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I am hoping to get some troubleshooting advice from the community about a problem with my UM not printing at the set temperature. I have an Original UM with the UM heated bed upgrade, running the latest version of Cura on Windows 7, and connected to the computer via USB cable. The printer has been working well for over two years, until now! The problem is: When I start a print, first the bed temperature rises to the set point (70C) and then the extruder temperature starts rising. The extruder temperature reaches the set point (218C) and keeps rising to MAXTEMP without the print starting. The work around is to cancel the print when the set point is reached, close the print dialog box, and start a new print; this time, as the extruder temperature falls to the set point the machine starts printing. This is problematic in several ways, including possible damage to the machine, extra time needed monitoring the printer, and causing the filament to melt further up (requiring a disassembly of the extruder to clear things up.) Here's what I have tried so far: - Made sure that the cooling fan cable is away from other cables - Updated firmware (twice) - Tried an earlier version of Cura - Replaced the amplifier circuit board (twice) - Replaced the cable from the amplifier circuit board to the main board The problem still persists every time I print. I'd appreciate any suggestion.

Thank you all for your suggestions. It turned out the problem was the extruder motor.

I have tried two different nozzles (both new), and the problem persisted with both. The flow is better when I raise the temperature to 240-250, but the print quality is not good at that high a temperatures (I use PLA).

Yes, it happens with at least 3 different filaments I have tried. I changed the tube clamp on top of the hot end too, which seems to help keep the bowden tube in place, but the prints are still very thin and porous, and they crumble easily. Any suggestion?

Yes, I had replaced the teflon spacer too.

Thank you for the advice. I have ordered 0.8mm drill bits, and will try modifying a nozzle myself. I'll post an update here.

I have been using my UM1 for nearly a year, and it has been working pretty well. Recently, I am seeing a lot of extrusion problems, and I'd appreciate any advice. Small prints work fine. Larger prints work fine for about 20-30 minutes, and then the rate of material flow slows down significantly, the bowden tube pops out of the top of the extrusion head, and the filament flow stops. I fix the bowden tube, and the next print works fine for the first 20-30 minutes, then the problem presents itself again. I have completely replaced the hot end, the bowden tube, and the material feed mechanism, but the problem still persists. Any ideas or suggestions?

Can anyone suggest a source (preferably in the US) for buying 0.6mm or 0.8mm nozzles for UM1? Thanks.

Thanks a bunch; your suggestion worked like a charm

It appears that Cura cannot print the STL output from Embossify (http://www.embossify.com/). The file loads and appears on the platform, and then Cura seems to freeze. Embossify is a service for converting 2D jpegs to 3D STLs. I'd appreciate any help or suggestion.