Pittsburgh 1 Ton Engine Hoist Valve knob

This knob is to prevent you skinning your fingers when using the harbor freight 1 ton engine hoist, which has the most terrible hydraulic valve "knob" (a metal shaft). It is impossible to get good control with the built in method and easy to skin your fingers. Also if you use a wrench or pliers to get a better grip, you over turn the valve and your hoist drops too quickly.

This came about as this is the engine hoist most people will use if they are buying/moving a Tormach CNC Milling Machine as it is relatively inexpensive and effective. But the knob absolutely sucks.

This printed no problem with the knob (larger part) down with no supports at the stock PrusaSlicer settings (0.15mm layers)

Anyway, this has a set screw, which I used a M3x6mm hex bolt (figured 3D printer folks had good access to M3 screws). The hole is modeled to be tapped, although with PLA you can just self-tap with the screw. I didn't bother tapping it as the set screw is hardly structural. I found you don't really need the set screw as the interference fit onto the knob is sufficient, but didn't want to lose the knob. Note: the clearance between the knob shaft and the adjacent red cap is very tight, so do NOT have the set screw stick out (make sure the screw is short enough). It can safely stick out about 1mm without causing problems.

This was designed in OnShape CAD. I have included a STEP file in case someone needs to modify the CAD (in case Harbor Freight changes the design)

Print instructions

Stock prusaslicer 0.15mm quality setting in prusament silver.