8 Piece Square Style Bolt Remover Set Type 421AG
Before you reach for a bolt extractor kit on a snapped stud, try a left-hand drill bit first — the counter-clockwise cutting action often backs the bolt out on its own while you're still drilling. This 8-piece square shank set covers a range of common bolt sizes and is designed for use with a T-handle or reversible drill, giving you a controlled, low-tech approach to broken fastener removal that works more often than people expect.
What's Included
- 8 left-hand spiral drill bits — square shank style
- Range covers common bolt and stud removal sizes
- Counter-clockwise flute direction — drilling action works against right-hand threads to loosen while cutting
- Type 421AG square shank design — fits T-handles and appropriate chuck styles
Specifications
| Pieces | 8 |
| Shank style | Square shank — for T-handle and compatible chuck use |
| Flute direction | Left-hand (counter-clockwise) |
| Type | Type 421AG bolt remover |
| Application | Broken bolt, seized stud, and stripped screw removal |
| SKU | DBRS-8SQ |
Best For / Applications
- Automotive repair — snapped exhaust manifold studs, broken head bolts, and stripped drain plug removal
- Heavy equipment maintenance — seized fasteners in engine blocks, frames, and structural components where bolt extractors tend to make the situation worse
- Machine shops — controlled broken bolt removal in steel and cast iron without damaging the surrounding bore
- Plumbing and HVAC — corroded or snapped studs in pipe flanges and equipment mounting plates
- General maintenance operations — anywhere a right-hand drill would just spin in a snapped bolt and a left-hand bit gives the fastener a chance to come out intact
About Left-Hand Drill Bits
Left-hand drill bits are ground with a flute that spirals in the opposite direction from a standard drill bit — they cut when the drill is set to reverse (counter-clockwise rotation). On a snapped or seized bolt with right-hand threads, this means the drilling action itself applies torque in the direction needed to unthread the fastener.
In practice, a significant number of broken bolts will back out on their own during left-hand drilling, before the bit even penetrates deeply. The friction and torque of the cutting action is enough to overcome the corrosion or stress that broke the fastener initially. This makes left-hand bits a first-attempt tool that can resolve the problem faster and with less risk of damage than drilling out and using a tap extractor.
The square shank on this set is designed for T-handle use, which provides better torque control and feel than a power drill in tight or precise bolt-removal situations..
Shipping & Ordering
- Ships within 1–2 business days from our warehouse
- Volume pricing available — contact us for multi-unit shop orders
- B2B accounts: Fleet managers, facilities teams, and machine shops can apply for a business account with custom pricing and a dedicated rep — contact us to get started