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Weird small hole inside the print


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Posted · Weird small hole inside the print

Hi, i am using ultimaker 2 and trying to calibrate my ultimaker. I am using .8mm nozzle with .4 layer height but the results keep giving me this small hole in the print. What could be the possible problem here? Thank you. 

292029922_568866578318228_7985956398850171856_n.jpg

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    Posted · Weird small hole inside the print

    I'm not sure but it could be where that outer wall line starts and ends it's loop around benchy.  If that is the case sometimes you can fix those by just slowing down or by playing with the order that the walls are printed or increasing fan speed (although it should already be at 100%).

     

    You could verify by going back into cura and looking at the layers near those holes and seeing if that's true.

     

    This is typical quality for a 0.8/0.4 combination (not as good as say 0.4mm nozzle with 0.2 layer height).

     

    What are your printing speeds for this print (default, outer wall, inner wall, infill)?

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    Posted · Weird small hole inside the print

    Here is the speeds for this sprint.

     

    More over should i play around print jerk and print acceleration to improve my print? Thanks 

    Untitled.thumb.png.21a9be96fb2bb9ada2ce71382e994415.png

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    Posted · Weird small hole inside the print

    I hate to repeat myself but

     

    1) Did you check if the fan was at 100%?

    2) Did you go into cura PREVIEW mode and check the layers with the dimples to see if they coincide with where it does the outer layer?   If so look at the order of the inner, outer, infill and consider changing that.  I think by default it does the outer layer last?  Or first?  I forget.

     

    I would probably try setting all the printing speeds to 35mm/sec (infill, wall, inner, outer).  Leave the travel speed high.  You lowered it to 130mm/sec which is probably fine but as a general rule:

    lower travel speed means lower quality print

    lower printing speed means higher quality print

     

    UM2 should be fine at 250mm/sec travel speed.  If not you may need to oil the gantry rods.

     

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    Posted · Weird small hole inside the print

    - So i increased travel speed to 200 mm/s.

    - By default i believe it is to be wall then infill last

    - I changed to random Z  aligment and you know what? The small hole appeared matched the location where the next start point of new layer. So how should i fix this?

     

    - Should i play with jerk and acceleration control or should i just turn it off? Thanks.

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    Posted · Weird small hole inside the print

    Is this burnt filament or what is this? This keeps showing up and i am don't know why.

    292425441_1406038793232530_481004891618662820_n.jpg

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    Posted · Weird small hole inside the print

    And the blobs show off as well. Do you have any suggestions? Thanks. 

    292562693_613664283475745_188031579658302110_n.jpg

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    Posted · Weird small hole inside the print

    Last photo I reply to fist.  You circled a layer in black that sticks out.  It doesn't go all the way around benchy.  If it did I would say you need to clean your z screw.  Some of the fainter horizontal lines are probably caused by a dirty z screw but most of them don't go all the way around.  The issue with dirty Z screw is that the bed doesn't always move down by exactly 0.4mm.  Sometimes 0.3mm or 0.5mm.  Because of dirt on the z screw.  If it move > 0.4mm then you have an underextruded layer and it sticks inwards a bit.  If it moves < 0.4mm then you are extruding too much for that layer and some squeezes out and you have a layer that sticks out.

     

    However most of those lines don't go all the way around so it's something else.  Not sure what.

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    Posted · Weird small hole inside the print
    On 7/9/2022 at 1:50 AM, mnidannydang said:

    Is this burnt filament or what is this? This keeps showing up and i am don't know why.

    Basically, burnt, yes.  Caramelized might be a more accurate term.  Oxidized.

     

    It's probably building up on the *outside* of the nozzle and dripping down into the print.  It's worse with some nozzles and materials than others.  Try cleaning the nozzle as it is doing the initial purge just before starting the bottom layer.  It's also possible it is caramelizing inside the nozzle but this is rare with PLA (quite common with PVA).

     

    I'm not sure how to fix this.  3dsolex has some "ICE" coated nozzles that is supposed to prevent this.  I'm not sure if that works or not.  I don't have this problem much so I don't pay much attention.

     

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    Posted · Weird small hole inside the print
    On 7/9/2022 at 1:41 AM, mnidannydang said:

    So i increased travel speed to 200 mm/s.

    - By default i believe it is to be wall then infill last

    - I changed to random Z  aligment and you know what? The small hole appeared matched the location where the next start point of new layer. So how should i fix this?

     

    - Should i play with jerk and acceleration control or should i just turn it off? Thanks.

    Maybe you should just post your project file so I can see all these things myself.  In Cura do "file" menu then "save project as" and post the resulting file here.  It will give us your STL file and it's position and any thing you did to it like scaling.  It will also include your printer settings and your profile and your settings overrides.

     

    >jerk and accel

     

    I don't like accel/jerk reduction (if you disable it chooses max possible values which I prefer).  Those are meant to stop ringing but cause other problems like the bumps you show.  You have to decide if you care more about precision or looks.  And you have to decide if ringing is worse or if those bumps are worse.  Rarely I have issues with ringing - like if I have lettering on the side of something that needs to be legible.  In those cases I might enable accel/jerk.  These should be off on a UM2.  By default.  Because UM2 doesn't have much of a ringing issue in the first place - it's more for the heavy print heads of the UM3/S3/S5 printers.

     

    >The small hole appeared matched the location where the next start point of new layer.

    Excellent.  You narrowed down the problem.  I'm not sure what to do but if you post the project file the first thing I will do is make sure "coasting" is disabled.

     

     

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    Posted · Weird small hole inside the print

    Hi here is the STL file and i believe coasting is disabled. Thank you for your time 😄 

    UM2E_3DBenchy 9.3mf

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    Posted · Weird small hole inside the print

    1) You have retract before outer wall enabled.  Turn that off.  That's probably the issue.

     

    2) You have outer wall speed at 15, inner wall speed at 15 and infill speed at 20.  You should make them all the same.  I definitely wouldn't go slower than 20 but 25 should be fine and print significantly faster.  Having these different speeds causes problems - when you stay at the same speed for a while, there is soon a balance where the pressure in the nozzle is perfect so that you get a nice extrusion speed to match the head movement speed.  If you speed up the XY then it will underextrude until the pressure balances at a new, higher pressure.  If you slow down the XY speed then it will over extrude for a few seconds until the pressure balances at the new, lower pressure.  So every speed change causes some over or under extrusion.  This could be the problem also but probably not - my money is on #1. See screenshot below showing all your speeds.  I only care about printing speeds - mainly inner wall, outer wall, infill, top/bottom.

     

    3) You messed with maximum travel resolution and maximum deviation.  I've never touched those things.  I'd put them back to default settings just in case this is causing a problem.  At least one time for a test. Then you can put it back to how they are now.

     

    I'd change all 3 things.  It's okay to change many variables at once until you get it working then undo the changes one at a time to figure out which variable it was.

     

    755127384_Screenshotfrom2022-07-1221-58-20.thumb.png.b1575871fe49ad91d1c7e4c26b2c0025.png

     

    By the way #2 above was specifically called out - saying a value of 0.05 is definitely a problem that can cause ugliness and it should be closer to 0.4 (default for UM2 is 0.5 but I guess default for his printer was .05 which was a problem).  Here's his post: 

     

     

     

     

     

     

     

     

     

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    Posted · Weird small hole inside the print

    Hi, i tried your recommended settings and the hole problem improved a lot but there are still some visible small hole.

     

    Moreover, i notice that on my print there are bumps like this is it because the filament is not properly cooled? I don't know. 

    291293642_1014875792533993_258953301160227569_n.jpg

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    Posted · Weird small hole inside the print

    Moreover, the extra line or blob or whatever it is called go arounds the benchy .. I don't know why. 

    291643438_1274958383039364_8272685355311994725_n.jpg

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    Posted · Weird small hole inside the print

    And in the back there are some weird gap. Thank you.

    293266419_1463583064078996_1092647602080854758_n.jpg

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    Posted · Weird small hole inside the print
    Quote

    Moreover, i notice that on my print there are bumps like this is it because the filament is not properly cooled? I don't know

    Maybe.  Probably.  I'm not sure.  With PLA, even the cooling that is built into the UM2 is barely enough.  When using a large nozzle like the 0.8mm nozzle then extra cooling could help a lot.  Maybe add a window fan or desk fan blowing into the printer.

     

    6 hours ago, mnidannydang said:

    Moreover, the extra line or blob or whatever it is called go arounds the benchy .. I don't know why. 

    Yes - that's probably a dirty Z screw.  I would clean the z screw.  Just the top 2 inches to see if it helps.  You can do a quick clean with a paper towel and a screwdriver but make sure you clean all 3 threads.  It is a triple helix screw.  3 helixes (dna is double helix).  So make sure you get all 3 grooves.

     

    Or you can do a thorough proper cleaning by removing the stepper motor from the bottom and sliding it out of the printer and then putting it all on newspaper and cleaning with a tooth brush and WD-40.   If you do a complete clean (only if) then add one pea sized drop of grease.  One pea sized drop is enough for the entire screw.

     

    6 hours ago, mnidannydang said:

    And in the back there are some weird gap. Thank you.

    Underextrusion.  Could also be dirty screw.  Maybe.  Many things cause underextrusion (such as speed changes, dirty Z axis, and 30 other possibilities).

     

    Keep in mind you are using a huge nozzle - 0.8mm is a big nozzle.  The quality won't be as good as with 0.4mm nozzle.  And large layer height (0.4mm).  The quality is better with 0.4mm nozzle and 0.2 layer height.  But it takes 4X longer to print.  And the quality is even better with 0.25mm nozzle and 0.1mm layer height.  But that takes another 4X longer to print.

     

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    Posted · Weird small hole inside the print
    On 7/9/2022 at 1:50 AM, mnidannydang said:

    Is this burnt filament or what is this? This keeps showing up and i am don't know why.

    Here is a possible source of dark spots in a white print (this is a feeder on an S3 or S5 but I guess any printer can have similar filament dust after hundreds of hours of printing.

    ultimaker_S3_S5_dirty_feeder.thumb.jpg.8a18dad28ed1d9126a223a9b0724589d.jpg

     

    Although usually I think it is filament that sticks to the nozzle, caramelizes, and then drips into the print.

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    Posted · Weird small hole inside the print

    Hi, i just got some improvement on the Benchy printing. I have done some changes and some improvement on the cooling system as well. What i have done so far:

     

    1. Cleaning the Z axis as you said ( i have not applied the magnalube on the main Z axis yet still waiting for order from amazon to arrive) , just simply cleaning the dirt and debris from the main Z axis and light cleaning on two Z pole.

     

    2. I have tightened the belt, clean the feeder.

     

    3. I have changed the print speed to 40mm/s .

     

    4. I have reduced the retraction length from 7.0mm to 5.0mm and reduced the retraction speed to 20mm/s .

     

    5. More importantly, i added the external desktop fan ( i am not sure but this may have solved the caramelized problem i don't see any caramelized filament anymore.)

     

    Now, the Benchy looks much better than before, less small holes (there are still 2-3 small holes) , the printing looks much smoother even though there are some light strings between the benchy hull. Overall, this print is much better than before. Thank you for your help. I am not sure if there are any thing that i could do to improve this even more. 

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    Posted · Weird small hole inside the print

    All of those ideas look great except for one:

    >reduced the retraction speed to 20mm/s .

     

    I would expect that to make quality worse, not better.  Unless there is something wrong with the feeder.  But I suspect the change in quality is too small to matter

     

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