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kazzaqov

Bed leveling problem or?

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Hello everyone.

I have an issue with leveling the bed. Even if I tighten all the screws, use,A4 paper, and try various options for Z-switch, I have a feeling that its not leveled, and the back part of the bed is always higher than the front one, no matter what I do. When printing pretty large objects (like iPhone case) the first layer sticks to the bed unequally: sticks well in some parts, in others the bed is too high or too low. So its impossible to print. I somehow printed with PLA before even with not perfect first layer, but now I have switched to ABS and its totally impossible. The first layer is spoiled and further layers are printed in the air. I can print some smaller objects though, like ultimaker robot, because its printing square is not so large. So, may this be some mechanical problem? I have a heated bed, but the problem was on non-heated bed as well. Maybe someone could upload a good bed level testing object with rounded corners and so on? I so far had no success in printing the perfect first layer, but first PLA prints were pretty ok. Every help will be much appreciated.

 

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Hello everyone.

I have an issue with leveling the bed. Even if I tighten all the screws, use,A4 paper, and try various options for Z-switch, I have a feeling that its not leveled, and the back part of the bed is always higher than the front one, no matter what I do. When printing pretty large objects (like iPhone case) the first layer sticks to the bed unequally: sticks well in some parts, in others the bed is too high or too low. So its impossible to print. I somehow printed with PLA before even with not perfect first layer, but now I have switched to ABS and its totally impossible. The first layer is spoiled and further layers are printed in the air. I can print some smaller objects though, like ultimaker robot, because its printing square is not so large. So, may this be some mechanical problem? I have a heated bed, but the problem was on non-heated bed as well. Maybe someone could upload a good bed level testing object with rounded corners and so on? I so far had no success in printing the perfect first layer, but first PLA prints were pretty ok. Every help will be much appreciated.

 

Hi Kazzaqov

Cura has a bed leveling wizzard. Besides that you could just adjust up your front screws 1/8 turn at a time and testing in between with a big print like your iphone. If it fails on first layer stop the print and adjust another 1/8 turn. When it looks right let it finish the print.

 

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There are a few cura settings to get around people who have trouble levelling. One of them is called "raft". The alternative is having the first layer be .3mm thick (you can have the first layer be thicker than the remaining.

Having said that here's my homing procedure if you want to do it PERFECT:

First heat up the head to 180C and when it is warmed up remove the filament. Then clean the filament off the head with a tissue. Don't burn your fingers.

Now to the Z axis homing only if you can e.g. proterface or UC controller. If you really must do X and Y also then you have to wait until the XY axes are turned off or turn them off with UC.

Now by hand move the head around and move it as close as possible to each screw. Use an ordinary piece of paper. I typically use a sticky note with the sticky edge near my fingers. This kind of paper is about .1mm thick. Typical printing paper is okay also. Slide the paper under the head and tighten the screws until the paper has zero friction, then raise the bed at that spot until there is an increase but not so much that the paper gets stuck or can't be inserted under the nozzle. Now repeat 3 times for each screw. Then repeat the whole thing again (again with a hot nozzle as a hot nozzle expands a little and you want to calibrate/level while hot.

Repeat going around all the screws many times. You might have to do it 5 or 10 times as when you adjust one screw it might mess up the others.

Once it seems really good then I usually just stop there if .2mm layers. If .1mm layers then I loosen each screw 1/8 turn to account for the paper thickness of about .1mm.

Having said all that your metal rods might be warped or your bed might not be flat. Some people grab the z axis and twist it WHILE PRINTING! To get the skirt good. On rare occasions when I mess up the leveling I get lazy and push down on the bed (if that's what is needed) to get the plastic to come out (sometimes I mess up and the head is touching the bed and pressure is building up and nothing is coming out). By the second layer I usually don't have to do anything.

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Thank you guys. I know about calibration wizard. The problem is that a cannot calibrate it to be even at all 4 corners, but I think I will learn how to with some practice

Thanks for a detailed procedure, gr5! I tried calibrating this way, but I don't understand how to swtich from one screw to anoter. For example, I have calibrated the first screw, but when I switch to the next one you say to raise the platform again, that will spoil the previous screw, won't it? And how is it possible to calibrate all screws at a time using that method?

Well I seem to have calibrated it a bit, but still was helping it with a hand while printing the first layer. So now I have a problem: at 40% of the print the new layer just don't stick to the previous one and fail the print. Is that also bed leveling problem?

I haven't had that problem before...Must be because I recalibrated the bed, which was calibrated by the professional before.

IMG_2364_1.jpg

 

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No, the bed leveling and height really only affect the first layer or two - if those print fine, then the rest should also. If you were having problems later in the print it's probably due to issues with your filament, or perhaps a pressure build up, or some other sort of nozzle blockage or feeder problems leading to under extrusion.

In this case, it was probably due to trying to print too fast - that is, too high of a volume of plastic per second. The most you can reliably print is around 8 to 10 mm³/s with a stock nozzle. With a bead width of 0.4mm, and a layer height of 0.2mm and a speed of 100mm per second, you're printing 0.4 x 0.2 x 100 = 8mm³/s. If you increase the layer height to 0.3mm, that increases to 12mm³/s - and that causes very high pressures in the nozzle, and can lead to stripping of the filament in the extruder drive, causing under extrusion and even blockages.

 

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1) Like illuminarti says, bed levelling only affects the bottom layer or two.

2) From the picture I can see your bed levelling is getting pretty good but not perfect. In the photo you can clearly see that the skirt is almost non-existent in a few places. This means the bed is too close to the nozzle and needs to be re-levelled just slightly. What happens when you print is the plastic can't get out yet the extruder keeps feeding so the pressure builds up and then when the plastic finally does come out it comes out all at once and makes a spurt or blob. Not a disaster if it only happens once or twice. To fix this issue you might simply have to smooth out your tape a little better. Maybe you need to reapply the tape. Normally the first layer is .2 or .3mm thick so that you don't have to level quite so accurately. Everything is a tradeoff.

As far as your question about moving from screw to screw, the reason I said you have to repeat the procedure many times is because you are right - each time you adjust a screw it messes up the platform somewhere else. But the spot you are fixing is moving more than the other areas so you get gradually closer and closer to the perfect level each time you repeat the process around the 4 screws (moving the head as close to each screw as possible as you go).

 

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Can I add to this thread. My unit has either got a bent glass plate - not much chance, or the rods are not running in a plane. The rear left corner of the bed is about 1mm high compared to the rest of the bed. Interesting? May not be the bed? I set the three points with feeler gauges and when the head moves over to the rear left it hits the plate. How do I fix a head that does not move in the one plane. No idea. The unit rocks around two of the four feet by about 3mm. But this is built into the design. Ultimaker2. Any suggestions other than the three leveling screws. Does anyone have a machine that does not rock on two of its four feet?

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@yerffoeg: Take out the glass plate and put it on a plane surface. Then press the each corner down (in turn) with your finger. If the glass plate is bent, you'd see it pretty quickly.

The rods could be bent too. This usually happens if the package got handled roughly during shipping or if the printer was pulled by the rods when it was extracted from the box.

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