Hi there, I read this concerning Bump Knurls like the one you posted.
From Mini-Lathe.com
Bump type tools are not recommended, especially for small lathes, because they impose considerable tangential force on the spindle which could lead to excessive spindle bearing wear. The shaft of the bump-style tool can be clamped directly in the mini-lathe toolpost. The head of the tool can rotate up or down on the pin that attaches it to the shaft so that the wheels automatically center themselves on the workpiece. Again, though, I do not recommend this style of tool for use on the mini-lathe due to the high forces it imposes on the spindle bearings In the scissors-style tool the forces are imposed on the clamp arms rather than on the lathe spindle. |
Thats why I made my El Cheapo clamp knurler and got rid of my bump one.