3D Benchy Issue

[BennyBoyW]

HI All
I have gone from extreme under extrusion to decent prints on my Prusa I3 B,
However, I am trying to print out the 3DBenchy boat model and have a fairly serious issue.
It all looks good until between 25 and 35 layers in, when for some reason the nozzle seems to grab hold of the model and move it.
Obviously, then all hell breaks loose and I get spaghetti nightmares.
My temp for the extruder is 210 for first layer and 205 thereafter. I have the bed set to 70 first layer and then 65.
It seems strange for the model to go so well for so long and then suddenly decide that it needs to move.
I had the extrusion multiplier set to 1.1 - not sure if that's a clue. I'm trying it on 1.0 right now.

Another issue - I want to set the Esteps in the firmware code - does anyone have good instructions on how to do this ? I know you have to uncomment something for the Esteps to save properly, but I tried this and compilation failed in Arduino IDE. I also tried to set the control knob to revers, but that doesn't seem to be happening either.

Thanks in advance
Ben

[Soadyheid]

[quote]It all looks good until between 25 and 35 layers in, when for some reason the nozzle seems to grab hold of the model and move it. [/quote]

Have you tried manually running the Z-axis all the way to the top of the printer and back again? It sounds to me that something may be binding or fouling at the height you mention which is causing the Z-axis motors (one or both) to stall and cause the print to be dragged off the bed by the other axies.

Play Bonny!

Soadyheid.

[BennyBoyW]

Apologies for the delay - work went mad for a while !
I sorted the issue with stick glue - I don't think the adhesion to the bed was good enough.
Not sure why it was only manifesting on this model but hey hoThanks for the help :)
Ben