How I calibrated my bed successfully first time.

General Hardware
1

I pretty much followed the “quick_start_guide_2.pdf” to level my bed, but there were a few things not mentioned, and I thought I’d share what I did.

this part is as described in the guide:

  1. Start Printrun and Connect to printer
  2. Lift extruder off glass about 50mm in Z
  3. Home X and verify position
  4. Home Y and verify
  5. Adjust Z End-Stop Knob counterclockwise (i.e. raise it ~ 1 cm)
  6. Home Z and it should stop above glass ~ 1 cm
  7. Put a sheet of paper on glass below nozzle, and adjust Z End-Stop Knob clockwise a little and Home Z each time to bring it closer and closer to the sheet of paper; as you get close, turn the knob in 1/2 turns at a time and Home Z each time until it nearly hits the paper. Now adjust the knob in small increments, 1/4 or 1/8 turns until the paper just barely has some tension to pull it out from under the print head.

this is my addition:

  1. once you get the paper to have just the right tension on the front left corner (i.e. all axii Homed), with motors off (default), slide the extruder assembly by hand manually to the right… check the tension of the paper as you move it to the right… adjust the front right corner height screw… up or down… to maintain the same tension. Slide the extruder carefully, and stop if you feel the slightest tension on the paper increase… if so, lower the front right corner using its adjustment screw (clockwise to lower). If too loose, raise the right corner using the screw (counterclockwise).
  2. now do this for back right corner, by manually sliding the Y glass bed all the way forward. The extruder is still very close to the bed, and you need to carefully maintain the paper’s tension (adjust the back right height screw accordingly).
  3. do the same procedure for back left corner, again slide the extruder assembly by hand and maintain the tension by adjusting its screw. Now all four corners should be pretty level.
  4. I repeated this procedure once more, then moved the head manually around the bed, checking the paper’s tension, very slightly adjusting the screws one final time until perfect

The advantage to sliding the extruder manually with the motors off, is that you will not force the print head into the glass damaging it. You can slide the extruder easily and feel the slightest drag or looseness. I would constantly check the tension of the paper by sliding it back and forth under the extruder.

This seemed to work great, and so far my prints have come out level and perfect on the glass. Hope it helps.

2

I created a bracket to hold a runout gage. Attaches where the fan does.

https://forum.lulzbot.com/t/bracket-for-runout-gage-bed-leveling/813/1

I level the 4 corners using the gage which allows me to see exactly how much I’m adjusting the height.

Only place I use the “paper feeler gage” technique is in center of table.
You should notice a rather significant difference in the gap between bed and nozzle in the four corners, compared to the gap in dead center of table.

3

very cool edlink! wish I had that a few days ago… all in all, the paper worked fine tho. I did notice a very slight bulg upward in the center of the glass like you mentioned… so far all is good. :smiley:

4

Thanks.

There’s a youtube video in the link I posted earlier showing how much of a difference there is between center of bed and edges.

This appears to be due to the x-axis bars drooping under the weight of the extruder head.

My runout gage is heavier than the cooling fan, so I doubt the droop is quite as drastic as the video would lead one to believe, but it is there for sure.