1. Belt tensioning

PSA: Don't follow that "Adjusting belt tension" link until AFTER you've done the calibrations and tests and whatnot. This section should just say "tighten up the belts to take the slack out of them, but not more than that."

here is my guide.
please prusa, improve the guides. I think they have lost overview, been over edited.
Pre steps / what you really should have before starting.
- the belt tensioning guide covers this too.
- given you have set up the belts with 3-5 teeth showing. i followed the tips to use 3 teeth showing.
- make sure the belts run smooth.
- make sure there is nothing in path of the gantry. i left cable ties loose. Bad me.
- you have aligned the gantry, so it runs back to front smoothly and touches on both sides without a gap. i.e. push one side to end and check if the other side has no gap. repeat on otherside/otherdirection. This is all in the comments and in the trouble shooting for the belt tension guide link. Shame it is not up front, as checks.

With these steps in place we can tune.
Tuning, as far as I am concerned is all in step 5 of the gantry alignment in guide, (5. Tighten both tensioner bolts gradually, alternating between them, tightening each by the same amount to keep the gantry straight. You may hold the gantry in place with your hand while tightening. After tightening both belts, make sure no gap has reappeared.). I want to expand on this.

- The belts should be super lose after building.
- Move the gantry to front, push the head into the corner as per prusa guides.
- Tightening belts. Aim tighten the belts so that they make a twang. The belts affect each other. Just tighten them, so the belt is no longer loose. As soon as either side of the gantry has pulled away from a stop, you have over tightened that belt. if you see this happen, loosen up the belt. Run the gantry back and forth to check the gantry sides hit stops. As noted in pre steps.
- With the belts tightened to the point that these is a sort of twang, there is some tension. If a belt 'thawps' you probably have not got the tension. I found one belt could be way loose and the other good, i had racked the gantry though.
- Pluck the belt with you finger, not too hard, as you don't want it to hit the metal. If it hits the metal with a gentle pluck the belt is most likely too slack.
- Run the prusa belt tensioner web page. Tick the 'experimental' box . Organise your screen to show the Hz, and waterfall plot. I liked the waterfall plot as it shows all the harmonics. Remember harmonics repeat: Wave with frequency an integer multiple of the fundamental frequency. The wave plot shows these harmonics.

- work in a quite room. I begged everyone to keep stum.
- Tighten the top belt as per instructions, slow half turns or less.
- The webpage tells us if we have it good.
- I had made mobile phone upside down, with it leaned up up against side, microphone pointing up.
- check gantry for racking, move gantry end to end. Any racking, undo, and do bottom belt. The belts can tension each other.
- keep an eye on the Hz and the waterfall wave plot.
- go back and forth between belts.
- Check for racking. Move gantry back and forth all the time.
- If the webpage says the hz is good, for one belt, don't forget the belts impact one another. So the other may need checking.
- On my fourth try all this took a few minutes.

Other points.
- The trouble shoot and belt tensioner is aimed at already working printers/belt changes/ general changes. Not first builds.
- The web page is good, put showing the harmonics, gives a firm idea that we have too slack a belt to start tensioning.
- The belts affect each other.
- Do not trust the AI diagnostics, I gave it two go's. Utter junk authoritive answers.
- The prusa forum has some big long threads on this topic. Very useful. It confirmed my suspicion that belts affect each other, that tensioning can be willy nilly as long the gantry is not racked. Start with aligned gantry, keep it aligned.
- been 3 days now, and probs 50 hours printing, looks good..very happy.

This is my first ever printer so I may be missing something, but from the comments probably not.

The initial belt tensioning step is VERY confusion and not very intuitive. After reading and re-reding the online tutorial on tensioning the belts I threw all that info out of the window and left the resonance at 95hz and slowly adjusted the screws until I obtained the belt movement needed. I repeated this until there was no adjustment needed to verify the belts were equally within the specified range. I hope that now I have a valid set point future adjustments will be easier.

What do I do? Turn on the printer and let wizard to do something?

I absolutely HATE tightening Prusa belts. I wasted a ton of time on this one. I was busily strumming, but kept getting vastly different results. I ended up downloading a separate app to ascertain what frequency the belts were, and found that they had considerably over-tightened (frequencies of ~250 Hz) which had happened simply screwing a few turns. I strongly suggest playing 98Hz on your computer/phone, and adjusting the belt tightness to approximate the sound before doing any of the processes described on this page or the accompanying belt tuning page!