Utility Knife Replacement Knob for OLFA L-1

prusaprinters

BackgroundAs the uploaded pictures show, the knob on my OLFA model L-1 utility knife broke. Rather than throw the knife out, I opted to create a replacement part myself. This part is more interesting than it looks, it's doesn't just set blade depth, it also provides a ratcheting feel/function. I took this feature for granted until I had to model the object and figure out how to print the details. Another interesting OLFA design decision was the way that the brass set screw is integrated into the knob, it appears to be molded in place! I opted to keep things simple and avoided trying to integrate the original set screw into the replacement knob. DescriptionThis replacement knob has the same dimensions as the original, but is intended to hold an M4 x 8mm socket head cap screw. It requires that one still has the steel ratchet mechanism that came with the knife. The tricky part was re-creating the radial grooves/detents on the bottom of the knob, as the triangular, tapered profile and the count/density of those elements arrayed 360 degrees set's the feel, or tension for the ratchet. This is what I ended up with:It may not be perceivable in the drawing or model preview, but note that the trianglar profile of the grooves/detents were modeled with 0.2mm flat spot as opposed to a point. Without a flat, early prints ended up without this feature printing properly, as details smaller than my nozzle diameter we lost. Take care in Prusa Slicer and ensure that this detail is realizable!SettingsA small diameter, 0.2mm nozzle is needed to print the detents on the bottom side of the knob. It may be needless to say, but I it's best to set the print orientation of the knob to upside down. Slicer will build some supports for the counterbored hole on the top of the knob.RulesPlease abide by the license and do not print these for commercial use. Please do not sell these for profit.Please leave a tip if you find it useful.Please reach out to me if you'd like me to print one for you.