Manually adjusting model Z-height?

Bambu Lab Software Bambu Studio
1

A number of my models (molecules) were having problems with small spheres as the bottom contact points. The bottom half of the sphere would be missing or warped slightly.

I found a trick to raise the model up off the bed by adding another small primitive, moving that down, and raising the assembly.

This seems a bit silly though. Shouldn’t I be able to take the model, raise it 2-3 mm and add supports if that’s what I want? Right now, if I try to move something in the Z direction, nothing happens.

2

Hi.
I think it is worth the effort to find the cause of the issue and try to solve it. 2-3 mm is a significant offset.

At your responsibility, you can set up the z-offset by tweaking within the g-code.

G29.1 Z{XXX}

Where {XXX} is the change in the distance between the nozzle and bed in mm. E.g. decrease the distance by 0.13 mm:

G29.1 Z{-0.13}

Notes:

  • This G-code was only tested for minor adjustments (e.g. BL used for the PEI textured with a value of 0.04mm). I am not sure about the limits.
  • If you follow this procedure, take care, at least for the first time, to monitor the print and prepare to unplug from power if you notice any issues.
3

While that would be useful for a few other ideas, I’m looking to push the model up off the plate to force the slicer to create better supports for the spheres at the bottom of the model.

I think the small spheres don’t get sufficient supports when they’re contacting the plate directly.

IIRC, adding that as g-code wouldn’t necessarily change the position of the model in the slicer to force new supports.

4

Have you tried to print your model with some raft layers in the support settings?

5

Yes - it helped solve some general adhesion problems. I’ve been using a 1 layer raft, but I’ll give a 3-layer raft a try now - certainly worth a try.

6

Another thing to try for your small spheres is to use variable/adaptive layer height in addition to the raft to reduce the deformation of the bottom.

7

I have just been looking at the feature called Assembly now I believe called Merge, represented by the jigsaw icon.
I havent got to grips with the whole thing yet but have discovered that you can lift your model off the bed by giving it a difrrent z height… you should be able to place it on a primitive and combine as a stl.
I am trying to go in the direction of negative z, so will investigate further.