The only way I have been able to make it stop happening is by unifying the subtools. The size of the zmodeler brush had no impact. I even tried importing the вЂњbase modelвЂќ at 1000% scale, but had the exact same issue. Nothing else in my workflow has changed, so this is definitely a bug that needs to addressed. I didnвЂ™t have this issue in ZB2019 or any prior releases. I have had no issues with extruding, stitching, bridging etc, even the smallest of distances. As I work with DAZ3D models, they are the exact same size models I have been using for the last 6 years. I am having this same problem (zmodeler is randomly welding points when trying to extrude or even when stitching 2 points together itвЂ™ll randomly stitch other points around the model). Polygroup island would be a more accurate target for that situationвЂ“if you have other polygons you arent aware of assigned to the same polygroup, it can cause unexplained behavior.ДЄlso be sure to attempt the operation with a mouse to rule out any potential issues with a pressure sensitive device. I notice also that your polygroup target is set to вЂњpolygroup allвЂќ. Meshes that are abnormally small or large in the Zbrush worldspace can perform oddly.ДЄnd then by way of general tip, reduce your Zmodeler Brush radius so you arenвЂ™t involving unwanted elements in your operation.

Some reasons youвЂ™d want to do this are shown in this video. I would suggest performing a unify on your model to make sure it is in the вЂњsweet spotвЂќ for working in Zbrush. I was able to start reproducing similar weird behavior by scaling the tool abnormally small in the worldspace, AND by using a brush radius that was too large for the areas I was trying to target. If I had to guess, IвЂ™d guess you have a combination of problems going on.

YouвЂ™ll see IвЂ™ve modeled something similar to your topology:

ItвЂ™s difficult to make out what is going on, but I canвЂ™t reproduce your issue under normal circumstances. Currently, IвЂ™m using a few different workarounds so as to continue my work, but it is an incredibly aggravating problem that is impacting my productivity and speed greatly.ДЄttached is a video taken in Zbrush to give a good example of what IвЂ™ve described above. This appears to me to be some kind of internal threshold set for automatically trying to weld vertices, however I havenвЂ™t found a setting yet that changes this. If releasing from the command action at a very small degree, for instance in the case of making a very tight, small extrusion, then this collapsing occurs, ruining the topology. To prevent this collapsing, the extrusion has to be dragged past what seems like some kind of internally defined threshold, at which point the collapsing behavior reverts back to the original topology. The edge loops nearby that are close together will collapse into one another in a manner similar to Qmesh actions while dragging for the extrude (or other) command. Below is a more detailed explanation with video attached:Д¬reate a mesh with some edge loops as вЂњhold loopsвЂќ around tight spaces for hard surface modeling then, select a poly or group of polys nearby and use ZmodelerвЂ™s extrude (or insetвЂ¦ or just about any other command).

Zmodeler 3 how to reduce vertices