retract retract retract retract

[tonycstech 5]

Since last update, CURA keeps my extruder retracting like crazy.

13.11 did not retract so much ever, why is that ?

When it does filling, at every end of rectangular fill it will retract.

Its all good with ABS because ABS can handle it, but PLA gets jammed EVERY TIME.

I just got my 1st roll of PLA (after lerning to print with ABS) and 1st thing i noticed was nozzle gets jammed as if flow was too much but it wasnt the case.

Flow was the same 90% as i do for ABS but because it retracts so much PLA filament gets pushed in and bends before the nozzle causing it to jam and grind over not pushing it in.

I tried changing fill percentage but no luck. It retracts like crazy

 

[illuminarti 18]

Retraction is controlled by three settings in the Expert Settings dialog.

The minimum travel is the largest move that WON'T have retraction. If you set that to zero, it will retract on every move. If you set it to 5mm, it will retract whenever it has to move more than 5mm. Set it to whatever amount makes sense, so that moves between parts of your print get retractions, and moves within parts, don't.

The minimal extrusion setting is the minimum amount of filament that has to be extruded (measured in mm of raw filament) after one retraction, before another will happen. Set this to a small, but non-zero, amount to avoid having the filament get retracted on the same spot over and over.

Finally, the 'enable combing' checkbox - when that it set, Cura will try to make all moves inside the print, and not cross boundaries - and when it does, it won't retract. With that off, then it takes the shortest route to move, and retracts according to the other two settings.

 

[tonycstech 5]

I do understand how those settings work, but why didnt i see this problem in the earlier version ?

Also do you have any PLA printing advice ? I have to turn off combing because nozzle wipes too much causing filament to get pulled out so when it starts to print, nozzle is empty and does not print until later.

I tried using retraction, but it makes the filament to bend before extrusion and stops feeding so i have it off as well as combing but then i have lots of mess and strings.

I tried 190-220 temps, speed 40. Could my PLA be bad ? Could it be the type of PLA i have ? Personally i have no clue what type it is. I bought it on AMAZON at http://www.amazon.com/gp/browse.html?ie=UTF8&marketplaceID=ATVPDKIKX0DER&me=A34DFZFYEZZ8FF

Thanks.

 

[gr5 2,270]

causing filament to get pulled out

 

I never seen this before. I've never heard of this before. It sounds like bad filament maybe. Sticky filament? Like gum?

Usually the colder you are, the less likely the PLA will come out so usually I recommend colder - maybe 190C. But if you have a .4mm nozzle and are printing .2mm layers, you probably need to print pretty slow - like 30mm/sec.

 

[tonycstech 5]

My usual speed is 40 so its not much of a difference.

0.4 nozzle printing 80% diameter as suggested, or 0.3 for all layer heights same as ABS.

ABS prints come out perfect except for warping, but PLA comes out a mess.

190c for PLA would stick and layers wont separate ?

 

[tonycstech 5]

This is crazy. Its retracting and retracting and mode retracting.

It does it so much while making fills that are not solid.

Each corner is retracting. I think its the slicer issue. Were there any changes with the slicer since v13.11 ? It did not retract like that, it would just go making a grid.

I guess i started to notice this when someone advised me with turning off "combing".

Turning it off makes retraction to go crazy, but with "combing" ON nozzle would travel around the perimeter so much that it would pull all the filament out of the nozzle on the way to its next extrusion point, and start dry and print nothing until nozzle is filled again.

Question:

Is there a way to make combing not travel around the perimeter so much, yet keeping it ON ?

Because when combing is enabled, there is not much retraction going on but it does make too much extra travel around the perimeter pulling the filament out.

When combing is disabled, traveler goes directly to the next target instead of moving allover the place pulling the filament out of the nozzle BUT then it retracts too too much.

There are no combing settings, they all relate to retraction so i am not sure how to change combing behavior and how far it should comb if ever

 

[illuminarti 18]

As I said above, if you disable combing, then you need to set your other retraction settings accordingly. What do you have minimum travel distance set to?

[tonycstech 5]

All default

I started experiencing all those problems when i discovered combing option.

With combing disabled it retracts allot but does not wipe. With combing enabled it does not retract as much, but wipes too much.

I guess i cant have combing enabled and not wipe as much at the same time, can i ? Combing does not have combing settings, it has retraction settings, so i am not sure how to make combing prevent long travels around the perimeter and go shortest route instead.

 

[illuminarti 18]

And what are the defaults??

[gr5 2,270]

@tonycstech I feel like you don't understand Illuminarti's point.

Look at a few layers in layer view and look at about how far the moves are when you *don't* want retractoin and then look at how far the head moves (approximately) for those where you *do* want retraction. If you are lucky - and usually - most of the ones where you don't want retraction are very short - maybe less than 1mm or maybe less than 5mm. And most of the ones where you *do* want retraction span a large gap. Maybe 10mm and maybe the moves are farther than the gap - maybe 15mm.

Then pick a threshold between these values - say 9mm and make that the "minimum distance". That way moves less than 9mm will not do retraction and moves longer than 9mm will do retraction. That is Illuminarti's point. I think he and I are getting frustrated because you don't seem to understand that. We thought if you simply looked at the settings you would understand the point. But maybe we are both wrong. Maybe you already understand this and maybe there is no threshold that will work for your part.

I just know that this usually works for me.

I agree - it would be nice if there was more control. Daid who wrote Cura likes to keep the options as simple as possible and strongly resists more options in the GUI. There are already 5 or so options related to retraction.

 

[tonycstech 5]

I like combing but not how it works. It should have an option how max distance to travel for combing before taking a shortcut.

This option would eliminate dry prints.

I have big gaps in my large prints because it would travel too far. I cant disable combing because too much retracting will simply grind filament to a point where it will not be getting pushed down anymore.

Combing is a good feature, but it needs options too.

 

[illuminarti 18]

If you turn off combing, then you can still set the travel distance and minimal extrusion options, so that your filament doesn't grind.

 

[gr5 2,270]

too much retracting will simply grind filament

 

Something is wrong with your feeder then. I've done incredible amounts of retraction on both UM original and UM2 and never had a problem with grinding due to retraction. In fact I did an 8 hour print last night with 42079 5.5mm retractions and no problems. That's 231 meters of retraction on a print that used 26.6 meters of filament. So every part of the filament was inserted and retracted an average of 9 times. Of course that's just the average - there were sections with no retraction so some parts of the filament probably retracted 20 times.

Your feeder is probably a bit too tight. Do you have UM1 or UM2? If UM2, where is the white square? When the square is at the bottom it is tightest. At the top is loosest. Mine is at the top. Or maybe nothing is wrong and you simply have a softer filament than I do. Are you using PLA or something else?

 

[illuminarti 18]

IIRC, it's not an Ultimaker at all. Are you using Marlin firmware?

[gr5 2,270]

Oh, right! Forgot. Well with non Ultimakers, retraction is probably less critical and can probably be reduced to maybe only 1mm or 2mm of total retraction distance.