Tool styles
Brazed carbide lathe tool styles
| ISO 243/514 | DIN | Name | What it does |
|---|---|---|---|
| ISO 1 | DIN 4971 | Straight turning tool | General roughing along the bar; the tip is set at an angle so it can also chamfer |
| ISO 2 | DIN 4972 | Bent turning tool | Turning and facing with the same tool; 45° approach, good for chamfers |
| ISO 3 | DIN 4978 | Offset corner turning tool | Turning up to a square shoulder and facing out from it |
| ISO 4 | DIN 4976 | Wide (broad-nose) finishing tool | Fine finishing with a wide, flat edge and high feed |
| - | DIN 4975 | Pointed turning tool | Light turning and getting into narrow corners and undercuts |
| ISO 5 | DIN 4977 | Offset face turning tool | Facing ends and large faces, working out from the centre |
| ISO 6 | DIN 4980 | Offset side (knife) tool | Turning to a 90° shoulder close to the chuck |
| ISO 7 | DIN 4981 | Parting / grooving tool | Grooving and parting off; tip brazed on its back face |
| ISO 8 | DIN 4973 | Boring tool | Opening up through-holes |
| ISO 9 | DIN 4974 | Corner boring tool | Boring blind holes and facing the bottom of a bore |
Right (R) or left (L) hand? On a normal lathe a right-hand tool cuts while feeding from right to left, towards the chuck. Left-hand tools feed away from the chuck, for facing a shoulder from the other side or working near the tailstock.
Choosing a grade
Carbide grades (ISO 513) - lower number = harder and more wear-resistant, higher = tougher
| Grade | Group | Use for | Cutting conditions |
|---|---|---|---|
| P10 | Steel | Finishing steel and cast steel | Higher speed, light feed |
| P20 / P25 | Steel | General turning of steel | Medium speed and feed |
| P30 / P40 | Steel | Roughing steel, interrupted cuts | Lower speed, heavier feed, tougher tip |
| M10 / M20 | Stainless | Stainless steel, cast steel, manganese steel | Medium speed; all-round grade |
| K10 | Cast iron & non-ferrous | Cast iron, aluminium, brass, plastics, hardened steel (light cuts) | Hard, wear-resistant |
| K20 | Cast iron & non-ferrous | General cast iron and non-ferrous work | Tougher than K10 |
Sizes and use
Square shank sizes (common)
| Shank h × b mm | Overall length mm | Typical lathe centre height |
|---|---|---|
| 8 × 8 | 90 | Mini lathes |
| 10 × 10 | 90 | Small bench lathes |
| 12 × 12 | 100 | Bench lathes |
| 16 × 16 | 110 | Medium lathes |
| 20 × 20 | 125 | Medium to large lathes |
| 25 × 25 | 140 | Large lathes |
| 32 × 32 | 170 | Heavy lathes |
| 40 × 40 | 200 | Heavy lathes |
Using and resharpening
- Set the cutting edge exactly on centre height. Use packing under the shank if needed.
- Keep the overhang short: no more than about 1.5 × shank height.
- Brazed tools are blunt-honed when new. A light touch on a diamond lap improves finish on soft materials.
- Grind carbide on a green silicon-carbide wheel and finish on a diamond wheel. Grind the steel shank clear first on an ordinary wheel.
- Never quench hot carbide in water: it cracks the tip and the braze joint.
- Typical angles for steel: clearance 6 – 8°, top rake 6 – 10°. Use less rake for cast iron and brass.
- Use the cutting speeds for carbide in the cutting speeds chart, but start at the low end: brazed tips are less rigid than inserts.