Straight Router Bits: Selection, Setup, and Technique

How to Use This Guide

The straight router bit cuts more joints than any other bit in the shop. Grooves, dadoes, mortises, inlay pockets, rabbets: most of the structural work in furniture and cabinetry starts here. At a rack of 40 bits, though, it's not obvious which diameter to grab, why one bit costs $35 while another costs $7, or what RPM to run.

This guide answers those questions directly.

• If you're buying your first straight bit: Start with Part 2 (diameter selection) and Part 6 (quality tiers).
• If you're setting up for a cut: Go to Part 4 (RPM and depth) and Part 7 (setup technique).
• If something went wrong: Head to Part 8 (troubleshooting).
• If you're deciding straight vs. spiral: Part 5 covers when each makes sense.

Straight Router Bits at a Glance

A straight bit cuts flat-bottomed, square-walled channels in wood. It's the right tool for shelf dadoes, cabinet grooves, furniture mortises, and inlay work. The diameter controls the channel width; the shank size, flute count, and carbide grade determine how clean the cut will be.

Click to expand

In this guide:

• What a straight bit cuts and when to plunge vs. enter from the edge
• Which diameter to buy for which operation
• RPM by diameter, feed rate, and the Rule of Half
• Budget vs. premium: what the money buys

Part 1: What a Straight Bit Does

A straight router bit is a cylindrical cutter with vertical cutting edges (flutes) that shave wood as the bit spins. The cutting edges run along the sides of the bit. The bottom may or may not be designed to cut. That distinction matters more than most buyers realize.

What a straight bit cuts:

• Grooves — channels parallel to the grain: drawer bottom slots, back panel channels in cabinets, tongue-and-groove profiles
• Dadoes — channels across the grain: the shelf supports in a bookcase, the case sides in a cabinet, anywhere you need a shelf to seat squarely
• Mortises — rectangular recesses for mortise-and-tenon joinery (requires a plunge-capable bit or a spiral upcut bit)
• Rabbets — stepped cuts along an edge, done with a straight bit and fence or a dedicated rabbet bit
• Inlay pockets — shallow recesses to exact depth for decorative string inlay or shop-made inlay pieces
• Template routing — following a guide bushing around a router template to cut a precise shape

Straight bits handle more of the actual joinery and casework cuts in furniture than any other type. If you're building shelving, cabinets, or drawers, you'll reach for one constantly.

Click to expand

Standard vs. Plunge-Cutting Straight Bits

This is the one distinction most buyers miss until they try to cut a mortise and the bit refuses to drill in.

Standard straight bit: Side cutting edges only. To start a cut, the bit must enter from the edge of the workpiece and ride through. It cannot drill down into the middle of a board.

Plunge-cutting straight bit (also called "bottom-cutting" or "boring point"): Has cutting geometry at the tip that allows the bit to drill down before cutting laterally. Required for:

• Mortises starting mid-panel
• Hinge mortises in solid wood faces
• Inlay pockets away from the edge

Look for "bottom cutter," "boring point," or "bottom cutting" in the product description. The Whiteside 1085F is a well-known example with a carbide boring point. Most bits sold in starter sets are not plunge-capable. Verify before routing mortises.

RELATED: Wood Routers
Covers fixed-base vs. plunge-base router differences. Choosing a plunge router is the other half of this equation.

Part 2: Choosing the Right Diameter

The diameter of the bit controls the width of the cut. Choose too small and you're making multiple passes to widen a dado. Choose too large and you're fighting vibration and blowout.

Click to expand

According to Infinity Cutting Tools' straight bit selection guide, a practical starter set covers 1/4", 1/2", and 3/4". Those three diameters handle most dado and groove work in furniture and cabinetry.

Shank Diameter Matters as Much as Cutting Diameter

Most woodworkers focus entirely on cutting diameter and ignore shank size. Don't.

A 1/2" shank has nearly four times the cross-sectional area of a 1/4" shank. Less deflection under load means straighter walls. Less vibration means cleaner surfaces. The collet grips more securely.

Use a 1/2" shank on any bit with a cutting diameter of 3/8" or larger. Reserve 1/4" shank bits for small-diameter fine work (1/4" and under) where the router collet only accepts that size.

One Spec Most Buyers Skip: Cutting Length

Cutting length is how deep the bit's flutes extend: the maximum depth the bit can cut in one position before you'd need to reposition.

A 1/2" diameter bit with 1" cutting length can only reach 1" deep. For deep mortises (1-1/2" or deeper in furniture legs), you need a bit with longer flutes, not just more passes at the same bit position.

Stability rule: Don't extend the bit more than twice its cutting diameter beyond the collet. Longer extension amplifies vibration and produces wavy walls.

Part 3: Single-Flute vs. Double-Flute

Most straight bits sold for furniture and cabinet work are double-flute. Here's what that means for cut quality and when it matters:

Click to expand

Double-flute (the standard for furniture work):

• Two cutting edges engage the wood per revolution
• Produces a smoother surface finish than single-flute
• Can feed faster because each revolution removes more material
• The right choice for nearly all hardwood furniture and cabinet routing

Single-flute:

• Larger chip pocket between the one flute and the bit body
• Better chip ejection; the slot is never stuffed with chips
• Stronger bit body (more material means less deflection)
• Rougher surface finish
• Better for: plastics, softwoods where chip clearing is critical, CNC production work

As Fine Woodworking's straight bit overview notes, most woodworking applications are well-served by double-flute. Single-flute is more common in CNC shops and sign routing. If you're buying at Rockler or Woodcraft, double-flute is the default and the right choice for furniture.

Part 4: RPM, Feed Rate, and Depth of Cut

Burning, tearout, and chatter share a short list of causes: RPM too high, feed rate too slow, or depth of cut too deep per pass. Fix any one of those and the problem usually disappears.

Click to expand

RPM by Bit Diameter

Rim speed is what matters: how fast the cutting edge moves through the wood. A larger diameter bit covers more distance per revolution, so it needs to spin slower to stay in the safe 100–120 mph rim speed range.

According to the Pro Tool Reviews router bit speed chart:

For common straight bit sizes specifically:

• 1/4" straight bit: 22,000–24,000 RPM
• 3/8" straight bit: 20,000–22,000 RPM
• 1/2" straight bit: 18,000–20,000 RPM
• 3/4" straight bit: 16,000–18,000 RPM
• 1" straight bit: 14,000–16,000 RPM

The common mistake is leaving a variable-speed router at its maximum setting for every bit. Moving from a 1/4" bit to a 1/2" bit at the same RPM doubles rim speed. At 1" or larger, the error compounds dramatically.

Feed Rate: The Feel Test

Exact feed rate numbers are hard to prescribe because they depend on wood hardness, bit sharpness, and RPM. The practical test is sound and feel:

• Burning or gloss on the wall: Feed rate too slow, or RPM too high. Increase feed rate first.
• Chatter, rough walls, bit fighting you: Feed rate too fast, or depth too deep. Slow down or reduce cut depth.
• Clean, consistent resistance: You're in the right range.

Hardwoods need a slower feed rate than softwoods at the same RPM. Cherry and pine leave resin deposits on the bit. Cleaning bits every few hours of use in resinous woods prevents heat buildup that looks like dull-bit burning.

The Rule of Half: Depth of Cut Per Pass

Never exceed 50% of the cutting diameter in a single pass:

• 1/4" bit: 1/8" maximum per pass
• 1/2" bit: 1/4" maximum per pass
• 3/4" bit: 3/8" maximum per pass

For a dado that's 3/4" deep with a 1/2" bit, that means at least three passes.

The whisper pass: After the final structural pass, set the bit 1/32"–1/16" deeper and take one more very light pass. That final shave removes any tearout or burn from the previous passes and leaves clean walls. Worth the extra 30 seconds.

Part 5: Straight Bit vs. Spiral Bits

Spiral upcut and downcut bits are close relatives of the straight bit. The decision guide:

Click to expand

Why straight bits still dominate furniture work:

According to Woodcraft's spiral vs. straight comparison, spiral bits cost roughly twice as much as comparable straight bits and last longer per linear foot. For most dado and groove work, the straight bit's cut quality is perfectly adequate. The 3/4" straight bit also comes in widths that don't always have spiral equivalents, which matters for full-width dados in 3/4" plywood.

When to spend on a spiral:

• Mortising in dense hardwoods (the upcut geometry clears chips continuously from a deep slot)
• Any routed surface that will be visible in the finished piece and requires minimal tearout
• Production work where bit longevity directly affects cost per piece

RELATED: Router Tables
Router table setups change the technique for both straight and spiral bits. Feed direction, bit height adjustment, and climb cutting all work differently with a table vs. handheld.

Part 6: Quality Tiers: What You're Paying For

A wall of straight bits ranging from $7 to $45 for the same nominal diameter is confusing without knowing what the price actually buys.

Click to expand

What Changes at Higher Price Points

Carbide grade: Budget bits use standard carbide (C2 or similar). Premium bits use micrograin carbide: a denser particle structure that holds a sharper edge longer and resists chipping. Per Fine Woodworking's quality router bit forum, carbide grade is the primary driver of cut quality and edge retention.

Carbide thickness: Thicker tips can be resharpened multiple times. Budget tips are thin. There's little material to remove during sharpening, so they're effectively single-use. Whiteside's tips are thick enough for 3–5 resharpening cycles.

Grinding precision: A precisely-ground cutting edge runs true. An imprecise grind produces slight imbalance. The bit vibrates, leaves wavy walls, and burns under load.

Coating: Freud applies a PTFE (Teflon-like) coating to reduce friction and prevent resin from bonding to the bit. Useful in cherry, pine, and other resinous species. Whiteside doesn't coat; they rely on the carbide quality itself.

The Three Tiers

Budget (under $15/bit — generic imports, off-brand sets): Fine for pine, MDF, construction lumber, and one-off projects. Skip for hardwoods, visible surfaces, or production use.

Mid-range ($15–$25/bit — CMT, Amana, Bosch): Better carbide grade, more consistent grinding. The right choice for a woodworker who routes hardwoods occasionally and wants reliable performance without premium pricing.

Premium ($25–$45+/bit):

Whiteside Machine Company (Claremont, NC): Micrograin carbide, thick resharpenable tips, rated #1 for cut quality and value by Fine Woodworking magazine across multiple surveys. No coating. Made in the USA. The benchmark for quality-to-dollar in router bits.

Freud: Proprietary C4 TiCo Hi-Density carbide, PTFE coating, Quadracut geometry on end-grain tearout. Strong for production environments and resinous species.

The Resharpenability Calculation

A $35 Whiteside bit resharpened 4 times costs $7 per cutting cycle (assuming ~$8 per bit at a sharpening service). A $10 budget bit that's effectively one-and-done costs $10 per cycle. The premium bit is cheaper at that volume, and it cuts better throughout.

For a weekend woodworker routing furniture hardwoods, the Whiteside is the call. For occasional softwood work on a budget, mid-range carbide does the job.

Part 7: Setup and Technique

Setting Up for a Dado or Groove

Click to expand

1. Mark the dado location on the workpiece with a marking knife (not a pencil; the knife line is the reference)
2. Set bit height to 1/4" for the first pass
3. Clamp a straight fence or use a router guide rail aligned to the cut line. Measure from the bit's near edge to the fence face.
4. Test the cut in a scrap piece of the same thickness
5. Check the fit; adjust fence position as needed and re-test
6. Route the first pass; check walls for chatter or tearout before continuing
7. Increase depth in 1/4" increments for subsequent passes
8. Take a final whisper pass (1/32" additional depth) to clean up

Feed Direction

For a handheld router routing along a fence:

• Move left to right when the fence is to the left of the bit
• The bit rotates clockwise (viewed from above), so moving left-to-right means the bit cuts into the wood rather than riding along the surface

As Stumpy Nubs explains in his feed direction guide, the bit should always be cutting into new wood. Resistance is your friend.

Climb cutting: Moving the router in the same direction as bit rotation (opposite of conventional) produces a cleaner surface but is dangerous at full depth. The router can lunge forward. Use climb cutting only as a light final pass (1/16" or less) on the router table, in controlled conditions. Never climb cut freehand at depth.

Collet Engagement

The bit shank must engage at least 3/4" into the collet for proper grip and vibration control. Don't bottom out the shank either. Leave a small gap between the shank bottom and the collet bottom. The rule: insert full depth, then back out 1/16"–1/8".

A worn or dirty collet is a major source of chatter and bit runout. If your router is old and cuts that used to be clean are now rough, check and replace the collet before blaming the bit.

Part 8: Troubleshooting

Click to expand

Burning

The walls are brown or glossy. The bit is leaving heat marks.

1. Feed rate too slow. The most common cause. Speed up your feed. The bit rubs when it isn't cutting, and if the router moves steadily forward, burning stops.
2. RPM too high for the diameter. Drop the speed setting one step for large bits (3/4" and above).
3. Resin buildup on the bit. Cherry, pine, and other resinous species coat the bit with sticky residue that insulates and traps heat. Clean the bit with a resin remover (or oven cleaner in a pinch). Increase cleaning frequency with resinous species.
4. Dull bit. If none of the above fixes it, the edge is gone. Resharpen or replace.

Tearout

The walls are rough, with fibers torn rather than cut.

1. Cutting against the grain. The bit lifts fibers instead of shearing them. Rout the section from the other direction, or break the operation into grain-friendly segments.
2. Too much depth per pass. Reduce to 1/4" maximum. Lighter passes produce cleaner walls.
3. Dull bit. A sharp bit shears; a dull one rips. Replace or resharpen.
4. Figured wood with reversing grain. Take very light passes (1/16") or switch to a spiral upcut bit.

Chatter and Wavy Walls

The walls have a washboard texture or visible vibration marks.

1. Bit extending too far from the collet. Pull the bit up to engage at least 3/4" of shank in the collet. Longer extension amplifies vibration.
2. Too much depth per pass. Reduce to the Rule of Half.
3. Worn or dirty collet. A collet that can't grip the shank firmly causes runout. Clean the collet; replace if worn. Per Toolstoday's vibration guide, the collet is the most common source of persistent chatter that doesn't respond to other fixes.
4. Workpiece not clamped. A workpiece that moves even slightly produces wavy cuts. Clamp it flat and firmly.

Bit Drifting Off-Line

The cut isn't tracking true to the intended line.

1. Depth too deep for a single pass. Reduce depth; the bit is deflecting sideways under load.
2. No guide. For straight cuts, always use a fence, guide rail, or edge guide. Freehand straight cuts over a few inches won't stay straight.

Quick Reference

Straight Bit Speed Guide

Diameter Selection Summary

Brand Summary

Sources

Informed by manufacturer specifications, authoritative woodworking publications, and expert practitioner sources.

• Infinity Cutting Tools — Choosing the Correct Straight Router Bit — diameter selection guide
• Fine Woodworking — Sorting Out Straight Router Bits — flute count and bit selection criteria
• Rockler — Beginner's Guide to Choosing Router Bits — starter set guidance
• Pro Tool Reviews — Setting Router Bit Speed Chart — RPM chart by diameter
• Woodcraft — Straight Talk on Straight Bits — applications overview
• Woodcraft — Spiral vs. Straight Router Bits — straight vs. spiral comparison
• Toolstoday — Straight vs. Spiral Showdown — performance data
• Katz-Moses Tools — Spiral Router Bits — spiral guidance
• Stumpy Nubs — Safe Router Feed Directions — feed direction and climb cutting
• Katz-Moses — 6 Tips for Clean Router Table Cuts — burn and tearout prevention
• Fine Woodworking Forum — What Makes a Quality Router Bit — carbide grade detail
• Toolstoday — Carbide vs. Steel Router Bits — HSS vs. carbide lifespan
• Toolstoday — Reducing Router Bit Vibration — chatter causes and fixes
• Cutter-Shop — Understanding Flute Count — single vs. double flute performance
• Canadian Woodworking — Straight Router Bits Primer — practical applications
• Woodcraft — Understanding Router Feed Direction — feed direction basics
• Whiteside Router Bits — manufacturer specifications