Vintage Radio Knob

thingiverse

Human: Created to replace a knob on an old valve radio (the restoration of which unfortunately hasn't progressed beyond this point), this solid knob is specifically designed to fit potentiometers with 6.3mm "D" type shafts that have flattened sides. This size of potentiometer shaft is probably the most common. The knob it was based on is the yellow one in the last image. The side grips turned out more pronounced than in the original, which actually allows for a better grip. Print Settings Printer Brand: MakerBot Printer: Cupcake CNC Rafts: No Supports: No Resolution: 0.22mm Notes: A fairly sparse infill should be sufficient, but decide based on how much abuse the knob is likely to receive. Post-Printing Acetone Smoothing: This print inspired my first attempt at using Acetone to smooth out the surface of prints. The top of the knob is concave with a shallow angle, and as can be seen in the right-most knob in the below image, the layers are very noticeable at my later height of 0.22mm. The middle knob was given a brief bath in Acetone (after I got impatient with the vapour technique), but ended up too greatly distorted and unevenly smoothed. The knob on the left simply had a few drops of Acetone deposited in the hollow on top until it was sufficiently smooth. However, this area alone is rough while the other areas were left untreated, expecting later painting to cover the layer lines visible from the side. Unfortunately, this painting has never been completed. Note that the rougher side surface does make the knob easier to grip with force. How I Designed This The design was created in the Pro/Desktop CAD program, a short-lived spin-off from the well-known Pro/Engineer, which is now called Creo. The design file is in the native ".des" format of Pro/Desktop. If you have the software, many elements should be easily adjustable.