Sticking Issues – Root Cause?
I finally have my Mk2 built & printing. However, I've been unable thus far to get my PLA to stick to the build plate. I recorded a couple videos attempting to show the sticking issue. The problem is primarily with the first layer perimeters on this object, but once it gets to the infill it seems okay. I've determined 2 most likely causes for this:
Calibration Issues
When I run XYZ calibration is says that I have severe XY skew, which would make think there might be issues. However, it also says it is adjusting for the skew; does this mean it's not a problem?
Temperature Issues
We keep our house around 70°F (20°C). The printer is in my basement, in an uninsulated room, therefore the temp may not be perfectly steady (don't have a thermometer in the room, so not sure). I have a space heater I can move into that room, maybe that will help?
Could there be another issue I'm not seeing that might cause problems like this?
Here are the videos showing the issue:
1/2
2/2
UPDATE: I let the last print from the second video finish. I'm attaching the result. There was some serious warping and layer separation, but maybe it's all due to a bad first layer?
Re: Sticking Issues – Root Cause?
Based on my experience I would rather specify two much more important issues:
1. Dirty bed.
The bed must be absolutely clean (degrased) to make PLA stick well. I usually get best results with IPA or clean alcohol.
2. First layer height.
If first layer is too high or too low, it won't stick.
Axis skew has nothing to do with first layer sticking in most of the cases. If the printer passed calibration, it is good enough to be successful with sticking.
Temperature might be a problem, but not as big as two issues mentioned above. Try to increase bed temperature by 5°C. If you don't see any change, it is not the issue.
I watched your videos. I think the problem is dirty (greasy) bed. First layer height looked good (talking about first video).
Re: Sticking Issues – Root Cause?
Thanks David, I have rubbed it with a 90% isopropyl alcohol a couple times, but I will try it again for sure. To help me recognize, what gives away that it's dirty?
Re: Sticking Issues – Root Cause?
I guess by my experience gained so far. 9/10 my issues with sticking were first layer height or not fully degreased bed. I can't be 100% sure, of course. There might be another issue I didn't see.
BTW, looking at your updated pics, are you sure you're printing from PLA? What type of PLA is it? I've never seen PLA warping so much.
About that print - is it PRUSA sign gcode provided on SD card with printer or did you slice it yourself?
Have you cleaned the bed using another cleaner before using IPA?
Re: Sticking Issues – Root Cause?
And one more thing: V2Calibration.gcode - what was the result? Did it stick at the end?
Re: Sticking Issues – Root Cause?
Embarassingly, I missed that step in the first print guide. I noticed it earlier when I was rereading and I've already run it a couple times. It's pretty clear that the nozzle is too far from the bed to achieve proper adhesion, so my next step is to keep raising the probe until the nozzle is at the right height.
Re: Sticking Issues – Root Cause?
BTW, looking at your updated pics, are you sure you're printing from PLA? What type of PLA is it? I've never seen PLA warping so much.
About that print - is it PRUSA sign gcode provided on SD card with printer or did you slice it yourself?
Have you cleaned the bed using another cleaner before using IPA?
It's the blue PLA I ordered with my Mk1 kit back in February. I printed using the gcode I downloaded from the Prusa site and copied to the SD card (this was the upgrade kit from the Mk1, so I didn't get a new card).
No, I've only used IPA (the alcohol, not the beer, haha) on this so far. First the pads it came with, now using cotton squares with a bottle of 90% IPA.
Re: Sticking Issues – Root Cause?
It's pretty clear that the nozzle is too far from the bed to achieve proper adhesion, so my next step is to keep raising the probe until the nozzle is at the right height.
Interesting conclusion. I don't say I disagree, I'm only a bit surprised. Could you please get and show more detailed image of test print from first video? That infill layer looked quite consistent.
Re: Sticking Issues – Root Cause?
Could you please get and show more detailed image of test print from first video?
I'll take some shots in a moment and post them here. In the meantime, I'm also working to get a video of the V2Calibration print that shows how far the nozzle is from the bed. I had z adjusted over -1, which should never be necessary. Unfortunately the probe isn't registering ATM, but once I fix that I'll upload a video.
Re: Sticking Issues – Root Cause?
What is your relative height of nozzle tip and probe tip? The probe should be about 1-2mm higher than nozzle. If it is too high, nozzle will hit the bed during MBL autoprobing. If it is too low, it could crash into printed object.
Re: Sticking Issues – Root Cause?
Okay, so I took the nozzle down far enough that the PINDA probe actually skimmed the extruded filament and still no sticking. So it's definitely beyond a nozzle height issue. Here are some more pics of the Prusa logo attempt from my first video, and a video of the V2Calibration run showing the nozzle up close. It started with no (or very, very little) z adjustment and I lowered it throughout the video.
Sorry for the blurriness on those two; the iPhone camera doesn't do that well with macro photography like that.
There's a little bit of splitting in this one, but probably not enough to be super-concerned about. Just seems like the infill is a little far apart.
Notice here that it's warped on the left side, AND just under the "U".
And here is the back where you can clearly see how bad the first layer came out.
Re: Sticking Issues – Root Cause?
What is your relative height of nozzle tip and probe tip? The probe should be about 1-2mm higher than nozzle. If it is too high, nozzle will hit the bed during MBL autoprobing. If it is too low, it could crash into printed object.
They are about even atm, but I've had it slightly higher than that and still had the same issues.
Re: Sticking Issues – Root Cause?
Allright, last image is self-describing. 🙂 The nozzle is too high. If you can't live adjust Z further down, you will have to reposition the probe a bit higher. After that, don't forget to run all calibration routines again (including XYZ).
Re: Sticking Issues – Root Cause?
After that, don't forget to run all calibration routines again (including XYZ).
That could be part of my problem. The XYZ calibration takes like 20 minutes to run. It really doesn't work well with the "move the probe and try again" workflow. I actually measured the distance between the probe and nozzle with some gauges and the probe is now 1mm higher than the nozzle. I'm already rerunning the XYZ calibration, so we'll see if that helps.
Re: Sticking Issues – Root Cause?
Generally, the higher the better. Higher positioned probe means more clearance between probe and printed object. Set it as high as possible, but the nozzle must not hit the bed during autoprobing/calibration.
Re: Sticking Issues – Root Cause?
Also another thing I usually do when I have a tricky print is to lower the speed ALOT, 10% or so... that will give you more time to fine tune the Z Live Adjust values and also the flow which I find useful to adjust "live" sometimes. When you are all set, you can crank up the speed to 100% again.
Usually the brim printing is enough time to get the Live Z adjust value right.
Re: Sticking Issues – Root Cause?
After that, don't forget to run all calibration routines again (including XYZ).
That could be part of my problem. The XYZ calibration takes like 20 minutes to run. It really doesn't work well with the "move the probe and try again" workflow. I actually measured the distance between the probe and nozzle with some gauges and the probe is now 1mm higher than the nozzle. I'm already rerunning the XYZ calibration, so we'll see if that helps.
When adjusting the PINDA probe, realize that 1/3 to 1/2 a turn makes a significant difference, so you may need to make very small changes before re-testing.
Is your XYZ calibration really taking 20 minutes, or are you exaggerating? I think it takes about 5-8 minutes for me. The very first time I ran it, it took a long time. I had also checked nozzle height with a piece of paper, and realized the probe was too high. Once I lowered it to a better level, the XYZ calibration went much faster.
Re: Sticking Issues – Root Cause?
That could be part of my problem. The XYZ calibration takes like 20 minutes to run. It really doesn't work well with the "move the probe and try again" workflow. I actually measured the distance between the probe and nozzle with some gauges and the probe is now 1mm higher than the nozzle. I'm already rerunning the XYZ calibration, so we'll see if that helps.
Joe
You are not supposed to move the probe every time. Set the probe about 0.75mm above the level of the nozzle, run the XYZ calibration once only and if that completes without error, print the V2Calibration GCode file and use the Z Live Adjust to set the nozzle height so that the filament sticks to the bed. Repeat the print of the V2Calibration GCode until the filament sticks and is nicely squished.
Do not adjust the probe unless the XYZ calibration fails.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Sticking Issues – Root Cause?
Is your XYZ calibration really taking 20 minutes, or are you exaggerating? I think it takes about 5-8 minutes for me. The very first time I ran it, it took a long time.
I could have been exaggerating. I haven't actually timed it, but it does take awhile.
I finally got a few decent prints, and a couple bad ones. The problem was definitely the probe height. Followed PJR's advice to set it 0.75mm above the nozzle and that worked great with appx -0.6-0.7 z adjustment.
Thanks everyone for the advice! Very happy to finally have this working again!
Re: Sticking Issues – Root Cause?
Is your print cooling fan working after the 2nd layer? I would expect the tip of the dino's nose to look better.