Had a talk with an old tool grinder that made me rethink my speeds and feeds

Ran into a guy who sharpened drills for 40 years at the old Caterpillar plant in Peoria. He said he saw more crashed parts from guys running too fast than from anything else, and it hit me that I've been chasing cycle time at 12,000 RPM for no good reason. He showed me his setup running at 8,500 with a much better finish and no chatter. Anyone else ever slow down and find they actually gained more than they lost?

2 comments

2 Comments

ryan_gibson841mo ago

Yeah that tracks with what I've seen on some older machines too. Sometimes dropping the RPMs back gives way more tool life and the surface finish ends up way better than chasing numbers on a spreadsheet lol.

allen.ivan1mo ago

The bit about chasing numbers on a spreadsheet really got me, because I got burned on that with aluminum work. I was running an endmill at like 14k RPM because the calculator said so, but the thing would scream and leave a rough finish. Dropped it to 9k and upped the feed a bit, and suddenly the chips came out nice and heavy instead of that dusty powder. Tool life went through the roof too, I think I got almost triple the cuts out of one tool. Sometimes those old guys just know from feel what the numbers don't tell you.