Quick answer
A 5/16 left hand brazed carbide tool bit cuts from left to right, making it ideal for threading and facing operations on a lathe with the toolpost on the far side. It is not a direct replacement for a standard right hand bit in general turning.
Why cutting direction matters
Standard right hand tool bits cut from right to left (toward the headstock). A left hand bit reverses that, cutting from left to right (toward the tailstock). This matters most when your lathe setup forces the toolpost to the back side of the cross slide, or when you need to thread up to a shoulder without reversing the spindle.
For bench top machinists, the choice often comes down to lathe geometry and personal preference. If you run a mini lathe with a rear-mounted toolpost, a left hand bit can simplify operations and reduce tool overhang.
Carbide vs HSS in this size
This 5/16 left hand bit uses C6 grade carbide, which is formulated for steel and steel alloys. In hobby-scale use, C6 also works fine on aluminum and non-ferrous metals, though edge life may be shorter than with a dedicated aluminum-grade insert.
Brazed carbide bits like this one offer a lower entry cost than indexable insert tooling. The tradeoff is that you cannot change the cutting geometry once the bit is ground. For one-off jobs or simple profiles, the fixed geometry is rarely a problem.
Tradeoffs: left hand brazed carbide vs standard right hand bit
- Cutting direction: Left hand bit cuts left to right. Standard right hand bit cuts right to left. Choose left hand when your toolpost sits behind the work or when threading up to a shoulder.
- Material versatility: C6 carbide works on steel and steel alloys, and hobbyists find it acceptable on aluminum and brass. Standard HSS bits are more forgiving on soft metals and easier to resharpen. Pick brazed carbide for longer edge life on steel; pick HSS if you frequently switch between soft and hard materials.
- Cost and resharpening: At $1.95 (catalog price $2.95), this bit is inexpensive. But brazed carbide requires a diamond wheel to regrind. Standard HSS bits can be resharpened on a common bench grinder. If you lack a diamond wheel, treat this as a disposable bit. For repeated use, HSS may be more economical.
Product facts
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Tool Bit, 5/16" Left Hand, Brazed Carbide: C6 grade carbide, designed for steel and steel alloys C6 carbide holds an edge well on mild steel and tool steel, but on aluminum it works fine in hobby use — just expect slightly faster edge wear than a dedicated aluminum grade.
Tool Bit, 5/16" Left Hand, Brazed Carbide
Which bit fits your work?
Best for
- Machinists who need to thread up to a shoulder on a mini lathe
- Users with a rear-mounted toolpost who want to cut toward the tailstock
Not for
- General turning on a lathe with a standard front toolpost — a right hand bit is simpler
- Work that requires frequent regrinding without a diamond wheel