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Unsuccessful print

davidmjod3b70f13
(@davidmjod3b70f13)
Prominent Member

I was almost successful in printing a mermaid, which is really great as I have not been at all successful in the past. I attribute my success to your courses. However, I was not fully successful as the supports for the mermaids hands did not work correctly. Not only were the supports not sturdy enough, several times I saw the extruder head brush uo against them. As you can see in the photos her hands and lower arms were not printed correctly

IMG 0744
IMG 0743

 

Quote
Topic starter Posted : 04/02/2021 6:40 pm
Luke
 Luke
(@lmf5000)
Expert Moderator

Hi David,

Your supports are showing signs of underextrusion. That could be caused by having support print speed being to fast, or extrusion width being too low, or layer height being too great etc. Fortunately the mermaid proper looks to be printing with good quality, so it's just support settings that we have to address.

Could you post a screenshot of the support settings you're using in your slicer software? I will give you specific advice on what settings to change 🙂

Regards,
Luke

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Posted : 04/02/2021 11:15 pm
davidmjod3b70f13
(@davidmjod3b70f13)
Prominent Member
Screen Shot 2021 02 05 at 9.15.20 AM

I agree, the main body printed perfectly. Once I get this right I need to shrink the image. I am working on an HO scale train layout. If your not failure with model trains. HO scale is 1/87 of an inch. Which means my mermaid needs to be about 1 inch or maybe 1 1/4 inches tall. From what I have learned so far, I think I need a smaller extrusion nozzle. I currently have a .4mm nozzle. I believe I will need a .2mm nozzle. What do you think?

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Topic starter Posted : 05/02/2021 2:21 pm
Luke
 Luke
(@lmf5000)
Expert Moderator

Hi David,

I see that you haven't exposed all the settings in Cura. To do that you have to press the three lines on the top right and then press "All" -

image

Your support overhang angle might be a bit too optimistic at 65° (the default is 45°) so that might be a contributing factor, but there are a great deal of hidden settings.

Since this might be a support placement issue rather than just settings, I will need a project file so I can look at where your supports are being generated.

To get that file, load up the mermaid exactly as you did before with the same settings as before and go to File -> Save Project (

image

That will generate a .3mf file - please attach that. If the filesize is too large or the forum won't permit upload, either zip it or use wetransfer and post the link 🙂

 

As for the nozzle, yes a 0.2mm nozzle will be able to clearly print details half the size of a 0.4mm nozzle. Just keep in mind printing takes 4x as long because not only is the extrusion width halved, but the layer height limit is halved as well (to 0.1mm). Your other option is a 0.3mm nozzle, but for a 1-inch model, 0.2mm would be best as you want all the detail you can possibly extract from your printer. In fact, you're approaching resin printer territory if you desire any significant detail at that scale.

 

Regards,
Luke

ReplyQuote
Posted : 05/02/2021 2:46 pm
davidmjod3b70f13
(@davidmjod3b70f13)
Prominent Member
ReplyQuote
Topic starter Posted : 05/02/2021 9:56 pm
Luke
 Luke
(@lmf5000)
Expert Moderator

Hi David,

Excuse the delay in getting back to you. I've analysed the 3mf and I have these comments. I know you're transitioning to PrusaSlicer now, but the rationale behind this will still help you gain more insight on 3D printing, and some of this will be directly translatable over to PrusaSlicer:

  • Layer height - I prefer an initial layer height of 0.2mm rather than 0.3mm, for more "squish" and hence more adhesion. I don't recommend anything below 0.2mm because then the first layer becomes a little too thin and levelling the bed perfectly becomes too critical. For the model's layer height, this would benefit a lot from adaptive layer height. I will demonstrate this later in the answer.
  • Top/bottom thickness - I have found 0.6mm to be adequate for decorative prints (corresponding to 3 layers of 0.2mm layer height or 6 layers of 0.1mm layer height). For functional prints that need more strength, typically perimeters are the biggest factor influencing part strength, but you can raise top/bottom thickness too.
  • Infill density - lower to 20%. There's usually no need for more because infill mainly functions to give you something to build the top layers onto - the strength of the part primarily comes from the perimeters (at least up to crazy high infill values of 80-100% - video with lots of testing on this by Stefan from CNC Kitchen here: https://www.youtube.com/watch?v=AmEaNAwFSfI ). With a high infill you just spend more time and material printing the shapes inside the model.
  • Untick "infill before walls" - there's a risk that infill shows through the walls of your print with it ticked. The ideal printing order is inner walls first, then outer walls, and finally infill. The reason is that printing inner walls first gives the outer walls something to stick to (which is especially important for overhangs).
  • Printing temperature - raise to 200 or 210°C. Ideally print a temperature tower for this and find the optimum temperature for your filament and printer. I use 210°C on all my printers with all brands of PLA because my prints typically print on the faster side and don't have particularly difficult overhangs. In theory, PLA should be printable at 190°C, but in practice your printer will suffer printing at high speeds at such a low temperature (not enough time to fully melt the filament). The result is underextrusion as the extruder grinds the filament or skips, and poor layer adhesion. This might be part of the reason your support had underextrusion issues. Mind you, for smaller models (like your ultimate small-scale one) it does make sense to use temperatures on the lower end of the scale because overheating with PLA could become an issue with really small parts.
  • Speed - infill speed - lower to 60mm/s; inner wall speed - lower to 60mm/s; outer wall speed - lower to 30mm/s. Your old speeds are fine, but these slightly lower values will ensure higher quality and no underextrusion, particularly when you use lower temps for smaller models
  • Cooling - regular fan speed at layer - make that layer 3. You want to have three layers without fan so that you don't risk cooling the filament too much and having it warp up and off the bed.
  • Minimum layer time - raise to 10 seconds. This is crucial to prevent overheating in smaller models
  • Add "lift Z" (z-hop)  and set to 0.2mm. This helps prevent the nozzle from knocking over fragile parts of the print when it travels if there's a tiny amount of overextrusion or warping that makes the plastic rise above the level of the nozzle.
  • Support - I recommend normal support rather than tree support. It is significantly easier to remove and means less of a chance of damaging the model during the process. Also, in this case tree support uses 21g material and 3h19m whereas normal support consumes 19g of filament (a 10% savings) and 3h 9m (a 5% savings). If you do use tree support, I found that lowering the Tree Support Branch angle seems to use less support and makes it more stable (less steeply angled) which increases the chance of a successful print.

Here's 40°:

 

image

Here's 20°:

image

Here's normal support:

image
  • Build plate adhesion - with a well-calibrated printer, you can do away with the rafts, brims and skirts and save considerable time and material. You just need to add a pair of priming lines in your starting script to establish stable filament flow before you start the print itself. As an alternative to that, you can just use a brim with two lines.

---

I mentioned earlier about variable (adaptive) layer height. This is a feature where thick layers (for fast printing) are used on areas where there aren't too many details/overhangs, and thin layers (slower but more detailed) are used on areas with more details/overhangs. The advantage is that you get the speed of thick layers and the quality of fine layers by letting the slicer intelligently apply different layer heights to different regions based on the print itself.

Cura can do it but it's not very customizable, you can input three numbers and cura will auto-calculate the rest (here the colour is the layer height):

image

Here's a demonstration with a sphere to better show what's going on:

image

As you can see the bulk of the sphere is printed with thick layers. The middle part has relatively vertical sides so you can afford to speed through it with thick layers because it's not so critical. But at the top and bottom of the sphere where the wall angle is steeper and you really need fine layer heights to get a good smooth finish (not a staircase of thick layers), it progressively decreases the layer height as evidenced by the green and then blue colouring in the height preview.

---

In PrusaSlicer, adaptive layer height is configured simply by setting the min and max limits in the printer settings -

image

(In this case "0" for max means "automatic" and translates to 75% of the extruder width) -

image

Then in the print preview you open the adaptive layer height dialog:

image

Click "adaptive" and you can see what it calculated by default:

image

The graph on the right shows the layer height it automatically generated based on the automatic algorithm. You can then increase or decrease any height by left/right clicking a region with the mouse -

image

Or press "smooth" at the bottom to make the transitions smoother so the difference in layer heights isn't so apparent in the model -

image

(the above pic is taken after smoothing)

This comes in at 1h42m and 12.84g using adaptive layer heights of 0.08-0.3mm and the speeds/settings I recommended earlier in PrusaSlicer -

image

I've attached the project file for reference, you might be able to extract my profile from it and adapt it to your printer by changing the bed dimensions and start/end codes (or create one from scratch if you want more hands-on experience with PrusaSlicer):

Hope this helps, let me know how you're getting on with PrusaSlicer 🙂

Regards,
Luke

ReplyQuote
Posted : 07/02/2021 6:08 pm
davidmjod3b70f13
(@davidmjod3b70f13)
Prominent Member
IMG 0750

 

OK Luke, I know I am going to get this eventually! However, right now I am very frustrated. I started this morning with a fairly good print. Lets back up. I shrank the mermaid down to the appropriate size. Then I printed the image on the left. Not great but overall not too bad. So I changed the nozzle from 0.4 mm to 0.2mm. I made the changes in the print settings and then did the secondnprinting. Much improvement!! But no support for the hands. That was the last successful print I had for the dy. Since then I have had nothing but problems!!! Filament isn starting atb the right time then filament won't stick and the the filament is building up around the nozzle!!! I am going to attach the exported copy if the latest setup. I hope! The boat is the one that will be used on my layout. 

 

I tried to print the leveling squares but I finally gave up ion frustration. I did do a new slice of the leveling squares but that was a disaster s well.

 

ReplyQuote
Topic starter Posted : 13/02/2021 11:08 pm
Luke
 Luke
(@lmf5000)
Expert Moderator

Hi David,

Good progress so far! 🙂

Looking at your attached .3mf file there are some settings that are not good for a 0.2mm nozzle, and some that could be improved in general, so I've made all the changes and attached the updated .3mf file for your perusal.

Here's an explanation of the changes and their rationale:

  • Layer height is way too large at 0.2mm. LH should be limited to no more than 75% of extrusion width, but ideally 50%, which means 0.1mm. I'm going to suggest 0.08mm for even better quality (you really need all you can get at this scale)
  • First layer height - same problem. The max is 0.15mm with a 0.2mm nozzle so I'd go for that.
  • Minimum shell thickness is set to "0" - this is a neat feature in PrusaSlicer where you can specify a desired top/bottom shell thickness and it automatically adds layers to the top and bottom to achieve it, depending on your layer height. For standard printing I use 3 top and bottom layers of 0.2mm each, so my usual thickness is 0.6mm. Setting 0.6mm in the top/bottom minimum shell thickness means that for this print (at 0.08mm layer height), the software will automatically up the number of top/bottom layers to 8 (since 8 x 0.08mm = 0.64mm, just over my 0.6mm minimum). This is handy because by just setting these numbers you can set any layer height you want and never have to worry about increasing top/bottom layers to suit. Of course the minimum number of top/bottom layers is always 3 because that's how many you need to achieve good sealing and a nice appearance in my experience.

So at this point, the first page looks like this (I've marked the minimum shell thickness numbers for context):

image
  • For printing figures, I suggest "seam position" to be set to "rear" so it hides it at the back of the model where it doesn't detract from the aesthetic appearance as much.
  • Infill pattern - I suggest adaptive cubic. It won't make a difference here, but when you eventually do large prints you will save significant time and material because adaptive cubic hollows out the center of the print, focusing all the infill on the areas near perimeters and top and bottom layers where they're actually needed.
  • Skirt and brim - removed these. They just add more plastic to clean up during post-processing. I will add priming lines in your start script later to make sure the nozzle is fully primed before it starts printing the actual print
  • Support settings - Overhang threshhold should be 45° as this is already very conservative (I've found that even a setting of 30° gives good results in practice)
  • Contact Z distance - I use 0.25mm for 0.2mm layer heights, but around 2 layers would be a good value. Since you're now going to print at 0.08mm layer height, I've set this to 0.16mm.
  • "with sheath around the support" - untick this one, it makes the support very strong and hard to remove, which works against you for such a delicate print
  • Pattern spacing - make this smaller, I suggest 0.4mm. This makes the software's internal resolution (support grid) greater, so it targets the support better. The default value of 2.5mm means support columns are at least 2.5mm big, which tends to put extra supports where they're not needed and gives you more to clean up
  • XY Seperation - I've had good results with 75%. If you had no difficulty removing supports with 50% you can leave it at that, but for the attached file I've gone to 75% because this is a delicate print and you don't want to damage it because of stubborn supports.
  • Speed - I've lowered all your speeds quite a bit. A 0.2mm nozzle is very restrictive (extremely tiny orifice) so it can't sustain high printing speeds like a 0.4mm nozzle. All the speeds have been limited to 45mm/s or less.
  • Acceleration control - added some numbers to lower acceleration for perimeters to 500mm/s2 to improve your quality and 1000mm/s2 elsewhere to improve your speed.
  • Advanced - I've set the first layer extrusion width to automatic by putting a zero in the box). This equates to 1.125x nozzle diameter, which is 0.225mm. The printer will find this much easier to extrude than the old value of 200% (0.4mm extrusion width).
  • Elephant foot compensation - set to 0mm, based on your pics it seems to hinder rather than help you because your first layer is inset relative to the rest of the print rather than bulging outwards (the bulging is called elephant foot and is what this setting tries to compensate for)

 

  • Filament settings - I notice your bed doesn't have a temperature defined. I've set it to 60°C
  • You're missing density and cost numbers, I set 1.25 and 35 respectively
  • Cooling - you need quite good cooling to print this small so I've increased min fan speed to 50%, ticked "keep fan always on" (to enforce the 50% minimum on all layers, even slow ones) and increased minimum layer print time to 7 seconds instead of 5

 

  • Printer settings -> Extruder 1 - your printer has a bowden extruder (that is, the extruder motor feeds filament through a long Bowden tube that eventually feeds it to the nozzle some distance away) so your 2mm of retraction length isn't sufficient (2mm is enough if you had a direct-drive extruder, that is, the extruder motor is mounted on the print head and feeds the filament through a very short length of tune). I've upped retraction length to 5.5mm and speed to 70mm/s
  • Increased "lift Z" to 0.2mm. This is equivalent to z-hop in cura and raises the nozzle during travel moves so it doesn't bump into and knock over parts of the print that may have curled up.

Added custom start script to heat up bed and nozzle simultaneously and draw a pair of priming lines at the edge of the bed to prime the nozzle before it starts printing (much more convenient than a brim and/or skirt because you can just peel them off the bed after printing whereas a brim has to be cut off and generally ruins the first layer, and a skirt can grow significantly large when you have a larger print, which wastes a lot of filament).

M190 S{first_layer_bed_temperature[0] - 5} ; wait for bed temperature minus 5
M140 S[first_layer_bed_temperature] ; continue bed heating
M109 S[first_layer_temperature] ; concurrently heat up nozzle and wait
M190 S[first_layer_bed_temperature] ; make sure bed is at proper temp before continuing
G28 ; home all axes
M204 P400 R1000 T1000 ; Set accelerations for Print and Travel moves
G92 E0 ; reset extruder
G90 ; absolute positioning
G1 Z1.0 F3000 ; move z up little to prevent scratching of surface
G1 X0.1 Y20 Z0.3 F5000.0 ; move to start-line position
G1 X0.1 Y180.0 Z0.2 F1200.0 E10 ; draw 1st line
G1 X0.4 Y180.0 Z0.2 F5000.0 ; move to side a little
G92 E0 ; reset extruder
G1 X0.4 Y20 Z0.2 F1200.0 E10 ; draw 2nd line
G1 Z1.0 ; move up to avoid scratching bed
G92 E0 ; reset extruder

Added custom end script to gracefully stop printing and shut everything down.

M104 S0 ; turn off extruder
M140 S0 ; turn off bed
G91 ; relative positioning
G1 Z0.3 E-5 F5000 ; move up 0.3mm
G90 ; absolute positioning
{if layer_z < 4.0}G1 Z4 F1500{endif}; if z is below 4mm move up to 4mm to clear clips
G1 X0 Y0 F2000 ; move to home position
G91 ; relative positioning
G1 E-70.00 F5400 ; remove filament
M84 ; disable motors
M106 S0 ; turn off fan
M300 P42 ; beep

Here's what the supports look like by default:

image

Now, in PrusaSlicer you can customize it by clicking the "paint-on support" button in the layer view:

image

If you click "autoset by angle" you'll see where you have overhangs greater than the specified angle (45° in this case). The areas in red are the areas that need support with that threshhold angle:

image

You can move the slider to see how the areas change with different threshhold angles. For example, if I were to set it to 80°, most of the model will turn red (meaning it would think most of it needs support):

image

I'm going to leave it at 40° so I only get support on the parts that really need it:

image

If you click "enforce" then it will add supports to those areas (the areas previously marked in red):

image

This screen shows you the enforced and blocked support areas. Blue is enforced (it will print supports there), red is blocked (it will not print supports there). You use the left mouse button to enforce supports, the right mouse button to block supports, and shift + left mouse button to clear selections.

I'm going to block supports from the side of her hair because I feel that these should be printable without support. Here's the result after drawing some blockers with the right mouse button (use Alt+mouse wheel to resize the brush, or the slider on the screen, to make it smaller to facilitate drawing in such fine areas) -

image
image

Here's the end result in layer view with the customized supports:

image

You can see some superfluous supports in the belly area, so go back to 3D editor view (the cube in the bottom left), open the support painter, and paint a blocker as needed:

image

And now we no longer have that extra support there, which will make cleanup much easier (the last few remnants are an artefact of the way PrusaSlicer makes supports, they shouldn't be there but they can't be removed with blockers):

image

And here's the .3mf project file with all of the above:

Hope this helps. I actually attempted to print this 30mm high with a 0.4mm nozzle, I will post my attempt in a second post 🙂

Regards,
Luke

ReplyQuote
Posted : 14/02/2021 10:19 pm
Luke
 Luke
(@lmf5000)
Expert Moderator

Here's my first attempt with a 0.4mm nozzle at 0.08mm layer height. The arms didn't come out well because they're basically too thin to print at this scale (not wide enough for a full circle, the printer just deposits a droplet of plastic there). One bent during printing and they ultimately both broke off during support removal, so I cut the arms off to make it look more like a sculpture 😋 . The filament is Spectrum Pearl Bronze PLA. This spool is almost 2 years old so some stringing is inevitable as it's absorbed quite a lot of moisture by now 😆 .

IMG 20210208 155114
IMG 20210208 155743
IMG 20210208 155758

If you wanted to improve the arms, you can increase the XY size compensation value under Print Settings -> Advanced.

image

A positive value here thickens the print. So say +0.2mm will offset each face of the model by 0.2mm (making the arms 0.4mm thicker in total). This makes it look more bloated and loses some detail, but will make the arms stronger and more likely to survive printing.

Here's the arms with a 0.2mm nozzle and the default (zero) XY compensation:

image

Here's the same layer with +0.2mm of XY compensation:

image

Notice how the wrists have now thickened enough to have two perimeters instead of one... but the rest of the model looks slightly deformed as all faces have been offset/thickened by 0.2mm -

image

It's a useful tool when all else fails - you decide whether more reliable arms are worth the loss of fidelity on the rest of the model 🙂

Regards,
Luke

ReplyQuote
Posted : 14/02/2021 10:31 pm
davidmjod3b70f13
(@davidmjod3b70f13)
Prominent Member

OK, I understand. However, I need to edit the image ultimately. To fit the diorama I am working on I ultimately will need the arms to be reaching forward at more of a 90 degree angle. I also need a fishing hook in one and and a fish in the other. So that it looks like she is removing the fish from the hook.

 

Can you reckoned a program that would allow me to edit the image and then save it again as a .stl image?

ReplyQuote
Topic starter Posted : 15/02/2021 3:39 am
Luke
 Luke
(@lmf5000)
Expert Moderator

Hi David,

Stl files are actually three-dimensional point clouds rather than images. You can do some simple editing of an existing STL with Meshmixer (it's free and covered in a masterclass) and you can create engineering designs from scratch with Fusion 360 (also free). "Engineering designs" are things like products you'll find around the house, made mostly of geometric shapes, like say a smartphone, your 3D printer itself, all sorts of useful knicknacks around the house (hooks, clips, mounts etc.)

For organic shapes (people, mermaids, animals etc.) you'll need a sculpting program rather than a CAD program, and much like creating 2D-art you'll need to have artistic talent to make the most of it (something I'm sadly lacking in both the 2D and 3D sense 😆). Fusion360 has some sculpting built-in but I'm not sure it will be up to this task. Blender is popular and free and can probably do this, but it's famously very hard to master (steep learning curve). Personally I'm an engineer so I've gone the CAD route (non-organic modelling) and learned Fusion 360 and never learnt blender.

You might be able to achieve what you're asking with meshmixer by stitching together the body, and a downloaded set of arms, fishing hook and fish, but it will be tricky. Other options are to teach yourself blender (or a non-free equivalent 3D sculpting software like Cinema4D, Maya or Zbrush), or try to look for a 3D model that already has the right pose, or, if this is just a one-off, probably the easiest solution is to commission a 3D artist to make you the STL (maybe even ask the original author of that mermaid since they will have the original source design to modify). However if you're going to print all that at this small scale, you will need a resin printer (DLP or SLA). The arms are already borderline unprintable, a fish hook would probably end up unrecognizable even with a 0.2mm nozzle, unless it's significantly enlarged.

Regards,
Luke

ReplyQuote
Posted : 15/02/2021 6:08 pm
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