Powdered Sheet - Is this a heating problem?
While working on something else I was monitoring temps and started to monitor the temp swings on a powdered sheet that I was attempting to print some PETG parts on.
What I found was the surface temp was between 13-5 degress below programmed level. Once it hit a low, the heater would come on and slowly the powdered sheet surface would rise, but never completely to the desired level. The heater would go off and immediately the surface temp would start dropping..
For the PETG print, I raised the desired temp by 10 degrees and have watched the temp swings for a while, but at least it is staying closer to the programmed level..
Such temp swings on PLA would certainly help explain the loss of hold that has been causing my PLA prints to fail..
I see much less dramatic swings with the non-powdered steel sheets..
Anyone else seeing anything like this?
RE: Powdered Sheet - Is this a heating problem?
Are you looking at the temp reading on your LCD or are you measuring the surfacetemperature of the steel sheet yourself? I assume it is the latter?
A temp difference between the LCD reading and the actual surface is not entirely improbable as the printer measures the temperature on the bottom of the pcb (and controls the temp with that information) and you measure on the surface.
How significant is the difference between the powder coated and non-powdered sheets? Maybe it is due to higher contact area when heating the non powder coated sheet.
If your parts release from the build plate you should also look into your surfac cleaning and first layer height. There are plenty of postings with that topic.
RE: Powdered Sheet - Is this a heating problem?
Neither a surface cleaning nor a first layer issue.. Both are fine..
The temp diff is between the LCD and the bed surface.. just now 13C -- 77 on powdered sheet surface and 90- on LCD .. my desired level was actually 80 but it was dropping to the 60s on the surface of the sheet so I hiked the temp to 90.. Now I see between 76 and 88
Assuming the thermistor is correct, and no reason up to this time not to, then there is definitely an issue between the temp measured on the heating bed and the heat stability being seen on the surface of the powdered sheet..
Will retest with PLA but if the swings are as violent, that would explain alot.
In the meantime, I am running the powdered sheet 10 degrees above my otherwise desired level for PETG and will try to find an appropriate level for PLA and see if that stabilizes the hold for a change..
Definitely a difference between the heat retention and dissipation using the powdered sheet vs. the non-powdered, just not sure of the affects..
More testing ..
RE: Powdered Sheet - Is this a heating problem?
How where do you measure the surface temp?
Those videos indicate that there is quite a bit of temp spread along the surface.
RE: Powdered Sheet - Is this a heating problem?
I measure as close to the center as is possible .. The variation as I move toward the edges is significant ..
The LCD shows 90 as the target temp and the temp read on the thermistor..
Measurements:
78c at the center .. 76c toward the left edge..68 at the left edge. Interestingly, the right edge measures closer toward the center reading while right edge itself is 73.. No reflective surface.. I won't be able to test the PLA temp drops until tomorrow due to need to complete some other projects first ..
I am becoming more and more convinced that the heating issue is significant to the performance of the powdered sheets, or lack thereof with PLA for me, and will need to be factored in somehow.. hopefully, this is not a sheet by sheet issue, within the powdered sheets that is ..
The print has been running for ~4 hours and shows no signs of hold problems..