Benchy failing at top of door arches  

Benchy failing at top of door arches

Hi,

I'm new to 3D printing so perhaps do not understand how reliable it should be. I had an excellent experience putting the Prusa Mk3 together with my son over the weekend, all calibrated ok and the Prusa logo printed along with the whistle (1 y axis crash).

Using the supplied grey PLA and Benchy on the provided SD card my first Benchy was one of the best, it completed at least but had a layer shift and 22 y axis crashes:

So I googled around and read through the following post and several other trouble shooting pages: https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f64/y-axis-fake-crash-detections-let-s-debug-t15501-s30.html

I had belt tension values of 276,270 the link suggested loosening the tension so I tried that a bit down to 278 for the Y. This had no conclusive effect.

I noticed that a lot of the y axis crashes occur in a similar location along the front of the bow resulting in the blips visible here:

The poster had belt tensions of around 250 the centre of the expected range, so I moved the belt tighter by a notch in the belt holder brining my belt tension to 254.

Alas this has not helped either. I tried printing Benchy with collision detection off and the base prints much better, gone are the blips and I get a pretty good base boat up until the layer where the door arches are joined, at this point the extruder crashes into the opposite side and takes the benchy off the print bed.

Next I tried slicing the benchy myself in the Pruia Slic3r.

I start the print with collision detection on and print the base successfully I end up having to switch collisions off once they begin to add up and make a mess around the front port holes, once these are done I switch it back on I re-enable it. However in the next 3 benchys printed like this they all failed pushing the boat off the bed during a collision spanning the door archway.

I believe I have good bed adhesion, in that if I remove the print before the collision occurs it requires reasonable force. (Bed cleaned with Isopropyl alcohol between every print)

My main issue above the false Y crashes which I hope are being looked into as they have been reported by others is why I'm experiencing a real crash at the door arcs as this is now preventing me from actually printing a full Benchy.

Any ideas on what I should try next?

Firmware 3.1.3-245