Print bed lowers too early!

[Orbis_PSL 0]

Hi,

I have just received my Ultimaker 2! Yay!

I followed all the setup instructions, and it seems to be printing perfectly.. until the last two layers. It printed every layer perfectly until the last two layers, at which point it lowered the bed about 5-10mm and started printing in mid air.

I haven't had a chance to inspect the gcode yet, but I find it odd that the sample file "double_heart_veronoi.gcode" is in some way faulty if UM are sending it out with new machines!

The other odd thing that happened, was when the print finished, the bed lowered to the bottom of the machine (as you would expect), but it stopped half way down and spluttered a little (as if it had got stuck). It all happened too quickly to see if the belts were jumping or the motors were skipping steps etc..

I've had a search and can't find anything that relates to these same problems (although I am new to this forum, so apologies if this is a duplicated thread). Any help would be greatly appreciated!

Chris

[Orbis_PSL 0]

Update:

I was asked to downgrade the firmware on my UM2 to 14.12.1 which I did. It seemed to fix the problem and I didn't see any problems on subsequent prints.

However, during a print, I acknowledged a sound that had been happening since I first started using the UM2 (I just hadn't got around to checking it out). It was a knocking/clicking sound, as if the print head was hitting something. On investigation it turned out to be the bed lead-screw (threaded rod) turning slightly, then releasing (this occurred mid layer, it wasn't moving to a new layer). Once I had found this was making the noise, I decided to place a light rotational force on the lead-screw with my fingers. As expected, the bed stayed still due to the holding torque of the motor, however, when the noise occurred, it released the holding torque and the bed lowered!!! I expect this was the problem all along, and that firmware version 14.12.1 has somehow improved the issue, but not resolved it. If anyone has seen anything like this, please let me know.