Re: ISO30 tool holder marks: is this normal?
If multiple tool holders have similar marks, the spindle taper is damaged.
Probably had chips jammed in.
Often fixable with some work.
A ding / scratch in metal will usually result in a depression/low area, but also raised/high areas. These high areas in the spindle taper will cause run out and damage tool holders
The spindle taper can be reground, or sometimes stoning of high spots can remedy the situation.
A few low spots don't matter - a small reduction in spindle taper contact area is not an issue
7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)