Why is the startup so bloody slow?!?  

RE: Why is the startup so bloody slow?!?

What is nozzle cleaning? Why does it take literally 21 slow motion taps? What is even happening? My MK3Sswent years without a single nozzle cleaning or clog. Never. Zero.

The Mk3 had a fixed live z that you had to manually calibrate (first layer calibration). Once set, it didn't matter if there was crud on the nozzle or not.

The Mk4 uses a load cell to determine the distance of the nozzle to the steel sheet. So no first layer calibration needed, the printer does it effectively itself every time a print is started. Downside: if there's crud on the nozzle, it will throw off the measurement as the load cell will be triggered too soon. So the nozzle cleaning is meant to remove anything sitting on the nozzle that may affect the first layer performance.

Why is the bed leveling so damn slow? Can I get it to take fewer slow pecks at the build plate? I am not printing nanobots and I have nearly zero printbed-related failures?

Doesn't seem any slower to me than the Mk3.

What are there so many taps for homing the X and Y axes?  My MK3Ss do three taps each. I think the MK4 does literally 20 total. Why? I am not printing brain implants.

Why, oh why? I have no idea why it's doing it and why this would be important for the Mk4 but not the Mk3 but it is indeed irritating as hell. It seems particularly bad the first time you print after booting the printer. But even for subsequent prints it feels like way too many times the X and Y positions are probed. There are open GitHub tickets on that topic.

RE:

Thanks for your sensible answers, FoxRun3D.I am grateful for the answers to some of my questions. Let me address them systematically.

Nozzle cleaning: Are you saying that by repeatedly mashing the heated nozzle on the heatbed will remove old filament from the tip? Thanks! I didn't think of that.  Now I have so many more questions.

Bed leveling: You say it's about the same. In fairness, MK3 did the same number of taps regardless of big or tiny object, so good job MK4. But formerly with the G80 gcode you could pick 3x3 or 7x7 or whatever, and also choose the number of taps. I don't even see G80 in the MK4 gcode made by Prusa Slicer.

Homing OCD: What else can I say. I got fabulous results on MK3 with 2-3 taps. Shrug. It would be nice to hear what the rationale is. It might be easily streamlined, like the problems with Prusa Connect.

Any idea why the bed heats to only 175C, does the bed leveling, then the additional 95C needed? In fact, it the bed is already at 200C it waits to cool down. So frustrating.

What about random voodoo printhead movements? left, right, up, down, up down, diagonal in midair, for no apparent reason.

Thank you for your thoughtful answer, FoxRun3D.

Tom

RE: Why is the startup so bloody slow?!?

Any idea why the bed heats to only 175C, does the bed leveling, then the additional 95C needed? In fact, it the bed is already at 200C it waits to cool down. So frustrating.

I assume you mean the nozzle temperature? The bed only goes up to 120C. 

They set the nozzle temp to 170 to avoid leaking from the nozzle during the bed leveling. Same as for the Mk3. I have modified my startup gcode to go to target temp-40c, which works fine for most filaments. 

What about random voodoo printhead movements? left, right, up, down, up down, diagonal in midair, for no apparent reason.

Huh, I can't say I noticed that. 

I really hope they do something about the repeated x and axis calibration. It's crazy.