PLA Sticking – just not well…

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This topic contains 17 replies, has 4 voices, and was last updated by  Jeff 5 months ago.

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  • #89354

    Jeff
    Participant

    Thanks for all the advice everyone!  I’ve got the PLA sticking now – kinda.  I’m thinking it’s a bed level/Z height thing now but I’m not sure.  I’ve spent the past 2 hours trying to dial it in and I’m getting closer but I wanted to ask you all if I’m missing anything or if I’m barking up the wrong tree here.  I’ve attached a picture and movie so you can see what is happening.  I’ve got the extruder at 205 and the bed at 65 (just numbers that I started with, I’m not sure why).  Any advice would be greatly appreciated!!  Thanks again for all your help!

    #89364

    Jeffeb3
    Participant

    Start with something smaller, like a 20mmx200m test cube (check thingiverse).

    I’ll watch your movie and see what else is sticking out, but trying to get the whole 200×200 surface level is an expert level task, which you can try once you know how to do the small stuff.

    #89365

    Jeff
    Participant

    Thanks Jeffe!  Good idea going small.  I didn’t even think of that – I was just thinking of trying to get the bed level before I started working on Z Axis tasks…  I’m also not sure if my steppers are moving too quickly which is one of the reasons I took a movie of it.

    #89366

    Jeffeb3
    Participant

    You’re just too far away from the bed.

    Use your feeler guage, or the paper trick to get the corners at the same height from the nozzle, then adjust the Z endstop so it moves the nozzle closer. Don’t use the bed screws for that, or you’ll lose your mind.

    So load up a 20mm cube, go a bit too low first (if you actually had a gap of about 0.1mm when the printer thought it was at 0.2mm, you’d get a squished bottom, but it would stick and print). From there, you can back it off a bit.

    When you’re printing the first layer, including the skirt, you can look at how one line fills up next to the last line. If they aren’t touching you’re very far away. If there is extra filament smooshing out and up, then you’re too close.

    Shoot for OK first, and get better with each day. For now, don’t worry about a squished bottom and just get some objects made.

    #89367

    Jeffeb3
    Participant

    Slowing down can really help too. Something like 25mm/s on the first layer should be fine though.

    #89372

    Jeff
    Participant

    Jeffe – you’re the best!!  Thanks yet again!  I was hoping the video would be able to help you figure out what the heck I was doing wrong.

    In leveling the bed – do it with the glass plate and tape on the plate?  Or just the glass plate?  Or just the aluminum bed itself?

    Here is what I have for my speeds as well.

    Attachments:
    #89377

    Jeffeb3
    Participant

    In leveling the bed – do it with the glass plate and tape on the plate? Or just the glass plate? Or just the aluminum bed itself?

    Do it with all the stuff you’ll be printing on, so in this case, glass and tape.

    Here is what I have for my speeds as well.

    If you’re not in a hurry, I would slow those down a bit more. There’s plenty of room for faster speeds in my settings, but I don’t like to waste plastic, and my machines are idle most of the time anyway, so I print on the slow side all the time.

    screenshot-2019-02-16-1550338539

    Looking at my settings, my perimeters are 35, and first layer is 0.6x and external ones are 0.8x slower, so that external first perimeter is 17mm/s and the other first layer perimeters are 28mm/s. The first layer infill is 32mm/s. These should be pretty bulletproof speeds for starting out.

    #89380

    Jeffeb3
    Participant

    20mmx200m test cube (check thingiverse).

    200m test cube… Stupid phone.

    #89387

    Jeff
    Participant

    20mmx200m test cube (check thingiverse).

    200m test cube… Stupid phone.

    HAHA – I saw that as well and knew what you meant.

    So, I just leveled the bed (without the tape on it but with the glass on – I didn’t see your message about that tape).  Anyway, here is what I got with my feeler gauges and it’s about as close as I can get it with the 3 point bed base I am using – I’m guessing going to a 4 point base would give you more leveling control but also give you more gray hair when trying to level the damn thing.  lol.

    Here is what I got in Thousands of an inch from the nozzle tip using my feeler gauges:
    Back Left: 0.0025          Back Right: 0.005
    Front Left: 0.011            Front Right: 0.007

    The Right side looks pretty good only being off by 0.002 front to back.  The left side and the right-left is another story.  The left side is off by 0.0085.  To me, this seems like a lot (85 ten-thousands) but I’m not sure if it really is a lot or not??  Seems like more layers are printed in the .2mm range which is equal to 8 thousands (which is about what I’m off front to back on the left side).

    Now that I’m looking at those numbers, I guess I have more leveling to do…  Ug.  I’m thinking to leave the single left sided leveling screw alone and see what I can do by playing with the 2 on the right side. Looking at the numbers I’m thinking I need to Raise the Front Right of the bed a couple of thousands.  That should bring the Front Right and Back Right into alignment at 0.005 from the tip and will hopefully raise the Front Left a little bit so I can get rid of some of that gap as well.

    Also, I set my Z Axis zero/end stop with the bed centered in the machine in both X and Y Axis.  I have that set to a gap of 0.0016 (or 0.04mm).  Should I do it in the Center or set it in the true Home position (Front Left Corner).

    I can feel myself getting grayer as I type this.  Lol!

    #89390

    Jeffeb3
    Participant

    IMHO, you’re focusing too much on the numbers. Those all seem well withing tolerance to me.

    I think the “right” value is the nozzle touching the bed when the bed and nozzle are hot and the coordinates say Z=0.0.

    But that doesn’t matter, because if it’s too high, you adjust the Z endstop screw to move the endstop position down and if it’s too high, you move the endstop up.

    Get it close enough to stick and then try to fine tune it. Right now, you’re going gray because you don’t have a choice, you’re stuck messing with the bed. Bed leveling is the hardest part of 3D printing. Once you get something working, you can give yourself a pat on the back and take your time tuning other things.

    There is a feature in Marlin called “babystepping” where you can adjust the Z after starting a print through the LCD. That’s worth looking into as a future project.

    You can also eventually mess with a raft, which just makes a couple of messy layers under the print so you endbup with a temporary super flat surface to print on.

    But printing a little cube with bell bottom feet is the next step.

    #89392

    Jeff
    Participant

    Thanks Jeffe – I got a chuckle out of that and I needed it!!  I’m a numbers kinda guy.  I just spent some more time getting it to within a little tighter tolerance and now have the Z Endstops set so the nozzle is just touching the bed… but I didn’t do that with the nozzle and bed hot.  Time to heat things up and tweak it a bit.  Then I think it’s time to start making some stuff.

    Cube with Bell Bottom feet?  You lost me on that one.  Lol.  I have a calibration cube https://www.thingiverse.com/thing:2543469 that seems like a good place to start?  I also have the 3D Benchy for when I really want to pull my hair out…

    #89394

    Jeff
    Participant

    Ok, so did my first test with the new settings and had to kill it.  Something was wrong with the steppers.  The Y Axis was missing steps somewhere and I could hear it “ratcheting” so I have to check that out.  Maybe the belt too tight/loose?  I’m not really sure, it’s about the same tension as the ones on my LR2.

    I also noticed on the rapid movements while it was jogging back and forth, that the bed top was “rocking” on the springs.  I’m guessing I have to tightening all those down more so they let me adjust the bed without them wobbling like that.

    3D printing (or at least building your own 3D printer definitely isn’t for the faint of heart.  lol.

    #89399

    Jeffeb3
    Participant

    Cube with Bell Bottom feet?

    When you print too close, the bottom layer sticks well, but is a little wider because of the closeness to the bed. So the first two or three layers are wider (like bell bottoms). It’s also called Elephant foot.

    3D printing (or at least building your own 3D printer definitely isn’t for the faint of heart. lol.

    Only crazy people build their first printer. There’s enough to learn without also having to tune and assemble a machine. You’re doing great though.

    Also, it’s a much more messy process than you’re thinking. I mean that both in the fact that it’s not a precise numbers game and in the fact that it can sometimes mean a hack to get things working. Hot filament is probably more like silicone sealant when it comes out of the nozzle. It is not legos.

    I’m not sure what’s up with your Y, unless you were dragging the nozzle hard. The nozzle and the heatbed should get a little closer when they warm up.

    #89400

    Jeff
    Participant

    The nozzle wasn’t dragging because it didn’t happen until about the 3rd or 4th layer I think.  I’ll have to run it again to see what is really going on with it.  My desk is such a mess something might have gotten caught in the Y axis to cause it.

    #89402

    Bill
    Participant

    Sometimes the wires from the heat bed get in the way of Y movement if you didn’t use those holes at the back left corner to zip tie them in place.

    #89415

    Jeff
    Participant

    I think my Y Axis belt was too loose and it was skipping over the top of the pulley when it was going in the Y Negative direction (at least I hope that’s what the problem was).  I’m about to run another test to find out.

    #89464

    George Vaccaro
    Participant

    A few weeks ago I started using this PEI sheet for my PLA printing and it’s amazing!

    https://www.amazon.com/gp/product/B074XLD5QH

    It takes a lot of the required precision out of bed leveling.  It doesn’t have to be perfect anymore.  My prints are much more successful now.  Before using it at least 50% of my prints had curling, and I even resorted to applying tape to the brim after it printed to hold the prints down better – which does seem to work but is a real pain.  Now I don’t do that anymore and I almost never have curling at all.  Occasionally I’ll have one part of a multi-part print (something I’d never even try prior to having this sheet) get a little rough around the edges on the first layer.

    If you get it, be sure to clean it off with Isopropyl alcohol, preferably between every print.  I didn’t realize that at first and it makes a bit difference over time as the sheet will get a bit slippery if you don’t clean it.

    Also, my prints are so much better and I haven’t even properly secured the sheet to my bed with the included self adhesive.  I’ve just clamped it down.  I imagine my results would be even better if I did that.

    If you do get it, please post your results.  This thing has totally changed how I use my printer.

    Btw:

    “Only crazy people build their first printer. There’s enough to learn without also having to tune and assemble a machine. You’re doing great though.”

    I built my first 3D printer and my first CNC (this lowrider2).  I must be crazy! 😉

    Seriously though, this combination has been great and I learned so much more than I would have if I just bought them – also saved a ton.  There’s so much more you can build having a CNC and a 3D printer.

    #89474

    Jeff
    Participant

    My first build was a LR2 as well – I love that thing!!  I’m now concentrating on dialing in the printer.  I will give a look at the PEI sheet you linked to.  Every little bit helps!

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