Compound pulley and bearing plate for slowing a drill press

thingiverse

I created these pulleys in order to utilize a standard 12k/8k wood drill press for drilling stainless steel. I had previously been regulating the pressure by hand to partially stall the motor and slow it down to the necessary speed for drilling steel, but wore out numerous HSS-Co drill bits in the process. The original drill press featured two compound pulleys: driving pulley attached to the motor: 17mm and 22mm output pulley attached to the drill head: 22mm and 33mm This design adds a bearing plate holding two standard 625 bearings (5x16x5) and compound pulleys that can be secured using M5 cap screws. Sources are located at: https://github.com/hyperair/drill-press-pulleys Instructions Insert the 625 bearings into the bearing plate. Thread an M5 screw through each pulley and bearing, with an M5 washer in between. Secure with an M5 nylock nut on top. Determine how to route the belts correctly. Small to big, basically, from the driving pulley to the output pulley. Do not assemble it in reverse unless you are certain the drill will be content with it - it totals up to about a 8x speed difference, so 12k RPM x 8 = 96k RPM. I am unsure what may blow at that point. Replace drill press safety cover before turning on in case the entire assembly explodes.