First layer of print being destroyed by 2nd layer

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Re: First layer of print being destroyed by 2nd layer

Post by Redwizard000 » Sat Jun 06, 2015 5:11 am

Ok it is now printing... acceptably. One corner is still a little messed up but I can fix that.

*sigh* I feel sooooo much better now that I know there is nothing wrong with the machine. I would much rather be an idiot n00b than have to shell out money for parts :)

Posts: 1864
Joined: Thu Apr 10, 2014 4:00 am

Re: First layer of print being destroyed by 2nd layer

Post by jsc » Sat Jun 06, 2015 6:37 am

Bed leveling: there are numerous threads on leveling. I had some links in my M2 tips thread, you may want to check those out. But it's really not that hard. Here are my steps, they are very similar to what MG has in one of their videos.
  1. Turn all screws clockwise as far as they will go (clockwise looking from the bottom). The screws pull down on the bed, so tightening them increases the gap. You want them to be as tight as possible, so after tightening them all you will only ever be loosening them as you need to.
  2. Raise the bed up to the nozzle. It is best to do this with a clean glass bed, with a light colored background so that you can see the nozzle and its reflection in the glass. With the bed raised so that there is a small gap between the nozzle and its reflection (to avoid any accidental contact), hold it there by the Z knob while moving the bed back and forth with your other hand. Make sure you are not inadvertently pressing down on the bed as you move it. You should be able to see the gap shrink and grow as you move the bed back and forth.
  3. There are three screws, two front and back and one to the right. Ignore the one on the right for now. On the side (front or back) where the gap is larger, loosen that screw until the gap shrinks to about half of what it was. Check the front and back level again by moving the bed back and forth, and continue to adjust front and back screws until the gap remains the same (the glass may have a slight bow, so you may see that the center is higher than the edges; adjust until the gap is smallest just in the center). You should retighten any screws that you loosened in preference to loosening the other screw. Remember, loosening a screw = raising the bed on that side = shrinking the gap. Tightening = lowering the bed = increasing gap. Once you have it more or less correct, you can move the bed up with the knob slightly and double check with a smaller gap to get more accuracy.
  4. Once front to back is leveled, do the same while moving the X axis back and forth and tightening/loosening the right side screw. If you find that you need to tighten the side screw but it is already tight all the way, you will have to loosen both front and back screws the same amount (and relevel front to back), but if I recall correctly, the right side is generally the low side so you shouldn't have to. (If I'm wrong about this, just start in step 1 by tightening all the screws, then backing them off just a little bit to give yourself some headroom).
  5. Once you have side to side level, just double check front to back one more time, it shouldn't have changed.
Takes just a minute, no special tools required.

Finally, raise the bed until the Z end stop is just triggered and make sure it gets triggered before the nozzle hits the bed. There should be a very small gap just when it's triggered. If it doesn't trigger until the glass is contacted, you will have to futz with the end stop screw. Get the trigger point more or less correct, it doesn't have to be perfect. Then, print out a calibration cube, set your extrusion width multiplier, and use the height of your cube to enter a g-code offset into your slicer to get the bed height perfect: viewtopic.php?f=3&t=1964 (I've added a link to Jules' post on how to do that at the end of my extrusion calibration post so I could stop having to search for it).

If you want to be extra anal, you can print out cubes in the center and all four corners of your bed, measure their heights and take an average, or you can just optimize for the center of the bed where most of your prints will take place.

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Joined: Fri Dec 19, 2014 3:07 pm

Re: First layer of print being destroyed by 2nd layer

Post by msmollin » Sun Jun 07, 2015 3:01 pm

Bed leveling the M2 is def a chore. It's my one gripe about the machine.

Just to add on to jsc's post, I use Simplify3D's bed leveling wizard to move the nozzle all over the bed to make the process quicker. I end up doing it several times before I get the bed into level. One of the nice things in S3D's wizard is you can tell it the height of your reference object so it'll bring it up to the height where it thinks it should be, and then you can adjust the bed to match.

As for "no special tools required" - I would just like to say that while not *required* a proper set of millimeter gapping shims and a micrometer makes the process much more straightforward. MG's suggestion of using a business card and/or a sheet of paper IMHO is like telling someone to use an adjustable wrench to removed a bunch of nuts from hard to reach places on a car. Yes it'll work, but you'll want to punch all the kittens afterwards.

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