Anyone know what it’s doing when it spends all that time whirring and churning when it starts up?

Ain’t it cleaning the ink jet things?

It’s squirting ink into a little sponge that it likes to keep handy for these sort of circumstances. 🙂

If you have time to spare, you could productively use it ordering more cartridges full of expensive ink. 😥

I don’t think it cleans them every time, cos there’s a separate cleaning cycle. But even if it were, that should just be moving the head over to the sponge and giving it a squirt. No idea what the restof the clacking and whirring is for.

Auto-pencil-sharpening. Innit.

Mine likes to go through this cleaning fuss even when I’m only scanning which seems a bit odd (its a multi-function one). Just seems to be the machine’s character coming through.

Likely to be calibrating things, like the carriage, plus some cleaning. Lots of noise because it uses the same motor for lots of functions, so lots of gears and linkages.
If you really want to know, look up some HP patents, there’s a few.