Z axis crashing midway through print due to slicer programming?

[Tektechnician 0]

Hi, 

I don't really know how to describe the problem, but let's start by what I know.  I know it isn't a end stop issue, nor a print direction/configuration issue with my printer. I  currently have a anet a8 (prusa i3 clone) with a ramps 1.4 and I have had this issue ever since I got my printer. This issue has carried through the stock control board, a MKS gen 1.4? Board and the ramps 1.4. Simply what happens is when the print starts it draws the first line on the print bed which usually starts from left to right and then either raises/lowers the Z axis until it crashes the print head into the physical limits of the printer e.g. stretching z couplers or hitting the supports.

I've tried searching online and found few similar reports of the same behaviour, but I don't know how to describe it without also searching end stop/ configuration issues.

 

Here's what usually causes it:

 -Large object (~2cm margin on bed)

-Cura 3.x.x

- commonly skirt, brim (also rare with none)

 

What I know doesn't fix it:

-Changing Cura bed size

-Changing Marlin bed size

-SD Card vs streaming gcode

-Marlin version

-electrical (I've rewired it twice)

-control boards

 

How I deal with it:

-print smaller objects

- rotate/translate object

-turn off brim/skirt

-redesign parts

- use a different slicer like repetier host, slic3r, cura 15

 

Reason why I think this has to do with Cura 3.x.x is because I have only ever experienced this issue with Cura 3.x.x. In fact it was why my first slicer was repetier host (curaengine), I couldn't figure out why I was having strange printer movements with 3.x.x. I've used repetier, slic3r, curaengine, cura 15 and never experienced this issue. The frequency of this issue is almost every large print, so well over 20 prints now. I still want to use cura because of its integration with octoprint but don't want to have to run over to the printer just to hit kill when the issue arises.

I'm hoping that it's something simple that I've missed, so if you know what I'm doing wrong, let me know.

Edited July 29, 2018 by Tektechnician
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