Collet Drill Stop (<1mm to 14mm)

thingiverse

A drill stop loosely based on an ER20 collet. Select the correctly sized collet for your drill bit, insert it into the nuts and secure it tightly over your drill bit. The collet clamps firmly over a large area, reducing the likelihood of it coming loose or shifting during operation. Additionally, collets are more concentric with the axis of drill rotation, resulting in a lower risk of marring the surface when drilling wood. It performs significantly better than those metal-rings-with-set-screw devices that are commonly used. The nuts are designed with knurls for easy hand tightening and removal. I recommend applying a small amount of PTFE lubricant or vaseline to the threads and taper, which have an M28x2 thread specification. This will help ensure smooth operation. The collets themselves should be capable of flexing up to +/- 1mm without breaking; if you can still move the drill bit even after tightening it down all the way, a smaller collet is likely in order.