Which temperatures to use and why?

K8200 3D Printer K8200 - Issues while printing
1

I print with 3mm white PLA, most often with succes. I post this because I have some questions about bed and extruder temperatures.

This is how I work: Every time before a large print I check and if needed, recalibrate the Z-axis at each corner of the gp8200 glass printing bed. I do this accurately with a piece of paper. Than I clean the bed using a warm cloth and handsoap and I dry it with a towel. After I cleaned the bed I heat it using the bed heater itself and I also use a hairdryer as I am yet to install a 24V supply (takes forever to heat the bed) when the bed is warm I degrease it using 70% cleaning alcohol. Moments before I hit “print” I apply a gluestick for the much needed extra adhesion, I used to use hairspray but this would drop the bed temperature with about 10C so I always printed at 50C and hairspray cost more €€€
I still use the stock extruder with 0.5mm nozzle
For the first layer I print with about 30mm/s and slightly more PLA than the other layers. I attached the glassplate with schotchtape on the corners, had some issues with the clips.

so far I learned that:

  • If I only miss 1 spot with the gluestick an object can start curling upward.
  • Nozzle height listens very closely. Slightly to high results in bad adhesion.
  • really need to get me a 24V power supply for the printbed.

Though most of the prints come out ok, I still can’t leave the house during a print. Today I finally fixed the stock Z-axis which would skip a step occasionally (lost many prints because the extruder would slam of an object). If I now get the bed adhesion techniques under control. I can go to school in peace once again :wink:

What I want to know are the temperatures which give better adhesion to the bed. I know I can print with 50C and 60C for the bed and 190C-210C for the extruder head.

  1. How does bed temperature affect adhesion and what would be the optimal bed temperature be for white PLA 50C, 60C, or even 70C? (doesn’t a hotter bed make the PLA softer that it wants to curl up more easy??)
  2. During printing should I let the bed cool down to below 50C, 50C or just let it be at 60C.
  3. I print normally with a 190C extruder temperature because you know it works…, does a higher extruder temperature affect bed adhesion or does it affect print quality and how?
  4. is 30mm/s slow enough for the first layer or does it help alot to make it even slower?

If anybody knows any of the answers, I would be very gratefull. (if you number the answer(s) like my questions I would be even more gratefull :wink:

2

Ok I got the answers and they are quite usefull.

  1. The optimum bed temperature is 70C. With this temperature PLA will stick without flaw to the glassplate. It sticks like there is no tomorrow. Having this said I came to the conclusion that there is absolutely ZERO need for any alternative adhesion products, such as tape, hairspray, gluespray or gluestick. You do need a 24V power supply to reach this temperature.

  2. During print you should just let your bed be at 70C. As long as it is at 70C no PLA can come lose. If your print bed cools down to room temperature after a print. The PLA will simply let go, and you can blow it of.

  3. If your printer works at 190C do not increase the extruder temp. Higher extruder temperature result in more leaking and oozing.

  4. 30mm/s for a first layer is slow enough, just make sure the bed is degreased properly and that the bed is leveled. Also make sure that your bottem layer is slightly thicker.

3

Slic3r lets you set first layer temperatures for the bed and hot-end. I have the bed set to 70C for the first layer, dropping to 60C, then an idle temperature of 50C set in the end code. Very good adhesion, with parts popping loose on their own once the bed has dropped to 50C. I run the hot-end temperature 10C above normal for the first layer too.