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Why is the startup so bloody slow?!?  

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tdk408
(@tdk408)
Trusted Member
Why is the startup so bloody slow?!?

Josef Průša is a god of 3D printing. All 3D owners everywhere owe him a debt of gratitude for his contributions to this art. His newest MK4 is freaking awesome. Tons of great engineering choices, and even a MK2 can be upgraded rather than buy a new printer.

But the freaking MK4 firmware. Ignoring the forever that Prusa Connect adds to the process, it takes almost five minutes to go from "start print" to actually starting to print.

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.

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?

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.

And why WHY does it heat the bed to only 175, then farts around with bed-levelling and some other mysterious unncessary slow voodo movements, and then heat from 175 to 270? It could have been heating this whole time!

So literally after I hit print, I'm waiting 4:45 to actually print. All these numbers are real not hyperbole, and yes I have the most recent firmware.

It could be me. What am I doing wrong?

Thanks, Tom

Posted : 05/11/2024 6:08 pm
FoxRun3D
(@foxrun3d)
Famed Member
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.

Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...

Posted : 05/11/2024 10:08 pm
tdk408
(@tdk408)
Trusted Member
Topic starter answered:
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

This post was modified 1 month ago 2 times by tdk408
Posted : 06/11/2024 12:04 am
FoxRun3D
(@foxrun3d)
Famed Member
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. 

Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...

Posted : 06/11/2024 12:59 am
tdk408
(@tdk408)
Trusted Member
Topic starter answered:
RE: Why is the startup so bloody slow?!?

I am thinking a MK4 superpinda downgrade would save me tons of time. :/

Posted : 06/11/2024 7:02 am
tdk408
(@tdk408)
Trusted Member
Topic starter answered:
RE: Why is the startup so bloody slow?!?

Wait! I missed this, @foxrun3d.

What code did you use to change your startup to go to target temp minus 40c?

Thanks!

Posted by: @foxrun3d

I have modified my startup gcode to go to target temp-40c, which works fine for most filaments. 

Posted : 28/11/2024 6:26 am
Neophyl
(@neophyl)
Illustrious Member
RE: Why is the startup so bloody slow?!?

Probably something like 

M109 S{first_layer_temperature[0]-40} ; wait for extruder no-ooze warmup temp before mesh bed leveling

I use -50 myself but whatever works I guess 🙂  

Posted : 28/11/2024 7:26 am
tdk408
(@tdk408)
Trusted Member
Topic starter answered:
RE: Why is the startup so bloody slow?!?

THANKS @foxrun3d ! I am super grateful!

Tom

Posted : 28/11/2024 7:39 am
tdk408
(@tdk408)
Trusted Member
Topic starter answered:
RE:

Thanks, @neophyl! You are always super helpful!

Posted : 28/11/2024 7:59 am
FoxRun3D
(@foxrun3d)
Famed Member
RE: Why is the startup so bloody slow?!?

Yes, as Neophyl said. 

In recent times, their startup gcode has become more complex. Now they set the temp for bed leveling based on the filament type, using the ternary operator condition ? value_if_true : value_if_false

M104 T0 S{((filament_notes[0]=~/.*HT_MBL10.*/) ? (first_layer_temperature[0] - 10) : (filament_type[0] == "PC" or filament_type[0] == "PA") ? (first_layer_temperature[0] - 25) : (filament_type[0] == "FLEX") ? 210 : (filament_type[0]=~/.*PET.*/) ? 175 : 170)} ; set extruder temp for bed leveling
M109 T0 R{((filament_notes[0]=~/.*HT_MBL10.*/) ? (first_layer_temperature[0] - 10) : (filament_type[0] == "PC" or filament_type[0] == "PA") ? (first_layer_temperature[0] - 25) : (filament_type[0] == "FLEX") ? 210 : (filament_type[0]=~/.*PET.*/) ? 175 : 170)} ; wait for temp

Truth be told, since upgrading my Mk3's to Mk4's I've used the stock gcode. Before I used to use the command Neophyte showed above to set the target to 40 below first layer temp.

Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...

Posted : 28/11/2024 2:38 pm
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