Start 303 stainless steel at 70 SFM with a HSS lathe tool bit: about 267 RPM on 1 inch stock. Rough at 0.0060 in/rev and about 0.03 inch depth of cut, finish at 0.003 in/rev and 0.005 inch.
What RPM and feed for 303 stainless steel?
| Work diameter | Ideal RPM | RPM on a 2500 RPM mini lathe |
|---|---|---|
| 0.25" | 1,070 | 1,070 |
| 0.5" | 535 | 535 |
| 0.75" | 357 | 357 |
| 1" | 267 | 267 |
| 1.5" | 178 | 178 |
| 2" | 134 | 134 |
| 3" | 89 | 89 |
| 4" | 67 | 67 |
Feed: roughing about 0.0060 in/rev at 0.03 inch depth of cut; finishing about 0.003 in/rev at 0.005 inch. On a 7x mini lathe the power feed rates are fixed by the change gears, so pick the nearest.
Tools for cutting 303 stainless steel
How does 303 stainless steel machine?
303 is the free-machining stainless and the one to choose for machined parts that do not need welding. It still work hardens, so keep the tool cutting at all times.
Why a HSS lathe tool bit?
Ground HSS tool bits are the classic mini lathe tool: they can be ground razor sharp with positive rake, which is exactly what a low-power lathe needs to cut without pushing the work away.
Adjust speeds with the RPM calculator and milling feeds with the feed rate calculator. The cutting speed chart compares every material.
Frequently asked questions
What SFM for 303 stainless steel?
A starting surface speed of 70 SFM with HSS and 250 SFM with carbide, and 50 SFM for HSS drills. These are conservative for hobby machines; raise them in steps if the chips come off clean and the tool stays cool. 303 stainless steel rates fair (about 78% of free steel) for machinability.
What happens if my machine cannot reach the RPM?
Run at your top speed. Running below the ideal surface speed only makes the job slower; it does not damage the tool. For milling and drilling, keep the chip load per tooth or feed per revolution the same so the edge keeps cutting instead of rubbing, which lowers the feed in inches per minute in proportion.
Other tools in 303 stainless steel
Other materials with a HSS lathe tool
- 6061-T6 aluminum
- 7075-T6 aluminum
- 360 free-machining brass
- 932 bearing bronze
- 110 copper
- 12L14 leaded steel
- 1018 cold rolled steel
- 1045 medium carbon steel
- All