mbef

Just realized I never posted the outcome here. This is what happened: I tried hard to fit ... well, anything ... to the bed. I couldn't source the right connector, as it's supplied with the bed as a complete unit. But the pads that I was trying to connect to were badly frazzled anyway, and gradually the whole area disintegrated; there was nothing stable to solder anything to. Problem was that the whole bed acted as a massive heat-sink, and I couldn't inject enough local heat to control the solder. The thermistor started falling off too... I contacted Creat3D - our original vendor - who were helpful, but in the end I just bought another bed from them, which was quite expensive but was a quick and non-bodged solution. The new bed has a different - far better - style of connector, so I'm glad I did it. The cost is filed under "reasonable wear and tear".

Hi, I noticed that when I touch the metal surfaces of our UM2, I could feel a slight electrical buzz in my fingers, which was stronger when not wearing shoes. This includes the Z-axis guide rods, and the thin exposed metal on the edges of the laser-cut front panel. The buzz feeling was still there when the UM2 was switched off. So I checked the power supply DC connector with a multimeter, and I can see 100-110V AC between the connector's outer and real ground (checked against a PC back-panel, and a gas pipe). It's got almost no power behind it - which is why we're not in hospital! - but it's clearly floating to somewhere around mains/2 (mains is UK nominal ~230V). I measured the current to ground through a 2k2 resistor and saw 0.8mA => 1.7V under load => 1.3mW. Seems unusual - but a weak floating ground isn't automatically evil. But I don't remember the tingling being there before... does anyone else have this? What is the local ground on a UM2 PSU normally? Cheers, mbef

Hey Torgeir, thanks for that ... yep, I was looking at those, but I was rather hoping to find the exact connector - that way, I won't have to do too much improvisation around mounting and fixing it. I've become a bit cautious after the smoke and sparks :-) Cheers, Mbef

Actually, let me simplify the question: Does anyone know where I can source a replacement heated bed 4w connector, please? Thanks!

I suspected there was something funny when my UM2 (now UM2+) smelled a bit different. But when I saw some magic smoke coming out of the wires at the back of the heated bed, and then a little sparking, my suspicions were confirmed. Something bad was going down. On close inspection, the big heater power wires were charred to carbon, and on removing the build-plate and bed assembly, the main brown wire (#2) was melted into the connector. The connector is toast - literally. It has made me think, because we've had a few Temp Sense Error: BED alerts over the years, which get better when you poke the bed wires: wondering if the wires were loose, or whether the connector is up to handling the current (this is a 2013 machine, I recall seeing comments to that effect). I inspected them when we did the UM2+ upgrade in the summer, and they seemed ok then. I unsoldered the connector, and unfortunately the connector came away with the two thermistor pads - I think the solder wasn't melted properly because the heated bed was acting as a heat-sink, and perhaps they had degraded with heat. Not a total disaster: I think I can solder a wire to the stub ends of the tracks. But I need to reconnect the four wires to the board. So my questions are: 1. Does anyone know where I can source a replacement connector, please? I've been digging around on RS and Digikey, but I can't see one like it. OR 2. Are there any standard hacks for this situation? I'm wondering about soldering new wires to the bed PCB, clamping/restraining them to the bed using the existing connector mount screws, and then using a separate connector to affix the supply wires - is that feasible? OR 3. Am I an idiot who needs to buy a new heated bed?

Marvellous - thanks for the detailed instructions, despite my inability to spell "rectangular" in the title It's actually quite difficult to get the pulleys into a position where they can be adjusted - on one of the diagonals, I could only get at one pulley or the other. But once I knew that I had to loosen pulleys, it was easy to follow your instructions and improvise. I have re-calibrated once, and it's better, but still not quite right. I am printing some little spacing parts that will fit into the gaps between the sliding blocks and the pulleys to make it easier to get the distances exactly the same on both sides. They should make it easier to tighten the pulley screws without nudging things - I'll report back how I got on. Thanks again.

Hi, I have an Ultimaker 2 which has been working well for over a year. I printed an object with a rectangular base the other day, and a casing to hold it, and when I put them together (one inverted), to my surprise they didn't fit. The corners are no longer rectangular, and squares are coming out rhombic in the X-Y plane. By the looks of it, the print-head rails are no longer lined up with the frame or each other. I suspect the belts have slipped a tooth - oddly, in each axis. Or perhaps the toothed pullies that hold the belts are slipping on their rods. Of course, I'm now measuring everything I've printed recently to see what's out of true. I have no recollection of any great disturbance or event that might have caused this, so it's all a bit of a mystery! Is there a correct procedure for aligning the belts or whatever so that it runs true, please? I measured the position of the head's Y-axis rail - the one running front-to-back - and I found that it's about two millimetres closer to the left side of the frame at the front than at the back. Does that tally with the possibility that it has slipped a tooth? Thanks! Mbef