First layer issues
Starting a new thread so as not to clog up the sticky thread. Again, here's my experience so far.
Here is my starter advice for getting your printer going well, and avoiding some of the common frustration inducing issues.
0) Make sure the belts are tight, and all of the axises are free to move smoothly. Make sure the wire bundle coming out the back of the extruder is held high and does not droop down where it will hit the print when the extruder is at any height. Make sure the X and Y axis are as perpendicular as you can judge by eye.
1) Run the Self Test from the menu. Make sure everything is connected correctly.
2) Make sure PINDA is above nozzle tip by <1mm but above the nozzle. About 0.6mm is a good starting point (but anything between 0.5mm and 1.0mm is fine), which is about the thickness of a credit card. Place a sheet of paper on the bed, and run the XYZ Calibration from the menu. Stay with the machine, and watch it. As it hunts for the calibration points, watch if the paper moves. If it does, STOP THE PRINTER. That means the nozzle is dragging and the PINDA sensor is a bit too high, lower it and try again, but make sure it is still higher than the nozzle tip. Repeat until you have a good XYZ Calibration. (Note the instructions on the XYZ calibration, and make sure the nozzle tip is clean.)
3) Set your Live Adjust Z roughly correct. This lets the printer know the distance between your PINDA sensor and the nozzle tip. The printer can measure the distance from the PINDA to the bed so this lets the printer know where the nozzle is relative to the bed.
a) Set Live adjust Z = 0.00. (XYZ Cal does this).
b) Do a Calibrate Z. (Head must be clean of drips and lumps).
c) Do a Home. This leaves the head at Z=0.15mm. DON’T SKIP THIS STEP.
d) Use Setting -> Move Axis X and Y to get in the approx center of the print space. DON’T TOUCH Z.
e) Put a piece of printer paper under the head. Printer paper is approx 0.1mm
f) Wiggle the paper while adjusting "Live Adjust Z" (in settings) until the paper just starts to drag on the paper.
g) Back off a bit (50) on the “Live Adjust Z”. Backoff: If you started seeing the paper drag at -0.675mm, change it to -0.625mm.
NOTE: If your Live Adjust Z value is >1mm something is wrong. It should be approx the distance from the PINDA probe to the nozzle. Anything between 0.4mm and 1.0 should be fine. (Less than 0.4 means the PINDA probe might catch on some print that curles up a bit, greater than 1.0 means either you did something wrong, or are just barely in the PINDA’s detection range.)
NOTE: The above may not be correct. The Live-Z value might be different from the PINDA to nozzle spacing if the PINDA is particularly sensitive or particularly insensitive. If the value is out of bound, proceed, but with caution. Most users on the forum report numbers “near” the distance from PINDA to Nozzle, but some seem to have more sensitive PINDA sensors which can me moved significantly higher than 1mm, and the Live-Z value is drastically different.
Note: Now you have set the nozzle approximately 0.15mm (paper +0.05mm) above the bed while the printer’s electronics think the Z is at 0.15mm.
I've done all this to here to the letter. Perfect XYZ calibration, PINDA properly located about a credit card thickness above the nozzle. Here's where it gets weird. The Live-Z value for step (f) is -1.280 at the point where the paper starts to catch, and backed off to -1.230 later in step (g). I thought I might have received one of those sensitive PINDA units so I carried on anyways.
4) Load some filament.
a) Make sure the tension screws are about 14mm from the body with no filament in the extruder. (This is looser than is intuitive for most people. Too tight or too loose will cause issues.)
b) Heat the extruder. You can do this with pre-heat or settings->temperature.
c) Use Load Filament from the menu. Continue until you have a nice thin strand coming from the extruder.
d) Cool it back down.
5) Make sure the bed is very clean.
a) Wipe with as pure an isopropyl alcohol (IPA) as you can find. The little toweletts are not enough in my opinion. Use (and re-use) a paper towel and a good squirt of IPA.
b) (If really dirty, you can use Windex followed by Acetone followed by IPA, but that should only happen if you had used glue stick or other things on the bed and want to really clean it off). I do this if I am changing materials.
6) Get your Live Adjust Z dialed in real well. This ensures the first layer is properly squished down to the bed for good adherence and print quality.
a) Print using "Calibration_surface_PLA_75x75@200um_v4.gcode" found in Jeff's "Life Adjust My Way" Thread (Read through page 7 or so till you see the .v4 code. Look at the pictures.)
http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/life-adjust-z-my-way-t2981-s150.html
b) Repeat until you have a nice test print - all stuck together and one nice clean sheet.
So the first time I printed this (with Live-Z set at -1.230), I experienced pretty bad extruder skipping right away so I quickly backed the Live-Z value off to the region of -0.700 and -0.600 on the 2 halves of the square in order to print at all, but they turned out pretty bad.
I did another print at -0.550 and -0.500 (pictured) and they look like I need to dial it down a lot more still but I'm not sure if I should, because the outer perimeter of the square lifted off at -0.550 and I was lucky that the second pass stuck it back down somewhat. It seems to be a common problem for me where if I set the Live-Z to a high enough value where the middle of the square prints in neat, non-wavy or torn up layers, then the skirt and the perimeter of the square either won't print or won't adhere to the heat bed.
I know from troubleshooting this printer for countless hours over the weekend that the bed levelling is pretty out of whack - it feels like the left side of the bed sits lower, and the front as well (but to a lower extent). But I have had no luck with the default bed level control settings, not even at 100 microns. The next step might be to try custom firmware that allows for 8 points of adjustment.
All in all, I don't know if what I'm experiencing is symptomatic of a larger issue that I don't quite see. I've printed 2 Benchys, a Prusa logo and a whistle to completion, and all the bottom layers were quite mangled but I pushed through it without knowing any better at the time. They turned out acceptable, but I don't want to print any more until I solve my first layer issues.
7) Do the PID calibrations for the bed and the extruder from the calibration menu. Note: Some users don’t like the PID calibration and feel it has caused problems. Others have had great luck with it.
Later on I did the PID calculations in the printer itself - didn't seem to do anything. I did the temperature calibration as well, and set "Temp Cal" to on for a test print, but even after waiting about 90s before the print started, it still failed on the first layer.
I've also tried changing my extruder multiplier to 1.11 based on my test extrusion - didn't seem to help either.
I feel like I'm going in circles here. Before I try to flash new firmware, is there something I'm missing? I'm pretty bummed at the moment.
Re: First layer issues
I am hoping someone can move this discussion over to it's own thread, instead of in the sticky "before you ask" thread.
It does look like your Live Z is still too low (too large a negative number) and the nozzle is dragging though the filament. I would keep going. Try -450 -400 and see how those look.
I can't explain why you didn't drag the paper, UNLESS YOU DID NOT DO A HOME FIRST. If the nozzle was up a bit (not at the 0.15mm left by the HOME command), and you tried to drag, it would register a much larger number. You may want to verify that again.
I did the Auto Home before doing the paper test, so I'm not sure why this is happening. I'm on Firmware version 3.0.12.
Re: First layer issues
This is strange. So when you only have straws, you grasp at them.
It might be that you have something in the system that moves - specifically with temperature. So when cold, your Z-Offset is one thing, but when the bed/extruder heat up, it is something very different. I would check the screws that mount the bed to the Y chassis. I would make sure the PINDA can't move or flex (do you have a MK2 or MK2S PINDA mount? I would check for any play or give in the Z-direction on the extruder (e.g. the extruder itself can move even if the lead screws don't.
I would also do an additional Calibration Z - where you crash the head against the top rails to make sure the two Z motors are aligned.
Again, this is strange, so I am thinking of improbable things because they are all I can think of given what you have done so far.
Hopefully more experts will chime in shortly.
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 or loss. If you solve your problem, please post the solution…
Re: First layer issues
I just redid XYZ again (perfect X/Y alignment, congratulations) and did the wiggly paper test. I measured the thickness of my paper, which came up to 0.1mm.
The point at which the live-Z adjust allows the paper to move freely without catching on the nozzle is at -1.400mm. This indicates that the nozzle was exactly 1.5mm above the heat bed at the centre point of the heat bed where I did this adjustment, which by the instructions should be as expected.
I don't see how we can expect to get live-Z values of -0.800mm or lower like in the example of -0.675mm, when the nozzle is supposed to be 1.5mm above the print bed? My latest test proves this.
Here's a photo of the nozzle after AUTO HOME and centralising on the bed by moving the X and Y axis:
And here's one after doing the wiggly paper test and the live-Z reads -1.400mm, just at the point where the paper catches:
Re: First layer issues
It might be that you have something in the system that moves - specifically with temperature. So when cold, your Z-Offset is one thing, but when the bed/extruder heat up, it is something very different. I would check the screws that mount the bed to the Y chassis. I would make sure the PINDA can't move or flex (do you have a MK2 or MK2S PINDA mount? I would check for any play or give in the Z-direction on the extruder (e.g. the extruder itself can move even if the lead screws don't.
I would also do an additional Calibration Z - where you crash the head against the top rails to make sure the two Z motors are aligned.
What specifically about the screws that mount the bed to the Y chassis? Should I tighten/loosen them? Anything different I should take note of for the screws in the orange printed part that connects to the bed in the middle?
My PINDA mount should be the MK2 one, it's the one with 2 screws, even though it shipped as an MK2S (this was a couple of months ago when the MK2S was newly-released. I ordered before the MK2S was announced but by the time it shipped it was MK2S). No there is no play or movement in the PINDA probe..I tried wiggling it.
I always do an additional Calibration Z even right after the Calibration XYZ as per the instructions..just to be safe.
Not sure what you mean by any play in the Z-direction on the extruder? I just loaded up some filament and gave it a gentle tug to see if the filament moved, but it's held firmly by the extruder and can't move.
Re: First layer issues
Just from comparing with my own, your PINDA looks way too high in the second picture compared with the nozzle. It's supposed to be less than 1mm from the nozzle end, and you look like you have maybe 3mm or so there. Might just be perspective, though - but it's worth verifying. I did the zip-tie method described when doing mine, and found that it was quite a bit too high when I did it that way. I think I had to turn it almost 3 whole turns "down" from there to get a proper height (and ended up with a live-Z adjust around -0.475, so I probably over shot a bit)
Re: First layer issues
Just from comparing with my own, your PINDA looks way too high in the second picture compared with the nozzle. It's supposed to be less than 1mm from the nozzle end, and you look like you have maybe 3mm or so there. Might just be perspective, though - but it's worth verifying. I did the zip-tie method described when doing mine, and found that it was quite a bit too high when I did it that way. I think I had to turn it almost 3 whole turns "down" from there to get a proper height (and ended up with a live-Z adjust around -0.475, so I probably over shot a bit)
Ah, I think it's perspective. Hard to get a good shot of the nozzle/PINDA due to the awkward angle. Perhaps it's better to try and compare the visible screw threads of the PINDA?
I checked the height difference with a credit card - it's actually just a bit shorter than the thickness of the card.
Re: First layer issues
Yup, that's reasonable. Apparently a CC is ISO to 0.76mm, so if it's less, you're on the lower end. Maybe worth raising it up and testing. You're right on the threads, while mine looks lower when I look at it, I have almost a full thread visible above the holder. I don't know how good of a reference that is.
Re: First layer issues
This is very strange. Have you calibrated your extruder? How tight do you have the tension screws on the extruder?
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 or loss. If you solve your problem, please post the solution…
Re: First layer issues
UPDATE - Is this observation relevant?: Doing the wiggly paper test for live-Z at the home position results in a live-Z value of -0.460mm before the paper starts to resist. Doing it at the centre of the print bed results in a live-Z value of between -1.400mm and -1.750mm (I tried this test a few times after recalibrating XYZ a number of times and getting the Congratulations message each time).
This is very strange. Have you calibrated your extruder? How tight do you have the tension screws on the extruder?
Yes I have, but I haven't done the process of actually writing the extrusion multiplier into the EEPROM, so far I've just been writing it into each Gcode I print. The distance of the tension screws from the extruder is 14mm according to my digital calipers, or as close as I can reasonably get it anyway.
Another interesting observation as I did the step where I centralised the nozzle on the print bed and slowly lowered the live-Z value until the nozzle touches the sheet of paper:
The distance of the bed relative to the nozzle gets larger and larger from X:0 to X:250!! This may be why when I centralised the nozzle on the print bed, the live-Z value goes lower than -1.000mm.
So the print bed obviously isn't level, and it seems to follow an observable gradient from higher on the left, to lower on the right, especially as you move the nozzle along the X-axis and eyeball it. I should add that I also took the calipers to measure the distance from the table surface to the top of the black rings on each side of the Z-axis threaded rod, and both sides are within 0.1mm of each other.
Before I try to flash the firmware to enable the 8-point bed control, I suspect there must be a more basic fix to at least get my live-Z value to something that's more 'normal'.
Any thoughts, experts out there?
Re: First layer issues
Another update: I am an idiot. I just realised after all that moving around, the rear left corner Y-piece is higher than the others, hence inducing a lift in the bed on the left side. 👿 👿 👿
I must have read thousands of words of instructions over the past few days and have forgotten what is the best method for leveling the Y-frame again without disassembling the printer. I remember there was a way to loosen certain nuts and allow the weight of the assembled printer to kind of self-correct any Y-frame errors?
Can someone enlighten me? Thanks!
Re: First layer issues
You OBSERVATION is very critical. Yes! That will solve it.
Your bed has a lot of warp to it. The mesh bed leveling takes that out, but it takes it out at what level. I have not gone and checked the code, but let's assume it takes it out at the AVERAGE level. Since the center of your bed is very low, the mesh bed leveling makes a mathematically flat surface at the average, so it will be much higher than what you measure there - just as you are seeing. In addition, the mesh level adjust for large variations can create some of the waviness you see in your calibration print. It works best when it only has to remove a smaller amount. A mm of difference is a lot!
There is an M code to retrieve the mesh bed level adjustment, but I can't think of it off hand.
Anyway, with this new knowledge, what can you do to get success?
The best course of action would be to get your bed to be as perpendicular as possible. This means your Z gap should be nearly the same in the four corners and the center. To do this, repeat the paper wiggle Z test for the four corners and the center, and write down the 5 numbers. From this information, you might find which corner(s) you need to shim. You can do this by placing a thin washer between the Y carriage and the bed at those points. Or, you can look at your Y frame, and adjust it in the lots between the bolts to make sure it is level if the issue is only in Y. Once you have it reasonably level, you will have much better luck with the prescribed methods.
You might also find this thread interesting:
http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/hyperfine-bed-leveling--t4330.html
Good luck! Please report back what you find.
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 or loss. If you solve your problem, please post the solution…
Re: First layer issues
Another update: I am an idiot. I just realised after all that moving around, the rear left corner Y-piece is higher than the others, hence inducing a lift in the bed on the left side. 👿 👿 👿
I must have read thousands of words of instructions over the past few days and have forgotten what is the best method for leveling the Y-frame again without disassembling the printer. I remember there was a way to loosen certain nuts and allow the weight of the assembled printer to kind of self-correct any Y-frame errors?
Can someone enlighten me? Thanks!
Yup. That is the problem! See Step 15 here:
http://manual.prusa3d.com/Guide/4.+Z-axis+assembly/296
Picture 3 of step 15.
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 or loss. If you solve your problem, please post the solution…
Re: First layer issues
UPDATE: Ok I think I got it. I placed wrenches under the Y-corners to the left and right of the offending corner and gave it (and the diagonally opposite corner) a quick push downwards and that seems to have solved the problem. Now..to power on and hope the XYZ calibration is still good!!
Another update: I am an idiot. I just realised after all that moving around, the rear left corner Y-piece is higher than the others, hence inducing a lift in the bed on the left side. 👿 👿 👿
I must have read thousands of words of instructions over the past few days and have forgotten what is the best method for leveling the Y-frame again without disassembling the printer. I remember there was a way to loosen certain nuts and allow the weight of the assembled printer to kind of self-correct any Y-frame errors?
Can someone enlighten me? Thanks!
Yup. That is the problem! See Step 15 here:
http://manual.prusa3d.com/Guide/4.+Z-axis+assembly/296
Picture 3 of step 15.
So before I read your reply, I already did that and made sure the threaded rod was seated right at the bottom of the aluminium frame. Indeed, I could push it down a bit, indicating that I hadn't pushed it down all the way during initial assembly.
Here's the thing - now my front right Y-corner is hanging above the ground! The right-side threaded rod of the Y-frame is seated in the aluminium frame as low as it can go (I adjusted it again to be sure) - and now we're back to the same issue? How to get rid of the floating Y-corner?
Re: First layer issues
So before I read your reply, I already did that and made sure the threaded rod was seated right at the bottom of the aluminium frame. Indeed, I could push it down a bit, indicating that I hadn't pushed it down all the way during initial assembly.
Here's the thing - now my front right Y-corner is hanging above the ground! The right-side threaded rod of the Y-frame is seated in the aluminium frame as low as it can go (I adjusted it again to be sure) - and now we're back to the same issue? How to get rid of the floating Y-corner?
Sorry. Your words are not making a picture for me.
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 or loss. If you solve your problem, please post the solution…
Re: First layer issues
So before I read your reply, I already did that and made sure the threaded rod was seated right at the bottom of the aluminium frame. Indeed, I could push it down a bit, indicating that I hadn't pushed it down all the way during initial assembly.
Here's the thing - now my front right Y-corner is hanging above the ground! The right-side threaded rod of the Y-frame is seated in the aluminium frame as low as it can go (I adjusted it again to be sure) - and now we're back to the same issue? How to get rid of the floating Y-corner?
Sorry. Your words are not making a picture for me.
Don't worry about it, all I meant to say was that I thought I still had the problem because another Y-corner got lifted up after I adjusted the rear left Y-corner, but I managed to solve it in an update.
Also, now my live-Z value is at -0.280mm on the wiggly paper test!!! Amazing!!! Backing it off to -0.230mm now and going through the rest of the calibration steps.
Re: First layer issues
Okay so still no luck printing, seems like the moment the printer heats up, all the Live-Z values go out of whack. So I went back to Calibrate XYZ and started again. This time I measured the live-Z values at which the paper stops resisting for each of the 9 points around the bed.
All measurements are in microns and the rear right spot is marked with an 'X" because the nozzle was already so close or touching the bed (even at Live-Z = 0.000mm) that I couldn't fit the paper under it. This seems highly unusual..any idea why this happens? Calibration Z passes perfectly, and the PINDA probe centres itself in both circles more accurately than ever.
I feel like now is the time to try to hyperfine bed adjustment firmware..
Re: First layer issues
If you place a ruler across the bed, does the bed seem flat or bowed? Check in both X and Y and at different places (edges, middle).
If the bed if flat-ish then you could try putting a washer under the two right corners to bring those values up.
If it is this bowed, then trying the hyperfine bed level might be your best bet.
Since once corner is slow low, you may want to move the PINDA up a smidge.
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 or loss. If you solve your problem, please post the solution…
Re: First layer issues
The picture of your first layer definitely looks like z-height issues. This thread http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/life-adjust-z-my-way-t2981.html has a good description of getting your z-height set more accurately. It also has some pictures of first layer issues that look a lot like your picture.
Re: First layer issues
Okay so still no luck printing, seems like the moment the printer heats up, all the Live-Z values go out of whack. So I went back to Calibrate XYZ and started again. This time I measured the live-Z values at which the paper stops resisting for each of the 9 points around the bed....
but you still know that the meshbed levelling only works during a print, not when you move the extruder through the menu (either through the axis menu or the live z adjustment level) ?
so what you've "measured" with your values is only of limited usage... and only gives you the information, that your right "bumper" at the top of the z-axis is slightly lower than the left one.... so "calibrate z" delivers a slightly askew x-axis.
dem inscheniör is' nix zu schwör...