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Gaps in temp tower

hazmatt99
(@hazmatt99)
Trusted Member

Hey guys!

So I printed a temp tower for this black filament, spool said it recommends between 190 and 210 C so I ranged it from 189-210 in 3-degree increments. The problem I ran into is that literally every layer was the same quality and they were all less than ideal. Just looking for some more expert eyes on this. I got a lot of gaps in the print (red arrow) and the oozing/blobs/stringing was also not great (yellow arrow)

Unfortunately, I can't provide a complete list of my slicer settings because my computer is borked but the basic settings were 0.2mm layer height, 60mm/s print speed, 50C bed temp, Retraction I think was set to 4mm (can't remember if I changed it to 6-7mm yet), Z-hop not enabled.

0.4mm nozzle with 0.4mm print width.

TBH compared to the other filament I've used this one hasn't been great, I haven't done too much in the way of extensive testing and calibration but this filament has been very leaky so far and really doesn't like low temps. I think it's possible that the filament is just temperamental, but also possible that there are some general changes I could make to get better quality. Lemme know what you think I should try!

20210421 104313
Quote
Topic starter Posted : 21/04/2021 4:09 pm
Pablo
(@placherre)
Member Moderator

Hi Hazmatt99!

Good to talk with you once more. How was your experience regarding the previous post you made?

So, let's see what is going on with your tower. First of all, are you printing with the same machine (TRONXY)? This new filament you are testing is from the same supplier of your other spools? Also, did you have the fan at 100%? This will affect your print with PLA if it is off or at a low speed. Would you reply to me also with the brand of your spool? If you can show the temperature label, that will be great.

When I look at the picture, although I can see a uniform print across all the tower, it is not the ideal quality that I always look for. Therefore, I could suggest the problem is a constant set up. Therefore, I would adjust the speed, retraction speed and flow rate. Let's go step by step with all these.

First of all, I recommend you to reduce the printing speed. Even PLA is a very forgiving material, you should be aware of the basic set up for every material. Once you feel confident and find the correct performance, you should be able to adjust parameters that will lead to speed up a print, for instance. A recommended value of speed for PLA is around 50 mm/sec, which is a little below the 60 mm/sec to adjust for this material. By decreasing the speed, you give time to the deposited filament to cool down properly. When you reduce the printing speed, the fan spends more time in the area helping with the deposited filament to cool down. When using PLA, always remember to keep the fan at 100% speed (except for the first two layers).

Retraction also plays a key role. Before making some changes, remember to set the retraction distance to 6 mm (up to 7 mm). If you already made it, adjust the retraction speed to 25-30 mm/sec. By adjusting the retractions you would be able to eliminate blows or excess of material when changing position or layer high.

Flow rate is also very important when adjusting the set up. As I can see in the picture, there is an excess of material among all the layers of the model. Once you have your computer back, would you check what value you have set up? In Cura you adjust that setting in Material > Flow, and in Simplify3D in Extrusion Multiplier.I will show you those settings in the following pictures.

- Cura Extrusion Multiplier Configuration:

Extrusion Multiplier Cura

- Simplify3D Extrusion Multiplier Configuration:

Extrusion Multiplier S3D

Before going into the next explanation, make yourself a cup of tea or go to the bathroom, because it will require some concentration… 🙂

Before changing the flow rate on the slicer, you could make a quick check of your E-step calibration (the amount of filament being extruded). In this case, I will give a step-by-step guide:

  1. Heat up the nozzle. In your case, heat it up to 210°C, just to make sure the filament will flow correctly. Note: dark filaments require a few degrees more (5°C) compared to the temperature of light colors.
  2. Make two marks on the filament from the extruder’s beginning: the first one at 100 mm and a second one at 120 mm (in case there is over extrusion, will explain this later). Take a look at the picture below for reference (if you have a Vernier caliper, will suit you better, but a ruler works fine).
TRONXY Filament Measure
  1. Next, go to the screen and select Settings > Motion > Move Axis > Extruder > 10 mm step > click on “+” until you select 100 mm > Wait until the extrusion is finished.
  2. Next, measure the distance left between the extruder beginning and the mark you made. Remember if it is the 100 mm or 120 mm mark. Therefore, if the machine is over extruding, the 100 mm mark will be gone (that is why you made a mark at 120 mm); but, if you still can see the 100 mm mark, it means it is under extruding. Write down this distance.
  3. Now, find out how many steps are set up in the machine. Go to the touch screen > Configuration > Advanced Settings > Steps/mm. Write this number down.
  4. Next, let’s do some math to determine which are the real steps/mm. I will do it with an example:
    1. If you measure 5 mm left to the 100 mm mark, then the calculation is:

[Expected Amount of Filament (100 mm) x Current E-Steps (extracted from Configuration)] / Actual Extrusion Amount (95 mm)

  1. If you measure 6 mm left to the 120 mm mark, then the calculation is:

[Expected Amount of Filament (120 mm) x Current E-Steps (extracted from Configuration)] / Actual Extrusion Amount (114 mm)

  1. Once you have the real value of E-Steps, you should change it in the machine. In order to do this, go to the screen: Configuration > Advanced Settings > Steps/mm (+ to increase to the calculated value or - to reduce to the calculated value) > Ok (check icon) > Go back on the menu > Store Settings. Then, you can go back to the E-Steps value to check if the new value has been saved.

Once you set up the new value, the flow rate in your slicer should be 100%. Because you just calibrated the correct amount of filament being extruded.

 

Well, I hope you made it all the way here… 🙂 It seems complicated, but is easier than it looks. You are always more than welcome to reply to me with more questions if you have any doubts.

Before going any further, make sure you have covered the points I have mentioned before, in order to narrow down the causes of the print quality you showed

I look forward to seeing your results…

Kind regards,

Pablo

ReplyQuote
Posted : 21/04/2021 11:12 pm
hazmatt99
(@hazmatt99)
Trusted Member

Alright! Hello, yeah I got some really good info from the last post. Thanks for helping me get caught up to speed.

Part one, yes same printer TRONXY XY-2 pro, yes my cooling was at 100%, no it's not the same as my other spools, in fact all of my spools come from a different manufacturer because when I started buying them I didn't think that mattered (oops lol). If you guys have a recommended manufacturer to buy spools from let me know, I'd love to have some consistency. The black PLA came from Snapmaker.

image

Adjusted print speed to 50mm/s, adjusted retraction distance to 7mm  (up from 4 or 5 can't remember) adjusted retraction speed from 40mm/s -> 30mm/s. Flow rate is set to 100%

And very unfortunate but I won't be able to do an E-step calibration on the tool simply because I have very limited control. In terms of extruder manual control, I can literally only tell it to go forward or backward. Below is a photo of the basic menus I have access to.

image

And here I have a picture of the extruder manual control (the 19/0 is the temperature, indicating that the current temp is 19C and the current set temp is 0 because I haven't preheated the nozzle

image

I'm going to run another temp tower using the settings I've just changed to see if there's some quality improvement but based on what you've seen so far would you recommend an increase or decrease in flow rate? this might end up being a trial and error test lol.

ReplyQuote
Topic starter Posted : 24/04/2021 10:37 pm
Pablo
(@placherre)
Member Moderator

Hi Hazmatt99!

 

Many thanks for your words, I am glad I was able to help you speed up your learning process.

Also, thank you for your feedback info and pictures!

The supplier will depend on your location, depending where you live. Most filament brands have a good quality in their materials; but, the final result will depend on your printer status and the slicer configuration. In my personal opinion, every material will have its own slicer settings; even if you have two identical printers, settings will vary from each other. I have the chance to experiment with three different suppliers, deciding to choose two of them. Despite the brand you are able to buy, you can check a few items when buying a new spool, in order to verify the overall quality:

  • Diameter consistency: If you buy a 1.75 mm diameter filament, measure it in several parts (a Vernier caliper is suitable for this task). Even +/- 0.1 mm advertised width can lead to irregular extrusion. Make sure the filament is clean when you measure it.
  • Make sure the packaging is vacuum sealed when you buy it. Also, it should contain a dessicant (5 g silica gel bag for moisture). 
  • Snap Test: Bend in half a piece of filament, it shouldn’t snap; if it does, do not use it. Stale filament won’t print well.
  • Spool Binding: When printing, check the filament is well wired; also, keep it tight when printing or storaged, in order to prevent tangles.

The filament you show in the picture has the normal temperature range. It doesn’t have the recommended bed temperature; but, don’t heat up the deb above 55°C in order to prevent issues when printing. Have in mind the concept of Glass Transition Temperature (GTT) concept. This temperature changes the internal structure of the material, from rigid to soft (but not melted) material affecting the printing quality. The GTT for PLA is between 60-80°C.

It is a shame you can not modify the E-Steps in your machine. But, do not worry, you can manage the extrusion by adjusting the flow rate in your slicer. Recalling my previous answer in this post, you can see how to modify that parameter un Cura and Simplify3D. If you are using a different slicer, please let me know and I will help you with it. Anyways, don’t worry about changing the flow now, since you made some changes in the slicer. Once you have the tower printed with this new configuration, please reply to me with your result. If you make too many changes at the same time, you won’t know which change made an impact. In addition, it will help you to recognize patterns which will help you to determine the cause of a problem when something is going wrong.

 

Good luck with your print!

I look forward to hearing back from you!

Kind regards,

Pablo

ReplyQuote
Posted : 26/04/2021 2:21 pm
hazmatt99
(@hazmatt99)
Trusted Member

Hello again!

So after testing the quality definitely increased.

20210426 172446

Don't know if you can tell from the image quality but the number of gaps significantly reduced as well as the number of strings and blobs. Small feature detail also increased in quality.

It's not perfect but there's at least a noticeable difference depending on the temperature now. I'd say F and G are the best sections so I'm going to say hovering around 195 for a nozzle temp is probably good. Im using cura for the slicer so in your expert opinion what should I try changing the flow rate to try and eliminate those gaps? (that's I'm guessing what we're trying to do here right?)

Miscellaneous stuff: you mentioned bed temp and GTT. So I'm guessing this is the part that mainly contributes to elephant's foot? I currently have my build plate temp set to 50C, would you recommend setting it lower for the initial layers? And would you use the built in initial temp setting

image

or set it up to change at a specific layer height like with the temp tower?

Also for keeping these spools clean and dry, so far all I've done is buy some vacuum bags for them, would you recommend I also buy desiccant packs? For keeping them clean, I've heard I can print a line filter that can fit on the filament line and have it catch dirt as it goes? Is there a file you recommend for that? And finally for cleaning dirt out of the nozzle I've seen that cleaning filament exists, any one of those you recommend? Or any recommendations for how often to clean and how much of the cleaning filament to use? (this might have been something you answered in my first post so sorry if you did lol)

ReplyQuote
Topic starter Posted : 26/04/2021 11:05 pm
Pablo
(@placherre)
Member Moderator

Hi Hazmatt99!

I am glad and happy you were able to improve your print quality; but there are few details to adapt in order to get the most out of it. 

Comparing both pictures, I can see an improvement in the quality and the “floor” where the temperature works better. Just to be aware, when using dark colours for printing, you might require an increase in 5°C order the nozzle temperature. Therefore, if you try to print the same tower with a light colour (green, red, yellow, etc.) you will notice the section of temperature will be different; for instance, between E and F. In conclusion, for black 195°C will work fine and for the rest of the colour somewhere in 190-195°C. Anyways, you will notice this when experimenting with different colours.

Recalling your last picture, I could suggest you to decrease the Flow Rate, since you are not able to adjust the E-Steps. I can still notice some sloppy layers which indicates over extrusion; hence, I would adjust the value to 95%. This change might seem a little bit drastic, but you will be able to notice a change. In addition, you could adjust the printing speed. Since you mentioned that you are printing at 50 mm/sec, is that the overall value? Because you could adjust the Wall Printing Speed to a fraction of that value, for example at 30 mm/sec; this will slow down your printing time but improving quality. In Cura, you can adjust this value in the Speed tab, and change the sub-values Outer Wall Speed and Inner Wall Speed, I am sharing a picture where you can find this set up:

Outer Inner Wall Speed

Also, when printing with PLA, keep the Fan Speed at 100% at all times; except when printing the first two layers (in order to acquire a strong bond between the layers and the bed). The reason for using the fan at full speed is that you must cool down quickly the temperature of the deposited filament. 

Regarding the bed temperature, I recommend you to keep it at 50-55°C at all times. Do not set it up below 50°C because you will experience warping (when the first layer is detached from bed). Despite this recommendation, you will learn throughout your experience the correct setting. But for now, keep it close to 55°C. You are correct when you mention there is a relationship between Bed Temperature and Elephants Foot. But also, the distance between the Nozzle and Bed is a key factor. If the first is too close to the former, the Nozzle will “squish” deposited material. Therefore, when checking for bed level before printing, make sure you keep the correct gap between both parts with the paper method. Remember to place the Nozzle in four corners of the bed and check the distance, you should notice some resistance when placing the paper, shouldn’t slide easily. Also, it is recommended to calibrate this distance with the working temperature, in order to compensate for thermal expansion. In conclusion, there is an optimal setting before ending up with warping (too cold) or elephant foot (too hot and nozzle too close).

According to best practices for filament storage, there a few tips to consider:

  • Keep the spool in sealed and dry bags (like you mention). Ziploc bags work fine, due to the design you can seal them very easily, while taking out the air. Also, it is recommended to place a 5 g desiccant bag in order to keep the spool free of humidity. In addition, by keeping the material inside a bag you prevent dust from depositing. Also, you can print a filament cleaner for when the spool is in the printer; I found this one on Thingiverse: https://www.thingiverse.com/thing:3033662
  • Since UV rays affect all types of polymers, keep your filaments away from the sun or inside a cabinet.
  • Keep the spool tight: In order to prevent tangles, clip the loose end of the filament.
  • Snap Test: This quick revision test will help to determine if the filament you are using is still good to go. You just have to bend it in half and watch if it snaps; if it does, throw it away. 
  • Filament Tolerance: Measure the filament diameter and check if it is the same in different lengths. Small variations will affect your prints.

I recommend you to regularly check the Nozzle obstruction; but also, check if there is any material left in the Bowden tube (debris from old filament will also affect your print). In the market you will find different brands of cleaning filament, actually I do not have a preference regarding suppliers. But, keep in mind that this filament helps with partial clogs; if you have a severe clogging issue, you will have to remove the Bowden tube in order to make a full inspection. In addition, when changing and purging filaments, look at the melted material coming out from the Nozzle, it should be smooth with no blobs (take a look at the following picture to compare).

Signs of Block Nozzle

I hope I was able to clarify some doubts… 😀 

If you have any doubts, please let me know and I will reply to you.

I wish you good printing!

Kind regards,

Pablo

ReplyQuote
Posted : 27/04/2021 5:34 pm
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