Blade Selection¶
The difference between a clean cut and fighting the saw for 20 minutes. Choose wrong and you'll burn through blades and your reputation.
TPI - Teeth Per Inch¶
The most important number on the blade.
The Basic Rule¶
Three teeth in the cut - minimum:
- Too few teeth = grabbing, breaking
- Too many = clogging, burning
- Just right = smooth cutting
TPI Selection Guide¶
| Material Thickness | TPI Range | Best For |
|---|---|---|
| Under 1/4" | 18-24 | Sheet, thin wall |
| 1/4" - 1" | 10-14 | Most common range |
| 1" - 3" | 6-10 | Solid stock |
| Over 3" | 4-6 | Heavy sections |
Material-Specific TPI¶
Aluminum¶
- Use coarser than steel
- Chips need room
- 6-10 for most work
- Skip tooth helps
Steel¶
- Standard recommendations
- 10-14 most common
- Variable pitch reduces harmonics
Stainless¶
- Finer teeth better
- 14-18 typical
- Positive rake important
- Keep cutting pressure constant
Tubing¶
- Based on wall thickness
- Not overall diameter
- 14-24 for thin wall
- Variable pitch best
Blade Materials¶
Carbon Steel - The Cheap Option¶
Best Uses¶
- Occasional use
- Soft materials
- Wood (if desperate)
- Learning/practice
Not Suitable For¶
- Production work
- Hard materials
- Any serious shop
- Your sanity
Bi-Metal - The Standard¶
What it is¶
- High-speed steel teeth
- Spring steel back
- Best of both worlds
- 90% of shop blades
Why it works¶
- Teeth stay sharp
- Back stays flexible
- Resists breaking
- Good blade life
Use for¶
- All general cutting
- Mixed materials
- Production work
- Daily use
Carbide - The Premium Option¶
When you need it¶
- Hardened materials
- Exotic alloys
- Maximum blade life
- Tight tolerances
When to skip it¶
- General shop work
- Cost matters
- Interrupted cuts
- You're still learning
Tooth Patterns¶
Regular/Raker¶
Pattern: Same size teeth, one raker
Regular Pattern Uses¶
- General purpose
- Consistent materials
- Most common
Skip Tooth¶
Pattern: Every other tooth missing
Skip Tooth Uses¶
- Soft materials
- Aluminum
- Plastics
- Better chip clearing
Variable Pitch¶
Pattern: Varying tooth spacing
Variable Pitch Uses¶
- Reducing vibration
- Mixed thicknesses
- Smoother cut
- Less noise
Blade Width¶
For Horizontal Saws¶
Usually fixed by machine:
- 1" x 0.035" common
- 1.25" for larger saws
- Don't modify!
For Vertical Saws¶
Width determines turning radius:
| Blade Width | Minimum Radius |
|---|---|
| 1/8" | 1/8" |
| 1/4" | 5/8" |
| 3/8" | 1-1/2" |
| 1/2" | 2-1/2" |
| 3/4" | 5-1/2" |
Choose based on¶
- Tightest curve needed
- Material thickness
- Desired accuracy
- Blade life
Set Patterns¶
How teeth are bent alternately.
Standard Set¶
Teeth alternate left/right:
- Most common
- General purpose
- Good chip clearing
Wavy Set¶
Groups of teeth wave:
- Thin materials
- Varied thickness
- Smoother cut
- Less grabbing
Straight Set (Raker)¶
Some teeth straight:
- Aggressive cut
- Thicker materials
- Faster cutting
- Rougher finish
Common Blade Problems¶
Premature Dulling¶
Dulling Causes¶
- Speed too high
- No coolant
- Wrong TPI
- Cheap blades
Dulling Solutions¶
- Check speed chart
- Use coolant
- Right blade selection
- Buy quality
Blade Breaking¶
Breaking Causes¶
- Tension wrong
- Guides misaligned
- Forcing curves
- Material movement
Breaking Solutions¶
- Proper tension
- Align guides
- Let saw cut
- Secure work
Crooked Cuts¶
Crooked Cut Causes¶
- Dull blade
- Uneven set
- Guide problems
- Feed pressure
Crooked Cut Solutions¶
- Replace blade
- Check guides
- Even pressure
- Don't force
Stripped Teeth¶
Stripped Teeth Causes¶
- Too few teeth engaged
- Material too hard
- Hit hard spot
- No break-in
Stripped Teeth Solutions¶
- Right TPI
- Slower speed
- Check material
- Break in new blades
Blade Care¶
New Blade Break-In¶
Critical for blade life:
- Reduce speed 20%
- Light feed pressure
- First 10 cuts
- Full coolant flow
- Gradually increase
Skip this = short blade life
Storage¶
Do¶
- Coil properly (3 loops)
- Oil lightly
- Hang on pegs
- Label clearly
- Keep dry
Don't¶
- Kink or twist
- Store loose
- Mix different types
- Leave on machine
- Let rust
When to Replace¶
Visual inspection¶
- Missing teeth
- Cracks in gullet
- Heavy wear
- Won't stay sharp
Performance¶
- Cutting time doubles
- Can't cut straight
- Excessive heat
- Poor finish
Blade Selection Chart¶
Quick reference for common jobs:
| Material | Thickness | TPI | Type | Speed |
|---|---|---|---|---|
| Aluminum bar | 2" | 6-8 | Bi-metal | High |
| Steel tube | 1/4" wall | 14 | Variable | Medium |
| Stainless | 1" | 10-14 | Bi-metal | Low |
| Brass | Any | 8-14 | Regular | High |
| Plastic | 1/2" | 10 | Skip | High |
Cost vs Value¶
Cheap Blades¶
True cost¶
- Replace 5x more often
- More machine downtime
- Frustrated operators
- Poor cut quality
- Material waste
Quality Blades¶
Investment return¶
- Last 3-5x longer
- Better cuts
- Less rework
- Happy operators
- Consistent results
Do the math¶
$30 blade lasting a month beats $10 blade lasting 3 days.
Blade Brands That Don't Suck¶
Without getting into religious wars:
- Lenox
- Starrett
- Simonds
- DoAll
- Amada
Avoid¶
- No-name imports
- "Bargain" multipacks
- Used blades (really?)
- Mystery metal
The Bottom Line¶
Right blade selection:
- Count teeth in cut (3 minimum)
- Match speed to material
- Use appropriate tooth pattern
- Buy quality bi-metal minimum
- Break in properly
- Replace when dull
Remember: The most expensive blade is the one that doesn't cut. Buy quality, set it up right, maintain it properly. Your saw (and sanity) will thank you.