Reference

Here are the cutting parameters I use as starting points for deep hole drilling. These are starting points — adjust based on the specific material, machine, and tooling. I’ve collected these numbers over years of setup work, and they save me a lot of trial and error. Cutting Speed Selection by Material Cutting speed is the first parameter I set. It directly affects tool life and hole quality. Run too fast and the tool edge breaks down. Run too slow and you risk work hardening and poor chip formation. ...

Why Surface Roughness Units Matter In my years of deep hole drilling, I have seen countless specification sheets where the customer calls out surface finish in a unit the shop floor does not use regularly. European prints often specify Rz, aerospace jobs use RMS from the old MIL standards, and medical device prints stick with Ra. If you convert wrong, you scrap parts. I keep this conversion chart posted in the inspection area for quick reference. The conversions here are based on the ISO 1302 standard and verified against actual profilometer readings on gun-drilled and BTA-drilled bores. ...