Talked with an old timer at the shop yesterday and he made me question my whole approach to speeds and feeds

Been running CNC mills for about 4 years now. Always thought I had a solid handle on speeds and feeds. This guy whos been doing it since the 80s saw me program a job on a Haas and just said 'you're burning your tools out too fast, slow it down by 20% and let the chip load do the work.' I laughed it off but tried it on a batch of 304 stainless yesterday. Cut time went up by 10% but I didnt have to swap an endmill halfway through like usual. Now Im wondering what else Ive been doing wrong all this time. Anyone else had an old head drop some simple advice that flipped your whole setup?

2 comments

2 Comments

baker.ben1d ago

Wait, did he also tell you to check your stepover? That one got me good. Ngl I had a similar thing with an old school manual machinist who watched me roughing out some aluminum and just shook his head. He said I was taking too light of a cut and the chips were coming out like dust instead of actual chips. I bumped up the feed and let the tool actually bite and the finish was way better with less heat buildup. Honestly it makes me wonder how much of the modern "optimized" toolpaths are just marketing. Tbh I still catch myself second guessing every tool change now because of that one conversation.

miles2771d agoMost Upvoted

Gotta disagree a bit though. Modern toolpaths have their place, especially with complex parts. Those old school methods work great on simple 2D stuff but try them on some wild 3D surfacing where engagement angle is all over the place and you'll smoke your tools just as fast. It's not all marketing, there's real engineering behind the adaptive stuff.