Vintage Radio Knob

thingiverse

Created as a replacement for a knob on an old valve radio (the restoration of which unfortunately hasn't got beyond this point), this solid knob is designed to fit potentiometers with 6.3mm "D" type (flattened side) shafts. This is probably the most common size of potentiometer shaft. The knob it was based on is the yellow one in the last image. The side grips ended up more pronounced than in the original, though this does allow for better grip. Print Settings Printer Brand: MakerBot Printer: Cupcake CNC Rafts: No Supports: No Resolution: 0.22mm Notes: A fairly sparse infill should be OK, but decide based on how much abuse the knob is likely to recieve. Post-Printing Acetone Smoothing This print inspired my first attempt at using Acetone to smooth 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 knob in the middle was given a breif 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 the top until it was sufficiently smooth. The other areas of the knob were left untreated, with an expectation that later painting would cover the layer lines visible from the side. However 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 made in the Pro/Desktop CAD program, a short lived spin-off from the better 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.