Also known as a ‘tray bit’, this Big Stiffy bowl bit (1″ inch diameter, 1/4″ shank) for CNC routers is an excellent bit for removing a huge amount of material quickly, while keeping a baby’s-bottom smooth radius along the entire cut. With the extra-long flute length and bowl radius of 0.375″, it can remove large amounts of material in a single pass. The ‘super-shear’ blade is designed to leave exceptionally clean cuts at higher feeds rates.
Affectionately called “big balls” in the CNC router community, this is the only 3/8″ radius bowl bit available for home-based CNC router owners. Bits in this family are also known as rounding bits or round over bits.
Why is it called the Big Stiffy? 2 reasons. The first is, this bit has extra mass, which absorbs vibration you’d get from other smaller, more common, CNC router bits of this type. The second reason is, the overall bit length is shorter than the standard bit. This little design modification keeps your bit stiffer while cutting, which gives you a 50% improvement in your surface finish. In other words, the potential for chatter is virtually eliminated.
This bit has a carbide blade brazed to a 4140 body.
- Shank: 1/4″ (6.35mm)
- Radius: 0.375″ (9mm)
- Cut diameter: 1.0″ (25mm)
- Length: 2.0″ (52mm)
- Flutes: 2
- Flute length: 0.825″ (19mm)
- Material: 100% tungsten-carbide tipped
- Feed: 80 inches per minute (16mm/sec)
- Plunge: 15ipm
- Speed (rpm): 10000-14000
- Max pass depth: 0.375″ / 9mm
- Stepover: 30%
- For CNC routers, see this speeds & feeds table
FREE Feeds & Speeds table PDF. Download by clicking here