Printing weirdness continues…

New Home Forum Milled Printed 3D Printer -MP3DP Troubleshooting – MP3DP Printing weirdness continues…

This topic contains 86 replies, has 7 voices, and was last updated by  Jeff 2 months, 2 weeks ago.

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  • #89721

    Jeff
    Participant

    So I’ve had a few problems that I’ve been able to fix:

    1.  Forgot to tighten the Y_Bed_Bearing screws.
      1. Fixed by tightening them.
    2. Extruder tip was too far out of the heating element.
      1. Fixed by putting in a couple of washers between the bottom of the tension stack and the heater.  This let me thread the tip tight against the throat while having it sit fully into the heater (I do need to check this though).
    3. Printing via USB cable instead of off of the LCD.
      1. Fixed by printing off the LCD now.
    4. Springs holding the heated bed up were too long.
      1. Replaced the  long springs with the shorter ones that Ryan sells and tightened them down till there is almost no “spring” left in them – just enough for me to level the bed, which I did again.

    It looks like fixing these has helped some but I’m still having issues and I just can’t figure out what is wrong.  There is still something going on with the bed – it almost seems like it is “hopping” during rapid movements; and it’s not just the heated bed – but actually looks like the Y Plate is moving up and down during rapid movements.

    I’ve also check to make sure it’s extruding the correct amount of filament and as far as I’m able to measure with my calipers it appears to be extruding 100mm when that is what it is supposed to extrude.

    I was also having it miss steps or the belts slipping, I’m not sure which.  I tightened both the Y and X axis belts 2 clicks on the zip ties to see if that would help.  I’m not sure it has because of the other issues.

    I took a video and posted to YouTube https://youtu.be/QI2FuoQQx3k so hopefully someone can see what I’m doing wrong.  I’m using the slic3r settings that Ryan posts on the Extruder Assembly page.

    I hope someone can help me figure this out.  I know it’s something I’ve done wrong with my build but I’m totally out of my element here and “research” can only get you so far.  If I could, I would fly Ryan out here to fix it!  lol.

    Edit:  In going back and looking at the video myself, it looks like the bed is doing that bouncing when the print head is going over and area on the print that has built up too much PLA and is too high on the Z Axis and the head is bumping over it.  I think the bouncing in the bed is more of a symptom of whatever problem I’m having then the cause (but I’m not sure).  The test cubes I’ve been printing out aren’t that good – they aren’t terrible, just not what they should be.

    #89723

    Ryan
    Keymaster

    I can’t find your other thread but now the bed is moving because of the extruder rubbing the print. I can’t see your Z rods, but try moving the Z axis 100mm and make sure it is exactly 100mm, actually test every axis.

    #89727

    Jeffeb3
    Participant

    Can you do two favors for me?

    1) Can you post in the same topic each time? I am worried I’ll miss something, and it’s hard for me to review the progress.
    2) Can you post a picture of the washer/hotend situation you’re talking about?

    Ryan’s suggestion about the Z axis is good advice. It should move 100mm when you ask it to move 100mm.

    #89729

    Jeff
    Participant

    Thanks guys.  I wasn’t sure if new threads were better then one continuous one, but I guess since it’s all the same issue, then 1 thread makes sense.

    I will try to get some pics of the hot end up soon.

    Good suggestion Ryan, I never thought of making sure it was moving the amount I was telling it to.  I will test that soon as well – once my kids let me.  lol.

    #89876

    Jeff
    Participant

    I just did some measurements with my digital calipers to test movement distances.

    I made repeated measurements to try to get an average just because are variables in me holding the calipers and the calipers themselves (Harbor Freight – Mitutoyo calipers are a little more expensive that what I want to spend on something I don’t use all that much, but I am starting to use them more so it might be worth the investment).  I used Repetier and moved in 50mm increments for all axis because that’s the largest it can do without me sending Gcode commands (it’s just easier to hit a button each time to repeat the tests).

    My Z (on both sides) seems to be moving an average of 50.02mm in both directions on both sides.
    My Y Positive averages out to 49.94mm and my Y Negative is 49.82mm
    My X Positive is 49.75mm and X Negative is 49.71mm

    My Z seems to be the most accurate whereas my X and Y are definitely not.  My belts are pretty darn tight without being guitar strings.  I’m definitely at a loss as to what is going on.  I’m thinking of running a 200mm 1 layer square test to see what that does but my first layer is still having problems sticking.  I’m not sure which problem to tackle first – the stepper motor movement, the layer not sticking or working on getting my bed as level as possible.

    I wish I had a way to more accurately test my movements other then just holding my calipers steady and using the printer itself as a stable rest for them.  An accurate laser measure would be awesome.  Lol.

    Anyway – any thoughts as to what my next steps should be?

    #89877

    Jeff
    Participant

    Jeffe – here is the best pic I can get of the washers. Basically I just put 2 washers between the heater and the bottom of the cooling stack to build up a little space so my extruder tip could screw further into the hot end. Before, the throat was taking up too much of the heater threads and the extruder  wasn’t really in the heater itself so I think my filament was cooling before it even hit the bed.

    #89879

    Bill
    Participant

    Here is a pic of the standard MK8 extruder:

    MK8 Extruder

    Notice the gap between the hot end and the extruder? That’s what the nut is for to hold them apart. If you have your hot end too close to the body of the extruder it likely won’t cool correctly.

    Attachments:
    #89884

    Jeffeb3
    Participant

    Those numbers are all close enough that the steops are probably right. I don’t “calibrate” the steps/mm on XYZ. You’re just looking for obvious problems like 20% off.

    You should have a gap between the heating block (which is wrapped in the kapton tape) and the orange cooling block. Just take those washers out and leave the gap there. The cold side keeps the filament hard enough to grip. The hot side melts it just past melted. The gap is important to keep those two things separate temperature wise. There is a nut that keeps it at the right height.

    #89885

    Bill
    Participant

    Heheh, beat you Heffe! 🙂

    #89888

    Jeffeb3
    Participant

    I’m not sure which problem to tackle first – the stepper motor movement, the layer not sticking or working on getting my bed as level as possible.

    Get the bed adhesion enough to print the cube, then focus on the cube. After the first 2-3 layers, that thing should be laying down smooth, even thickness layers, and even if there’s a little bumpiness on the sides, it should be 10x smoother than what you showed last time. The nozzle shouldn’t be bumping or pushing down on the print either. None of that is due to the bed.

    It’s a little bit of cat and mouse, because if you’re having temperature, extrusion, or mechanical problems, you can’t finely tune the bed. If your prints aren’t sticking, then you can’t work on that other stuff. If your temps get too low, then the extruder has to work harder, if the temps are too high, then the plastic can get sticky and droopy. It’s not easy to isolate, I’m afraid.

    A couple more questions, and comments:
    – How many perimeters and what infill are you using with the calibration cube? I would start with 3 perimeters and 20% infill. 3-6 top/bottom layers is fine. 3 might be better since it’s so out of whack. 100% infill is actually pretty hard to do, since it requires all the plastic being in exactly the right place.
    – Start another cube, watch the first solid layers really closely and look for things snowballing out of control. Those bumps in that video are pretty big. The nozzle was jumping pretty good, which isn’t a <1% Z motion problem.

    #89889

    Jeff
    Participant

    Lol – I LOVE these forums – guys fighting over answering questions is awesome!!   I will take the washers out.  I just put them there because I’m kinda anal and the gap was bothering me.  lol.

    I’m glad to know my steppers are ok and the variance is within spec…  Now if I could just get the damn thing to print properly.  lol.

    Any advice on bed leveling?  I’ve heard mention of the paper trick and I’m guessing it’s just leaving a small enough gap between the extruder tip and the bed that a piece of paper can be pulled out but with friction on it?

    Also, in the video I posted – was all the noise and racket coming from the printer “normal”?  I know some of that noise was from my power supply not being firmly attached to the printer and it was rattling around (I have to secure it better) but it also sounds like some of it is coming from the bed.  I’m also going to look into that entire assembly again and make sure I didn’t forgot to tighten anything else.

    Thanks again guys!!

    #89892

    Bill
    Participant

    You should use the nut, or a replacement if yours didn’t come with one (6mmx1 maybe?). Without it if you don’t have your wiring really solid it can move the hot end a bit, and any movement turns into clogs because the molten plastic fills in the gap between throat and nozzle.

    The paper trick is just as you visualize. It gives you a known good level, albeit at the paper thickness. Often suggested is to use a business card mostly because they are stiffer and won’t have as much tendency to bunch up if you’re pushing it instead of pulling. I use grocery store cash register receipts, because they are really thin, which gets me closer to the ideal 0.00mm clearance. They are flimsy though so you have to be more deft in moving them around. Remember with the three point leveling you do front to back first, then side to side.

    #89902

    BT
    Participant

    The noise sounds typical of 3D printers.  What did you end up for the various feedrates, i.e., first layer speeds and later layer speeds, perimeter speeds, etc.  The first layer wasn’t on the video, but this short video looked like you have the hotend moving at a good clip.  You should also check your accelerations as that can also affect corner adhesion on the first layer (you don’t want them too high, but also not too low – you’re looking for the goldilocks of accelerations but it’s a fairly big range for just right).

    #89937

    Jeff
    Participant

    Thanks for all the input.  I will have to look at what I had for setting but I’m pretty sure I have slic3r setup the way Ryan suggests on the bottom of this page: https://www.v1engineering.com/import-extruder/ but I’m wondering if those are best for the MPCNC and not the MP3DP?

    Another question I have – what should I be using to grease the smooth rods and the T8 Leadscrews with?

    #89939

    Jeffeb3
    Participant

    Don’t grease the rods. The bearings have grease. For tge threaded rod, I used bicycle grease.

    #89940

    Jeff
    Participant

    Thanks yet again Jeffe!

    #89945

    Aaryn
    Participant

    ad to know my steppers are ok and the variance is within spec…  Now if I could just get the damn thing to print properly.  lol. Any advice on bed leveling?  I’ve heard mention of the paper trick and I’m guessing it’s just leaving a small enough gap between the extruder tip and the bed that a piece of paper can be pulled out but with friction on it?

    I don’t know if it is cheaper or not but I use garage door screw grease.

    #89986

    Bill
    Participant

    And I use white lithium grease… To each their own, I guess. It’s more ‘what is handy’ than ‘what is best’. 🙂

    #89989

    Jeffeb3
    Participant

    And I use white lithium grease… To each their own, I guess. It’s more ‘what is handy’ than ‘what is best’. ?

    I think this is what my bike grease is, but I bought it from a bike shop that was close by.

    #89991

    Jeff
    Participant

    Lol.  I have all different kinds of grease lying around.  I guess I will grab the white lithium and use that – since it’s what I used on my LR anyway.

    #90054

    Jeff
    Participant

    I was wondering about the bed adhesion so I wanted to measure the temp of the actual aluminum heating bed (with it’s thermistor) and also measure the print surface (painters tape on my glass plate).

    Interesting finding.  The heating bed got to 65c fairly quickly (according to the LCD), but even 5 minutes after that the glass tape hasn’t even reach 60c.  Right now it’s hovering around 59c.  I’m measuring the top of the glass bed (with the painters tape on it) by taping a thermistor to it with thermal tape.  I quickly programmed my Arduino Uno to read the temp from this thermistor and this is what the log monitor is showing.  I was going to use my infrared thermometer but couldn’t find it when I got home so the Arduino was a good second choice.  I think it’s actually better because it is a constant reading sampled every second with the script I am running.

    Now 10 minutes later and its still sitting around 59 degrees.  I don’t think those 6-7 degrees will make a difference, it’s just an interesting finding.

    Just to compare apples to apples, I then taped the Arduino thermistor directly to my aluminum heating plate and it also strangely showed the same 58-59 reading!  So, either the top of the plate isn’t as hot as the bottom (where the plates own thermistor is) or one of the thermistors is reporting bad info.  The LCD is still showing 65 and my Arduino is showing 59.

    I guess the only way to try to narrow down were the error is would be to measure a temperature of a known value.  I’m thinking I am going to stick the thermistor hooked up to my Arduino into a pot of boiling water to see what it shows.  Lol.  Since I am only about 450feet above sea level at my house, then it should report back very closely to 100 degrees C.

    I guess all this really doesn’t matter to my printing issues, it’s just a fun squirrel to chase.  Lol.

    Too many squirrels, too little time!

    #90142

    Jeff
    Participant

    Sometimes my own idiocy amazing me…  I went to fix my hot end this morning by removing the washers and adding a space like the pic that Bill posted shows.  Anyway, I couldn’t get the nozzle off so I figured something was wrong.  Glad I have jewelers glasses for this stuff!  Looking at it closer, filament had oozed out in places it shouldn’t be, I didn’t have the throat in contact with the nozzle.  So, I had to heat the extruded up to take it apart, that was “fun”.  I got it apart and then had to run an M6x1 .0 tap through the hot end in order to clean out the shmoo.  I have it cleaned out but had to take my son to school before I could put it back together.  So, once I get home from breakfast I’ll be able to put it back together and start testing again.

    First step, make sure that the extruder is working correctly.  Then, check the bed level again.  Set the Z Axis Zero and test.  If that is still giving me bad first layer results, I will take off the glass plate/painters tape, and just put tape on the aluminum bed itself and see what happens.  I also have a sheet of PEI waiting in the wings in case nothing else works.  I would like to get the glass bed/tape at least close and then switch to the PEI but I’m not sure if that is gonna happen…

    #90155

    Jeffeb3
    Participant

    I’m guessing the two temp sensors are just a little off from each other. These kind of sensors are not great at absolute temperature correctness but pretty good at relative temps.

    So if it measures 5.0C rise, it’s probably between 4.9C and 5.1C, but if it says 60C, it could be 55C.

    That’s not a huge problem, because it doesn’t really hurt to set it to 65C and only get 60C.

    If the glass is causing a 5 minute delay, that is a problem. If the glass is showing 5C lower, thats not a big deal.

    The nozzle is a similar situation. I bet if I set 195C on both my printers, one would be 10C higher than the other. But on either printer, if I drop it by 10C, it will make a difference.

    #90158

    Jeff
    Participant

    The delay in the glass heating up could be part of my problem with the first layers not sticking properly.  It seems that when it starts to print, the first 30 seconds or so of print isn’t sticking, and then it starts to stick.  The problem this causes is now filament that should have been stuck is being dragged around and causing issues.  This is something that I am look at now.  I am going to try preheating my bed, let it come to temp and then wait 5 minutes before I start the print job itself.  This will hopefully give the glass enough time to heat up prior to the first layer going down.  Only experimentation will tell.

    #90164

    Aaryn
    Participant

    I am going to throw this tip out there.  It isn’t life changing but it helps a little.  You can insulate the underside of your heated bed.  Cork board works Excellent.  Gator board (also known as foam board or foam core) works really well.  Cardboard works ok.  As long as your heated bed stays below something like 130 c you will not have a problem with fire.  That usually helps the bed to heat faster and stay more of a consistent temp.  I don’t know if it would help much in your case since the heat has to go up through the aluminum and then the glass.  Like I said just throwing that out there.

    Here is one of many links on the topic.

    #90171

    Jeff
    Participant

    Thanks Aaryn, any tips and hints are well worth throwing out there.  I have been thinking of insulating it, just haven’t had the chance.  I really need to sit down this weekend and just run tests on this to get it working.

    #90201

    Bill
    Participant

    Calibration consistency on those sensors really sucks … it’s one of the reasons why they are so cheap. I’m running a PEI sheet on top of the aluminum and also see about 5° lower on the top surface than reported by my thermistor. I just tell the heatbed to be 5° higher than I really want and it comes out OK. 🙂 If you really want to get a correct calibration test your sensor in boiling water and in ice water. My guess is both will be off by the same amount.

    #90228

    Jeff
    Participant

    My next step if I can’t get the prints to stick consistently to my glass/tape will be to put my PEI directly on my aluminum and just go from there.

    I have to do more testing after I check all my slic3r numbers and then post video of the beginning of the print.  I think the first layer is really what’s causing my problems in my prints.

    #90231

    Jeffeb3
    Participant

    My next step if I can’t get the prints to stick consistently to my glass/tape will be to put my PEI directly on my aluminum and just go from there.

    I like the idea of testing heating the bed for a few minutes before starting a print. You can add a 5 min pause to the starting gcode:

    G4 S300

    http://marlinfw.org/docs/gcode/G004.html

    If the 5 min wait helps, then I would just change the bed temp to 70C and take out the pause.

    I have PEI on the aluminum, but the bed isn’t very flat. I hope your glass is flatter.

    The PEI will stick better than the tape. Another thing you can do to make the tape stickier is to clean off the grease with iso. alcohol.

    Can you try printing just the first layer, and canceling it after 1 layer and posting a picture? That should help (us) see if it’s doing well enough.

    Are your later layers looking any better? The cube you posted before looked pretty rough.

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    #90235

    Jeff
    Participant

    Things are improving.  I think I’ve finally got my hot end/extruder figured out and setup properly.  I’m gonna spend time this weekend testing everything.  I think putting the PEI on the glass will be my next step.  The glass should be flatter then the aluminum.

    I also didnt realize I need to clean off the tape in between prints, lol.  I’ve just been knocking the print off an reprinting.  Lol.

    so much to learn…

    Also, any way in Slic3r to adjust where the print goes on the bed?  It always autocenters and I can’t figure out how to stop that…

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