Valve knob for Pittsburg 1 Ton engine Hoist (Harbor Freight)

thingiverse

This knob safeguards your fingers from injury when using the harbor freight 1 ton engine hoist, whose hydraulic valve "knob" - a metal shaft - is notoriously difficult to control. The built-in method falls short, making it easy to skin your fingers in the process. Furthermore, attempting to gain a better grip with a wrench or pliers can result in over-turning the valve and causing the hoist to drop too rapidly. Fortunately, this knob features a set screw that I replaced with an M3x6mm hex bolt, accessible to 3D printer enthusiasts who have a steady supply of M3 screws on hand. The hole is designed for tapping, but PLA can accommodate self-tapping with the screw itself. I opted not to tap it, considering the set screw's negligible structural importance. Interestingly, you may find that the interference fit between the knob and its shaft provides sufficient grip, rendering the set screw unnecessary - although I chose to retain it to avoid losing the knob altogether. A word of caution: the clearance between the knob shaft and the adjacent red cap is extremely tight, so ensure that the set screw does not protrude excessively. A safe margin is about 1mm without risking any issues. This design was created in OnShape CAD software. I have included a STEP file for anyone who needs to modify the CAD model, should harbor freight alter their product's design.