First layer sticking issues…

New Home Forum Milled Printed 3D Printer -MP3DP Advice – MP3DP First layer sticking issues…

This topic contains 24 replies, has 8 voices, and was last updated by  Jeff 3 weeks, 6 days ago.

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  • #94316

    Jeff
    Participant

    So, I’m still trying to dial my printer in and am having issues with the first layer sticking.  On short lines it sticks fine, but on long lines is peels up and scallops.  I’ve tried various temps on the extruder and the heated bed, replaced the glass/PEI with just a cheapo glass piece and am still having the same problem.  I’ve Zero’d out my Z with the paper trick numerous times and have adjusted my print start both up and down in the Z direction.  I just can’t dial this thing in.  Any ideas since I am totally out of them?  My next idea is to get a BLTouch to zero out across the bed but I don’t think that’s the issue (but I could be wrong).

    On small parts, its fine – it’s just on bigger parts with long, unbroken extrusion runs.  It almost seems like the extruder itself as it goes past an already put down line is somehow sucking up the line it had just put down.  Once about 4-5 lines get sucked up, the next line lays down ok and then the process repeats itself.  Too hot maybe?  I’ve been turning my temps up, maybe I should try turning them down?  In the pic below, the temps were at 77 bed and 209 extruder at the time when I stopped the print (I stopped it on the long scalloped section).  I had started this print at 73 and 205 and turned them up a degree as I saw the problem occurring.  I let it make a few more passes to see if the problem went away and when it didn’t I turned them up another degree.  Maybe I should be turning them down?  I’m just at a loss at this point.

    #94319

    Ryan
    Keymaster

    I’ve Zero’d out my Z with the paper trick numerous times and have adjusted my print start both up and down in the Z direction. I just can’t dial this thing in. Any ideas since I am totally out of them? My next idea is to get a BLTouch to zero out across the bed but I don’t think that’s the issue (but I could be wrong).

    The paper is for leveling. Same as the BL Touch. The pictures look level.

    As for Zero, the pictures look well placed. Spaces between lines would be too far away and a rough surface would be to close. Anything in between that should work fine.

    I separate those two things because they are very different, but both of yours look perfect.

     

    That leaves surface, temp, and speed.

    You do not mention filament type (chemistry)? First layer speed? Print fan?

     

    #94321

    Jeff
    Participant

    I’m using Hatchbox PLA (it’s all I have).  My speeds are the ones that you give as examples on the extruder page.  Print fan is Not on for the first layer (I have it come on with other layers).  I’m running another test right now using all the default settings that you list for Slic3r and will see how that turns out.  I’ve monkeyed around with enough stuff that I want to go back to a baseline and start from there.

    Thanks for responding and letting me know that my Z seems to be fine and it’s a slic3r issue more then anything.

    The reason I was leaning towards some kinda temp issue, is that my perimeters Always stick just fine, it’s only when it starts to fill in long lines between perimeters (or other features) that I see the scalloping.

    #94322

    Aaryn
    Participant

    Could I see the underside of these prints?  Also a video of this happening might be helpful. Can you test to see if there is any air moving across the print as it is doing the first few layers. You want to make sure there is 0 air flow until you are up a few layers. Maybe tape a tiny string or something near the nozzle to see if it moves in a draft or is still.

    I agree from this picture it “looks” like it is level and at a good Z height. What filament type and brand is this?  Do you have any others to test?  Have you cleaned the bed with isopropyl?  Any oil from hands can cause spots where the bed doesn’t stick.

    Have you tried printing the same part on a different part of the bed?  Is it always peeling up on the same part of the print or the same spot on the bed?

    #94323

    Jeff
    Participant

    So, in my new test with all of the default settings, I’m getting the same problem but a little worse.  I clean the glass between every print with Denatured Alcohol to remove any oils.  I have moved to other areas of the bed and the same thing happening.

    Here are a couple of pics of the bottom of the print and a couple videos of another print I just did.

    #94328

    Aaryn
    Participant

    Great pictures and video. The underside looks good in the first two. The third picture looks like there isn’t enough actual surface contact. Meaning you can see that the round bead is only partially smashed flat against the glass. So I would suggest lowing the z a little to smash that down a little more. You want the bottom to be about 95 % in contact with the bed.

    Onto the videos. Great videos very helpful. It clearly doesn’t get enough adhesion to the bed to let it stick in the first place. So we know it isn’t a problem where it lays down a good bead then comes along later and knocks it loose or something. So we need to improve the actual adhesion when it touches the bed.

    Try the following.

    • lower the Z a bit to smear the bead into more contact with the bed.
    • Try lowering the bed temperature. It may be so hot that the filament melts right off of it. Try this in increments of about 3 degrees. Go as low as 50 and see if it makes a difference.
    • Check for air flow. I have seen kind of curling up when air is flowing over the print. It causes the filament to cool on top faster than the bottom so it curls up.  We have seen a case or two where the cooling fins on the hot end cooler are pointing the wrong direction. So instead of blowing air out the sides it was blowing air up and down causing similar adhesion issues. (Kelly did you ever fix that or are you still using the tape to block it?)

     

    We will will get this figured out. One step at a time.

    #94329

    thesfreader
    Participant

    I would also have suggested lowering the bed temp (Mine is around 60C)

     

    We have seen a case or two where the cooling fins on the hot end cooler are pointing the wrong direction. So instead of blowing air out the sides it was blowing air up and down causing similar adhesion issues. (Kelly did you ever fix that or are you still using the tape to block it?)

    Good one !

    #94330

    MegaDad3D
    Participant

    What I see is that the adjacent previous pass is pulling up the new pass. I don’t see the adhesion issue on the thinner strands or where there is more time between passes for the newly extruded filament to cool. Based on that, I’d look at the factors that affect the cooling of the prior extrusion, particularly bed temperature and cooling fan. I think Aaron’s comment (quoted by thesfreader) is a reasonable place to start.

    #94331

    MegaDad3D
    Participant

    What I see is that the adjacent previous pass is pulling up the new pass. I don’t see the adhesion issue on the thinner strands or where there is more time between passes for the newly extruded filament to cool. Based on that, I’d look at the factors that affect the cooling of the prior extrusion, particularly bed temperature and cooling fan. I think Aaron’s comment (quoted by thesfreader) is a reasonable place to start.

    #94335

    Ryan
    Keymaster

    That first layer looks too fast. I print at 30-35mm/s and I have the first layer set to 50% speed, no fan until layer 3-4 (not a big deal just not layer 1 for sure.

    Yup a tiny bit less gap would help a bit.

    I have my bed at 63C first layer a few less after that.

    Agree with all of the above, clean bed, I have mentioned it before somewhere but you might want to try a magic eraser with Windex for a first real good scrub then just alcohol after that. On PEI I do the magic eraser thing about once a year.

    You are really really close, for some that first layer really is a killer but I promise you are close. What you are seeing used to be acceptable a few years ago, not anymore. You can get it really nice now.

    #94339

    Jeff
    Participant

    Thanks for all the input everyone!  I’m off to have family dinner at my mother’s house now but will put these suggestions to work this evening and will let you know how it goes.

    Stay tuned…  lol…

    #94343

    Kelly D
    Participant

    I use isopropyl alcohol to clean up but had been using the 70% stuff and getting bad scalloping. Switching to the 95 percent (or whatever it is) seemed to fix that part of my puzzle. Switching to glass has proven to be the ultimate win for me but you’re already there.

    #94345

    Jamie
    Participant

    I had this same issue a few months ago.

    On this dinosaur I didn’t catch it at the time, but later I looked closely and saw exactly the same thing as in your video.

    dinosaur_bottom

    One thing to check is the height of your first layer.  Some slicers have an option to make the first layer thicker, and if your layer heights are a bit thick to begin with, the first layer height can begin to approach your nozzle size.  In such a case the extruded plastic is just barely smashed against the bed.  It’s a long shot but if your first layer multiple is say 150%, then try setting it back to 100%.

    #94376

    Jeff
    Participant

    To answer a few questions, I’m using a 0.4mm tip and here are my settings:

    layer
    speed
    temp

    #94382

    Ryan
    Keymaster

    Hmmm, I don;t think it matters much on the first layer but I am using 218 (on all layers) for my PLA I think it was 213 when I used hatchbox, but I know it still works as I printed a roll the other day.

    #94384

    Jamie
    Participant

    I would venture that the first-layer height of 0.32 is pushing it for a 0.40 mm nozzle.  If it were me, decreasing that one value to 0.25 or less would be the first thing I would try.

    #94385

    Jeff
    Participant

    So, here is my latest test print – 75mm square, 1 layer height with the settings I posted above but with my temps set to 65 bed and 200 filament.  It definitely is better but still not where I want it to be.  The first pic is the top and the second is the bottom (while the print is still on the glass plate).  In the second pic, ignore that strange whitish spot, it’s actually a small chip in the bottom of the glass (what do you expect from a Walmart 8×10 picture from that cost less then $2)…

    #94388

    Ryan
    Keymaster

    Is that just plain glass? No glue, hairspray, or anything?

    #94389

    Jeff
    Participant

    Is that just plain glass? No glue, hairspray, or anything?

    Yup, nothing on it. Just wiped down with denatured alcohol and then printed.

    I have a PEI sheet on a Borosilicate Glass plate but I swapped it out for this cheapy because I noticed that the PEI has very small “bubbles” between it and parts of the glass – at least that’s what it looks like,  not total adhesion (I think).

    #94392

    Ryan
    Keymaster

    Shoot I have no idea how much of my advice is valid. I use PEI, if you end up switching back tiny bubbles are okay, some don’t even need to heat it to use it with PLA.

    #94393

    Jeff
    Participant

    I’ll have to try my PEI again with the lower temps. I wonder if I was just running things too hot?  I’ve also noticed that the bottom of my first layer never has the same “striped” appearance that your prints do (comparing my prints to the MP3DP printed parts I bought from you).

    #94401

    Aaryn
    Participant

    I know you won’t like this but now you are a little too close to the bed. You can tell two ways.  The top picture shows that the filament smashed out hit the bed then oozed out to the sides and up the side of the nozzle.  It leaves behind those thin razor like ridges as the nozzle is sculpting the plastic that goes up.  Then from underneath you can see that the first bead smashed flat and was in the way of the next bead.  So it isn’t the clean lines.  They are overlapping and jagged.  So you need to go up just a tiny bit.

    #94413

    Jeff
    Participant

    I know you won’t like this but…

    The way I see it, any advice/info is useful and helpful and I appreciate it!  I did lower my Z for this print, I’ll raise it up again for the next test.  Thanks Aaryn!

    #94435

    Dui, ni shuo de dui
    Participant

    2 possible causes:

    -glass is either too clean (I mean that there might be some spots where it is microscopically too flat for stuff to correctly stick), or there are some greasy spots on it. I recommend you to use glue stick, it costs close to nothing and gives nice results. Put the glue just right before the  autolevel (so around 1 minute before it actually prints), it works better when it is not completely dry but just a bit tacky. No need to put 25 layers, just one or two is fine.

    What I found out is that the dirtier my glass plate is, the better the adhesion. Except of course if there is any kind of oil/grease on it. The only problem with the glass being dirty is that, at some point, it will impact the looks of the first layer.

    To clean the glass, I only use water and soap. I never used any alcohol on it, don’t think it hurts but water and soap are just fine. Then, dry it thouroughly with a paper tissue (this is important) and avoid touching the glass with your fingers (important too)

    -An other possibility is that you are over extruding a little or that the  diameter of your nozzle is slightly larger in reality than what you’ve set in the slicer, or that your step per mm is slightly incorrect. In which case, when printing long lines, the extruder will tend to print wider lines than necessary, which will lead to the nozzle printing over already printed lines. This doesn’t cause much problem when the lines are short, so it usually doesn’t affect the small parts, but it becomes very important when you print large infill areas, because the nozzle will tend to move around, hit already printed stuff and sometimes print on already existing material, sometimes being pushed and printing again on glass. It leaves horrible results just like the ones you got on your square and sometimes will lead to bubbles or spots where it won’t stick. It is easy to spot on big nozzles because you can see it clearly, but much harder to see with smaller nozzles.

    I’m 99% sure this is over extrusion, but anyway the first possibility is very easy to check so I recommend you to start with this one (careful cleaning + glue stick). This should at least solve the issues of adhesion, but I suspect you will still have visually unappealing results. So to fix this problem, try to increase the extrusion diameter in the software by maybe 10-20% (from 0.4mm to 0.44 or 0.46) and see if it improves this specific issue. This is not a fix, just a way to diagnose. In which case, you’ll have to tweak either your extruder step per mm, measure your actual extrusion diameter (the diameter of the filament that is actually coming out from the nozzle: measure it with good calipers at different locations) or correct your X-Y steps per mm. Some slicers offer the possibility to set different nozzle diameters for the infill and the perimeters, in which case you’re golden. That’s how I solved the same problem you have on my machine, I’ve set 1.2mm for the perimeters and 1.3 mm for the infill and it did the trick. I finally narrowed it down to a slight over extrusion and corrected my extrusion factor, now the problem is gone.

    From what I see of the pictures my vote would go for the over extrusion.

    Do not touch your Z height, closer will create elephant foot issues and you will have even more problems with over extrusion. Higher just won’t stick correctly. I don’t recommend to set a different height on the first layer from whatever height you are printing the others layers. If your printer is properly tuned those values should be the same, otherwise you’re using a band aid to poorly solve deeper issues which will be noticeable elsewhere in your prints.

    #94459

    Jeff
    Participant

    Thanks for the help Dui!  Glue stick is easy, I have them already (young kids art projects) so I will give that a shot.

    Over extrusion is something I need to check because I have been seeing what you are describing, it looking like it’s printing over itself.  I have calipers, not good one, but better then nothing.  I will give it a shot at measuring.  Seems like I’m 90-95% of the way there,  it those few extra percentage points take a lot of testing and tweaking to get just right.

    Now, if only my pesky job didn’t get in the way, I would have more time to play with this.  Lol.

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