I3X Acrylic 8mm /GT2560 hotbed wrong temperature measurement

[Torm]

Hello all,
my printer behaves unexpectedly - the temperature of the hot bed, indicated by firmware (both LCD and PC control software ) does not correspond to the actual temperature measured at the surface with thermometer. When firmware reports temperature 95°C, real temperature is only 76°C, the difference varies between 20-30°C. Some ideas?
Oh, yes, to make matters worse still, I can not reach a temperature higher than about 98°C (LCD), which means about 78°C on the surface. I use sandwich hot bed - aluminium platte - borosilicate glass plate.

[Mark]

I think the surface is a little far away form the bed center, so it won't be that hot.
And how about the resistanc of your hotbed, it is usually 1.2-1.5ohms, if too high then the temperature won't pass 100 degrees, check this link:
http://www.geeetech.com/forum/viewtopic ... 13&t=17039

[Torm]

I think the surface is a little far away form the bed center, so it won't be that hot.
And how about the resistanc of your hotbed, it is usually 1.2-1.5ohms, if too high then the temperature won't pass 100 degrees, check this link:
http://www.geeetech.com/forum/viewtopic ... 13&t=17039

Thank you for quick reply, Mark. Hot bed resistance is exactly 1,45 Ohm, voltage 10.1 V. Therefore, current via hot bed is about 7 A. Is it sufficient? At what power is hotbed plate designed ?

[Mark]

should be 12V, 10.1V is a little low.

[Torm]

Yes, Mark, it would confirm my suspicions I have a follow-up question - on how input voltage is designed GT2560 board? I ask, therefore, whether it would not be a solution to add voltage on the power PSU, e.g. to 13-14V?

[Torm]

So, after a week of experimentation, I have some results that might help others as well.
1. The power supply I (with trimmer on the PSU) rise up to 13,6V.
2.On the underside Hot bed I attach the adhesive felt pad from a local hobby shop (thickness about 4 mm)
3. When warming, I cover glass with another felt pad, without adhesive layer
To work with the ABS, the hot bed temperature can be preheat to 118 ° C, after removal of the upper felt pad , the temperature drops to about 105 ° C, for sufficient adhesion ABS enough.

[Mark]

thanks for your suggestion, it's really helpful!

[sniper1212]

Torm, can you please explame me how rise you heatbed voltage to 13,6V??

I get only 10,7V on my headbet...

[William]

Hi,
You can test the DC output(around 12V) of the PSU,you can adjust the potentiometer if the output is not sufficient:

0..png (472.72 KiB) Viewed 13327 times