55° Carbide Insert
While not inexpensive, carbide inserts offer excellent value—each insert provides four cutting edges, significantly reducing the need for frequent sharpening and saving valuable time.
Carbide cutters perform well on hard-to-machine materials like cold-rolled steel and are also effective on aluminum, brass, and leaded steels, offering exceptional durability. However, for the finest finishes on softer metals, a well-sharpened high-speed steel tool still delivers superior results.
This is the 10-pack of replacement carbide inserts for the following tool holders:
- Straight Insert Tool Holder
- 55° Carbide Tool Holders
- 55° RH Boring Bar
- 55° LH Boring Bar
- 55° RH 3/8″ Boring Bar w/2 Flats
- 55° LH 3/8″ Boring Bar w/2 Flats
- Quick-Change Carbide Insert Tool Holder
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INSCRIBED CIRCLE | 0.250″ (6.35 MM) |
CUTTING EDGE LENGTH | 0.254″ (6.45 MM) |
INSERT THICKNESS | 0.094″ (2.38 MM) |
CLEARANCE ANGLE MAJOR | 11° |
INCLUDED ANGLE | 55° |
ISO INSERT DESIGNATION | DPMT 21.51 |
CORNER RADIUS | 0.016″ (0.4 MM) |
MINIMUM FEED PER REVOLUTION | 0.002″ (0.05 MM) |
MAXIMUM FEED PER REVOLUTION | 0.006″ (0.16 MM) |
DEPTH OF CUT MINIMUM | 0.004″ (0.1 MM) |
MAX DEPTH OF CUT | 0.059″ (1.5 MM) |
Related products


3-piece Center Drill Set
Center drills are essential for accurately drilling starter holes in the ends of workpieces, particularly when mounting stock between centers on a lathe. Each drill creates a small pilot hole followed by a 60° countersink, which provides a seating surface for the 60° point of the lathe center.
In milling applications, center drills are commonly used to start holes precisely. The exact hole location can be dialed in using the mill’s calibrated handwheels, and the center drill ensures the hole begins accurately without drifting.
This set includes three double-ended, high-speed steel (HSS) center drills:
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#1 drill: 1/8" shank
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#2 drill: 3/16" shank
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#3 drill: 1/4" shank
The larger shank diameter of a center drill ensures the tip remains centered, reducing the risk of the drill "walking" as the hole is started. After the center drill has established the starter hole, it is replaced with a standard drill bit to complete the hole to the desired diameter.
⚠️ CAUTION: Always use a suitable cutting lubricant and back the drill out frequently during use. This prevents the delicate tip from overheating or breaking off.


80° RH and LH Tool Holders w/Carbide Inserts
These holders are available individually in right-hand and left-hand configurations, or as a matched pair. Each includes an 80° carbide insert, a hold-down screw, and a Torx® key for installation.
Specifications & Features:
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3/8" square shank, compatible with standard 3/8" insert tool posts
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5° offset angle provides better tool clearance for complex operations
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Tip height is 0.375" from the base, meeting industry standards
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Constructed from case-hardened steel with a durable black oxide finish
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80° inserts are ideal for roughing cuts
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55° insert holders are also available for sharper corner access
For example, when the holder is squared with the crosslide, it allows you to turn an O.D. up to a shoulder, then finish the shoulder by backing the tool out—while maintaining proper clearance throughout the cut.
Advantages of Inserted Tip Carbide Tools
Although more expensive than high-speed steel (HSS), carbide inserts offer key benefits:
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Each insert can be rotated 180°, giving you two cutting edges per insert
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Maintain a sharp edge when cutting exotic alloys or abrasive materials
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Enable faster cutting speeds and improved surface finishes
While HSS tools are ideal for general use due to their affordability and ease of resharpening, carbide tools are essential for challenging jobs, which is why they're widely used in professional machine shops.
Note: Tool orientation is based on the direction of chip flow. A right-hand tool has its cutting edge on the left, with chips exiting to the right.
Chip Breaker Update: The previously used straight-groove chip breaker is no longer available. Current inserts now come with the improved spider web-style chip breaker, as shown in the updated product images.