hi. i have trouble with the printer only printing on the right side of the board. it looks like the noozle is coing to close on the left side. what can be the problem??
This is OBVIOUSLY a problem with bed levelling! This is the very first skill you need to MASTER with complete confidence! It seems so highly unlikely that this hasn’t been spelled out for you SOMEWHERE, but my cursory glance at EweToob didn’t reveal anything like what I’m going to tell you! I had to figure this out for myself, but it’s a method that should work as reliably as any precise list you can find. First of all, I’d like to point out that four-point levelling like this is a THEORETICAL DIFFICULTY! Any surveyor on the planet can tell you that their instruments operate on THREE points, not four, as that is geometrically FAR superior! If that’s not apparent to you, try considering it like this: imagine that you HAVE it perfectly level, solidly on each of the 4 points with equal weight (bearing). What would happen if you turned just one screw? Ans: that one corner would be out of alignment with the other three, which remain co-planar, So if you had turned your one screw downward, the glass (or whatever the straight, rigid structure is) would still sit solidly on the 3 coplanar screws. Only if you PUSH the plate down toward that one lowered screw would the plague move to it - by ROCKING on the two ADJACENT screws, coming up and off the one opposite corner screw. Now what???
OTOH, if you had turned the one screw of your choosing UPWARD, you will of necessity be picking the bed up and OFF the other screws - at least ONE of them, and that one will be one ADJACENT, NOT the one OPPOSITE. This means that you’d be able to rock the bed back and forth by pressing down and either adjacent corner, thereby lifting the bed up and off the OTHER adjacent screw. You could rock back and forth, pivoting on your adjusted screw and the one opposite it, but never being able to stabilize the rocking without adjusting at least one of the adjacent corners. If you’re confused by now over this (and I seriously hope that you are NOT) please reread (with a dictionary if necessary) until you DO understand it all. It will help you to know the theory.
Either way, here’s my routine, which ASSUMES that you are proficient in repositioning the nozzle/bed manually by axis movement in the Prepare menu, awkward and kludgy as it is:
- Home all 3 axes (in the Prepare menu). You want the 0,0 corner after homing to NOT be pressed down into the spring of the adjusting screw. If you see or feel ANY movement of the bed when Z is being homed it means you need to adjust that corner LOWER in order to avoid that collision (This is assuming, of course, that your X and Y at 0,0 positions the nozzle directly over the print surface, very near both edges of that corner. Otherwise Z home will be GUESSING! So if after autohoming the nozzle is NOT over the bed, move the Z up a few mm and move X and Y enough to get onto the bed surface. Then you can adjust the Z screw of that corner DOWN enough to clear the nozzle, just barely.)
- For ALL adjustments with the four screws you need to have this well-engrained in your thinking: when looking DOWN on the bed from above, twisting any of the adjusting screws CLOCKWISE (CW) will TIGHTEN the gap between the bed and the nozzle - by RAISING the bed. Since the usual check of that fit involves sliding a piece of paper between bed and nozzle, if it’s too tight to move the paper back and forth you need to LOOSEN the fit, or turn the screw COUNTERCLOCKWISE (CCW).
- Now for the X,Y positions that you need to use for the leveling procedure, along with the suggested order: 35,35 - 275,275 - 35,275 - 275,35 (these positions match the adjusting screws). To be most efficient with the axis movement of the manual menu, I suggest moving X and Y to 5,5 with the 1mm option FIRST, From then on, ALL your movements can be done with the 10 mm movements! Non-trivial! Now, ALL four points will have to be done multiple times, gradually zeroing in on that perfect, coplanar and equidistant setting where you can consider your bed LEVEL! And one more thing: you can do this all COLD, both bed and nozzle, but you really DO NEED to recheck and adjust with BOTH up to temp! That adjustment, though, should be fairly minor!
- The order I suggest is, as stated, starting at 35,35 and then 275,275. For the first rough setting you can go to either adjacent spot next (35,275 or 275,35) and then the other (last remaining) one. From there, it will be most efficient to go back and forth ACROSS diagonals to dial them in perfectly, then switch to the OTHER pair of diagonals. Finally, when the tension on that piece of paper is perfectly matching in all 4 points, you can make a final check at 155,155 - the point central to the adjusters. Hopefully this matches the tension on the paper very closely; anything else would indicate a warped bed, so it better be really close! If it’s too far for comfort, perhaps a “fix” could be contrived by manually mapping the bed: in essence, manually trying to replicate the bed mapping process used on printers with automatic bed leveling sensors (like the CR Touch or impedance sensors). Marlin can store a “map” of your bed and use that map to adjust your first few layers to compensate. But that’s a whole different chapter.
- Backtracking now: this further detail actually belongs somewhere in #3, being the efficient routine for movements to make adjustments possible: Once you have tested and adjusted the tension on a piece of paper, so you have just a LITTLE resistance to it slipping back and forth by pushing and/or pulling FROM ONE GRIP in the paper (NEVER have it so tight that you have to grab the paper with both hands, from opposite sides, so you can PULL with one or the other!) !!! And ANOTHER important detail: BE SURE that your nozzle does NOT have a goober of plastic on the tip, as that will obviously throw your adjustments WAY off!!! Anyway, back to movements: you have adjusted with Z=0 at ONE of the grid points. Now you want to move Z up a little. I usually move up 2 mm. THEN go to the next desired X,Y point and then move the Z height back down to 0, Adjust the tensioning screw, then move Z back up 2 mm. Then move on.
This may seem like a complicated mess, but if there’s a better and more bullet-proof description, you’re welcome to 1) follow it instead, and 2) throw it in my face and tell me how I have hereby wasted your time as well as mine. I’m a big boy - I can take it.
But I’ve also been in this game for well over a decade and brought certain skills when I first arrived: mechanical aptitude and dogged analytical skills. Just saying….
I hope this helps you or any other passers-by. I gotta get back to MINE….
!!! PS: I have observed another problem in similar printers: you need to make sure nothing is LOOSE that needs to be TIGHT. Yes, nuts, bolts and screws GENERICALLY, but one I discovered I recently had serious sloppiness in the WHEELS that roll on the aluminum extrusion - like the X carriage, for instance. If any of the 3 wheels can spin freely, there is too much play. You don’t want them too TIGHT, but you want to get rid of any free play (akin to “backlash”). This is done by adjusting the one eccentric post - it should be easy enough to find? —-END of PS