Reamers — Catalog and Selection

Compiled 2026-04-04 · 50 chunks, 15 posts · reamers · hole-finishing · precision-tooling · surface-finish · tight-tolerances

Summary

Reamers are precision finishing tools designed to enlarge existing holes to exact dimensions while achieving superior surface finishes. Unlike [[drilling]], which creates holes from solid material, [[reaming]] removes only 0.010-0.030" of material per side to achieve tolerances of ±0.0005" or better. Essential for press fits, bearing bores, and precision assemblies, reamers deliver surface finishes from 8-80 µin Ra depending on material and reamer type.

Reamer Types and Applications

Hand Reamers

Seco N5TS Series (Taper Shank)

  • Part Numbers: N5TS-2H7-EB45 through N5TS-9.525H7-EB45
  • Sizes: 2mm to 3/8" (9.525mm)
  • Tolerance: H7 grade holes
  • Application: Manual reaming in drill press or lathe tailstock
  • Speed Range: 50-200 RPM for HSS versions

Seco N5BS Series (Straight Shank)

  • Part Numbers: N5BS-2.01H7-EB45 through N5BS-9.525H7-EB45
  • Sizes: 2mm to 3/8" with 0.01mm increments available
  • Features: EB45 coating for extended life
  • Best For: Bench work and manual operations

Machine Reamers - Straight Flute

Seco SR80/81/82 Series

  • SR80: General purpose, 6-8 flutes
  • SR81: Heavy duty, increased rigidity
  • SR82: Fine finish applications
  • Size Range: 1/4" to 2-3/16" (SR80-x.xxx-EN to SR80-xx.xxx-EN)
  • Speeds: 200-800 RPM in steel, 800-1500 RPM in [[aluminum-6061]]

Machine Reamers - Spiral Flute

Seco NF Series (Right Hand Spiral)

  • NF06: 6mm nominal (4.5505mm actual)
  • NF10: 10mm nominal (11.0505mm actual)
  • Advantage: Better chip evacuation in through holes
  • Disadvantage: Can pull workpiece in manual operations

Seco NS Series (Left Hand Spiral)

  • NS06/NS10: Same sizes as NF series
  • Advantage: Resists pulling workpiece, better for manual work
  • Shop Floor Tip: Left-hand spiral preferred for CNC applications to prevent tool pull-out

Carbide Reamers

Seco PMX Series

  • PMX5: 5-flute design for general applications
  • PMX6: 6-flute for improved finish
  • PMX8: 8-flute for finest finishes
  • Example: PMX05T-AD-04100-16N1 (8.825mm dia)
  • Speeds: 2-4x HSS speeds (400-3000 RPM depending on material)
  • Cost: 3-5x HSS price but 10-20x tool life in production

Speeds and Feeds by Material

Steel (1018-4140)

HSS Reamers:

  • SFM: 50-120 (Start at 80 SFM)
  • Feed: 0.002-0.008 IPR (0.004 IPR typical)
  • RPM Calc: (SFM × 3.82) / Diameter
  • Example: 0.500" reamer = (80 × 3.82) / 0.5 = 610 RPM

Carbide Reamers:

  • SFM: 150-400 (Start at 250 SFM)
  • Feed: 0.003-0.012 IPR
  • Shop Reality: Forum users report running 20% slower than catalog recommendations for better finish

Aluminum (6061)

HSS Reamers:

  • SFM: 200-500 (Start at 300 SFM)
  • Feed: 0.005-0.015 IPR
  • Surface Finish: 16-32 µin Ra typical

PCD Reamers (for production):

  • SFM: 800-2000
  • Surface Finish: 8 µin Ra achievable
  • Tool Life: 10,000+ holes vs 100-500 for HSS

Stainless Steel (304/316)

HSS Reamers:

  • SFM: 40-80 (Conservative due to [[work-hardening]])
  • Feed: 0.003-0.006 IPR (maintain constant feed to prevent work hardening)
  • Coolant: Flood coolant essential

Carbide Reamers:

  • SFM: 120-250
  • Feed: 0.004-0.010 IPR

Cast Iron

HSS Reamers:

  • SFM: 80-150
  • Surface Finish: 50-80 µin Ra typical
  • Note: Excellent reaming material - self-lubricating

Toolholder Selection

Floating Holders

Best Practice: Essential for maintaining perpendicularity

  • MariTool Adjustable Reamer Holders: HSK50-E with runout adjustment
  • ER Collet Style: Common shank sizes with ER16/ER20 interface
  • Adjustment Range: ±0.002" runout correction typical

Rigid Holders

When to Use: Only when machine spindle runout <0.0002"

  • Hydraulic Holders: Best grip, minimal runout
  • Heat Shrink: Good for carbide reamers
  • ER Collets: Adequate for manual operations

Pilot Hole Preparation

Standard Practice

Hole Size: 65-85% of finish diameter

  • Example: 0.500" reamer requires 0.484" pilot (3.2% stock per side)
  • Typical Range: 0.015-0.030" per side removal

Shop Floor Reality

Forum Experience: Many machinists prefer smaller pilots for better surface finish

  • Heavy Stock Removal: 0.030"+ per side can cause [[chatter-vibration]]
  • Light Stock Removal: <0.010" per side may not clean up drill marks
  • Sweet Spot: 0.015-0.020" per side for most applications

Custom and Special Reamers

When Standard Won't Work

Non-Standard Sizes: 7.85mm with G8 fit tolerance

  • Custom Reamer Cost: $150-500 for single tool
  • Lead Time: 2-4 weeks typical
  • Alternative: [[boring]] with single-point tool for one-offs

Grinding Services

Rework Existing Tools:

  • Drill Modification: Send oversize drills out for custom grinding
  • Cost: $25-75 vs $200+ new custom reamer
  • Process: Test hole, measure, grind to size, recoat

Common Problems and Solutions

Poor Surface Finish

Symptoms: Drill-like finish after reaming

  • Cause: Excessive speed, insufficient feed, dull reamer
  • Solution: Reduce RPM by 25%, increase feed rate
  • HSS in Steel: Try 165 RPM with 0.004 IPR instead of catalog 600+ RPM

Chatter

Symptoms: Audible vibration, poor finish, dimensional variation

  • Primary Cause: Insufficient rigidity
  • Solutions:
  • Reduce RPM (start at 50% of calculated)
  • Increase feed rate to maintain chip load
  • Use floating holder
  • Reduce pilot hole size for more engagement

Reamer Breakage

Prevention:

  • Never reverse spindle with reamer in hole
  • Chamfer pilot hole to ease reamer entry
  • Use adequate coolant to prevent heat buildup
  • Hand feed initially until cutting action stabilizes

Size Variation

Causes and Fixes:

  • Machine flex: Use floating holder, reduce feeds/speeds
  • Thermal growth: Allow 20-minute warmup, flood coolant
  • Tool wear: Monitor with micrometers, replace at 0.0002" wear

Shop Floor Tips

Manual Operations

Feed Rate Control: Consistent hand pressure more important than exact IPR

  • Feel for Cut: Should feel like light resistance, not binding
  • Backing Out: Rotate spindle by hand when withdrawing to prevent scoring

CNC Programming

Canned Cycles: G85 (bore/ream) preferred over G83 (peck drilling)

  • Spindle Stop: Program M5 before rapid retract
  • Dwell: 0.5-1.0 second dwell at bottom for finish

Coolant Strategy

Flood Coolant: Essential for dimensional stability

  • Concentration: 5-8% for reaming (lower than drilling)
  • Pressure: 50-150 PSI (lower than drilling to prevent deflection)
  • Through-Spindle: Ideal for deep holes >3D

Size Standards and Availability

Inch Sizes

Common Fractional: 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4" Decimal Equivalents: Available in 0.001" increments for most sizes Letter/Number Drill: Reamers available for A-Z and #1-80 sizes

Metric Sizes

Standard: 1mm increments from 1-50mm Precision: 0.01mm increments available (2.01, 3.02, etc.) ISO Fits: H7 tolerance standard, H6 available on request

  • [[reaming]] — Process fundamentals and techniques
  • [[drilling]] — Pilot hole preparation methods
  • [[boring]] — Alternative for non-standard sizes
  • [[toolholder-selection]] — Floating vs rigid holder selection
  • [[surface-finish-problems]] — Troubleshooting poor finishes
  • [[chatter-vibration]] — Eliminating reaming vibration issues
  • [[tolerance-fits]] — Understanding precision requirements
  • [[aluminum-6061]] — Material-specific reaming parameters
  • [[4140-steel]] — Heat-treated steel reaming challenges