Ultimaker Clone Heated Bed Problems!?
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Can anyone help? I have built an Ultimaker clone and it works (amazingly) however I have an issue with the heated bed not being able to reach above 85°C. It is my understanding that the bed should be capable of at least 110°C.
I am on my second bed however both appear to have the same limitation. Here is the item in question: http://www.ebay.co.uk/itm/Heated-Bed-for-Ultimaker-2-UM2-Extended-2-3D-Printer-/162261178505?
It is rated at 24v 165w apparently?
Could it be a setting on in the config (it is currently set to max bed temp of 150)?
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I suggest you measure the voltage that appears on the bed terminals as the bed is heating up. If it's significantly less than 24V, then you have a configuration, power supply or main board problem. If it's close to 24V, you have a problem with the bed heater, in which case I suggest you disconnect it and measure its resistance.
Chinese PCB bed heaters are notorious for poor quality control over the resistance,
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Will do. I quickly switched it over at lunch time and checked the resistance (not plugged in to anything) and was getting 5.5ohm?! Seems high to me, but it was identical on the 2 I currently have. I will check the bed terminals tonight, can you change the voltage/current in the configuration? Power supply is a meaty 400w 16amp so should be more than powerful enough. My other guess would be that perhaps the pt100 is just not picking the temp up correctly but it matches the hot end for room temp so that seems unlikely. I might try lining the back of the board with cork and see if that helps.
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24V @ 5.5 ohms gives 105W, which is significantly less than the claimed 165W and is under-powered for a bed of that size. But you should also see what resistance reading you get when you short your meter leads together, and subtract that from the bed resistance that the meter indicates.
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So following your advice I checked the shorted measurement and it was 0. Checked the power and it was 24.1v checked the resistance and it is still 5.5ohm. So it appears as if both the beds from 2 different suppliers are identical. Both underpowered! Can anyone suggest a supplier that I can get a reliable properly powered bed!
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What about a silicone type heater rather than a PCB heater? They tend to be a bit better in my experience. Also, add some sort of insulation if you haven't already. Even a very thin reflective barrier can make a big difference.
