Gyro: some rare effect on a side

[coduy 0]

Hi everyone, a complete newbie here so sorry if this is a silly question. I am doing a Gyro print and wondering what're those PVA "hair" doing at one of the sides, right opposite to a prime tower; marked with red arrows on an attached photo. I know this doesn't really matter as this is just a support but would like to know if this is something to do with prime tower or seam option that are in Cura custom settings. Is this a starting point of each layer?  In other world I would just run another print job to test it but seeing the print cost I prefer save some euros by asking the community.

 

Many thanks!  

 

 

[Shadowman 53]

I see the same; always along the one vertical edge which is often the ending point for the Print Core extrusion prior to it heading to Prime Tower.

 

If I were to guess; the retraction is simply slow when compared to how quickly the Print Core moves towards the Print Tower and because it is support material it has not been a concern presented by many.

 

Like you; I would like to see it crisper looking and yet I also share that the PVA support has allowed us to do much so I have not thought much about it because within minutes of the print completing it is getting a bath to remove all of it.

 

Enjoy

[Smithy 1,141]

I will try to explain the behavior we can see here.

First, PVA and the BB print core with its different inner shape, tends to drip more than PLA and the AA print core.

And when one layer has finished and the head moves to the prime tower a retract happens. But a retract don't mean that the nozzle stops immediately to extrude material. So the filament will be pulled back, but there is still some melted material in the nozzle and this material drips out, resulting in those strings.

[Shadowman 53]

10 minutes ago, Smithy said:

I will try to explain the behavior we can see here.

First, PVA and the BB print core with its different inner shape, tends to drip more than PLA and the AA print core.

And when one layer has finished and the head moves to the prime tower a retract happens. But a retract don't mean that the nozzle stops immediately to extrude material. So the filament will be pulled back, but there is still some melted material in the nozzle and this material drips out, resulting in those strings.

 

Perfectly understood.

 

The only time that this has ever caused me any mechanical concern is when ....... the Prime Tower falls over at which point the mess can become extreme and even find PVA being integrated into the print.

 

I am looking forward to Ultimaker Cura 3.5...3.6... or whatever it becomes being debugged as I understand that the Prime Tower is more stable.

 

For now; it is Ultimaker Cura 3.4.1.

 

Thank you 

[Smithy 1,141]

3 minutes ago, Shadowman said:

I am looking forward to Ultimaker Cura 3.5...3.6... or whatever it becomes being debugged as I understand that the Prime Tower is more stable.

 

For now; it is Ultimaker Cura 3.4.1.

 

I mean there are some options in 3.4.1. to make the prime tower more stable, but I don't know what to tune. Maybe you can add a brim or make it wider - but personally I have never played with these settings.

 

And yes, in 3.5 the prime tower should be more stable (but only the tower not the sw version ? )

[Shadowman 53]

11 minutes ago, Smithy said:

 

I mean there are some options in 3.4.1. to make the prime tower more stable, but I don't know what to tune. Maybe you can add a brim or make it wider - but personally I have never played with these settings.

 

And yes, in 3.5 the prime tower should be more stable (but only the tower not the sw version ? )

 

Last thing first; LOL!!!

 

To bad I can’t just have the Prime Tower advances; oh well.

 

I do recall reading some time ago that tweaks to the Prime Tower can be made in 3.4.1 however, this is no longer the case with the next stable version with a number yet to be defined because it is suppose to be rock solid; I think the ability to tweak should remain but then; what do I know.

 

The Prime Tower failures have all been a separation between the PLA and PVA and in all incidences when the percentage of PVA is very high.

 

Moving forward....

 

Its all good; I learned my lesson with 3.5; and a big lesson learned it was.

Edited October 24, 2018 by Shadowman
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[coduy 0]

4 hours ago, Smithy said:

I will try to explain the behavior we can see here.

First, PVA and the BB print core with its different inner shape, tends to drip more than PLA and the AA print core.

And when one layer has finished and the head moves to the prime tower a retract happens. But a retract don't mean that the nozzle stops immediately to extrude material. So the filament will be pulled back, but there is still some melted material in the nozzle and this material drips out, resulting in those strings.

 

Thanks, I think I get it. However, what if the PLA noozle is the one that retracts and then goes to the prime tower. In this case we end up with PLA strings on the edge. Is this correct? How do we get rid of them? Using sand paper? 

[Smithy 1,141]

No, PLA is not so fluid as PVA, someone here said its like honey and yoghurt. And the AA print core has another internal shape which helps also that the material will not drip. So normally you will have no strings and if you have strings they are like hairs and you can easily remove them. 

 

If you have massive stringing then you print too hot and decreasing the temperature in steps of 5° can help to avoid these stringing. But it depends also which material you use. PETG for example has more stringing than PLA, and it is more less normal.

 

Some strings can also occur in the infill of an object, because Cura thinks it doesn't matter if there are strings inside the object and do no retract when printing infill pattern. So this is also "normal" or works as designed / slice.

 

If you have something to remove in post processing, then yes sand it carefully or cut it with a blade. Be careful when sanding, because PLA has a low glass temperature and you can get crumbles very quick if the surface gets too hot due sanding.

[Shadowman 53]

18 minutes ago, coduy said:

 

Thanks, I think I get it. However, what if the PLA noozle is the one that retracts and then goes to the prime tower. In this case we end up with PLA strings on the edge. Is this correct? How do we get rid of them? Using sand paper? 

Most strings can be scrapped off and others a small pair of end cutters, razor blade, and certainly sandpaper or a nail file. I try to stay away from sanding unless my intention is to paint the surface.

 

You should not see much stringing from the PLA.

 

The same is true throughout the print; there will typically be an imperfection here and there and if a concern a little detail work will make you smile.

 

 

 

 

[coduy 0]

7 minutes ago, Smithy said:

No, PLA is not so fluid as PVA, someone here said its like honey and yoghurt. And the AA print core has another internal shape which helps also that the material will not drip. So normally you will have no strings and if you have strings they are like hairs and you can easily remove them. 

 

If you have massive stringing then you print too hot and decreasing the temperature in steps of 5° can help to avoid these stringing. But it depends also which material you use. PETG for example has more stringing than PLA, and it is more less normal.

 

Some strings can also occur in the infill of an object, because Cura thinks it doesn't matter if there are strings inside the object and do no retract when printing infill pattern. So this is also "normal" or works as designed / slice.

 

If you have something to remove in post processing, then yes sand it carefully or cut it with a blade. Be careful when sanding, because PLA has a low glass temperature and you can get crumbles very quick if the surface gets too hot due sanding.

 

One of my 1st prints had PLA strings on the edge, quite similiar to the PVA ones from the Gyro's photo I attached earlier. However, for this print I didn't use prime tower, simply forget to set it up. I will try to submit a photo tomorrow, I guess I will need to follow your advice and try to lower temperature to see if this helps. Many thanks! 

[Smithy 1,141]

The default profiles in Cura are a very good start point, for PLA I never changed the material settings and just print with that profile. 

 

If you are printing with just one extruder, you don't need the prime tower.

[coduy 0]

9 minutes ago, Smithy said:

The default profiles in Cura are a very good start point, for PLA I never changed the material settings and just print with that profile. 

 

If you are printing with just one extruder, you don't need the prime tower.

 

Yup, the print that ended up with lots of PLA strings was send using Recommended options. The print required 2 extrudes. Although not sure if I am just panicking about number of PLA hair/strings, will upload a photo tomorrow for your opinion on this. Many thanks for your time and support!  

Edited October 24, 2018 by coduy

[Shadowman 53]

1 hour ago, Smithy said:

The default profiles in Cura are a very good start point, for PLA I never changed the material settings and just print with that profile. 

 

If you are printing with just one extruder, you don't need the prime tower.

Agreed

 

However, if printing a single item; particularly a small item without support then I find printing a small disposable part at the same time such as a small diameter cylinder helps to produce a better print. This allows the layers sufficient time to cool. 

 

If printing more more than one piece of a comparable height then a disposable part is not suggested.

 

Now this is simply an example of what works for me which was suggested to me by another.

 

 

Edited October 24, 2018 by Shadowman
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[Smithy 1,141]

Ok, with dual extrusion it could happen that you get some strings without a prime tower also with PLA. 

 

2 minutes ago, Shadowman said:

I find printing a small disposable part at the send time such as a small diameter cylinder helps to produce a better print. This allows the layers sufficient time to cool. 

 

For very small items this a very good idea. It should also help to increase the min layer time in Cura, but never tried it myself.

[coduy 0]

9 hours ago, Smithy said:

Ok, with dual extrusion it could happen that you get some strings without a prime tower also with PLA. 

 

 

For very small items this a very good idea. It should also help to increase the min layer time in Cura, but never tried it myself.

Hello, so this is a print with strings that I mentioned before. It's PLA with PVA and no primer tower was used. Is this amount of strings can be considered normal? For the reference, the red line is 40 mm long. 

 

 

[Smithy 1,141]

I would say, no this is not normal, but on the other side I haven't tried a dual print yet without a prime tower, so maybe it is related to it. 

 

Which material brand do you use? Ultimaker? Is this the ToughPLA that comes with the printer?