Vase printing problems (stringing)

[thirty6 3]

Newbie Warning..

Hi, Trying to print a vase i created on Project Shapshifter, it is all okay except if i try and print it at 50% scale i cannot stop the stringing on the holes.

I have tried slowing the machine down and lower tempratures, but still having problems.

I have enclosed images of settings and close up of vase.

Any help appreciated.

 

[illuminarti 18]

There's a https://github.com/daid/Cura/issues/635 (and maybe earlier versions?) that will be fixed in the next release, that retraction doesn't trigger when the distance being moved between parts is less than 10mm. Perhaps that is what you are seeing?

 

[gr5 2,004]

In expert settings, set the two retraction values to 0. ESPECIALLY minimal extrusion. If you have this as low as 1mm, it still takes about 200mm of horizontal printing (at .1mm layers) before it has moved enough to retract. Just set these both to 0mm and you will be safer.

edit: arrg. edited this 5 times. It's about 200mm.

Math:

2.85 diameter versus .4mm diameter nozzle means 1mm extrusion of filament is (2.85/.4)^2 or 50X as much or 50mm of .4mm diameter extrusion.

50mm extrusion of .4mm at .1mm layer height should be about 50 / 0.1 (layer height) gvies you 500 dots of extrusion times about .4mm length of each dot gives you about 200mm extrusion.

 

[thirty6 3]

Thanks both for the replies, if i print at full size (holes over 10mm) it is a lot better so thanks for the advice.

gr5 0 retraction values is this something you would always use on prints with perforations i.e bracelets, vases, lamp shades?

Do prints of this type always need cleanup or is it possible to print a item that need no finishing?

Also, unrelated question how do i check if my machine is running the latest firmware?

 

[gr5 2,004]

gr5 0 retraction values is this something you would always use on prints with perforations i.e bracelets, vases, lamp shades?

 

Yes. But I set these to 0 for almost everything I print.

 

is it possible to print a item that need no finishing?

 

With most PLA filaments (and ABS is better) you can often get a "zero clean up" print with zero stringing. But this is *not* easy. It takes experimenting and some filaments string no matter what you do.

In general I print very cold (maybe 190C depending on the brand and color filament) and very slow (20mm/sec).

Some prints are meant to be beautiful. Some prints are meant to be functional. Some prints have no "holes" to jump over *and* are meant to be beautiful. So I do different printer settings for different prints.

Here is an experiment I did with stringing:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/

 

[dree 0]

In expert settings, set the two retraction values to 0. ESPECIALLY minimal extrusion

gr5,

I don't see minimal extrusion, I heard you say this before, I do not remember the other one you mentioned.

I only see Speed and Distance (default 40.0 and 4.5) am I missing something or are that the two to put to 0 ??

(Ultimaker original)

Groet Dree

 

[illuminarti 18]

Speed and distance is on the 'Advanced' tab (for UM1). Instead, go to the menu: Expert -> Open Expert Settings.

 

[thirty6 3]

Thanks again for the info

gr5 I had looked at your article before I started printing, but did not know about the retraction. Will try this tomorrow.

gr5 and illuminati how standard are your machines?

I am looking to go the heated head route for ABS but do I need to look at changing out any other bits ?

[dree 0]

Speed and distance is on the 'Advanced' tab (for UM1). Instead, go to the menu: Expert -> Open Expert Settings.

Ah, OK Illuminarti, thanks, now I see.

So gr5 suggests;

Minimum travel; 0

Enable Combing; ticked.

Minimal extrusion before retraction; 0

OK so?

Dree

 

[illuminarti 18]

That's a good question! I think that when 'Enable Combing' is checked, then when making moves within areas of infill, it will ensure that the move stays within the infill when possible, and when it does, it won't retract.

When it is unchecked, then it will move in a straight line as needed, without regard to whether it is crossing boundaries or not, and in that case it will always do retractions.

One thing I am not sure about is what happens about the moves between lines of solid infill? Do those obey the same retraction rules as other parts of the print? You probably don't want to do a retraction when just moving over 0.4mm to print the next line of solid infill. Is it the combing rule that prevents that? I think I need to do some slicing tests.

I can see benefit in avoiding crossing boundaries when you don't need to. But I can also see benefit in retracting when making any long moves, even internal to a shape. Because if you don't retract, you leave a trail of plastic that damages the surface quality on top/bottom surfaces, and you empty the head somewhat, so that when printing resumes, there is under extrusion at first.

I'd personally like to see the option to retract AND lift when printing the very bottom and top flat surfaces of objects, in order to avoid marring the surface finish. For instance see the move scars left on this sample print I just did:

 

I didn't slice that one though, just used provided gcode, so I'm not exactly sure what the settings were.

 

[dree 0]

Thanks for the info.

I do not think retraction is happening within a solid infill. But I also do not know the rules of triggering the retraction. Sometimes with a greater surface it prints diagonally from the middle to a corner and the travels all over the project to finish the layer at the other end... does it retract then? And is it a disaster if it doesn't? I don't think you will ever notice,

Dree

 

[illuminarti 18]

If you look at the example print I posted, you can see the top surface is covered in scars where it moved around between areas of solid infill, leaving a thin bead of plastic which it later failed to cover up properly.

 

[dree 0]

Yes I see now, I thought I only saw the familiar surface parts due to different peaces of the surface are printed at a different angle.

We have to see if this happens with gr5's 0 settings.

Dree