Shopsmith power coupler hand knob

thingiverse

This is a knob used on Shopsmith Mark V and Mark 7 models that have a drive-hub guard installed, or just to get more leverage on the drive hub on older models. Sometimes it is desirable to manually turn the quill using the auxiliary-tool drive hub on the left end of the headstock. Shopsmith sells what they call the "Quill Twister" for this purpose but I was never enamored of their design because it 1)is way too expensive for what it does, 2)needs a coupler to work, 3)requires a spring to avoid leaving it on the headstock, and 4)just looked too clumsy. I did find another design for a similar aid on Thingiverse that resembled a crank. I liked it but it was a little too fragile (broke the handle off rather quickly) and because it could stay on the drive hub, it could get, shall we say, "exciting" if I forgot to remove it before powering up the headstock. My design takes the 4-spline end of a power coupler found on Thingiverse and marries it to an upsized (70mm diameter) generic knurled knob also found on Thingiverse. This knob provides good leverage and won't cause a heart attack if you forget to remove it before powering on the headstock. I printed mine in orange PLA filament for visibility.