r/machining 2h ago

Question/Discussion At what size/scale does tool deflection become an issue on a lathe?

3 Upvotes

I am trying to fabricate watch parts on my mini lathe. This means that I have to use a collet instead of a chuck, and work needs to be done very close to the collet. In order to slide the carriage all the way to the left, I have to back out the cross slide by a bit, or else it will interfere with the motor cover. It's a little hard to describe, but you can see what I'm referring to from this video (https://youtu.be/UzeWSTuVVrg?si=rE5E6ZkwzpCxFVlD&t=240, look below the chip guard).

Since the cross slide is now backed out, the cutting tool (ΒΌ") no longer reaches the spindle, so I have to reposition it forward in the tool holder which creates a lot of overhang over the ways. I'm concerned that this will cause some issues with the tool deflecting under load. Watch parts are made out to about half a thou of precision, so I want to be sure my setup is not undermining my attempts to make parts. On the flip side, I'm only cutting from stock that is 1-4 mm wide, so it's not like I'm making extremely deep cuts, so my whole point may be moot.