Nozzle does not lift during travel over the print

I thought my X rod was completely dry from the sound of the nozzle slamming the print, but after careful look it turns out that the nozzle does not lift when it retracts and travels and it hits the print all the way.

How do I fix this?

Regards,
Antonio

Edited 1 time(s). Last edit at 11/21/2014 09:27AM by Sardi.

The nozzle does not retract - it stays at the same level all the time while printing a layer. The only retraction that takes place is of the filament (to prevent oozing). It is normal for the nozzle to bump over the print a bit on non-printing moves. If you get a particularly bad curl-up (which can happen, especially on an overhang), the nozzle can catch on it and dislodge the print or cause the axis to skip a step - but then the curl-up would almost certainly have resulted in a bad print anyway. On a part that has overhangs prone to curling you can try printing at a lower temperature, and fitting a cooling fan would probably help as well. On some prints I have to stand ready with a flat tool or needle file and push down the curl-ups between layers while it is printing.

Dave

Well the sound that the nozzle makes is all but not nice and it leaves marks on the printout.
I dont see why shouldnt the nozzle be lifted a little bit just not to hit on the printed part, cause I print small long parts (13cm x 1,3cm x 4mm) and the nozzle hits the printout pretty hard damaging it on the way.

Cura has Z-hop and Slic3r has Lift Z, im setting it both to 0,1mm, just enought for the nozzle not to hit the printed parts.

The Lift is set with your slicing software not obn the printer. The printer does not distinguish between printing moves and moving moves. If your nozle does not lift during a print, your slicer is not configured to do this.

Exactly that DasBasti. I heard the nozzle dragging itself on the printout before and I dont know now why I didnt pay more attention to it.

Z lift is definitely something worth activating if the nozzle kicks the printout too much as it is my case.

Quote
Sardi
Well the sound that the nozzle makes is all but not nice and it leaves marks on the printout.
I dont see why shouldnt the nozzle be lifted a little bit just not to hit on the printed part, cause I print small long parts (13cm x 1,3cm x 4mm) and the nozzle hits the printout pretty hard damaging it on the way.

Cura has Z-hop and Slic3r has Lift Z, im setting it both to 0,1mm, just enought for the nozzle not to hit the printed parts.

If it is hitting the print hard it would tend to indicate that you are over-extruding. Unless there are curl-ups I find the nozzle just bumps very lightly over the surface without leaving a mark (apart from sometimes leaving a thin string of ooze). I've not noticed the options you mention in either Slic3r or Cura. The last version of Slic3r I used was 1.1.6, and Cura 14.01 Maybe they are only featured in later versions, or I've just not seen that item.

One thing that comes to mind is that it could possibly result in layer banding due to mechanical backlash in the Z train causing the resumed height to be slightly different than the height prior to the lift.

Dave

In Cura 14.03 it is under Expert -> Expert settings -> Z hop, and in Slic3r 1.1.7 under Extruder options -> Z lift.

I have just printed a file with Z hop (Cura) with 0,1mm setting and the file was "intact", nozzle didnt hit it and it looks much nicer.

Quote
dmould
..On some prints I have to stand ready with a flat tool or needle file and push down the curl-ups between layers while it is printing.

Dave

I can relate to that, just had a 2 x 6 hour baby sitting session with a print, a model of a GSX1000 sliced in two length wise, the fuel tank was hollow and of cause printed with support, but the support did not fuse to the perimeters as infill would have done so lots of curl-ups

I use two butter knifes, a cool one and a hot one (about 100C, resting on a soldering iron)
If I can get to a curl-up just as the nozzle move away it will still be soft and I can press it down with the cold knife and it will stay down
If I cannot get to the curl-up before it cools I use the hot knife to soften and press down the curl and then hit it with the cold knife

The temperature of the hot knife is kind of critical, too cool and it will not work, too hot and it will stick to the print and leave a mess

Erik