Maximum working temperature?  

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ed.y
 ed-y
(@ed-y)
Eminent Member

Hi
Can anyone tell me what the maximum working temperature the MK2 can print in?
I've got the printer in the enclosure and the temperature inside has hit 46C, I'm printing ABS.

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Posted : 18/06/2017 4:34 pm
PJR
 pjr
(@pjr)
Antient Member Moderator

There are a few temperatures you need to consider and they will mostly depend on your ambient.

The electronics have to be considered but probably more important is the filament temperature. The filament needs to be cool enough to feed properly and in an enclosure you have the enclosure temp to take into account plus the heat from the extruder stepper heating up the spindle and drive pulley. If the drive pulley exceeds the GTT of the filament, then it will dig into the filament and your extrusion will become inconsistent.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 18/06/2017 5:13 pm
koder
(@koder)
Trusted Member

Since I have access to thermal imaging camera, I'm going to check filament temperature at extruder gear under my normal ambient conditions. This should give us some rough estimation.

What is max recommended operating temperature for PSU & RAMBO? I am aware that they can be mounted outside of enclosure, but that severly limits mobility of the device.

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Posted : 19/06/2017 12:36 pm
koder
(@koder)
Trusted Member

With ambient temperature of 26.0'C, nozzle at 255'C (and heatbed at 100'C, which should be irrelevant), I have measured filament temperature inside extruder as 29.4'C at most. Even taking into account inaccuracy of this type of IR imaging, filament temperature in extruder should be non-issue.

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Posted : 19/06/2017 7:26 pm
PJR
 pjr
(@pjr)
Antient Member Moderator

With ambient temperature of 26.0'C, nozzle at 255'C (and heatbed at 100'C, which should be irrelevant), I have measured filament temperature inside extruder as 29.4'C at most. Even taking into account inaccuracy of this type of IR imaging, filament temperature in extruder should be non-issue.

Is this after a few hours printing in high power mode?

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 19/06/2017 8:14 pm
koder
(@koder)
Trusted Member

Is this after a few hours printing in high power mode?
No, this is beginning of a print in silent mode. Nozzle was, of course, at working temperature. You make a fair point, I will make another test at end of this print. Here is mid-print situation:

Ambient temperature is now 26.9'C. This is 1:20 of the print.

I was led to believe that high power mode changes only current supplied to steppers, they should have little impact on filament temperature. Why do you believe it will have an impact? I can of course make another test in high-power mode - i still have lots of things to print.

Also, do you have any data on allowed operating temperature of PSU & RAMBO?

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Posted : 19/06/2017 8:28 pm
ed.y
 ed-y
(@ed-y)
Eminent Member

For me I did a 12 hour print with ABS, nozzle temp 250C heatbed 110C. My enclosure got to 46.5c sometimes hit 47c. The rambo Bix measured 60c. Didn't notice any issue. I did notice some pla filament I had on a spool droop

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Posted : 19/06/2017 8:47 pm
koder
(@koder)
Trusted Member

Didn't notice any issue. I did notice some pla filament I had on a spool droop
It might be a good idea to mount filament outside of enclosure, or in separate (ventilated) box. I initially thought that keeping spools inside enclosure would be beneficial, as they should get de-moisturized for free.

Does your enclosure help significantly with ABS prints? I have some large (as in: near build area) ABS prints on queue and I'm thinking of building enclosure specifically for them.

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Posted : 19/06/2017 8:53 pm
ed.y
 ed-y
(@ed-y)
Eminent Member

Humidity inside enclosure is only 15% when I start printing. I've never printed abs outside enclosure. But it did take me a while to find the right settings to get decent prints. I've not had any warpping so far I have printed some large piece

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Posted : 19/06/2017 9:12 pm
koder
(@koder)
Trusted Member

As an update, this is after another 1:10 of print, tuned into in high-power mode:

Ambient temperature right now is 26.4'C

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Posted : 19/06/2017 9:51 pm
PJR
 pjr
(@pjr)
Antient Member Moderator

I was led to believe that high power mode changes only current supplied to steppers, they should have little impact on filament temperature. Why do you believe it will have an impact?

The filament is driven by a stepper motor, which passes its generated heat through both its casing and spindle, the latter connects to a brass (or maybe steel - it used to be brass) filament drive pulley which is constantly in contact with the filament. The extruder motor current is about 450mA in "silent" mode and 500mA in "high-power"mode.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 20/06/2017 12:44 am
koder
(@koder)
Trusted Member

The filament is driven by a stepper motor, which passes its generated heat through both its casing and spindle, the latter connects to a brass (or maybe steel - it used to be brass) filament drive pulley which is constantly in contact with the filament.
Fair enough. Here is thermal image of extruder after 1:30 of printing in high-power mode:

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Posted : 20/06/2017 10:02 am
PJR
 pjr
(@pjr)
Antient Member Moderator

So, assuming the FLIR is set OK, that's 20 degrees above ambient.

When running in an enclosure at 45 degrees, the extruder could be above GTT of PLA and some other plastics, so enclosure temp should not exceed 40 degrees.

And that is assuming the extruder motor is run at around 500mA which can be increased (in the MM upgrade) to 750mA (and the motors can get very hot).

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 20/06/2017 11:25 am
koder
(@koder)
Trusted Member

Well it does make sense to have optional airflow for printing PLA anyway, since you want to cool down your part. For ABS and PC this should be non-issue, right?

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Posted : 20/06/2017 11:28 am
PJR
 pjr
(@pjr)
Antient Member Moderator

Well it does make sense to have optional airflow for printing PLA anyway, since you want to cool down your part. For ABS and PC this should be non-issue, right?

Yeah, they are both GTT > 100 degrees so with the single extruder, should not be too much of an issue.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 20/06/2017 11:30 am
ed.y
 ed-y
(@ed-y)
Eminent Member

For some info in my enclosure my temps are:
ABS Nozzle 250C, Bed 110C enclosure temp max about 47C
PLA Nozzle 205C, Bed 55C enclosure temp max about 37C

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Posted : 20/06/2017 12:03 pm
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