Also note that the as-shipped Anet A8 firmware is notorious for not having thermal runaway protection enabled, so unless you have upgraded to a version of Marlin compiled with thermal runaway protection enabled, *DO* *NOT* print unattended, even for only a few minutes.
Fully aware of this issue and appreciate the warning. The printer has been upgraded with the MOSFET for both the extruder (not necessarily needed) and the bed along with Marlin firmware. My goal was to add the Btouch (?) sensor, for auto leveling, but never got around to installing it.
Okay, here is the latest, something is odd. First off, keep in mind, I'm waiting on replacement rotary encoders that may or may not be the correct replacement due to size or whatever. With this being said, I'll gladly hold off trying to get a 3D printed knob that fits until these new encoders arrive.
With this being said, the most recent one still doesn't fit. I measured the encoder shaft, it's 5.98mm (I'm seeing 5.95mm at a few points - most likely worn down from removing the knob many times) and 4.48mm flat side to round part.
The Thingiverse part I printed (i.e. oversized knob) is approximately 6mm and fits tight enough that I can hold it upside down without it sliding off, but, if I hit the board on my hand, the knob falls off. The most recent one I printed from you is measuring approx. 5.44mm (and that's pulling on the calipers extremely tight).
Maybe something has shifted with my printer since I printed the Thingiverse one (because that fits and measures 6mm). Measuring the rest of the knob recently printed: base 18.25mm, top 17mm (hard to get a good measurement because it's rounded, height 13.05mm.
Give me a minute and I'll post a picture of the D hole being measured.
Edit: I also added a picture of the oversized Thingiverse hole size showing it's basically 6mm.