Watching this old tutorial from Daniele Angelozzi and he mentions this issue with certain Chisel brushes:
https://www.youtube.com/watch?v=7I5y0fJUI1c&t=562s
It’s the same in 2023. Half my chisels don’t work as intended:
I’m planning on just making my own custom primitive shapes Chisel at this point because of how useful it’d be, but I’m curious if there’s a way to fix the original brushes.
Hi @Jiggywatt ,
I’m not certain I see what the issue is for the “broken” brushes. These are the expected results for those particular meshes with those brushes going back to ZBrush 2022. However if it is the difference in the surface buildup behavior when multiple strokes overlap that is concerning you, this can actually be explained fairly easily 
Brushes like Chisel can use the feature described on this page in the “Non-Buildup of Overlapping Strokes” section to keep depth consistent and minimize buildup when two separate strokes overlap.
This feature requires that Lazy Mouse be active (not true by default for all VDM brushes), the base brush type be Chisel or Layer, and that a morph target be stored prior to making the strokes.
In addition, even if all the above was true some of the brushes in question have the Brush> Samples> Fast Samples option active. This is desirable in most cases but it will cause the above mentioned feature to fail because it specifically ignores morph targets.
If this is what is concerning you, you could:
A.) Save a new version of the desired brush with all the things I mentioned above corrected.
B) Use the Brush> Create > Copy Meshes and Paste Replace functions to copy the VDM meshes from one brush into the Chisel Brush. This will replace the meshes for that brush but keep the settings of the original. Change the stroke type to “Drag Rect” then save the brush out with Brush> Save as into the Lightbox folders and load it on demand.
I’ll have the team take a look at the default settings for the brushes and see if a change is warranted.
Hope that helps!
ah thank you for the clarification!
For anyone reading, In addition to the 3 requirements (Base Type Layer, Lazy Mouse on, and Morph Target stored), I got it to work by disabling “Fast Samples” like Spyndel suggested.
Also, if “Fast Samples” is greyed out, just set the Samples Radius value below it to something like .5 (I also set Normal and Pos values to 1)
Time to make some custom brushes! 