Heatbed cannot reach 110*C

I'm pretty new to printing. I purchased a Zonestar P802M variant from aliexpress. I cannot get the heatbed up to 110 no matter what I do. Using the factory firmware (repetier 0.91) I could not get to 110, and using 0.92 that i'm running now I couldn't get there either. It decouples after a couple of hours and never passes 100*C. It takes about an hour just to get to 100*C which seems extremely slow from what i've read.

I am using an aluminum plate (~3mm?) on top of a MK2 heater. I've replaced the power supply with a rewired/soldered 650w atx supply. I've change the power cables and wires going to the heatbed to a super overkill 10g stranded copper. I added a 7mm cardboard underneath my heatbed for insulation. The voltage off the power supply is ~11.78v and when the heatbed is heating it drops to ~11.65v. At the heatbed it's ~11.56v when it's heating. Is that sufficient power? I don't really know what else to try at this point other than just buying a new heatbed.

I'm open to any suggestions. Thank you.

Edited 1 time(s). Last edit at 12/13/2015 03:00PM by RunWreckRi0t.

The voltage drops seem to be OK.
Do you have a dual power MK2 heatbed suitable for 12 and 24V?
You probably have three solderpads underneath and only used two?
Then the bed would only heat with half the traces.
-Olaf

No mine doesn't. This is the exact one I have, the joints are pretty well soldered also.

MK2B Heatbed

Here is an interesting article on the differences of heated beds:
http://www.sd3d.com/not-all-heated-beds-are-created-equal/
I was never a fan of them to start with and usually fail to understand why you would need more than 100°C for a print bed.
Not trying to value these heated bed down but I cope fine without, even when printing Nylon on a cold bed...

I'm not familiar with repetier, but with Marlin I would autotune the bed PID and also see, if the full PWM range is allowed for PID control.
IMHO it's not a hardware problem.
-Olaf

If it has only two solder pads it is likely a 12 or a 24v head bed. Measure the ohms. Should be about 1.5 for 12v and 3 for 24v. According to the picture it doesn't look like a dual volt heat bed.

In Repetier "Printer Settings" you can set Max Hotend and Heatbed temps.

Hi,

Due to the large size of the bed of heat radiation, it is less than 110 Celsius.
I was glued to the bottom of the bed 3mm thick ceramic thermal paper.
Much has been heating up faster, have less demand for energy.
The extruder is made cap, the faster it was heating up.
Simple low-cost solution can be cut with scissors (200 x 200 x 3mm ~ 1euro)

something you should look for such a thing

[www.dualinvest.hu]

I have a new Prusa clone machine with the same conditions. There is no way i can get the Ally bed to 110. I used 110 on a different machine so caried it over but there is no real reason to run that high. The Ally bed is highly conductive and with insulation underneath and on the bed mine takes 25mins to get to 100. PID only activates after you hit the temperature target so don't get distracted by that. When i remove my top cover insulation at print start the bed wont hold 100C, the heater is maxed out and over time the temp drops to about 97. As a result i have reset my target temp to 99 to ensure i get to target temp and the print starts.
If you use a glass plate instead of the Ally you can get to 100 in under 15mins, and the max temp is about 105. You then print on the glass ( once you have dealt with all the getting it to stick issues).
Do you see a jump in temperature from 82 to 95 ? If so there is an error in the temperature table. The 95 is wrong so you need to get nearer to 100 for the real temperature to be reported.
In short - its probably not a missbuild or fault its just the spec of parts. I think the control boards limit the current to the heater to avoid damage to the controller so if you want to use a lower resistance heater then wire the power separately and use a relay from the control board. i am still looking for a material that will provide a flat surface, heat fast to high temp and have the parts stick easily.