I tried using a 0.5mm stepdown on a 4140 steel part with a 1/2 inch endmill yesterday and the finish was way worse than my usual 1mm cut.

The chatter was so bad I had to stop the job, but it taught me that lighter isn't always better for tool pressure, has anyone else found a sweet spot for stepdowns on harder materials?

3 comments

3 Comments

the_zara1mo ago

A half millimeter stepdown on 4140 is just asking for trouble.

robinp721mo ago

Yeah drewsullivan is right, that's way too light. It's like the tool is just rubbing instead of cutting. I had a similar thing happen on some 1018, went too shallow and the finish looked awful. Had to bump it up to get a clean chip. Sometimes you need that bit of bite to keep things smooth.

drewsullivan1mo ago

Wait you used a half millimeter stepdown on 4140? That's wild. No wonder it chattered like crazy.