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Extruder doesn't reach target temperature and white PLA

Posted by L_R_A 
Extruder doesn't reach target temperature and white PLA
February 02, 2017 01:40PM
Hi everyone,

I'm having a problem printing white PLA and I hope someone can help me.

I have a prusa i3 hephestos with heated glass bed. I use hair spray on the plate. I use Cura and tried both 15 and 2.4. I am thinking this filament I've got requires a higher temperature than the ones I used before so am banking in there being a problem with the extruder temperature.

When unloading or loading the temperature reaches 220ºC. Here the fans are not really going.
When printing the fans go full power and the temperature usually stays around 190ºC even though it shows a target temperature of say 200 or 220.

The problem I am having with the white PLA is:
- In general the filament does not stick to the plate. If I print it very very slow it will but it shows that it even has trouble to have cohesion between layers.
- I was able to somehow have a tiny part be well printed in the center of the printer and even manually increased the speed to like 90mm/s and it would print perfectly.
- When I tried to use Cura 15 multiply to print 12 of the same part, even doing the outline went wrong. In one of the sides, always the same it would come off and be dragged by the extruder.
- When lowering the speed to about 6mm/s the first layer was okay but it ended up dragging everything after some layers.
- This last print was using Cura 2.4 with first layer being 215ºC and 200ºC for the rest. But again. The temperature didn't raise past 190ºC

I suspected clogged extruder but when I tried the same 1 part with another filament it went well. Altough the temperature also didn't reach target.

If anyone could help me I would greatly appreciate it smiling smiley
Re: Extruder doesn't reach target temperature and white PLA
February 21, 2017 11:05AM
You need to ascertain if the problem is lack of heating for the extruder or over cooling by the 'fan'

Which 'fan' are you talking about?.. the extruder cooling fan or the filament cooling fan? The extruder cooling fan should just blow on the hotend cooling fins and not on the heater block itself. . I would disable the filament fan all together to see if the situation improves (you don't need the filament cooling fan to make prints). Are your filament cooling fans shrouded so they only blow on the filament after it has left the hotend nozzle or do they blow all over the hotend? I normally print PLA at 220 onto a 60 degree bed without a filament cooling fan for most prints as some filaments don't seem to bond layers together too well

If your extruder isn't getting to, or cannot maintain, the requested temperature and it is not being over cooled by the filament cooling fan then I would take a look at the power supply first (meter it's output to confirm it is maintaining it's voltage under load) and if that is ok then the extruder heater second......
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