Print Head movement WITHOUT extruding ??  

RE: Print Head movement WITHOUT extruding ??

Recently I had 'slight' ooze when doing moves only with PETG, and apparentely my temperature for it was just too high.
Get some temperature tower for your printer for given filament type and find the optimal temperature..

Also drying filament really helps to avoid oozing, because water makes this effect even more visible.

RE: Print Head movement WITHOUT extruding ??

I'm only using PLA filament, so I'm not sure if that's affected as much by temperature.

I don't know what you mean by "get some temperature tower".

RE: Print Head movement WITHOUT extruding ??

the easiest way to ensure no oozing, is to remove the filament

or specify an extruder temperature below say 150C   I believe the low temperature extrusion threshold is set to 170C

regards Joan

RE: Print Head movement WITHOUT extruding ??

Or I suppose I could just turn the whole machine off and that would guarantee no oozing!

And changing the extruder temperature?? Sure, let's see, it's doing some actual extruding and then I need it to do those special movements without extrusion, so I set the extruder temperature to below 150C and WAIT for it to cool down. And of course, after it's done with the  special movements I re-set the temp and WAIT for it to heat up again.

Ummm,no, those are not helpful suggestions/

Not much point in getting snarky if you get a correct answer to your question - but asked the wrong question.

Tel us what you're trying to do and why.  Tell us what you've tried that failed.

Then you might get a reply closer to your use-case.

We see all sorts of half-baked ideas attempting to use 3D printers as 2D plotters, cutters, routers and manipulators - most of them are incompatible with successful printing but all would be better attrmpted with unloaded hotends...

Cheerio,

RE: Print Head movement WITHOUT extruding ??

The only practical thing I can think of is to do a longer than normal retraction before whatever these 'special moves' are and then to feed in the opposite afterwards to put the filament back to where it was before hand.  One problem is that the total length of retraction possible is limited to the length of the feed path as if retracted too far it is essentially an unload and so wont load back in without manual help.

I suspect that would lead to an under primed nozzle when it resumed extruding though so there might be small gaps on restart.  The simple fact of the matter is that filament in a semi liquid state when its at printing temperature is still effected by gravity and will move downwards. That's just physics.

RE:

> I don't know what you mean by "get some temperature tower".

When you use a filament you never printed before (or you use it for come time and it starts to behave weird) then it is advised to print a special model named temperature tower designed for specific material such as temperature tower for PLA. This helps to select the best temperature to print with given filament, so that it reduces oozing or other nasty artifacts, such as stringing or not good enough layer adhesion. 

You should be able to find some ready to print models or gcode on printables.com

Why am I mentioning this? Because I had custom moves per each layer (taking a photo for time lapse) and I noticed that during this moves I had some filament oozing from the hot end. I was using recommended settings from Prusa for my filament but apparently in that case they were a bit too high and I had to actually decrease temperature because filament was cooking, making little bubbles and thus this ended in oozing.

Temperature tower showed me the temperature range that looked the best and since then I had no issues.

I hope this may help in your case.

RE: Print Head movement WITHOUT extruding ??

@Neophyl That's definitely a good suggestion. I had looked at some existing GCode, produced by PrusaSlicer, and there were indeed places where it seemed to be doing a filament retraction withe the E parameter, with very small values, but different values in different places. So I tried the smallest value and that had no effect. I'll be trying some other values and see if that works.

Here's some of the GCode that I found which seemed to be doing retractions:

G1 X131.125 Y111.125 E-.01385
G1 X127.72 Y111.125 E-.78615

All of the movement commands I've been doing in my code have been G0, not G1, since G0 is described as being without filament extrusions. But the ones I found in existing GCode that appear to be doing retractions all seem to be using G1. Maybe the E parameter is effectively ignored in G0 operations.

So, more testing to do.

My project does indeed do both filament extrusion movements as well as non-extrusion movements. Hence the request for assistance on getting the oozing to stop.

RE: Print Head movement WITHOUT extruding ??

I don't think Prusa Slicer uses G0 at all.  There is even a firmware type called "No Extrusion" which unsurprisingly produces no E commands at all.  Even so all the movement commands use G1 still.

For normal firmware types the 'normal' amount of retraction can of course be configured.  That's done in the Printer Settings>Extruder (if you weren't aware), as well as settings for retract on layer change and options like % retract before a wipe move. 
So the small retraction settings you are seeing might be because its split into sections for a wipe.  Without the project you are using to test these things its going to be difficult for anyone else to debug things.
Normal retraction distances for a direct drive extruder are usually in the 0.4-1mm range.  Bowden printers can go into the 20+mm range sometimes (although 5mm is more normal).  That's because they are inherently more 'leaky'.  They can also use far larger values safely as their filament feed lengths are so long too.