Drill 360 free-machining brass with HSS at about 150 SFM: 1,146 RPM for a 1/2 inch drill, 2,292 RPM for 1/4 inch, feeding about 0.0045 in/rev at 1/4 inch.
What RPM and feed for 360 free-machining brass?
| Drill | RPM | Feed (in/rev) | Feed (IPM, capped 2500 RPM) |
|---|---|---|---|
| 0.0625" | 9,167 | 0.0011 | 2.81 |
| 0.125" | 4,584 | 0.0022 | 5.63 |
| 0.1875" | 3,056 | 0.0034 | 8.44 |
| 0.25" | 2,292 | 0.0045 | 10.31 |
| 0.3125" | 1,833 | 0.0056 | 10.31 |
| 0.375" | 1,528 | 0.0067 | 10.31 |
| 0.5" | 1,146 | 0.0090 | 10.31 |
| 0.625" | 917 | 0.0112 | 10.31 |
| 0.75" | 764 | 0.0135 | 10.31 |
Tools for cutting 360 free-machining brass
How does 360 free-machining brass machine?
C360 brass is the reference material for machinability ratings. It is also grabby: a drill or a tool with positive rake will pull itself in. Use zero or slightly negative rake on lathe tools and dub the cutting lips of drills flat before drilling brass.
Why a HSS twist drill?
Twist drill speeds are set lower than turning speeds because the cutting edge is buried in the hole with no escape for heat. Peck deep holes (clear chips every one to two diameters), and use cutting oil in everything except cast iron, brass and plastics.
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 360 free-machining brass?
A starting surface speed of 200 SFM with HSS and 500 SFM with carbide, and 150 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. 360 free-machining brass rates best of any common metal (the 100% reference) 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 360 free-machining brass
Other materials with a HSS drill
- 6061-T6 aluminum
- 7075-T6 aluminum
- 932 bearing bronze
- 110 copper
- 12L14 leaded steel
- 1018 cold rolled steel
- 1045 medium carbon steel
- 4140 alloy steel (annealed)
- All