Chatted with an old timer at the local machine shop about tool pressure

He told me his secret to getting mirror finishes was actually backing off feed rate by 15% on the final pass, not cranking it up like I always did. Has anyone else found that slowing down gives way better surface finish than pushing harder?

2 comments

2 Comments

richard_hall1d ago

That 15% number is almost exactly what I landed on too after messing with it for weeks. I was running a 304 stainless job (you know, that gummy stuff that loves to tear) and kept getting these ugly little washboard lines. Dropped the feed from .008 to about .0065 and it came out like glass. The old timer at my shop swore by the same thing, said you gotta let the tool catch its breath on that last pass. Its counterintuitive because you want to feel like you're making progress but the surface finish does all the talking once you try it. Just make sure your DOC is still solid or you'll get burnishing instead of cutting.

richardfox1d ago

Funny enough I had the exact same thing happen at my old shop. Was fighting with chatter on a finish pass for days, old hand walks by and says try dropping the feed like 20%. Night and day difference on the surface quality.