How Do I keep print head from knocking over structures?

[Explorer71]

I'm having a problem with the print head catching on delicate structures like supports when it fast travels to the next point. Is there any way to avoid this or at least minimize it?

[jimc]

in s3d there is a setting "retraction vertical lift". im sure its in all the slicers as well. usually a value of 1 or 2 layer heights works good. also check your extrusion rate. over extrusion can cause this as well.

[Capt. John]

What are you using as a bonding agent to stick the print to the glass surface?

[pyronaught]

I find that what causes this is the print head drops a goober at random and then on the next pass it is sticking up beyond the layer height and the print head runs into the solidified goober on the next layer or two until it levels out. Depending on how well your part is stuck to the platform, how tall the goober is and how tall your part is at the time it hits, there could be enough force to dismount the part. I find that glue stick on glass is the best thing for keeping parts anchored. I'm currently printing a 198mm tall part with goober prone filament and it is getting knocked around in the last inch of print but not breaking free.

If you REALLY want to nail a part down you can use BuildTak sheets on your glass, but beware that unless you have your Z-stop set exactly to the magic height you can wind up getting the part stuck so well to the surface that you wind up damaging it or the BuildTak trying to get it off. It's really the nuclear option of hold-down methods and usually creates a problem that is worse than the one you are trying to solve unless you can manage to find the magic Z-stop height that works just right. If you have a part with minimal contact surface area then BuildTak would be something to consider, although I'd try a raft or brim first before resorting to that.