Threading/Grooving Carbide Insert Tool Holder
Due to the variety of insert types and their cost, the holder is sold separately without inserts, allowing you to select only the specific inserts you need. The holder includes a clamp, 6-32 hold-down screw, and a 7/64″ hex key for secure setup.
⚠️ CUSTOMER NOTICE — July 8, 2020
We’ve identified a potential issue affecting a small number of our Threading/Grooving Carbide Insert Tool Holders. Specifically, the cutting insert may not be securely clamped in place.
When tightening the clamp, the inside corner of the clamp may contact the step adjacent to the insert pocket, preventing full engagement with the clamping notch on the insert. This was caused by an early in-house clamp design that mistakenly used symmetrical angles on both sides of the clamp nose, rather than the intended asymmetrical design. This issue has since been corrected.

To resolve the issue immediately:
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Use a bench grinder or file to slightly grind down the back side of the clamp (see blue circle in the image).
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This will allow the clamp tip to clear the step (indicated by the red arrow), ensuring full contact and proper clamping of the insert.
Fewer than a dozen affected clamps were shipped. If you received one of these defective clamps, please contact us immediately. We will replace any faulty clamps free of charge.
⚠️ CAUTION: Chips coming off the carbide inserts can be very HOT! Use extreme caution. Carbide inserts can also shatter. For these reasons, proper protective eyewear and clothing are especially important when using these tools. Materials like tool steel can form long, stringy chips that wrap around the part. Use a chip brush frequently, or pause machining to clear debris. Accumulated chips, especially when hot, can ignite. Keep the area around the cutter clean and free of chip buildup.
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Insert Holder Material | Case Hardened Steel |
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Body Coating | Black Oxide |
Related products


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.


Knurling Tool Holder
Sherline's knurling tool adds a professional touch to your parts by embossing knurls into the surface, rather than cutting them. Straight knurls are commonly used on the ends of shafts that will be pressed into other parts, while both straight and diamond knurl patterns are ideal for enhancing grip on handwheels and thumbscrews.
This tool can accommodate diameters up to 1" (25 mm) and features both right and left sides that evenly clamp down on your part as it's turned in the lathe, creating a consistent knurled pattern. It comes with one set of spiral knurls that form a diamond pattern.
Additional sizes of knurls for both diamond and straight patterns are also available in the addition knurls tab below.
Note: This knurling tool is not intended for use with riser blocks.


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