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


RH 55° and 80° 3/8″ Boring Bars w/Carbide Inserts
These 3/8" diameter boring bars feature a carbide insert secured with a Torx® screw and come complete with a Torx wrench. Choose between:
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A 55° right-hand insert, suitable for starting holes as small as 3/4", ideal for reaching sharp internal corners
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An 80° insert, which fits into a smaller 1/2" hole and offers added strength for roughing operations
Each holder measures 3-1/4" long and can bore to a depth of just over 2" when properly secured with two set screws. Manufactured from durable 1144 Stressproof® steel with a black oxide finish, these tools are available individually or as a discounted set.
Why Choose Carbide Insert Tools?
While high-speed steel (HSS) remains common for small machine tools due to its low cost and resharpenability, carbide inserts offer significant advantages in demanding applications:
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Longer-lasting edges when cutting hard metals like stainless steel, titanium, or abrasive materials such as carbon fiber
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Faster cutting speeds and greater efficiency
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Each insert can be rotated 180°, effectively giving you two cutting edges per insert
Although carbide inserts can't be resharpened, their durability and versatility make them a preferred choice in professional machine shops.
Note: The older straight-groove chip breaker insert is no longer available. Current inserts include the spider web-style chip breaker, as shown in the updated images here & here


Carbide Inserts (thread, groove)
These Carbide inserts are used in the Insert Tool Holder and are used for either threading or grooving.
Thread Cutting
- 60° threading insert for cutting outside threads (P/N 22675)
- .031" insert (P/N 2269)
- .062" insert (P/N 2270)
- .094" insert (P/N 22694)
- .125" insert (P/N 22695)
- .031" radius insert (P/N 22692)
- .062" radius insert (P/N 22693)


80° Carbide Insert-10 Pack
While carbide inserts may have a higher upfront cost, they offer excellent value by providing four usable cutting edges per insert and significantly reducing time spent on tool sharpening.
Carbide cutters excel at machining difficult materials such as cold-rolled steel, stainless steel, and bronze, delivering consistent performance and long tool life. They are also compatible with aluminum, brass, and leaded steels—though for these softer materials, a finely honed high-speed steel tool may still yield the best surface finish.
This is the 10-pack of replacement carbide inserts for the following tool holders:


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.