Start 360 free-machining brass at 500 SFM with a carbide turning insert: about 1,910 RPM on 1 inch stock. Rough at 0.0100 in/rev and about 0.05 inch depth of cut, finish at 0.004 in/rev and 0.005 inch.
What RPM and feed for 360 free-machining brass?
| Work diameter | Ideal RPM | RPM on a 2500 RPM mini lathe |
|---|---|---|
| 0.25" | 7,639 | 2,500 |
| 0.5" | 3,820 | 2,500 |
| 0.75" | 2,546 | 2,500 |
| 1" | 1,910 | 1,910 |
| 1.5" | 1,273 | 1,273 |
| 2" | 955 | 955 |
| 3" | 637 | 637 |
| 4" | 477 | 477 |
Feed: roughing about 0.0100 in/rev at 0.05 inch depth of cut; finishing about 0.004 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 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 carbide turning insert?
Carbide inserts need surface speed and a real depth of cut to work as designed. On a mini lathe, choose sharp, positive, ground inserts (CCGT or DCGT style for non-ferrous, CCMT for steel) rather than the heavy-chipbreaker inserts built for industrial machines.
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 carbide insert
- 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