcased in "The Demo," and later adopted by Honeywell for their PC version in the late 1990s. The original roller wheels of the VSXXX-AA were crafted from a highly fragile hard plastic material that could only be described as subpar. Upon inspection, my own rollers resembled a wheel of Camembert cheese, complete with a similar white mold layer. These delicate components would crumble at even the slightest touch, leaving behind remnants on one and nothing at all on the other. This project aims to create a functional replacement for these small parts. Initially, I considered machining new roller wheels from a 5mm sheet of polyurethane scrap using my Unimat lathe. However, this idea evolved into something more practical. The design consists of a button-like base with a seat and curved retaining lip, accommodating a small neoprene O-ring that projects 20% above the wheel face to establish contact with the desktop. Two holes facilitate easier removal using fine needlenose pliers or a bent paperclip. Printing Instructions: To successfully assemble the mouse, you'll need to disassemble it first by popping the two side catches and rear catch in the mouse body using a flat-bladed screwdriver. This will allow for proper press-fitting. The roller wheels and optical encoders are held onto small steel axle pins by weak magnets, applying gentle pressure on the wheels when on the desktop. I printed these components in ABS to achieve some degree of flexibility during press fitting. While PLA might also work, it may not offer the same level of flexibility. To print: 1. Set the TOLERANCE value to 0.5 (half a mm). 2. Render with F6. 3. Save the STL and slice the model. 4. Run a print. Even at 100% infill, this process should only take a few minutes. However, the printed part may be loose on the shaft. To address this, bump the TOLERANCE down by 0.1mm to 0.4 and run another test. Be cautious not to make the parts too difficult to press fit, as this could damage the encoder or the shaft housing. The O-ring used in this design was sourced from a cheap assortment kit found at "two dollar shops." If necessary, measure your own O-ring and adjust the parameters accordingly. While the O-ring's size is not critical, ensuring a proper shaft fit is essential. If the O-ring appears too loose, you can secure it to the roller wheel with a small amount of superglue. In my experience, the 20% protrusion amount has been sufficient to hold the O-ring in place without gluing.