Rotary potentiometers, switches, and encoders all share a basic design: adjustment is done via a shaft onto which a knob is attached, and knobs are sold separately. That doesn’t mean one knob fits all; there are actually a few different standards. But just because knobs are inexpensive and easily obtained doesn’t mean it’s not worth making your own.
Why bother 3D printing your own knobs instead of buying them? For one thing, making them means one can rest assured that every knob matches aesthetically. The ability to add custom or nonstandard markings are another bonus. Finally, there’s no need to re-invent the wheel, because [Tommy]’s guide to making your own knobs has it all figured out, with the OpenSCAD script to match.
By default, [Tommy]’s script will generate a knob with three shims (for interfacing to a splined shaft) when pot_knob(); is called. The number of shims can be adjusted by modifying potKnobDefaultShimCount. To give the knob a flat side (to interface with D-shafts), change flatted = false to flatted = true. And for adding a screw insert suitable for a set screw? Change tightenerDiameter = 0 from zero to the diameter desired.
When the tool you need doesn’t exist, you have to make it yourself. Come to think of it, even if the tool exists, it’s often way more fun to make it yourself. The former situation, though, is one that [Sean Hodgins] found himself in with regard to threaded inserts. Rather than suffer from the wrong tool for the job, he machined his own custom threaded insert tool for his Hakko soldering iron.
Like many of us, [Sean] has embraced the use of heat-set threaded inserts to beef up the mechanical connections on his 3D-printed parts. [Sean] dedicated a soldering iron to the task, equipping it with a tip especially for the job. But it was the flavor of iron proverbially known as a “fire stick” and he found that this iron was too hot for PLA prints. As the new owner of a lathe, he was able to make quick work of the job using a piece of brass rod stock. Luckily, Hakko tips just slip on the heating element, so no threading operations were needed. [Sean] made insert tips for multiple sized inserts, and the results speak for themselves.
Dremel has been helping people fit square pegs into round holes for years, and [concretedog] saw that the Dremel 220 Workstation — a piece of hardware similar to a drill press — could be convinced to hold a cheap soldering iron just as easily as it holds a rotary tool. A soldering iron makes an effective thermal insert tool, and the job of heating and pressing the threaded metal rings into plastic is made much easier when it can be done similar to operating a drill press. With a few modifications and a 3D-printed adapter, the thermal insert rig was born.
Whenever one is working around a design that already exists, it pays to be flexible and adjust to the unexpected. The Dremel 220 has a holder intended to clamp a rotary tool, and the original plan was to simply design and print an adapter so a soldering iron could sit in place of the rotary tool. That plan changed upon realizing that the entire rotary tool holder disconnected from the tool’s frame with a single bolt. It made much more sense to make the soldering iron replace the rotary tool holder, instead.
The resulting modified soldering iron is mounted via standoffs to a 3D-printed adapter with a copper foil heat shield. [concretedog] admits it’s not ideal from a heat management perspective, but it makes a fine prototype that seems to work well for light duty. The next step would be a metal version.