Bottom of parts squished / Z travel compressed near bottom? (Ender 3)

(Ken Johnston) #1

Hi,

I just got an Ender 3. Overall it’s been great but I’m seeing something weird that I haven’t seen posted online.

It appears that the Z- is traveling too little, only at the bottom of the part. The first several layers are squished and appear very “wet” when building, as if the machine is over-extruding. Parts bulge out (elephant feet) and features are lost.

But then at about 0.5-1.0mm, it sorts out and prints fine. I’ve played with temp / bed temp, bed height and leveling, etc, and the very first layer looks great. So I don’t think it’s a Z home issue. If I were to lower the bed to try and address this, the filament wouldn’t even touch it.

I put a ruler up against the extruder, and when I jog from Z 0.0mm to 1.0mm, sure enough it moves more like ~0.6mm. If I keep jogging in 1mm increments, those look well calibrated.

See pic of a 20mm XYZ calibration cube. Using calipers, the Z height is ~19.4mm (X & Y are fine). And from part bottom to the bottom of the “X” measures ~3.0mm whereas from the model, it should be 3.6mm.

For the print shown I used Cura with the default “draft - 0.2mm layer height” profile. But I’ve tried tons of other profiles and Simplify3d as well…

Any ideas on what might be going on here? Thanks! Ken

(Michael K Johnson) #2

Does it have mesh bed leveling enabled?

(Ken Johnston) #3

It’s a stock Ender 3 (Pro). So I don’t think that’s possible?

(anon57870006) #4

Printers with a screw on one side only (hoping carriages do the job of directing all fine) are technically bad designs. It can be that the Z stepper is loosing steps at the lowest position due to carriages difficult travel at that location. Try to remove the screw and see by hand how smooth travels up and down you gantry.

(Ken Johnston) #5

Thanks for the suggestion! And I see your point about the design.

I removed the lead screw and yes the x-carriage that rides up and down had quite a bit of resistance. I think I had the eccentric adjustment nuts too tight.

Loosened them a bit, and the problem appears to be resolved! Bottom of parts still seem a little short, but this might just be a question of Z0 height / bed leveling. Much much better than before. Thanks again.

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(anon57870006) #6

Thanks for the feedback @Ken_Johnston because it is valuable: we both know what to suggest for others in such a case :wink:

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