Gaggia Classic Heat Resistant Steam Knob

Many steam knob designs on printables have the issue of becoming soft around the flanged shaft. While this can seemingly be remedied with Polycarbonate, not everyone does have a spool of that at home (it is expensive and loves moisture), so I have pursued another avenue. At the core, the problem is not only the valve reaching the glass transition temperature of ABS, but the small contact surface onto which the force is applied. As a result, the flange works itself deeper and deeper into the ABS knob. 

Luckily, the 3D printing world has a common component that can be mounted on the shaft: GT2 pulleys (https://de.aliexpress.com/item/1005004075011758.html), available with a 6mm bore. On one side, the flange can easily be removed with pliers (thanks to whoever designed the Voron Z endstop for that idea), leaving you with a grippy surface all around, perfect to take on rotational forces and dissipate heat. Check the attached picture if this confuses you.

I have designed this knob for a 20T GT2 pulley of 15mm width, which gives plenty of stability. I made it from ABS. After a month of use, it is holding up nicely. Mount with the lid off if you want no visible gap.

The GT2 profile used here is derived from this project: https://www.thingiverse.com/thing:16627/files