Help with Anycubic i3 Mega S - 1st layer just not printing :-(

Hi all,

I posted a problem similar to this before, and curious aardvark pointed out that I am setting the nozzle too close to the plate. Remedying this helped for a few prints, but now I'm havingf a very similar problem again :-( .

The print begins. The skirt is a bit shoddy to begin, but I think that's "normal" because this is the purpose of a skirt, right? To settle into a nice print-flow before begining the main event. The skirt doesn't really print well by the time it's completed either. Then when the main print starts the nozzle simply gathers a large blob of PLA on itself :-( .

I have adjusted the plate so that the paper-measure fits:

with little resistance - poor print
with medium resistance - poor print
with high resistance - poor print.

The nozzle/plate distance doesn't seem to make any difference.

I have uploaded a video of one of the (8!) attempts here: https://youtu.be/9yRwQ9FfI4M and I've uploaded the g-code file.

If anyone with with more expertise than me (not difficult) can take a look and help, I would be grateful.

Thanks.

You are so close to having your 3D Printer work.
You are still just a little too high. maybe 0.1mm
This can be adjusted by using the Z-Offset from the LCD menu

https://www.youtube.com/watch?v=Q5M7DvdMcew

Quote:

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Originally Posted by Roberts_Clif

You are so close to having your 3D Printer work.
You are still just a little too high. maybe 0.1mm
This can be adjusted by using the Z-Offset from the LCD menu

https://www.youtube.com/watch?v=Q5M7DvdMcew

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I think I'm possibly too much of a noob to go rebuilding the printer to add levelling sensors. I'll need to get a bit more confident before I venture into that.

As far as I can see there is no native z-offset setting on the Mega S. Should I level the plate using a very precise thickness of paper, or is there a command I can instert into the g-code file to execute the z-offset for each print?

This was another useful vid I hunted down just now: https://youtu.be/6QhUgq4C008

Many thanks for the guidance.

What !!!!! ! ! !


Somehow I attached the wrong You-Tube Video.

The first thing to try for problems of the 1st layer not sticking is to clean the bed with isopropanol (propan-2-ol)
Iif that doesn't work, clean it with detergent (rinse very thoroughly but make sure you don't let the water get where it shouldn't and dry the machine thoroughly).

Most of us went thru the exact same experience, we were not blessed with a perfect print every time.
We had to learn that the first layer height is in a small range that is hard to achieve. Especially when trying to adjust mechanical sensors or switches.

I found several ways to make this simpler to achieve.

One: I created a mechanical proximity sensor slide mount with a thumb screw to be able to adjust these tiny differences in nozzle height,
this allows me to turn a thumb screw to make microscopic adjustments to slowly get the nozzle into that perfect height.
When achieved I can print many weeks or even months before readjusting. Then the nozzle height process starts all over again

As the mechanical sensor adjustment is a slow process and requires many tries to get the nozzle into the correct position.

Two: I have set the Baby Steps enabled on my Marlin firmware this way I can use the LCD in order to nudge to nozzle or baby step it into position.
This adjustment occurs at the beginning of every print using the LCD control to nudge or baby step the nozzle into place,
this process occurs during a skirt that is printed before the model printing begins.

Three: I use both process along with other mechanical bed leveling techniques to get the bed as close to level as possible then final software Auto bed level.

As stated I make microscopic changes to the nozzle using the Baby Steps while the skirt is being printed until that perfect height is achieved.
Note: I keep track of the distance changed from the LCD to get this nozzle height, an after many weeks of practice have determined this number can be translated into
a fraction of how far to turn the thumb screw and in what direction so to more quickly adjust the mechanical proximity sensor slide mount.

Simple with logical steps that can be made with precise adjustments, when manually adjusting a locked switch, repositioning switch we cannot guarantee accuracy.

Wow! that's an amazingly complex process, if it works for you all well and good.

We have 15 Anycubic Mega printers, so we can't justify that rigmarole, I do all the Z clearance adjustments visually...

<Home All> <Turn Off Motors> then set the height on each of the corners; when I move from left to right I note if the nozzle gets too close to the bed, if so I adjust the front right screw until the nozzle can reach the Right corner and set the clearance at the two corners to be equal. I then move it back to the front centre and adjust BOTH front screws by the same amount until the centre clearance looks to be approximately 0.12mm.
Then I repeat the exercise for the two rear screws,
Finally I check the centre of the bed and if necessary make equal adjustments to all four screws until the centre clearance looks to be approximately 0.12mm (with a really clean bed and printing PL, anywhere within 0.1mm to 0.15mm is OK, although below 0.12 tends to give a more marked elephant's foot effect).

As we use 'PETlock' bed adjusters, the beds then usually don't need any adjustment over several thousands of hours of printing.

Thanks for your suggestions Roberts_Clif & Xanthe.

I just just revisited this thread after some time (because I've not had any problems :) ). I'm getting much more reliable orints now that I'm more regimented with bed levelling.