Hotend temperature automatically set to 170C for PLA  

RE: Hotend temperature automatically set to 170C for PLA

This is a slicer setting.

The temperature for probing the bed prior to a print is set to 170 to prevent blobs of filament being deposited on the bed during this process.

The temperature is increased to 215 (PLA) before the print starts.

Peter

RE: Hotend temperature automatically set to 170C for PLA

It's done that way for a reason! Don't fix it without understanding what it does.

RE: Hotend temperature automatically set to 170C for PLA

Posted by: @bobstro

It's done that way for a reason! Don't fix it without understanding what it does.

That’s a bit harsh.  I noticed it too, and IIRC it is odd because MK3s temp goes to print temp before bed leveling.  I agree that this new way is better- less chance of burning some PLA left in a noozle when switching to something like a nylon.

RE: Hotend temperature automatically set to 170C for PLA

@milehigh3der

It prevents oozing and leaving globs of plastic on bed while probing. Second function is that MINDA does not have thermistor, there is no calculation for any deviation of measurements based on temperature - i3 printers with PINDA do it in firmware. Constant temperature helps getting more accurate results.

RE: Hotend temperature automatically set to 170C for PLA

Starting up with a newly received Mini this new behaviour is surely quite astonishing and unsettling. Until one finds out what is going on quite some time is wasted. Why is this new behaviour not explained in the enclosed printing handbook???

RE: Hotend temperature automatically set to 170C for PLA

Posted by: @frans-h

Starting up with a newly received Mini this new behaviour is surely quite astonishing and unsettling. Until one finds out what is going on quite some time is wasted.

Why would it be unsettling? It's one of the most common gcode customizations that was developed for the Mk3 in the years since release. It eliminates potential PEI print surface damage as well as leaving little dots of filament all over the print area during mesh bed leveling. No time is wasted. The heating simply stops at 170C, mesh bed leveling is completed, then the nozzle finishes heating up to final print temp. If you completed a print moments before, there's a chance you might wait briefly for the nozzle to cool down to 170C, but it's hardly time consuming. 

Why is this new behaviour not explained in the enclosed printing handbook???

Unless I'm mistaken, the start gcode for the 2-step nozzle warmup has always been this way for the Mini. It's not new behavior unless you're comparing it to a totally different hardware. You'll notice the prime line is also not explained in detail. They're just part of the normal startup, and you can customize it if you like. I'm sure just as many people are wondering why such a useful routine hasn't been rolled into recent PrusaSlicer profiles for the Mk3. If it bothers you, comment the lines out and see if you prefer the results. If not, there's your answer.

RE: Hotend temperature automatically set to 170C for PLA

Bitten by the short edit window again...

I don't think this is really a bit deal. This is a beneficial feature that should be applauded since it deftly addresses a common problem that frustrates the target demographic for the Mini. Having said that, a bit more info provided to the user is a good thing. I believe the Mini is capable of handling output messages (via M117 gcode commands) properly during a print. There's no reason Team Prusa couldn't sprinkle in some M117 comments during the startup process to let users know what's going on. I've got such notifications in my startup gcode for the Mk3, but unfortunately it only works when printing via Octoprint due to a longstanding bug in the Mk3 firmware. Perhaps someone concerned about the issue could politely make a suggestion over on the PrusaSlicer github pages?

RE: Hotend temperature automatically set to 170C for PLA

I never doubted in my reaction, that this new (compared to MK3/s) behaviour is not useful. The problem is only, that I didn't know about it and first I didn't understand what was going on! So I stopped my print more than once because I concluded that the print would be printed at 170°C. I tried to find the cause and so I wasted quite some time until I found out about this new behaviour and for me (and I'm sure I'm not the only one) this (useful) behaviour is new.

RE: Hotend temperature automatically set to 170C for PLA

@bobstro

There are comments in gcode generated by Prusa Slicer, that's what's actually in "start gcode" section. But it's not reasonable to expect people start troubleshooting there 🙂 

G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S170 ; set extruder temp for bed leveling
M140 S85 ; set bed temp
M109 R170 ; wait for bed leveling temp
M190 S85 ; wait for bed temp
G28 ; home all without mesh bed level
G29 ; mesh bed leveling 
M104 S230 ; set extruder temp
G92 E0.0
G1 Y-2.0 X179 F2400
G1 Z3 F720
M109 S230 ; wait for extruder temp

; intro line
G1 X170 F1000
G1 Z0.2 F720
G1 X110.0 E8.0 F900
M73 P0 R37
G1 X40.0 E10.0 F700
G92 E0.0

RE: Hotend temperature automatically set to 170C for PLA

@bobstro

I aplaud to that feature. I noticed it and was plesantly surprised by it, because the leveling before Z calibration does not do it. The difference is huge.

RE: Hotend temperature automatically set to 170C for PLA

I would love to see them implemented in the Mk3S

RE: Hotend temperature automatically set to 170C for PLA

One thing I would like to change is heeting of the bed. Why is it heating bed when loading / unloading filament?

RE: Hotend temperature automatically set to 170C for PLA

Posted by: @hawwwran

One thing I would like to change is heeting of the bed. Why is it heating bed when loading / unloading filament?

agreed, I also like to add that to the list of things that need to be configurable (so I can turn it off)

RE: Hotend temperature automatically set to 170C for PLA

@hawwwran

I think the idea is that you are loading filament to start printing, thus printer gets ready, and you are unloading the filament to load another to start printing 🙂 

RE: Hotend temperature automatically set to 170C for PLA

@crawlerin,

you hit the nail on the head 🥀 . as the bed heating takes much longer after the load the printer is ready to do a great job.