Random gaps on the first layer due to...not flat bad?

[kazzaqov 0]

Hello everyone,

I've been leveling my bed forever, got tons of advices here (thanks for them) but I still think the problem is somewhere in the hardware. I tried 2 different beds, and I just get holes somewhere in the middle (this cant be calibrated by adjusting screws) of the bed. I tried both kapton and blue tape, same problem.

Can you please advice me on what might be the cause? I'm sick of getting bad first levels (extruder always makes clicking sound because of uneven extruding)

 

[gr5 1,761]

This is pretty good. To get any better than this you either need to do thicker layers or get more accurate equipment.

I have a thick MIC6 aluminum bed which is very very flat. But even if your bed is flat you need straight rods that hold the print head. Also if you want so flat then maybe blue tape is too thick - you might need to use aluminum bed with kapton tape instead.

 

[illuminarti 18]

What layer height are you printing? And what is your first layer height set to?

 

[kazzaqov 0]

Thanks for reply, guys. I am printing at 0.2, and first layer is 0.3. The sound that extruder makes during first layer, that what bothers me most. I am afraid filament might slip off the extruder.

 

[alex-marakesch 0]

Mark filament with marker and just check the motion.

 

[gr5 1,761]

>I am printing at 0.2, and first layer is 0.3.

Oh!! That's a problem. Your first layer is much too thin then. It looks like .1mm and thinner in spots. You need to lower the bed by about .2mm. Here's my leveling procedure:

Levelling here is defined as setting the Z height and also levelling. It's one procedure that does both at once.

Optionally heat up the nozzle to 180C because a cold nozzle shrinks and you will be setting the bed to the wrong height. Make sure tip of nozzle doesn't have any plastic on it or you may level to the wrong height. I usually prefer to level with a cold nozzle but if you want extra accuracy then use hot nozzle.

Home the z axis only. If you must home all 3 then you need to disable the steppers once it's done so you can move the print head by hand. Move the head as close as possible to each of the 4 screws in turn. Once at a screw tighten the screw and then slip a piece of paper between the nozzle and the print bed. Make sure the paper slides very freeley. Then loosen the screw until the paper gets slightly stuck. You want the paper to easily be able to slide in and out under the nozzle with one hand pushing the paper. If the paper gets stuck it's probably too tight under there.

Repeat this procedure for the other 3 screws. Then go back to the first screw and repeat on all 4 screws again. Then repeat on all 4 screws again. Then again. It may take you 20 minutes to do this the first time but the second time you do this it should take much less time because you are both better at it, faster at it, and because there isn't much to adjust the second time.

If you levelled with a cold nozzle you are done. If you levelled with a hot nozzle you should then loosen the 4 screws 1/8 of a turn to compensate for the thickness of the paper.

Once done levelling rotate the z screw by hand to keep the nozzle off your bed. This makes it less likely to damage your bed surface and gives the nozzle room to leak.

On a new ultimaker repeat this procedure before every print (at least every hour) because the print bed can move/droop like a new guitar string. After many months the droop slows down.

 

 

[gr5 1,761]

In case you didn't already know this:

z=0 should be the nozzle just touching the print bed.

When you tell Cura the first layer is .3mm thick, Cura will move to z=.3 when it starts printing. If you tell Cura the first layer is .1mm thick, Cura will move to z=.1 when it starts printing.

 

[illuminarti 18]

Yes, as George said, it rather looks like you're getting a lot less than 0.3mm on that first layer. So either your z=0 bed height position is wrong, or else your bed is very un-flat. A 0.3mm first layer should be able to smoothly cover up a normal range of bed variation.

 

[ulbie 0]

I think in this case the rods are the problem. I had the same look with the prints. And it wasen't the leveling. If the rods aren't exactly straight, you can level as much as you want, even with the flatest printbed ever. The problem mostly shows up in the middle where the rods cross each other, so for me this looks like the rods. I never heared of the problem on the left or right side of the bed...