Issues with printing the last few parts

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This topic contains 38 replies, has 8 voices, and was last updated by  clokisk 1 week, 5 days ago.

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  • #113724

    c_rt_prf
    Participant

    Hello! This is a question related to my 3D printer so I’m sorry if it’s not within the scope of this forum.
    I’ve tried Makerbot support but I’m not getting much help.

    So far I’ve printed 32 of the MPCNC pieces with some occasional issues (I will explain them later) but the prints eventually worked after a couple attempts. I mostly have the longer prints left to do: C-Roller, C-Roller M, XY_C_Burly, Tool_Mount_C_6-32.

    The first problem that I had early on was bed adhesion but I fixed it by increasing the number of external brims and lowering the speed + disabling the fan on the first layer. Changing from hexagonal to linear infill also helped with some other printer issues.

     

    Now onto the 2nd, persistent issue.
    It seems that on the longer prints it gets to a point where the filament begins to under-extrude.
    Always happens at a different Z-height. Most of the time it’s after ~60% but has also happened earlier.

    Hardware/Settings:
    Makerbot Replicator 2 (enclosed)
    Hatchbox 1.75mm PLA
    Retraction distance: 1.3 mm
    Print speed: Solid 90 mm/s | Sparse 80 mm/s | Shells 35 mm/s

    Images: https://imgur.com/a/8p4SYxL

    Changes/inspections I’ve made but did not fix the problem:
    – Was printing @ 230, decreased to 220, 210, and 205 with no improvement
    – Checked hotend fan
    – Replaced SD card
    – Checked tension on filament
    – Replaced nozzle + cleaned old one
    – Re-sliced STLs
    – The print speeds listed above used to be faster but I decreased them with no improvement

    I really want to get this working but the last few days have been very frustrating. I’ve probably “wasted” over 500g of filament 🙁
    Any advice for a beginner? Thanks so much everyone!

    #113741

    Ryan
    Keymaster

    I have no experience with that printer. I can tell you I print at 30-35mm/s maximum. I suggest slowing things wayyyyy down. As you start to consistently get working parts slowing increase each subsequent up 2-3mm/s until you hit another issue than back down a bit. Slower is better for layer adhesion and any underlying printer issues you may or may not have. I think CNC Kitchen did a good video on print speed vs strength.

    • This reply was modified 1 month, 1 week ago by  Ryan.
    • This reply was modified 1 month, 1 week ago by  Ryan.
    1 user thanked author for this post.
    #113768

    c_rt_prf
    Participant

    I have no experience with that printer. I can tell you I print at 30-35mm/s maximum. I suggest slowing things wayyyyy down. As you start to consistently get working parts slowing increase each subsequent up 2-3mm/s until you hit another issue than back down a bit. Slower is better for layer adhesion and any underlying printer issues you may or may not have. I think CNC Kitchen did a good video on print speed vs strength.

    Thanks for the reply!
    I’ll try slowing it down to your recommended speed and let you know how it goes.

    Searching through CNC Kitchen’s channel I coudn’t find one on print speed – only vidoes discussing cooling, temperature, and infill but those are probably beneficial to watch as well.

    #113800

    Jeff
    Participant

    I’ve run into this issue after I’ve built an enclosure for my printer. The extruder motor would slowly heat up over time, and eventually put enough heat into the extruder gears to soften PLA filament. This resulted in severe under extrusion very similar to what I see in your pictures. Sometimes it would recover for some layers and then go back into under extrusion. It does look suspiciously similar to your second picture.

    The issue occurred only with PLA filament and only after 5ish ours of printing.
    I easily solved it by adding fans for air circulation.
    I’m not familiar with your printer, but it is sold with an enclosure right?
    That makes me doubt that this is the issue.
    Does your enclosure have any fans?

    Do you have an option to print with the enclosure open?
    Might be worth a try if you can’t think of anything else that causes this issue.

    • This reply was modified 1 month, 1 week ago by  Jeff.
    #113804

    frosty
    Participant

    What is the exact nature of the extrusion failure? Is your drive gear chewing the filament? Is the extruder skipping steps? Is your filament snagging in the spool? Are your nozzle temps consistent throughout the print?

    Just a general Slicer setting comment: I only see two perimeters on those prints and you’ll probably be happier with three. You could also drop the infill percent a bit and not compromise the strength of the parts to shorten your print times.

    #113811

    c_rt_prf
    Participant

    The issue occurred only with PLA filament and only after 5ish ours of printing.

    I easily solved it by adding fans for air circulation.

    I’m not familiar with your printer, but it is sold with an enclosure right?

    That makes me doubt that this is the issue.

    Does your enclosure have any fans?

    Do you have an option to print with the enclosure open?

    Might be worth a try if you can’t think of anything else that causes this issue.

    The printer has an acrylic front panel, two side panels, and a lid that can all be removed (not 100% sure about the side panels, I’ll have to check when I get home).

    There are only two fans: one for cooling the print and the other for passing air through the heat sink.

     

    What is the exact nature of the extrusion failure? Is your drive gear chewing the filament? Is the extruder skipping steps? Is your filament snagging in the spool? Are your nozzle temps consistent throughout the print?

    Just a general Slicer setting comment: I only see two perimeters on those prints and you’ll probably be happier with three. You could also drop the infill percent a bit and not compromise the strength of the parts to shorten your print times.

    I’m not 100% sure what the exact cause of the failure is. I’m certainly not an expert and I’m going off things that I’ve read online.
    When I pull out the filament I’m not seeing any rough gashes on it, no clicking from the extruder motor, and no tangling in the spool. As for the temperature, I’d say it fluctuates +/- 1 or 2 degrees during the print.

    #113827

    frosty
    Participant

    When I pull out the filament I’m not seeing any rough gashes on it, no clicking from the extruder motor, and no tangling in the spool.

    If the extruder was clogged you would hear your stepper motor missing steps (clicking sound). If something was killing the heat to the hotend and the extruder was shut down for mintemp reasons you would see that in a temperature graph. If it was grinding filament and not extruding you would see the spot that was ground off. Given all of that I suspect there may be something weird going on with the firmware or the driver board.

    Are you using up to date firmware? Is the failure repeatable? (that is, if you print the same model does it fail in the same place). If it is a consistent failure then you are probably hitting some sort of firmware bug.

    When the extruder stops again, check to see whether the extruder motor is turning at all (or is, in fact, even energized. You could be having an intermittent failure of your wiring or the stepper driver.

    #113882

    c_rt_prf
    Participant

    When I pull out the filament I’m not seeing any rough gashes on it, no clicking from the extruder motor, and no tangling in the spool.

    If the extruder was clogged you would hear your stepper motor missing steps (clicking sound). If something was killing the heat to the hotend and the extruder was shut down for mintemp reasons you would see that in a temperature graph. If it was grinding filament and not extruding you would see the spot that was ground off. Given all of that I suspect there may be something weird going on with the firmware or the driver board.

    Are you using up to date firmware? Is the failure repeatable? (that is, if you print the same model does it fail in the same place). If it is a consistent failure then you are probably hitting some sort of firmware bug.

    When the extruder stops again, check to see whether the extruder motor is turning at all (or is, in fact, even energized. You could be having an intermittent failure of your wiring or the stepper driver.

    Yes the firmware is up to date.
    The failure always occurs at a different Z height and on different STLs.

    #114108

    c_rt_prf
    Participant

    Thanks again for the tips everyone!

    I started a new print last night with these changes:
    – All print speeds @ 40 mm/s
    – Removed all enclosure pieces
    – Added a large fan to blow air through the printer (I think this caused very poor bed adhesion, but I caught the part lifting up early on in the print so I taped the edges down, lol)
    – 3 shells (not necessary but it definitely feels a lot more sturdy)

    I should have tested the first three changes independently, but I only had enough filament to do one more part.
    Another spool is on the way, so pretty soon I’ll find out if I was just lucky with this last print or these changes were the real solution! 🙂

    #114333

    c_rt_prf
    Participant

    Well, I printed the C-RollerM part with the exact same method (except I slowed down printing of the first layer) and the problem has returned. 🙁

     

     

    Attachments:
    #114335

    Barry
    Participant

    Looks like it’s either not hot enough, or a clogged nozzle.

    #114338

    c_rt_prf
    Participant

    Looks like it’s either not hot enough, or a clogged nozzle.

    It was another brand new nozzle and I’ve been having this problem with PLA at all of these temperatures: 220, 215, 210, and 205 degrees.

     

    #114390

    Ryan
    Keymaster

    I think you have an extruder issue as well. Maybe some pictures of your exrtuder and we can spot something. But if it is an all metal hotend you might ant to try PETG instead of PLA to see if it is heat creep.

    #114401

    Barry
    Participant

    My pla prints at 225c.  Your spool should have recommended temps.

    #114403

    c_rt_prf
    Participant

    I think you have an extruder issue as well. Maybe some pictures of your exrtuder and we can spot something. But if it is an all metal hotend you might ant to try PETG instead of PLA to see if it is heat creep.

    I’ll try to take some pictures tonight. I can disassemble part of it to get some clearer pics.

    My pla prints at 225c. Your spool should have recommended temps.

    My Hatchbox PLA recommends 180 – 210

    #114490

    Ryan
    Keymaster

    I used to print hatchbox at 198.  In your case I would start at 185-195 and take away that large fan. If you are having heat creep issues lower print temps will help, also make sure your extruder fan (not print fan) is functional and not clogged with lint/dust.

    1 user thanked author for this post.
    #114496

    c_rt_prf
    Participant

    I used to print hatchbox at 198. In your case I would start at 185-195 and take away that large fan. If you are having heat creep issues lower print temps will help, also make sure your extruder fan (not print fan) is functional and not clogged with lint/dust.

    Thanks again for your continued support with this, I know it’s not 100% MPCNC related and more of a printer issue but I really appreciate your time.
    I didn’t get around to disassembling the extruder to take pictures, but I was able to successfully print one of the C-Roller M parts yesterday.

    I’ve found somewhat of a “sweet spot” by running the 3D printer without the enclosure panels and turning on the large fan after 30-60 minutes. On the second C-Roller M this morning, I must have waited too long to turn on the fan and the filament started to under-extrude again.

    I’ll try your suggested temperature tonight

    #114528

    Barry
    Participant

    Okay, that sounds like your extruder fan isn’t working.  That would cause these issues.  The fan that blows across the hot end should always be running, this is different than the part cooling fan, which for pla also should be running most of the time, just not as hard.

    #114537

    c_rt_prf
    Participant

    I used to print hatchbox at 198. In your case I would start at 185-195 and take away that large fan. If you are having heat creep issues lower print temps will help, also make sure your extruder fan (not print fan) is functional and not clogged with lint/dust.

    I printed C-Roller M last night @ 190 degrees with the large fan turned off and I did not have any extrusion issues! 🙂
    Still some problems with bed adhesion but I taped down all of the external brims after I caught them starting to lift up.

    Is it better to use rafts for these parts? I’ve been using 7 to 9 external brims.

    Okay, that sounds like your extruder fan isn’t working. That would cause these issues. The fan that blows across the hot end should always be running, this is different than the part cooling fan, which for pla also should be running most of the time, just not as hard.

    I was constantly checking on the printer during the build and I never noticed the fan stopping or slowing down.
    The fan + heat sink was recently cleaned and it is dust-free.

    #114694

    c_rt_prf
    Participant

    Lol just when I thought it was printing perfectly another problem came up.
    I’ve never seen anything like this before, and it was so close to completion 🙁

     

    Attachments:
    #114699

    Bill
    Participant

    That last one is mechanical. 🙂 Your head got caught on something and slipped the X axis by a bunch, then continued as if nothing had happened.

    Give us pictures of your print head and extruder from as many angles as you can. There’s got to be something going on there that shows as under extrusion.

    1 user thanked author for this post.
    #114749

    c_rt_prf
    Participant

    That last one is mechanical. 🙂 Your head got caught on something and slipped the X axis by a bunch, then continued as if nothing had happened.

    Give us pictures of your print head and extruder from as many angles as you can. There’s got to be something going on there that shows as under extrusion.

    OK, here are some pictures: https://imgur.com/a/9hxP8l8
    I took some other photos of the fan/heat sink if there are some other issues, but I think they are clean enough. The hot end looks pretty gross from underneath, but I assure you that the photos make it look worse 🙂

    I’ve now printed two larger parts after reducing my PLA temperature without the under-extrusion problem (one being this XY_C_Burly piece). I’m fairly confident that it’s solved, but now this new issue has popped up :\

    #114774

    Ryan
    Keymaster

    I see two things. Your heater cartridge seems to be hanging out really far, make sure it is centered and in there snug. Your nozzle is out really far.You should only have about a credit card gap from the nozzle shoulder to the block, for there the throat should be tight against the nozzle. That might give you a tiny bit more room to give the heat break a better chance.

    1 user thanked author for this post.
    #114777

    c_rt_prf
    Participant

    I see two things. Your heater cartridge seems to be hanging out really far, make sure it is centered and in there snug. Your nozzle is out really far.You should only have about a credit card gap from the nozzle shoulder to the block, for there the throat should be tight against the nozzle. That might give you a tiny bit more room to give the heat break a better chance.

    Thanks! I will attempt those fixes tonight.
    Am I correct to guess that these are both fixes that will help with the temperature and reliability of printing, but not really combat the extreme layer shift that I experienced? I’m hoping that was just a bit of bad luck, as I’ve never had anything like that happen on one of my prints.

    #114783

    Bill
    Participant

    Yep, those fixes deal with the heat/cool characteristics of your hot end. The fan is constantly blowing on the heat sink, which cools the mounting block that the hot end throat is screwed through. If you have any gap between the nozzle and the throat you will clog due to plastic oozing into that gap. If the nozzle is too far from the heat block as Ryan suggests the nozzle tip will be cooler than the heat block and the tip will tend to clog. Any clog shows as under extrusion.

    It’s a bit of a challenge to get everything just right. Screw the throat into the mounting block as far as it will go without hitting anything in the feed mechanism and lock it in place with a thin nut. Next screw a nozzle into the heat block so only a millimeter or less is away from the block surface. Then screw the heat block/nozzle onto the throat until the throat seats with the nozzle. Finally take the system up to temperature and reach in with a wrench and tighten the nozzle. When everything heats up things will expand enough that you’ll get another rotation or two on the nozzle to get it seated again. Once it’s fully seated it can still cool down without causing issues and won’t generate a gap when heated again.

    You can still end up non-optimal if your throat is too long or too short for your hot end design, but they usually come shipped setup with the right length. Measure your old one before buying a replacement though! It’s easy to get them the wrong length…

    1 user thanked author for this post.
    #114817

    c_rt_prf
    Participant

    OK, I just disassembled the extruder and I’m not sure about the results.

    1. The heater cartridge is actually in as far as it can go. The end with the protruding wires has a larger diameter that prevents it from going any further.
    2. I made some adjustments and got the nozzle to screw down MAYBE 1.5mm -2.5mm more

    Safe to try another print without the kapton tape? It pretty much crumbled away when I removed it 😉

    Attachments:
    #114819

    frosty
    Participant

    You’re fine without then kapton. Your hotend temp might oscillate a bit more because the PID loop is not as well tuned, but you should be fine.

    You’ll have to adjust you Z0 down a little bit because you shortened things up (not sure the procedure for your printer).

    1 user thanked author for this post.
    #114868

    c_rt_prf
    Participant

    OK, some better results with printing.
    No under-extrusion and no layer shift!

    Despite taping down all of the external brims, the edges lifted up somewhat.
    Is this good enough to use? Should I maybe try a raft for my next print?

    Thanks again! This is frustrating but rewarding whenever something works 🙂

    #114873

    frosty
    Participant

    Compare the horizontal hole locations against another part that didn’t lift. If the bearing will be in the correct spot the part should work fine.

    What are you using for a build-plate? What (if anything) are you putting on the build plate to help with adhesion? What bed temperature are you using? How level is your bed? What layer height are you using for the first layer?

    If all the above is in order something else you may try is to delay the part-cooling fan a little longer. My fan speed is 0, 33,67, and 100% on the first four layers  (vs. the standard 0, 100%). I also use a pretty warm bed (60-65C), print on glass and use hairspray to help with adhesion.

    #114937

    c_rt_prf
    Participant

    I tried posting this earlier but it wasn’t showing up. Spam filter maybe?

    What are you using for a build-plate? What (if anything) are you putting on the build plate to help with adhesion? What bed temperature are you using? How level is your bed? What layer height are you using for the first layer?

    The build surface has a sheet of 3D printing surface from Buildtak.
    I am printing with 9 external brims and after the printer has completed the the first layer, I’m putting blue tape down to help it stay down (which I guess didn’t work very well on my last print).
    The filament is PLA without a heated bed and I level the bed after 1-2 prints.
    “Floor solid thickness” is 0.05mm and “Floor surface thickness” is 0.25mm.

    If all the above is in order something else you may try is to delay the part-cooling fan a little longer. My fan speed is 0, 33,67, and 100% on the first four layers (vs. the standard 0, 100%). I also use a pretty warm bed (60-65C), print on glass and use hairspray to help with adhesion.

    I have the fan at 0% for the first layer with the print speed of 12mm/s

     

    I might try printing with a raft tomorrow with a 5mm margin.

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