Having trouble with bottom layer


#1

I’m trying to print the test object, but the bottom layer is a mess, and doesn’t seem to reach the sides of the object. How do I fix this?


#2

Here’s a picture from the top


#3

It looks to me like your Z-offset is set too high (too small of a number). The first layer should be printed a little bit low so that it spreads a bit as it prints onto the glass. Some good tips at this informal FAQ link:


#4

A quick way to make sure you are getting the right offset is to leave the setting set in firmware and compensate it in your slicer.

S3D does it very well by making the Z-Axis value a - (minus) number to move the nozzle closer to the bed. If you get the LulzBot version of Cura it also has this feature in the Machine Settings. Other slicers may have it you will have to check.


#5

Ok, I’m using LulzBot edition of Cura, so I’ll try a -1 in the Machine Settings after I’ve slept, if I’m understanding that right.


#6

-1 is minus 1mm that will most likely be too much.

You would be looking at -0.1 which going by you picture could be -0.2 or so but I’d go 0.1mm steps. Setup a small job in the center of the bed and maybe comment out G29 in your script to save time so it just does the G28 then starts to print.

Once you have the amount… say you move the nozzle -0.3 closer to the bed you can always use that to adjust the firmware as per the user guide.


#7

I’m thinking of writing a feature for marlin or a plugin for octoprint to do this setting…

I know it is trivial once you know what you are doing, but I found it confusing when starting up.

I’d see it working something along the lines of:

Enter Z-offset adjustment mode.
Move the nozzle to the right location using paper/feeler gauge
Press a button to store the new z offset.

In fact thinking further I think one could do an octoprint plugin to do a wizard step through all of Triffid’s calibration guide. Now all I need is the time to do it.


#8

Sorry for the late reply. Thankyou ant0ny, I tried 0.1mm steps, and the problem mostly stopped at -1.2mm. One corner is pretty smooth and happy, but the opposing corner is still messy. I’ve tried re-levelling the bed, but it doesn’t seem to have helped. What am I doing wrong?


#9

What I do for printers that seem to have this problem level everything.

Start with your frame and make sure it is level in both directions. The Wilson is pretty stiff but still the best way is to either have a table that happens to be level or get a piece of say Flat timber place it on your table/bench and level that then place the printer on top of it.

Then level your bed in both directions on the springs.

Then level your X axis by placing a level on the X axis top rod and wind one of the Z axis screws till its level.

Then do a test print. If it still the same you have a issue that the bed is maybe not flat enough.

First look for a sign that the Z axis lead screws are not sticking/jaming a little on the way up or down one side. If it is and you are using springy couplers this can be exaggerated causing one side to compress a little… remember you are talking about what 0.1 to 0.3mm error here.

Depending on what your bed type is. You have to look for things like the bed is warped when hot

Either a Bent X axis rod or a Bent Y axis rod or both… for bent rods rotate each individual Y and X axis rods 90deg at a time and do a print between each rotation. You could have one slightly bend rod and if so you might find a sweat spot that the issue is reduced… if so use a marker and mark the rod to housing position and if the rod is a little loose maybe hot glue it in that position.

After all that I am sure something will show up as an issue.

Depending on your nozzle size you could also increase your bottom layer to compensate as well.