What the designation means
| S | Bar type | steel bar |
|---|---|---|
| 20 | Bar diameter | 20 mm |
| S | Length | 250 mm |
| S | Clamping | screw through the countersunk hole |
| T | Insert shape | triangular |
| F | Style (cutting edge angle) | κr 90° · end cutting |
| C | Insert clearance | 7° |
| R | Hand | right-hand |
| 11 | Insert size | cutting edge about 11 mm |
Boring bars follow ISO 6261: first the bar type, diameter and length, then, after the hyphen, the same letters as external toolholders (ISO 5608). The minimum bore the bar can work in is not in the code: it is in the maker's catalogue.
Inserts it takes
It takes TCGT / TCMT inserts, size 11: the pages below explain each one. Grade and chipbreaker are chosen from the catalogue, by material.
Left-hand version
The left-hand version is S20S-STFCL11: same insert and size, mirrored. Right or left depends on the feed direction and on how the tool sits on the turret.
What it is for
Style F has a 90° cutting edge angle (end cutting): it is used for 90° facing.
Same type, other sizes
Designation to ISO 5608 (toolholders) and ISO 6261 (boring bars); cutting edge angles as in the ISO 5610 standards. No maker has approved this page: the catalogue is what counts.