Recip Blade TPI Guide: Matching Bi-Metal Blades to Metal
By Quality Industrial Abrasives and Tools | Benchmark Abrasives | Published: 2026-10-26
Category: How-to Guides
Learn how to choose the right recip blade TPI for cutting metal. This guide explains tooth count, blade thickness, and practical steps for clean, fast cuts.
Quick Answer
For most metal cutting with a recip saw, choose a bi-metal blade with 14 to 18 TPI for thin metal and 6 TPI for thick or nail-embedded material. Match TPI to material thickness to avoid blade breakage and rough cuts.
Why TPI Matters for Metal Cuts
The teeth per inch (TPI) on a reciprocating blade determines how aggressively it cuts and how smooth the finish is. A low TPI like 6 removes material fast but leaves a rougher edge, while a high TPI like 18 produces finer, cleaner cuts but cuts slower.
For metal, the wrong TPI can cause the blade to grab, chatter, or break. Thin sheet metal needs more teeth to avoid snagging, while thick steel needs fewer teeth to clear chips and reduce heat.
Blade Thickness and Material Compatibility
Thicker blades (0.050 inch) are stiffer and better for heavy-duty cutting, but they can be too aggressive for thin metal. Thinner blades (0.035 inch) flex more, which helps when cutting curves or thinner materials but may wander in thick stock.
Bi-metal construction gives the blade flexibility and durability, making it a solid choice for mixed materials like wood with nails or metal studs.
How to Match TPI to Your Metal Cutting Job
- Measure the metal thickness: Use calipers or a tape measure to find the exact thickness of the metal you're cutting. This is the single most important factor in choosing TPI. If the metal is thinner than 1/8 inch, move to a higher TPI; if thicker than 1/4 inch, choose a lower TPI.
- Choose TPI based on thickness: For metal under 1/8 inch thick, use an 18 TPI blade. For metal between 1/8 and 1/4 inch, use a 14 TPI blade. For metal over 1/4 inch thick, use a 6 TPI blade. A common mistake is using a low TPI blade on thin sheet metal, which causes grabbing and rough cuts.
- Match blade length to the cut: For deep cuts or thicker stock, use a 6-inch blade. For tight spaces or shallow cuts, a 4-inch blade gives better control. If the blade is too long for the cut, it can flex and break; keep at least 1 inch of blade engaged.
- Adjust saw speed and pressure: For metal, use a slower saw speed and let the blade do the work. Apply steady, moderate pressure—too much force can overheat and dull the blade. If you see blueing on the metal or blade, you're cutting too fast or pressing too hard.
- Test on scrap material: Before cutting your workpiece, test the blade on a scrap piece of the same metal to check cut quality and blade behavior. If the cut is rough or the blade wanders, switch to a higher TPI blade.
Bi-Metal Recip Blades to Consider
- 6" x .050" x 6T Bi-Metal Reciprocating Blade - 10 Pack: 6" x .050" x 6T Bi-Metal Reciprocating Blade - 10 Pack is MADE IN USA and built for fast, clean cuts on wood, plastic, metal, and nail embedded materials. The 6 TPI and thicker .050" body make this blade a strong choice for demolition and thick metal cutting where speed matters more than finish.
6" x .050" x 6T Bi-Metal Reciprocating Blade - 10 Pack - 6" x .035" x 14T Bi-Metal Reciprocating Blade - 10 Pack: 6" x .035" x 14T Bi-Metal Reciprocating Blade - 10 Pack is MADE IN USA and delivers fast, clean cuts on wood, plastic, metal, and nail embedded materials. The 14 TPI is a versatile middle ground for cutting both thin and medium-thickness metal without frequent blade changes.
6" x .035" x 14T Bi-Metal Reciprocating Blade - 10 Pack - 4" x .035" x 18T Bi-Metal Reciprocating Blade - 10 Pack: 4" x .035" x 18T Bi-Metal Reciprocating Blade - 10 Pack is MADE IN USA and offers high-performance cutting power for wood, plastic, metal, and nail embedded materials. The shorter length and 18 TPI make this blade ideal for tight spaces and thin metal where precision and control are key.
