More consistent bed leveling - BEST practices?

[j3d 0]

I would like to be more consistent with bed leveling. I'm using paper at .005 inch thick (.127 mm) but it seems that can be too tight. I would like to use shim stock at .0055 or .006 inch (.140 or .152 mm). But with springs involved, and with various thicknesses of glue, what are the best practices for the most consistent bed leveling?

If this topic has been covered before, links appreciated!

 

[illuminarti 18]

The thickness of glue should be irrelevant; if you are doing it right the glue should be almost imperceptibly thin; apply it lightly and then spread it with a wet paper towel until it all dissolves. Then allow it do dry during the bed heatup, so that it leaves an almost invisible film on the glass.

I get to level a lot of print beds every day, and here's how I do it:

The first thing to do is to make sure that all of your springs are reasonably tight. If they aren't, it's impossible to find the right height with a single sheet of paper, because the tension on the springs is minimal until they're compressed a bit. So, look through the bed from front to back, and adjust the back thumbscrew until the terminal block in the back left corner is about 1mm from touching the lower plate. Tighten the front screws about the same amount, to keep the bed roughly level as a starting point.

Then heat the nozzle and make sure it is clean at the tip.

Now run the leveling wizard again. When adjusting the rear height, just use the dial on the front of the printer. When adjusting the front corners, use the thumbscrews. I recommend not using the 1mm-then-a-paper-thickness approach. Instead, on both passes level the bed to the point where the nozzle just touches the glass. This is easy to see if you look along the surface of the glass; you can see the nozzle touch its own reflection. This approach will leave you 0.1mm closer than the firmware expects, but in conjunction with a 0.25 or 0.3mm first layer height, it helps to ensure that the first layer gets nicely squashed onto the glass for good adhesion.

When setting each point, move the bed up until it just touches the nozzle tip, then back it off and allow it to settle untouched, and then gently close the gap again.

If you find that you cannot compress the front springs enough to get the bed down to where it needs to be, then simply raise the back of the bed a few turns of the thumbscrew, and restart the leveling wizard. You want to end up with all the springs in a middle position, with a gap of about 10-13mm between the two plates of the bed assembly. The springs should be neither totally compressed, nor so loose that they aren't applying any meaningful upward force on the bed.

By doing two passes at the same height you should get fewer surprises; the second pass around should only require very minor adjustments. And aiming for the point where the nozzle touches the glass is a much easier target than trying to interpret the feel of nozzle on paper tension.

 

[j3d 0]

Thanks for the detailed response. I hadn't thought about leveling by eye. Hopefully my aging eyes are up to the task. Maybe I'll try with an eye loop.

:smile:

And that sounds like good advice to keep the springs reasonably tight. I find myself on the loose side usually.

 

[eldrick 65]

Or use a .004 (.1mm) flat feeler gauge - you know, those things we used back when cars had "spark plugs".

 

[illuminarti 18]

But 'feeling' resistance of a sprung bed against a small nozzle is very hard to do consistently anyway - especially if the springs are not properly compressed. What you want to avoid is leveling it too high, because then the first layer won't stick; I think that most of the time people overthink it. The only thing the bed height adjustment affects is the first layer; so just level it by eye - you'll take a fraction of the time, and end up slightly too close which is good for first layer adhesion anyway.

 

[themark 0]

Hello, I would like to use shim stock at .0060 or .010 inch why you not try this?

 

[gr5 2,170]

The software expects .1mm (.004 inch). If you use thicker or thinner shim then it won't be as good as a .1mm shim.

I recommend you do the leveling procedure only once ever on your machine. It's great for getting within .1 or even .05mm accuracy. If you ever need more accuracy just print a layer and adjust the screws based on what you see in the skirt or brim.

The machine is good at keeping it's leveling. I only have to go back to the leveling procedure if I add blue tape (which I haven't done in months) onto the glass.