Stringing 3d printing cura

Stringing 3d printing cura DEFAULT

How to fix Stringing/Oozing

In this article you will find how to proceed if you are experiencing stringing/oozing


                                               

EN

ES


 

Note: This is an advanced article. You'll have to tweak a lot of settings in BCN3D Stratos, if you don't see some of the settings listed here, update it to it's latest version, go to Settings/Configure settings visibility and click on the "Check all" box.

settings-visibility-en-stratos-check1

When 3D printing, it's possible that you have seen your parts with strings at certain points. This is a printing issue that can be solved easily by tweaking the BCN3D Stratos Settings or drying the filament. 

What is Stringing and why it happens

Stringing, also known as oozing, is easily noticeable, as you'll see fine strings left around on the print, those fine strings look like cobwebs or strands of hair. This normally is due to the filament oozing out from the print head while this is travelling. 

stringing-gifAs the print head travels across the build volume, some filament may ooze out in small quantities, this will solidify and stick to the printed parts. Normally stringing shouldn't happen, however, it will sometimes happen depending on the filament you are using. PET-G is notorious for stringing, and hygroscopic materials such as TPU or Nylon may have stringing issues if they are not well conditioned. 

 

 

There are many ways to fix this issue, luckily, it's easy to solve. Let's look at all the points that can influence stringing. 

How to fix it

Note: Our printers are open filament, this means you can print with whatever filament you like. However, every brand uses different additives on their filaments, this can cause some differences in the printing properties of a certain material. We recommend using BCN3D filaments with our 3D printers. The default BCN3D Stratos profiles for BCN3D filaments are tailored by our Lab to deliver the best quality and reliability on your prints. 

Retraction settings

Enabling retraction is key to solve stringing. Retraction is a feature that is  enabled in BCN3D Stratos by default. This particular setting will make the extruder motor pull the filament back before any movement, preventing it to ooze while the head is travelling. If you still experiencing stringing issues with the retraction enabled you'll need to tweak the retraction settings. These are located at the Custom configuration mode, in the Material menu.

 

No retractionWith retraction

 

1. Retraction Distance: It is the setting that most affects the printing quality, it is the distance which the filament is pulled back. If you increase it's value, it will reduce stringing, but if you increase it too much, your print will have gaps on its walls. Try to find the sweet spot by performing printing tests. This model can help you, it is quick to print and doesn't consume much filament: Basic Retraction test by Stefan_Alberts_

 

2. Retraction speed: The speed in which the filament is pulled out of the nozzle also affects on stringing. If it's too slow, the material will have a lot of time to ooze out while retracting, if it's too fast, the extruder motor gears can grind the filament and cause underextrusion to happen. You'll also need to run some tests to find the sweet spot. In PET-G, it is the opposite, you should lower the retraction speed as it is a very viscous filament, and if pulled out quickly, it will make even more stringing. 

 

3. Prime speed: The opposite of retraction is priming. This movement pushes the filament back in the nozzle exit so it can continue extruding. If you lower this speed, the filament will have a more controlled extrusion. If it's too fast, oozing will also occur at the start of the extrusion path, leaving behind a blob of filament. 

 

Set the right temperature

As the temperature increases, the filament becomes more viscous and runny, which means it will be easier for it to ooze and cause stringing even after tweaking the retraction settings. A lower temperature will leave less room for stringing, however, if you set it too low, underextrusion will appear. 

 

Once you notice stringing happening, you can decrease the temperature while the printjob is running by going to Settings/Temperatures and lowering the extruder temperature in 5ºC steps until you find it won't string anymore. You can run print tests to find the right temperature for a particular filament. Write it down so you can apply it on your next prints.

Travel speed

movement-bcn3d-epsilon-abs-pipe

The travel speed can also affect stringing, if the print head takes too long to go from one point to the other, stringing will be more likely to happen, as the molten plastic will have more time to ooze. A travel speed of mm/s is ideal for most of the filaments. 

Keep your hotend clean

Remember to clean the hotend regularly, specially when loading different materials in it. Also, clean the nozzle with a brass or copper brush before printing to prevent any residue to stick on your printed part. 

 

 

print quality issues EN

create-material-en


 

You can help improve the BCN3D Knowledge Base.

If you feel there are guides that we are missing or you found any error, please use this form to report it. Report form:)

Sours: https://support.bcn3d.com/knowledge/stringing

Stringing with prusaslicer solved with Cura  

Stringing with prusaslicer solved with Cura

Hi guys, so i got a general problem with stringing, even the prusament or quality filaments were making stringing and on in prusament it got solved with lowering the temperature (without lift Z) or lowering sooo much the temperature if i wanted to keep the lift Z option.
But with other not so known filaments i couldnt get to a solution, here you can see how it is printed with standard settings:

After a long time testing with this filament, trying to change the retractions, temperatures, speeds, and all the weird stuff I could think of I thought my problem was mechanical, something was wrong in the machine but I watched a video from Maker's Muse about the stringing in ender 3 and I decided to try another slicer so I went ahead and used the standard presets from prusa in Cura This is the resoult:

ZERO STRINGING, there was a small amount that when I touched it disolved in the air like it was antimatter Really really far from what I was (and still am) getting with PrusaSlicer.

So my question is: WHY IS THIS HAPPENING?

I mean PrusaSlicer is so usefull in many things and i dont want to change it for Cura, the supports are much better, they peal off easily and the custom adaptive layer height is an amazing feature Is there any way i can obtain those same resoults in PrusaSlicer? what is the SUPERBIG difference in both of them if settings are the same?

The settings I used for BOTH slicers are the usual "mm layerheight SPEED": º for the nozzle, retraction distance, 35mm retraction speed, lift Z, 2 perimeters, 10% infill grid I will add both Gcodes just in case somebody can understand what is actually going on and help me out

This topic was modified 2 years ago 2 times by Archetrico

Log in to be able to post
Posted : 15/11/ pm
Sours: https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-how-do-i-print-this-printing-help/stringing-with-prusaslicer-solved-with-cura/
  1. Amazon gallon of glue
  2. Mink teddy bear
  3. Custom super 73
  4. Autozone tire iron

How to reduce stringing

Today we want to talk and give some tips to reduce the stringing in our 3D prints.

 

A common issue in FDM 3D printing is the so-called stringing effect, which leads to stringy or hairy parts. The name comes from the plastic strings that remain on the printed part after the printing process.

PICTURE 1

This artifact happens because of the sticky nature of the hot plastic. When the plastic is hot enough it becomes fluid and that enables it to be extruded through the nozzle. However, in this state, the plastic is prone to stick to the model, and when the print-head moves to another region of the model it can leave a trace in the form of a plastic string. Just the same as would happen with glue, honey, or any other viscous and sticky fluid.

 PICTURE 2, PICTURE 3

It's important to note that the degree of stringing is not the same for all the printing materials available. When it comes to the most common 3D printing filaments, PETG and TPE/TPU filaments are more affected by this issue than PLA or ABS. This is due to the chemical and physical nature of those materials themselves. PETG is more viscous and sticky than PLA. The extra viscosity and stickiness make the parts stronger in terms of impact resistance but have the disadvantage of producing a worse stringing effect.

 

When our 3D printers are printing a model, sometimes the print-head is extruding material while moving, but other times the print-head is traveling from one region of the model to another without extruding. In these situations is when the stringing happens. The extruder stops pushing, but the melted plastic in the tip of the nozzle is in contact with some edge of the part, and when the print-head moves, a trail of plastic is left even despite the extruder is not pushing filament at all.

 

There are several things that we can do to improve or get rid of the stringing problem. However, is important to understand that in some situations is not possible to completely avoid the stringing. For example, in worse scenario cases like using PETG in a Bowden-extrusion printer and printing a model with a lot of spiky features and lots of traveling.

 

PICTURE 4

I will group the actions we can do to improve stringing in two categories: 1- Slicer-level actions and 2- Printer-level actions. I will start talking about the things we can do within the slicer because sometimes a little, fast tunning makes the problem go away. However, if the problem persists I recommend following the printer-level actions. These are good not only to fix the stringing but general tips to get the most out of our printers.

Printing settings

Lower the temperature

If we were to give one single tip that would be to decrease printing temperature. In fact, too high a temperature is the most common cause behind printing quality problems. This is also true when it comes to stringing. When the temperature is too high the melted plastic is more likely to ooze or leak down.

 

If you are having stringing issues, the first tip is to use a temperature in the lower range recommended by the supplier. Our suggested temperatures to print to avoid stringing would are:

 

PLA - degrees.

PETG degrees.

ABS - degrees.

 

Tune retraction

Retraction plays an important role in FDM 3D printing. When printing, normally the print-head moves from one point to another while the extruder pushes down material through the nozzle. This way the print-head deposits a track of plastic that allows to "print" the parts.

 

However, there are situations when the print-head needs to move but we don't want filament to come out of the nozzle. For example, if we print several parts at the same time, the print-head needs to travel from part A to part B but we don't want to extrude plastic during this travel movement.

 

Unfortunatelly, just stopping the extruder is not enough to prevent some melted plastic to come out of the nozzle, because of gravity and momentum.

 

For that reason, FDM 3D printers use the retraction mechanic when we want to suddenly stop depositing material. When retracting, the extruder pulls up the filament releasing some pressure inside the hot-end and finally preventing the unintended deposition of material.

 

The retraction movement is defined by 2 parameters, the retraction speed, and the retraction distance or size. The optimal retraction distance and speed depends on several factors such as the material used, the printing temperature, the hot-end, and the extruder. Because of this, is difficult to give general settings that work well for every user. The best way to go is to perform a retraction iterative test to find the optimal settings in each case.

 

In any case, we can suggest the following retraction parameters.

 

ABS/PLA in Bowden printer: 4 mm & 40 mm/s

ABS/PLA in Direct extruder printer: mm & 30 mm/s

PETG in Bowden printer: mm & 30 mm/s

PETG in Direct extruder printer: mm & 30 mm/s

 

Note how we suggest a different setting depending on the type of extruder used. This is because the extruder setup makes a huge difference when it comes to retraction performance, being the direct extruders more accurate and less prone to produce stringing problems.

 

Increase travel speed

We explained how the string happens during print-head travelings without extrusion. Therefore, one way to reduce stringing is to increase travel movement speed so the time the filament has to leak is shorter.

 

Normally, travel speed is limited by the firmware, so we can only choose a speed lower than that. Too high travel speed could lead to step loss and compromise quality due to vibrations.

 

The maximum travel speed can be found using a retraction test.

 

In our profiles for Ender 3, we use a speed of mm/s

Model arrangement

Reduce the distance between parts

The stringing problem can happen between regions of the same model or between two models printed at the same time. If we are having stringing issues when printing several models at once, there is an easy fix to improve stringing performance. You may just arrange the parts closer in the slicer, reducing the space between them and the distance the print-head needs to travel.

 

 PICTURE 5

Print sequentially

Another great way to get rid of the stringing when printing several objects at the same time. Instead of printing all the parts at once, print them sequentially which is printing them one after another. You can do this by simply repeating the print job several times. This method is easy to buy time-consuming, because we need to detach the part and prepare the machine as many times as parts we want to print. However, modern slicers allow to prepare a printing job in such a way that the printer prints several parts sequentially. For your convenience, here you have some links that explain how to perform sequential 3D printing in different slicers.

 

Simplify3D: https://www.simplify3d.com/support/articles/multi-part-printing/

Cura: https://www.quora.com/Is-it-possible-to-do-sequential-printing-with-Cura

PrusaSlic3r: https://help.prusa3d.com/en/article/sequential-printing_

 

Try different slicer

This may sound like an unconventional tip, but if we have tried all the other options and still struggle with stringing it is worth a try a completely different approach and use another slicing software. Despite slicing software are supposed to produce similar printable gcodes, sometimes there are big differences in the computed printing paths and there are subtle differences in how

some mechanics are performed. So in case of desperation, we would suggest trying another slicing software before giving it away.

PICTURE 6

Check hot-end and extruder

3D printing is a precision process and is mandatory that all the parts of the printer are in perfect condition to achieve good results. Within the 3D printing process, the mechanics that can lead to stringing problems are particularly delicate. To perform a clean retraction the extruder and the hot-end need to be in optimal condition. Sometimes, a 3D printer can be apparently working well because we are getting acceptable results with some material in some printing jobs. However, when we change to other materials or try printing parts with different geometry and requirements problems such as stringing arise. Is not uncommon that a printer has a latent problem that only shows under certain circumstances.

 

For this reason, our recommendation is not to give for granted that our printer hardware is not causing the problem. Regarding the stringing, the printer elements that we may want to double-check are the following:

  • Hot-ends PTFE tubing - The PTFE tubing inside the hot-end deteriorates over time especially when printing at high temperatures. If we keep having stringing problems, we may want to check the state of our PTFE and replace it in case it's worn or burnt.

 

PICTURE 7

  • Nozzle - Nozzles wore overtime and the rest of the crystalized plastics built up inside. Nowadays nozzles are fairly cheap, so if can't find a solution to our stringing problems replacing or cleaning the nozzle is worth a try.PICTURE8

  • Cooling fan and layer fan - Most hot-ends include 2 fans, one to cool down the hot-end, the other one to cool down the extruded plastic. It is very important to ensure that both fans are working well. The things to check are: 1- No blades are broken, 2- No dirt is blocking the airflow, 3- The funnel is well oriented and aligned. A humming sound normally indicates a problem. Take into count that fans deteriorate over time and need to be replaced.

  • Drive gear- This is the gear attached to the extruder motor. It may be dirty and not transmit the motion accurately to the filament. Check also that is firmly attached to the motor's shaft.PICTURE9

  • Extruder clamp- The mechanism that applies pressure on the filament against the drive gear. These can disadjust and get loose over time. PICTURE10

  • Bowden fittings and tube- Ensure that the fitting grips firmly the Bowden tube. It's an Ender printer's known problem that worn or defective Bowden fittings can lead to clogs and other problems such a stringing.

 

Calibrate e-steps

Is not uncommon that consumer-grade 3D printers are sold with not-so-well calibrated extruder steps. This means that the extruder might not be pushing or pulling the amount of filament it should. As mentioned, 3D printing is a precision process and retractions are subtle mechanics within this process that will not work correctly if something is out of place. When the extruder steps (e-steps) are not well calibrated the amount of filament pushed or pulled is bigger or smaller than it should and can lead to stringing issues. Follow this guide to check if your extruder is well calibrated and calibrate it correctly in the case is not:

https://all3dp.com/2/extruder-calibrationeasy-steps-2/

 

Consider using a direct extruder

No matter how well tunned our slicing settings are or how well adjusted our 3D printer, when it comes to extrusion accuracy direct-extruders are always going to outshine Bowden ones. Nowadays most consumer-grade 3D printers like the Ender series use Bowden extruder. The Bowden has it's own advantages, removing weight from the X-axis, allowing faster speed, and being easier to assemble/disassemble. But despite these advantages, the extrusion and retraction of Bowden systems are less accurate making them more prone to produce stringy prints. Is perfectly possible to get non-stringy parts with a Bowden setup, but if we are close to the worst-case scenario, using a stringy material like PETG or TPU and printing parts with a geometry that needs a lot of travel movements may be the only way to completely avoid stringing is switching to a direct extruder.

PICTURE 8

Sours: https://www.reprappertech.com/blog/post/how-to-reduce-stringing/

The 3D Printer Bee

Martin

Besides many test devices, Martin now has his fourth own 3D printer running and prints as a hobby for friends, family and himself. He is happy to share his experience with each new article.

Latest posts by Martin (see all)

Disclosure: Links marked with * are Affiliate Links. I earn from qualifying purchases if you decide to make a purchase through these links – at no additional cost for you!


Oozing and stringing, the dripping of the printer nozzle and the pulling of fine hairs on the printed model, are two phenomena that often occur in 3D printing. However, with the right settings for retraction in the Cura slicer software, these problems can usually be eliminated in a few simple steps. 

Therefore, in the following, the correct retraction settings in the free slicing software Cura are introduced and explained, so that you can look forward to flawless print results completely without threads and bubbles.

This is how you set the retraction settings in Cura correctly:

  • Retraction Speed = 20 &#; 45 mm/s (5 mm/s steps)
  • Retraction Distance (Direct Extruder) = &#; 2 mm (1 mm steps)
  • Retraction Distance (Bowden Extruder) = 4 &#; 8 mm (1 mm steps)
  • Retraction Minimum Travel = mm (up in mm steps)
  • Cura Combing on &#;Within Infill&#; and during tests completely off.
  • Wiping Distance = mm (up in mm steps)
  • Coasting Volume = mm³ (up in mm³ steps)

The individual settings have quite large ranges. This is due to the fact that some of the settings depend heavily on the individual printer and filament. However, they are a good guideline from which you can experiment with the steps recommended behind them in brackets and find the perfect value for your setup.

For experimentation, there are numerous test objects that do not consume too much filament:

Contents

What is Retraction?

In 3D printing, retraction is the process of pulling the filament back a bit in the hotend. This is done to reduce the pressure in the nozzle of the printer and to prevent the filament from dripping out of the nozzle during so-called empty runs, which could then lead to oozing or stringing. “Empty runs” here refers to printing movements during which the printer is not feeding any filament.

The Most Important Settings for Retraction in Cura

The decisive parameters for retraction in 3D printing are the Retraction Speed and the Retraction Distance. In addition, however, other settings such as the temperature of the nozzle and the speed of the empty runs, the so-called travel moves, can also influence the quality of the print results.

Retraction Speed

The Retraction Speed determines how fast the filament is retracted in the printer and is usually between 20 &#; 45 mm/s. However, it varies depending on the printer. 

To set the perfect retraction speed for your printer, you have to experiment a bit. To do this, call up the retraction speed settings in the Cura menu under &#;Travel&#;. Now you start to print a simple, preferably single-walled model of your choice with the default speed in Cura and observe the result. 

In small steps, preferably with an interval of 5 mm/s, you now start to increase the speed slightly in each step. When the stringing disappears, you have found the ideal value for the retraction speed for your printer. With most 3D printers, the retraction speed is usually limited by the firmware to a relatively low speed and stopped in an emergency, otherwise the printer could be damaged. Therefore, you can&#;t really do much wrong when setting the retraction speed.

The setting &#;Retraction Speed&#; can be found in Cura under &#;Travel&#; or by using the search function:

Retraction Distance & Retraction Minimum Travel

The optimal Retraction Distance also differs depending on the model of your printer. For printers with a direct extruder, &#; 2 mm is typical, while 4 &#; 8 mm is typical for Bowden extruders. 

Here it is especially important that you find a suitable setting for your printer. Incorrect values can lead to major printing problems later on. This can be, for example, interruptions in the material flow and even a complete blockage of the nozzle. A good starting point are the values mentioned above and rough steps of 1 mm at the beginning.

The setting &#;Retraction Distance&#; can be found in Cura under &#;Travel&#; or by using the search function:

For the correct setting of the Retraction Distance, you should also enter a value for the &#;Retraction Minimum Travel&#; in Cura, i.e. the minimum distance at which the software should perform a retraction. Again, the value should be as high as possible to avoid printing errors. For small objects, however, it is sometimes necessary to reduce the minimum distance so that they are printed cleanly. A low setting of the minimum distance for retraction also increases the risk of grinding of the nozzle.

Therefore, you should set the Retraction Minimum Travel depending on the printed object and slowly feel your way forward. It is best to start in the Cura settings under Retraction Minimum Travel in the &#;Material&#; category again at mm and slowly feel your way to the correct value in mm steps.

The setting &#;Retraction Minimum Travel&#; can be found in Cura under &#;Travel&#; or by using the search function:

Other settings regarding retraction in Cura

In order to set the retraction correctly, there are further parameters in the Cura software which, with the correct values, can lead to optimization of the print results. These include, for example, the speed of the travel moves, i.e. the empty runs of the nozzle. 

A fast speed reduces the printing time, but there is also the risk that the filament gets too hot if you set the speed too high. The temperature of the nozzle also has a high influence on the print quality. 

However, the optimal temperature always depends on your printer and, of course, on the filament used. It is also important to calibrate your extruder correctly to get the best result.

Cura Combing

There is another function in the Cura software that allows you to edit the retraction settings. Cura Combing ensures that your 3D printer does not make unnecessary retractions in order to protect the filament. 

By default, Cura&#;s combining is set to &#;All&#;. However, this is not always necessarily useful. To avoid the formation of threads and bubbles during printing, it is recommended to change the Combing settings to the &#;Within Infill&#; mode. In this way, combining only prevents retraction inside the infill of the 3D object, but not in the outer skin, where the threads would become visible accordingly.

You can find the &#;Combing&#; setting in Cura under &#;Travel&#; or by using the search function:

The Cura Combing retraction setting can also help with marks and scratches on the surface of your printed model. The trailing of already melted filament from the nozzle on the top layer of the object can cause so-called scars. However, if you activate the Cura Combing mode, the print head moves along the contour of the model, but no longer crosses it. This means that scratches on the surface can no longer occur.

While you are determining the appropriate values for Retraction Distance and Retraction Speed, you should completely deactivate Combing, otherwise you may not be able to determine the correct values.

Wiping & Coasting

While wiping and coasting are not direct retraction settings, they can still increase retraction performance. 

During wiping, the nozzle of the printer is moved over a short distance through the outer layer of the object in order to &#;smear off&#; any remaining or superfluous filament. 

When coasting, on the other hand, the extruder is switched off on the last millimeters of a print area in order to minimize the pressure in the hotend and thus also reduce filament and bubble formation, since this prevents excess molten filament from dripping onto the object. You have to also approach the optimal values for wiping and coasting in small steps, as they can vary greatly depending on the printer.

It is best to start with a distance of mm for wiping and mm³ for the coasting volume and then slowly increase in steps of mm and mm³ until you get an optimal result. 

You should be especially careful with the settings for the coasting since too high a value can lead to holes in the print object. To avoid too long coasts, you can also simply set a &#;Minimum Volume Before Coasting&#; of about mm³ before experimenting with the settings. The settings for wiping can be found in the &#;Shell&#; category under &#;Outer Wall Wipe Distance&#; and the parameters for coasting can be set in the &#;Experimental&#; category under &#;Coasting Volume&#; and &#;Minimum Volume Before Coasting&#;:

Further Information

Slicer Cura is a free open-source software that enjoys great popularity in the 3D printer community due to its ease of use and diverse features. 

It was originally developed by the printer manufacturer Ultimaker, but can now also be used for 3D printers from other brands. Cura can easily be downloaded for free via the website. In addition to the retraction settings, Cura offers numerous other features and tools. With Cura, for example, prints can be integrated into the CAD software and prepared extensively, and with more than different settings, they can also be set up and adjusted according to one&#;s own wishes.

However, Cura is not the only software that offers numerous retraction settings. Other slicing software also offers various parameters to prevent the problems of thread formation and bubbles on the print object. One of these is the open-source software Slic3r, which is also free of charge. 

At first glance, this seems to be a bit more complicated than Cura, but it offers even more settings than Cura, which is especially suitable for beginners. In other slicer software like Simplify3D and also MatterControl the retraction settings can also be adjusted.

Related Questions

For which operating systems is Cura available? 

The Cura software is available for Windows and Mac OS as well as for Ubuntu. Only the current version of the operating system and MB of hard disk space are required for installation.

With which 3D printers can Cura be used? 

The slicer Cura can be used with almost all commercially available 3D printers. It works with STL, OBJ, 3MF and X3D file types.

Are the retraction settings always the same? 

No, the retraction settings always differ depending on the printer and also filament type and print object. What works perfectly with one printer and material can lead to a lot of stringing with another model and device. Therefore, the optimal values must be found out individually by means of testing.

Conclusion &#; What are the Retraction Settings in Cura useful for?

Once you figure out the perfect retraction settings for your 3D printer and the appropriate model and filament, you can also look forward to flawless print results without annoying strings and bubbles. 

The settings in Cura are actually relatively simple to find and easy to set up thanks to the clear user interface. You just have to be patient and approach the optimal result with small steps and different values. 

Thanks to the additional tools such as Cura Combing, as well as Coasting and Wiping, you have further tools at hand in the Cura software to achieve an ideal result. If you try out the various values for the individual parameters such as Retraction Speed or Retraction Distance on a small test object, you don&#;t have much to lose and you can&#;t really break anything, you can only win, because in the best case scenario you end up with a beautiful, error-free 3D object in your hands.


Disclosure: This website is the property of Martin Lütkemeyer and is operated by Martin Lütkemeyer. Martin Lütkemeyer is a member of the Amazon Services LLC and other Affiliate Programs. These are affiliate advertising programs designed to enable websites to earn advertising revenue through advertising and linking to Amazon.com and others. Links marked with * are affiliate links.

Sours: https://the3dprinterbee.com/cura-retraction-settings/

Printing stringing cura 3d

If we think about 3d printing, the first thing that comes to mind is a machine that melts plastic while an extruder moves along 3 orthogonal axes while forming a solid object. It seems very simple, but as start to dig deeper into this technology, we quickly find out that there are countless parameters that determine the way in which this happens.

Depending on the type of model, the retraction settings can make or break your prints. If you own an Ender 3 printer (or any Bowden-type machine) the following retraction settings will definitely prove to be useful:

Being a Bowden-type printer, the Ender 3 requires a longer retraction distance and it is recommended to enable “Combing Mode” and to set it to “Within Infill”. Additionally, set the Retraction Distance to 6mm, Retraction Speed to mm/s, Maximum Retraction Count to 5, and Minimum Extrusion Distance Window to 10mm.

What is retraction and why is it important in 3d printing?

As you may already know, the hotend receives the filament from the extruder, which pushes the material through a toothed wheel. This thrust generates an increase in pressure inside the nozzle. If the temperature is sufficient, and the extruder motor steps are correctly calibrated, the plastic will begin to flow in the exact amount that is required to create the desired model.

The issue with this mechanism is that there is still a remaining pressure inside the barrel after the extruder motor has stopped, which forces the filament to continue flowing through the only free outlet it has (i.e. the nozzle). When printing requires the hotend to move from one point to another without depositing material, it is necessary to relieve that remaining pressure, in order to avoid the plastic from “escaping” during this movement.

The way to achieve this is to reverse the rotation of the extruder stepper motor, such that a few millimeters of filament come out of the hotend and compensate for said pressure. This reversal of rotation is called “retraction” and is a fundamental parameter to achieve printed objects with a good surface finish.

The over-extruded material from the nozzle will become thinner as the hotend moves, leaving a “thread” or “string” between two walls of the part. This is known as “stringing” and can be avoided (or at least minimized) through some printing parameters. You may not previously have heard about this term, but I’m almost sure that you have seen it before. Take a look at the following image of a chair that features a good amount of stringing.

Parameters related to retraction

First, we must make sure that the “enable retraction” box is activated, to access the retraction parameters. From now on, we will focus on Cura settings. You will find equivalent parameters on many slicers.

I should clarify that I’ll use the naming convention from Cura, but the same principles most definitely apply to all slicers.

Retraction Distance

Retraction distance tells the printer how many millimeters of filament to retract when required. Retracting only a very small distance won’t probably solve stringing, whereas exaggerating this value will cause no plastic to be available in the nozzle during the initial moments of the next extrusion.

In order to avoid this, there is the so-called “priming” setting, which returns the filament to the same position it was in before retraction. That is, if 5 mm of filament were retracted, after moving between two points without extruding, 5mm of filament will be pushed back into the nozzle.

Oftentimes, the model at hand requires too many sequential retractions during a very short period of time. If the retraction distance is too high, the gear teeth pushing the filament will start grinding it. If the filament becomes too thin, the gears will not push it but rather slide against it. As a result, no more filament will be extruded, and the print will obviously be completely ruined.

To avoid this, we are going to establish the minimum possible retraction distance that allows us to mitigate the stringing. The mm range usually works for most Bowden-type 3d printers. You can start with a retraction distance of 3mm and increase it by 1 mm if you consider it necessary.

While Ender3 printers have been on the market for several years now and are known for their reliability, many users choose to modify their settings in order to achieve better printing results. One of the most common modifications is to transform it into a direct extrusion system. While we do not recommend modifying a tested design (unless you are extremely confident of your engineering skills), you can give it a try and draw your own conclusions.

One of the advantages of a direct drive system is a more precise control of retractions. For those types of printers, start with a distance of mm and increase it in increments of that same value until you get an optimal result.

Maximum Retraction Count

This parameter allows us to define the maximum number of retractions that can be made along the same segment of filament. This way, the filament grinding mentioned above can be avoided. Start by setting this value in the range of 5 to The default for Cura is , but it is way too high.

Minimum Extrusion Distance Window

Here you can define the length of the filament segment to which the retractions specified in “Maximum Retraction Count” will be applied. Since the retractions will be between 3 and 6mm, an appropriate value is 10mm. This way, you’ll be sure that the filament will not be damaged by excessive retractions.

Retraction Speed

This specifies how fast the extruder will rotate in reverse. It has to be fast enough to prevent the filament from leaking through the nozzle, but not excessively so since an excessive speed will also require power that the extruder motor will not be able to deliver, causing it to lose steps. A good value to start with is 20mm/s. You can afterwards always can raise this value through a stringing test (links below).

Retraction Prime Speed

This value lets you set the speed by which the material is fed back into the nozzle. This parameter lets you control the way in which the hotend is ready to continue extruding as if nothing had happened.

The retraction speed is divided into two different parameters because of a good reason. When removing the filament, the pressure is higher at the beginning of the retraction than at the end, which relieves the stress on the extruder gear. On the other hand, during priming, the pressure (and therefore the strength in the gear) increases more and more.

For this reason, priming can damage the filament more than retraction. We recommend you to use a speed 5 mm/s lower in this parameter than that the one you set in “Retraction Speed“.

Extra Prime Amount

With this parameter, you can compensate for the amount of material that was lost due to oozing. If you set the retraction distance and speed correctly, you will not need to compensate for anything, so we recommend that you leave this parameter at 0 and perform the calibration tests instead. (links below)

Recommended retraction settings for an Ender 3 (Pro / v2) printer

Due to the fact that Ender 3 printers are definitely one of the most popular printers (if not the most), I’ll get into the specific settings that I recommend and also use on my own machine. Although all printers are somewhat unique, these settings will serve as an excellent starting point.

  • Combing Mode: ON and set to “Within Infill
  • Retraction Distance: 6mm
  • Retraction Speed: 20mm/s
  • Maximum Retraction Count: 5
  • Minimum Extrusion Distance Window: 10mm

These settings will prove to be useful for all Bowden-type printers. You can obviously tweak these values and improve them for you specific needs. Printing tests that were designed to specifically reduce stringing will help to accelerate the fine-tuning. I list them all at the end of this article.

You may also be surprised by the fact that printing miniatures require a specific retraction configuration in order to yield the best results. Obviously, I’ll also list them right now!

Recommended retraction settings for printing miniatures with an Ender 3 (Prov / v2) printer

  • Combing Mode: ON and set to “Within Infill
  • Retraction Distance: 6mm
  • Retraction Speed: 45mm/s
  • Maximum Retraction Count: 10
  • Minimum Extrusion Distance Window: 10mm

It is interesting to know that the Z-hop, a parameter that raises the Z-axis a short distance before moving without extruding and lowers it again when it reaches the next printing point, considerably increases stringing (regardless of the calibration you previously performed). I strongly recommend that you disable it, especially if you have achieved an optimal parameter setting.

Personally, this video by Makers Muse was invaluable back when I first encountered this issue.

Why is “Enable Combing Mode” recommended?

The problem with stringing is that it leads to the outer surface of your object being unpleasant to look at. If the stringing only occurred inside of the object, we would not be able to be displeased by it. Therefore, retraction only makes sense when the nozzle travels from one point to another thorugh an area that has no print layers underneath. By enabling combing mode, you can order the slicer to only move the hotend within printed areas (whenever it is possible).

There are 4 different options available to choose from, but my favorite is “within infill”. Although it increases printing time, it reduces the number of retractions to the very unavoidable minimum.

Retraction and stringing calibration tests

Temperature Tower

Although we haven’t mentioned it yet, one printing parameter that seriously affects stringing is the hotend temperature. The hotter it is, the easier the filament will flow, which will greatly increase the oozing from the nozzle. Because of this, the first thing you have to do is calibrate the temperature of your printer, until you achieve the best results. To do this, I recommend you print the following test, which consists of a temperature tower that increases by 5 ºC in a well-defined layer interval.

If you click on “Thing files” you will see a G-code file that is already compatible with the Ender3. Do not use your slicer program to generate a G-code as you usually do, as it will not vary the temperature throughout the printing. Using different processes in Cura is an option, but the appended file works perfectly.

Basic Stringing Test

Once the temperature is calibrated, disable retractions in your slicer and print the following file. Take a look at the picture and guess what it tries to asses.

The result will be a piece full of hairs between both cylinders. Re-enable retractions and compare the result with the newly printed part. From there on, increase or decrease the Retraction Speed and Retraction Distance values ​​until both cylinders are correctly printed and there are no hairs between them.

Retraction Calibration Tool

If you are not already amazed about how awesome the 3d printer community is, check out this free online tool that someone created. It allows us to create a G-Code for testing purposes that are compatible with our specific printer. The instructions are very detailed and helpful, but be sure to read them.

Frequently asked questions (FAQ)

Is retraction the same for Bowden and Direct extrusion systems?

Although enabling retraction is useful regardless of the type of printer, Bowden type machines usually require a higher retraction distance compared to direct driver printers.

The reason is the following: 3d printers that use the Bowden system (like the Ender3) place the extruder away from the hotend, and the filament is channeled through a PTFE tube. As the tube has an internal diameter of 2mm and the filament has a diameter of mm, the looseness between them requires that this difference must be compensated by increasing the retraction distance.

Direct extrusion systems lack this problem, and filament shrinkage tends to not be such a big deal.

Essentially, Bowden systems require a much longer retraction distance.

Is retraction the same for all filament types?

Luckily, PLA is a very stable polymer, so it is possible to adjust our printer to achieve almost no stringing. The same happens with ABS, although it presents other problems such as warping and cracking. Other materials, such as PETG, require a much higher temperature to melt, which favors the formation of strings as it cools down.

Flexible materials, such as TPU, compress during extrusion and stretch during retraction, so it is not very convenient to activate the retraction to print it. In this case, stringing is inevitable.

In addition to retraction settings, humidity in the filament can also increase the probability of stringing, which is why I always recommend storing our spools in an airtight container, with plenty of silica gel bags.

Conclusion

By now, you have a better understanding of all the retraction settings that are available and how they should be configured differently depending on our printer type (Bowden or Direct Drive). Bowden-type printers, like the Ender 3 (Pro and v2), require longer retraction distances. In summary, you should enable “Combing Mode” and set it to “Within Infill“. The Retraction Distance should be 6mm, the Retraction Speed 20mm/s, the Maximum Retraction Count 5, and the Minimum Extrusion Distance Window 10mm.

Sours: https://3dsolved.com/the-perfect-enderpro-and-v2-retraction-settings/
3d Printing without Stringing and Understanding 3d Print Failures

No one likes to have to clean up a bunch of stringy mess on a 3D model that they just finished printing! But what is the cause of that stringy mess and what can you do to eliminate, or at least greatly reduce the amount of stringing on your models? Here we delve into RETRACTION and how it is one of the most important factors in determining the quality of your 3D print jobs.

By enabling & tweaking your RETRACTION settings in your slicing software you can instruct your 3D printer to momentarily pull back some of the un-melted filament from the melt zone while the printer nozzle is traveling over a non-print area. This will help reduce the pressure in the nozzle on the molten plastic &#; which leads to the oozing and leaking that directly causes stringing.

We will also cover other settings such as temperature of the melted filament and the travel speed of the printer nozzle and how those factors can also contribute to stringing. Finally, we will explain various terms associated with retraction and some additional setting parameters for you to try to eliminate any stringing you my be experiencing when printing your 3D models.

Oh, and yes, of course we had to learn a LOT of this the HARD way&#;..


What Causes &#;Stringing&#; When Printing a 3D Model?

Definition of Stringing with Regards to 3D Printing:

Simply said, stringing is thin wispy threads of melted plastic filament that continues to move out of the hot end of your 3D printer while the printer head is moving during non-print times from one print location to another. Even though the extruder is no longer pushing un-melted filament into the melt zone during these non-printing movements &#; the built up pressure in the nozzle remains high enough to cause some of the already melted filament to leak out of the printer head. It is in essence OVERFLOW seeping out where no melted filament was intended to be deposited between print areas or off to the sides of print areas of the model.

What arethe causesof stringing when 3D printing? &#; There are three (3) main causes of stringing:

  1. Too much pressure in the nozzle during non-printing time as the nozzle travels over a non-print area,
  2. Printing at higher temperatures &#; the higher the temperature the more liquid the filament will be, and therefore more likely it will leak out of the nozzle when traveling over non-print areas, and
  3. The speed that the print head moves from one print area, over a non-print area to the next print area. The faster the print head moves from a print area over to a non-print area, the more likely it is to result in stringing.


Retraction Defined (For 3D Printing)

Retraction: Retraction refers to the distance the un-melted filament is retracted -or pulled back &#; towards the extruder motor (feeder) to reduce the pressure on the melted filament inside the nozzle. If the pressure is reduced on the melted filament in the nozzle &#; it is less likely that there will be leaking or oozing of melted filament from the print head as it is traveling from one print area to another. Leaking and oozing over these travel areas that are NOT print areas are what lead to stinging and nodules. Increasing the retraction levels can be one of the most effective means of reducing stringing associated with 3D printing.

Note – that it is the still solid and un-melted filament that is retracted from the melt zone in the printing head to reduce the pressure in the nozzle so that no additional melted filament is extruded through the print nozzle during non-printing moves. No melted filament is actually pulled, or sucked, back into the hot end (nozzle) of the printing head!


Primary Steps to Reduce Stringing

Adjust your RETRACTION settings! That is what we are focusing on in the this post.

  1. Make sure RETRACTION is enabled. In CURA you can find this under the &#;Travel&#; tab in the settings. (If you are unable to see it there you will need to go into the &#;Settings&#; menu in the upper left hand corner, select &#;Configure Setting Visibility&#; and then &#;Settings&#;. There you will be able to check mark the settings that you want to be visible in your settings menu.)
  2. Increase the Retraction Distance. &#; This is the distance, in mm, that the un-melted filament is pulled back away from the melt zone (and through the Bowden tube) towards the extruder motor. I would suggest that you try something like 5 mm for retraction distance first &#; and then go from there in increments of +/- 1 mm, generally staying within the range of 3 to 10 mm.
  3. Increasethe Retraction Speed &#; Increase the speed at which the un-melted filament in the Bowden tube is pulled away from the melt zone and back towards the extruder motor. I would recommend that you try 30 mm/s first &#; and then go from there in increments of +/- 5 mm/s.
  4. Limit Support Retractions. As indicated above &#; too much of a good thing can be bad. So with regards to retraction &#; consider only using retraction when printing parts of the actual model as opposed to the supports that you may need to print the model. After all, it doesn&#;t really matter if there is a little stringing around the supports!
  5. Maximum Retraction Count. By default &#; this is set to in Cura &#; which is probably way too high! This is the amount of times retraction can occur over any specific area of filament. If it is too high &#; the un-melted filament may be damaged &#; which may lead to areas of the print suffering from under- extrusion problems. Better to set this to something in the 10 &#; 35 range.
  6. Enable Coasting (Coast at End). You can find this under the &#;Experimental&#; settings tab in CURA Even with retraction enabled &#; it still takes a small amount of time for the oozing of melted plastic at the hot end of the printer to stop. So that is why there is a setting for coasting. Coasting instructs the 3D printer to actually stop extruding melted filament just a fraction of a second before the end of the area to be printed. It relieves some of the pressure at the nozzle just before it travels over a non-print area and reduces the need to use retraction. That way any material that oozes out of the nozzle will be deposited in the print area rather than the travel area &#; thereby reducing stringing.

Other Settings to Adjust to Reduce Stringing for 3D Printing

So now that we understand what retraction is, how it relates to preventing stringing on our 3D models, and the primary settings we should adjust &#; what are some other settings we might need to become familiar with to further reduce stringing and improve the quality of our 3d printed models?

  1. Tinker with your print speed. You can try both increasing print speed and reducing it.
    1. If you are using a lower temperature to print at you may find that at higher print speeds (say mm/s) you are experiencing under-extrusion. (Where areas of the print have too little melted plastic deposited) If that is the case &#; try lowering the print speed, maybe even as low as 20mm/s.
    2. On the flip side, If you need to leave the temperature on the higher end, increasing the print speed may actually reduce stringing &#; as there is less time available for oozing and leaking from the nozzle during travel times.
  2. See if you can lower the temperature of the nozzle for printing. Just lowering the temperature about 10 &#; 20 degrees (C) may be enough to prevent stringing. As I indicated earlier &#; the higher the temperature, the more liquid the filament will be, and therefore more likely it will leak out of the nozzle when traveling over non-print areas. When printing with PLA (like we usually do) we sometimes reduce the printing temperature to °C from °C which we usually use if we are having trouble with stringing.
  3. Enable Wiping (Outer Wall Wipe Distance / Wipe at End). Wiping moves the extruder back over the print area just completed to deposit any oozing before moving on to the next print area.
  4. Enable Combing (Avoid Crossing Outlines). Combing is a combination of wiping, coasting, and redirecting the travel path of the print head &#; so it is staying within the perimeter of the print for longer or eliminating it from crossing some open space to reach it&#;s next print location. This minimizes travel over open areas, thereby minimizes opportunities for stringing. Although it does result in more travel distance of the extruder head &#; it reduces the need for material retraction and can reduce the number of print defects on the outer surfaces of your 3d print model. This setting can be found under the &#;Travel&#; settings in CURA.

6. Please Note, it is possible to have too much of a good thing! Too much retraction (both speed & distance) can result in pock marks due to under-extrusion in those areas which is too little melted filament being deposited in the print area. It can also result in the un-melted filament getting a little chewed up from the additional travel through the extruder gears &#; which could eventually cause it to slip and manifest itself with under-extrusion in areas of your print. If you are starting to see dust around the extruder assembly &#; that might be a good indication that your retraction settings are causing some grinding of the un-melted filament.

7. Z-Hop: With Z-Hop enabled the print head moves up relative to the print model when retraction is performed &#; allowing the nozzle to travel over the printed parts of the 3D model without touching them.

8. Minimum Extrusion Distance Window. This determines the length of filament that the Maximum Retraction Count is implemented on. Any retraction commands in excess of the Maximum Retraction Count will be ignored for the given Minimum Extrusion Distance Window. So if the Maximum Retraction Count is set to 10 over a 5mm segment, any Retraction commands in excess of 10 will be ignored over any given 5mm segment.

9. Retraction Minimum Travel. This helps eliminate all retraction for very small areas of travel. If travel is not equal or greater than the length set here, then retraction will be prevented from occurring at all. Leave at the default of mm.

Nozzle Switch Retraction Distance, Nozzle Switch Retraction Speed, Nozzle Switch Retract Speed, Nozzle Switch Prime Speed and Nozzle SwitchExtra Prime Amount are all only relevant for 3D Printers with more than one printing nozzle. Since this does not apply to single nozzle printers &#; just leave it at the default settings. My understanding is that CURA does not like you reducing any of these settings to 0.

Definition: Priming. After the printer performs a retraction &#; the push back into the Bowden tube towards the melt zone is what is called &#;priming&#;.


Summary of Recommended Settings & Action Plan to Reduce/Eliminate Stringing for Your 3D Printed Model

Here are the settings I have been having success with lately. Remember &#; it is BEST to make as few changes to the settings to achieve the desired result of a clean print with minimal or no stringing!

First Line of Defense Against Stringing

  1. Enable Retraction in your slicing software
  2. Set you Retraction Distance to 5 mm first &#; and then go from there in increments of +/- 1 mm, generally staying within the range of 3 to 7 mm.
  3. Set Your Retraction Speed to 30 mm/s first &#; and then go from there in increments of +/- 5 mm/s staying with the range of 10 to 70 mm/s.
  4. Enable Limit Support Retractions.
  5. Change Maximum Retraction Count to something between 10
  6. Enable Coasting.
  7. Leave all other retraction settings at default values.

Second Line of Defense Against Stringing

  1. Consider reducing the speed of the print. Start @ 50 mm/s.
  2. Consider lowering the temperature of your print. For PLA although °C might be where you try first &#; don&#;t be afraid to consider using something as low as °C.

Third Line of Defense Against Stringing

  1. Enable CombingWithin Infill
  2. Enable Z-Hop

Basic Retraction Test Model

Here is a link on Thingiverse to the model I used to calibrate our 3D Printer. Thank you Southwester Applied Physics. Basic Retraction Test


Conclusion

Your retraction settings will most likely be one of the biggest factors determining the quality of your 3D printing jobs. Here we explained and reviewed many of the settings that you will need to be familiar with to properly adjust your retraction settings and eliminate stringing when printing your 3D models.

Although you may find the setting parameters that I provide here to be helpful as a baseline for your settings &#; you will likely have to refine them further for your specific printer and situation. Dealing with stringing, retraction settings, and 3D printing in general, can be frustrating at times! Just remember you will have a LOT less frustration if you are methodical in your approach and document the variables you change when trouble shooting. As an added benefit, it will also be much easier to replicate your successes in the future!

Keep things simple and don&#;t fix something that is not broken. The goal is to get the best print possible with the minimum amount of adjustments &#; including retraction.

Sincerely,


More Resources & References:


Our Setup @ the Time of Publishing This Post:

  1. 3D Printer: Creality Ender 3 Pro
  2. Slicing Software: Ultimaker Cura
  3. Filament Type: PLA

Search Terms

  • Retraction settings
  • Creality Ender 3 7 Ender 3 Pro
  • Ultimaker CURA Retraction Settings
  • Eliminating stringing in 3D printing

Share this:

Like this:

LikeLoading

Default image
Chip

My name is Chip and I am the trophy husband to my wife Melani and blessed father to 4 wonderful children! I definitely score very high on the geek / nerd spectrum assessment test and have a wide variety of interests. Deep down I think I aspire to be a true renaissance man!

Articles: 30
Sours: https://hobby3dprinting.com/retraction-in-action-eliminate-stringing-improve-the-quality-of-your-3d-printed-models/

Now discussing:

I have found that stringing and oozing rarely result in failed prints, but require additional work to get a print ready for use or display.

Set retraction distance to 3mm, retract speed to 55 mm/sec, and reduce printing temperature to fix stringing. Also consider increasing print travel speed (not print speed) and keep your print nozzle clean. If these don&#;t work, keep filament dry and reduce travel distance.

These tips should give you an idea of where to start so lets go into each one and discuss how to tune it more precisely for your printer.

What Are Stringing and Oozing?

When the nozzle moves between parts of a print, over an open area, some of the warm liquid filament in the nozzle may stick to one side of the print. As the nozzle moves across the opening, this liquid filament stretches across the opening like a spiderweb.

This is known as stringing.

Oozing can lead to stringing but is a separate issue. Oozing is caused when your temperature is too high and the filament has become too liquid and runny.

If your temperature is too high, rather than layers being laid down neatly on top of each other, the warm soft and possibly liquidy filament may run down the print before it cools and hardens.

As long as you don&#;t exceed the maximum recommended temperature for your filament, the most common problem oozing will cause is stringing.

Oozing causes stringing by creating warm liquid filament that flows easily out of the nozzle.

Enable and Configure Retraction

Because filament is being fed into the nozzle to enable printing, there is regular pressure on the liquid filament. Ideally, when the printer is done printing and needs to move the nozzle to another part of the print, the downward pressure would end.

This is not the case as gravity is still constantly pulling down on the liquid filament.

The solution is retraction.

Retraction pulls the filament up out of the nozzle to release the downward pressure and counteract the force of gravity.

There are 2 setting you need to set, retraction distance and retraction speed.

Retraction distance measures how much filament is pulled back by the extruder. A 3mm retraction distance will pull 3mm of filament back.

If you do not retract far enough you will still have stringing issues. Retract too far and the liquid filament will be pulled too far and potentially cause a jam. Too high of a retraction can also leave not enough filament in the nozzle when it come time to resume printing and result in holes in the print.

The general recommendation is to set retraction distance between 1 and 5 mm. Start with 3 mm and see how that works for you.

Retraction speed measures how fast the filament is retracted. A retraction speed that is too slow and you will still see stringing as the filament is not retracted enough in time to prevent it. On the other hand, if the retraction speed is too high, the solid filament may disconnect from the liquid and fail to pull it far enough.

The recommendation is to set speed between 20 and mm/sec. Start with 55 mm/sec and see how that works.

Print this simple stringing test print from Thingiverse.

If you keep having stringing and cannot eliminate it using retraction, the next thing to check is the temperature.

Reduce Print Temperature

As the filament heats up in the hot end, it becomes liquid. The hotter the liquid filament, the more liquidy and free-flowing.

When you print at the higher end of the recommended temperature range, the filament will tend to flow easier. The can be good for avoiding a jam at the print nozzle as the filament will more easily flow through.

However, the more easily the liquid filament flows through the nozzle, the more likely it is to flow out and string.

For PLA your print temperature range is °C to °C.

Since there is a trade off between print quality and stinging, you will want to make sure you have retraction as discussed above tuned in as best as you can.

Too high of a temperature can also counteract retraction settings. As noted above, if your retraction speed is too high, the liguid filament will separated from the solid during retraction.

As the temperature of the filament increases, the retraction speed that separates the liquid from the solid filament decreases. That means it is important to configure both setting to prevent stringing.

When calibrating your temperature, you can print this test print, a temperature tower specifically designed for testing stringing from Thingiverse.

Use the temperature that gives an acceptable print quality while minimizing stringing.

Increase Print Travel Speed

Configuring retraction and temperature setting should eliminate stringing in most cases. Don&#;t worry about travel speed until this setting have been tuned in.

It takes time for liquid filament to ooze out of the nozzle and cause stringing.

By increasing the print travel speed, the speed at which the print head travels while it is not printing, you give less time for the liquid print to ooze out.

If the travel speed is too fast, you may see print artifacts such as ringing or ghosting or misaligned layers.

There are no test prints designed for different travel speeds. Use this simple stringing test print from Thingiverse. Increase your travel speed in 5 mm/sec increments.

Keep an eye on each of the cones and watch for ringing or misaligned layers. When you start to see the cones printing with weird artifacts, you know you have reached too fast a speed.

Clean Your Print Nozzle

Example of an extruder.

Any filament stuck to the end of the print nozzle can lead to stringing. As the nozzle heats up, that filament will also begin to melt. When the nozzle moves across and opening, this residual filament sticks to the print and is stretched across.

Cleaning the nozzle doesn&#;t have to be a chore.

Check the nozzle for any filament that may have gotten stuck on it. This is most common when there is an oozing problem and some of the oozing filament got stuck on.

If the filament pieces are large, you might be able to pull them off of a cold nozzle with some pliers.

Any pieces that you cannot get off with some cold pliers will need to be removed with a bronze brush.

I would recommend avoiding using a brush harder than bronze. You do not want to damage you nozzle.

A bronze brush can be found at a gun store or in the sporting area of the super market as they are often used for cleaning guns. I recommend this one from Amazon. It is only a few buck and works great.

To clean the nozzle, you will need to set the nozzle temperature based on the filament you are trying to clean. Set it to the lowest temperature for that filament, °C for PLA.

Once the nozzle is warm, gently brush the filament off of the nozzle. If the temperature is too high, the filament may actually start stringing between the nozzle and the brush.

When you have removed all the stuck on filament, print out a test print.

Minimize Print Travels

So, you have configured your retraction and temperature setting to their optimal levels. But no matter what you do, there is always a little bit of stringing.

Since stringing only happens when the nozzle moves over an empty space, if we can get reduce the amount of times the nozzle has to travel outside the print, we can reduce stringing.

This is also a great way to avoid stringing when you cannot use retraction.

Retraction does not work well with flexible filaments like TPU. For flexible filaments your only option is to reduce travel outside of the print.

In Cura the setting to use is called Combing. If you use Simplify3D, the setting Avoid crossing outline for travel movement works the same way as combing in Cura.

Combing in Cura or Avoid crossing outline for travel movement in Simplify3D tells the nozzle to avoid going over gaps as much as possible. If the nozzle needs to move to another part of the print, the slicer will set a path for the nozzle that goes over already printed parts.

One issue with combing is that it will increase print time. How much will depend on the print itself.

Since the print head is combing over already printed parts, there is the potential that the nozzle may hit or stick to the print and pull it off the build plate. The nozzle can also pick up filament as it passes over potentially causing more stringing when passing over gaps is unavoidable.

Keep Filaments Moisture-Free

Filament, especially PLA, like to absorb moisture. If your filament has absorbed too much moisture, whether from the air or getting liquid on it, this moisture will turn to steam in the hotend.

Water expands much more than filament when heated, especially once it turns to steam. This steam will push filament out the nozzle and cause oozing. As mentioned earlier, oozing leads to stringing.

It is pretty simple to fix moisture. If you live in an area with high humidity, keep you filament in an air tight container with moisture absorbing packets. Most new filament comes packed this way.

I have used these large vacuum sealed containers from Amazon to hold multiple rolls of filament. I added these moisture absorbing dry packs to absorb any leftover moisture in the air. The dry packs can easily be renewed by heating them up in the oven.

While this worked great for me, the only problem I had was when I needed a new roll I had to open the package back up and reseal and repump to maintain the vacuum.

I switched over to using the Nanovac Vacuum Pump & Airlock Bag Bundle (non-affiliate) from Polyalchemy. The advantage of these bags is that they fit individual rolls.

How To Dry Filament Rolls

So you have oozing and can hear hissing and popping from water that the filament has absorbed turning to steam in the hot end. How do you fix this?

There is a filament dryer called the PrintDry Filament Dryer that can be used to dry out your filament. Using the Filament Dryer is pretty straight forward, put your roll of filament in, set the temperature based on the type of filament, and turn it on. After a preset determined time, pull out your dried out roll.

Another option is using your oven. Place your rolls in a preheated oven for roughly hours at a fairly low temperature. The temperature depends on the filament type. You want to avoid heating the filament to a too high temperature. If the temperature is too high, the filament will start to melt and adhere to itself on the roll, completely ruining the roll.

Here is a guide for different filament types:

Filament TypeTemperature in °CTemperature in °FTime
PLA50 °C °F3 Hours
ABS, PETG, CPE,65 °C °F3 Hours
Nylon70 °C °F12 Hours
PVA45 °C °F10 Hours
TPU, TPE55 °C °F4 Hours
ASA, HIPS60 °C °F4 Hours
PP55 °C °F6 Hours
PC, PEEK70 °C °F6 Hours

The last option to consider is a food dehydrator. These operate consistently at lower temperatures than ovens generally are able to. Set the temperature as in the above table and you should be good.

After you have dried the filament roll out, be sure to place it in a sealed container.

Sours: https://www.3dprintingrealms.com/fix-3d-print-stringing-oozing-witheasy-ways/


1314 1315 1316 1317 1318