How to set Z hop when printing infill with travel?

[Ninyyyyy 0]

May I ask how I can set it up to achieve Z hop when printing infill with travel to improve my prints.

Here are the printing parameters I have set.

[Ninyyyyy 0]

My cura version is 5.8.1

[Slashee_the_Cow 519]

Z-Hop while printing infill shouldn't improve your prints in any noticeable way. When printing infill, it won't even retract for moves which don't have to pass through any walls. If it has to do a travel move which passes through a wall (or on skin, depending on your combing setting) while printing infill, it will retract, and if it retracts, it will Z hop with the settings you already have set.

 

I would turn down the Z hop height to about 0.5mm, too. Higher hop = more time spent moving up or down = more chance of leaving a glob of drool where it starts or ends the move.

[gr5 2,280]

point 1: don't use z-hop

 

z-hop was created for people with delta printers which is probably < 1% of the printers out there.  Google image search delta printers - they have 3 vertical posts - they are a very unusual design.

 

z-hop slows down prints and greatly reduces the quality on most 3d printers unless you have one of those $100k printers that have no play in the Z axis.  There are probably some very cheap printers that have no play in the z axis but most - if you tell the Z to go up 1mm and then back down it will be at a different Z position and now you get lots of horizontal lines and other ugly results.

 

point 2: zhop only hops if there is a retraction.  I don't know why but that's how it is. 

 

So if you want hops in infill you need to increase the retractions.  There are several settings to do this.  For example you would need to turn off "combing".  Combing is a key setting that reduces retractions, increases quality, reduces print time (usually).

[Slashee_the_Cow 519]

7 hours ago, gr5 said:

point 1: don't use z-hop

Much better answer than mine. I suck at being terse.

 

7 hours ago, gr5 said:

Combing is a key setting that reduces retractions, increases quality, reduces print time (usually).

I think technically whether it saves time depends on how much more circuitous a route it has to path vs. how long you spend retracting/unretracting. But don't forget Slashee's Golden Rule™: Slow print > bad print. I certainly won't argue with the other points though - reducing retractions is a good thing because it stops the filament getting worn as it goes back and forth through the extruder, and increases quality because it's not going to string through walls or anything.

[GregValiant 1,436]

Hello to all.

I have a post processor (no surprise there) that will add z-hops to a gcode even when "Z-hop on retraction" is disabled.  It was written for a pellet fed printer (they can't retract) that was smashing into the print.

 

It wasn't difficult to add "Z-hop in Infill Only".  I just don't think it's going to be very useful.

I've never let that stop me though so here it is.

 

ZhopOnTravel.zip

 

Unzip it and put "ZhopOnTravel.py" into the "scripts" sub-folder of your Configuration Folder.  It will be available with the other post processors under "Extensions".

 

The main criteria is the "length of any travel move" so it is necessary to check that for every single G0 line in the Gcode.  That takes a second or 12 and so it is a slow running script.

 

The original code here had the retraction, travel, prime.  After being post-processed it's:

G1 F3000 X135.035 Y168.33 E1856.03577
G1 F2100 E1849.03577
G0 F600 Z1.7                            ; Hop Up
G0 F7200 X134.544 Y157.664
G0 F600 Z1.2                            ; Hop Down
G1 F2100 E1856.03577
G1 F3000 X138.729 Y157.664 E1856.17496

 

These are the settings:

 

I think Z-hops have their place.  For example - When printing lettering I prefer to have the nozzle raise up between letters.  Some of them are small/narrow features and the nozzle coming across one of those can hurt it, or leave a booger on the side.

The Ritz would be "Z-hop over Infill" but that would need to be implemented in the Cura Engine.  There really isn't a way to figure out if the nozzle is approaching an infill area that needs to be hopped over.  The proper "Combing" mode should take care of that though.

Edited Friday at 04:12 PM by GregValiant

[Slashee_the_Cow 519]

7 hours ago, GregValiant said:

The main criteria is the "length of any travel move" so it is necessary to check that for every single G0 line in the Gcode.  That takes a second or 12 and so it is a slow running script.

Hmm... trying to download that gives me an error from the forum so I can't see it to criticise it, but I don't see what's so hard - just keep track of the most recent X and Y co-ords before the move and apply a little Pythagoras to the travel moves to calculate the distance. Some quick squaring and square rooting shouldn't take that long, and if it does, you need to upgrade your computer.