Understanding the Three Most Common Woodturning Parting Tools

Parting tools are some of the most useful tools in a woodturner's shop.

Whether you're cutting a tenon, sizing a spindle, creating a decorative groove, or parting off a finished project, a parting tool is often the fastest and most accurate choice.

While there are many specialty variations available, most woodturners rely on three basic styles:

• Diamond Parting Tool
• Thin Parting Tool
• Standard Rectangular Parting Tool

Each has its own strengths and ideal uses. Understanding the differences can help you choose the right tool for the job and improve your turning results.

What Does a Parting Tool Do?

Parting tools are designed to cut straight into the spinning wood.

They are commonly used for:

• Creating tenons
• Cutting chuck recesses
• Sizing spindle diameters
• Forming decorative grooves
• Parting projects off waste stock

Because they remove material in a narrow cut, they allow for precise measurements and repeatable results.

Diamond Parting Tool

The diamond parting tool is the most popular style among modern woodturners.

Its blade is shaped like a diamond when viewed from the end, with tapered sides that narrow toward the cutting edge.

Advantages

• Reduced friction in deep cuts
• Better chip clearance
• Less chance of binding
• Smooth cutting action

Because the blade narrows behind the cutting edge, there is less metal rubbing against the sides of the cut.

Best Uses

• Creating tenons
• General spindle turning
• Sizing workpieces
• Parting off projects
• Deep grooves

For many turners, the diamond parting tool becomes the go-to choice for everyday work.

Thin Parting Tool

A thin parting tool uses a much narrower blade than other designs.

Its primary advantage is simple: it removes less wood.

Advantages

• Less waste
• Faster cuts
• Minimal material loss
• Excellent for small projects

This can be especially useful when working with expensive exotic woods where every bit of material matters.

Best Uses

• Pens
• Bottle stoppers
• Christmas ornaments
• Small spindle projects
• Delicate detail work

Because the blade is thinner, it's important to avoid excessive side pressure during deeper cuts.

Standard Rectangular Parting Tool

The rectangular parting tool is the traditional design that many turners learned with decades ago.

The blade maintains a constant rectangular shape from top to bottom.

Advantages

• Strong and durable
• Simple design
• Easy to sharpen
• Handles heavy cuts well

Because the sides are parallel, the tool is very rigid and capable of handling demanding work.

Best Uses

• Rough sizing cuts
• Larger spindle projects
• Production turning
• General shop work

The downside is that the parallel sides create more friction during deep cuts, which can sometimes cause binding if chips aren't cleared frequently.

Which Parting Tool Should You Buy First?

If you're purchasing your first parting tool, the diamond parting tool is usually the best choice.

It offers:

• Excellent versatility
• Smooth cutting action
• Reduced friction
• Good chip clearance

Many experienced turners use a diamond parting tool for 90% of their parting operations.

When to Use Each Tool

Choose a Diamond Parting Tool When:

• Cutting tenons
• Making deep grooves
• General spindle work
• You want maximum versatility

Choose a Thin Parting Tool When:

• Working with small projects
• Turning expensive woods
• Reducing waste matters
• Making delicate cuts

Choose a Rectangular Parting Tool When:

• Heavy-duty cuts are needed
• Maximum rigidity is important
• Performing rough sizing operations

Sharpening Tips

Parting tools are among the easiest turning tools to sharpen.

A few simple guidelines:

• Maintain the original bevel angle
• Keep the cutting edge straight
• Remove burrs after grinding
• Sharpen frequently rather than heavily

A sharp parting tool cuts cleaner, creates less heat, and is much easier to control.

Common Beginner Mistakes

Cutting Too Deep Without Clearing Chips

Wood chips can pack into the groove and create excessive friction.

Back the tool out periodically to clear debris.

Forcing the Tool

Parting tools work best with steady pressure.

Let the cutting edge do the work.

Using a Dull Edge

Dull parting tools generate heat, burn the wood, and require much more effort.

Applying Side Pressure

Parting tools are designed to cut straight ahead, not pry sideways.

This is especially important with thin parting tools.

Final Thoughts

While bowl gouges and spindle gouges often get most of the attention, parting tools are among the most useful tools at the lathe.

The diamond, thin, and rectangular parting tools each have their place, and understanding their strengths will help you work more efficiently and accurately.

For most woodturners, a quality diamond parting tool is the best all-around choice, while thin and rectangular styles serve as valuable specialty tools when the situation calls for them.