Problem with Heat bed temperatures  

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brian.m10
(@brian-m10)
Active Member

My Mk3S has been laid up for a while now and have just returned it to service. Having seen that there is a new Version of Software (s/w) V3_9-0-3421 I flashed this new S/W ready for printing. As I have disturbed the nozzle and PINDA probe I decided to re-calibrate the Z-height and PINDA offset. After following the various methods of setting the PINDA Probe heights (small narrow cable tie, feeler gauge 0.9mm) I was not  able to get consistent first layer calibration prints after many attempts. For some reason I have always wondered if this might be down to Heat Bed temperatures, so, combined with another purpose I purchased a Digital Infrared Thermometer and checked the accuracy against boiling water and Ice. 

Then I ran through all the various filament Pre-Heat settings for the heat bed and found the following:

Room Temperature = 22 degs C         5 minutes settlement time

PLA (screen) 60 C         (thermometer) 52 C....... discrepancy 8C

PET (screen) 85 C         (thermometer) 74 C....... discrepancy 11C

ASA (SCREEN) 105 c    (thermometer) 95 C....... discrepancy 10C

ABS (screen) 100C        (thermometer) 89 C....... discrepancy 11C

HIPS (screen) 100C        (thermometer) 89 C....... discrepancy 11C

PP (screen) 100C        (thermometer) 89 C....... discrepancy 11C

Flex (screen) 50C        (thermometer) 44 C....... discrepancy 6C

Can anyone account for these discrepancies between indicated temperature and actual temperature. The thermometer was positioned 30CM above the metal sheet so the reading was indicative of a large central area of the sheet.

Is this a Thermistor problem or a software problem...is there any way of changing the software values in code to correct for the discrepancy?? I did not try this experiment with earlier s/w versions but might try it if anyone is interested

Is this a reason I am not getting good filament adhesion for the 1st Layer print due to the temperature setting for a particular filament??

I welcome any comment on this matter.

 

Posted : 21/09/2020 12:52 pm
brian.m10
(@brian-m10)
Active Member

This topic should be in the Mk3S section not the Prusa Mini. My mistake but cannot find out how to move it to the proper section. Sorry

Posted : 21/09/2020 1:31 pm
3Delight
(@3delight)
Moderator Moderator

Moved it for you.

Posted : 21/09/2020 1:33 pm
brian.m10
(@brian-m10)
Active Member

I should comment that before the lay-up of the printer, and also before I flashed the new V9 software and messing around with the PINDA probe, the printer was working fine and giving good 1st layer adhesion/nicely squished filament. 

Posted : 21/09/2020 1:39 pm
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