Laser Cutting Tolerances on Stainless Steel: How Accurate Will Your Blades Be?
You are drawing a blade, a liner or a spring: how far can the cut part deviate from your DXF file? Here are the dimensional tolerances and hole limits of laser cutting on stainless steel, in the thicknesses used in knifemaking (1 to 6 mm).
What Is a Dimensional Tolerance?
No process cuts exactly to the drawn dimension. The tolerance is the maximum deviation allowed, plus or minus, between the dimension in your DXF and the real dimension of the part. With a ±0.10 mm tolerance, a 50 mm dimension will measure between 49.90 and 50.10 mm.
In laser cutting, this deviation depends on two parameters: the sheet thickness and the part length. The longer the part, the larger the allowed deviation, because small errors add up over distance.
Tolerances on Stainless Steel from 0.5 to 6 mm
For every thickness used in knifemaking, from 0.5 to 6 mm, the tolerance depends only on the length of the part:
| Part length | Tolerance | Knifemaking examples |
|---|---|---|
| 0–100 mm | ± 0.10 mm | Liners, bolsters, springs, pocket knife blades |
| 100–300 mm | ± 0.10 mm | Kitchen, hunting and table knife blades |
| 300–1,000 mm | ± 0.15 mm | Long blades: chef's knives, fillet knives, machetes |
Part length means the length of the complete blank, tang included. A 3 mm thick, 180 mm long blade blank is therefore cut to ±0.10 mm.
These values apply to our parts. Stated tolerances vary a lot from one supplier to another: always ask for the table before ordering.
Is ±0.10 mm Enough for a Knife?
Yes, by a wide margin: 0.10 mm is about the thickness of a sheet of paper. In practice:
- ✓The blade outline is ground afterwards anyway (profile, bevels, edge): the cutting deviation is absorbed by finishing.
- ✓Pin and fixing holes are positioned within ±0.10 mm: enough for a clean assembly, and a pass with a reamer gives a tight fit.
- ✓Parts that fit together (liner in a handle, spring in a liner): with ±0.10 mm on each part, the combined deviation between two parts can reach 0.20 mm. Design in a working clearance rather than a zero-clearance dimension.
What About After Heat Treatment?
The tolerances above apply to the part as it comes off the laser. Heat treatment takes the steel above 1,000 °C: a thin part may distort slightly. Straightening and final grinding are part of the normal process, see our heat treatment guide.
Minimum Hole Diameter in Stainless Steel
The laser cannot pierce just any small hole in thick sheet: below a minimum diameter, the hole is only marked on the surface instead of being cut through. Here is the smallest hole diameter cut in stainless steel, by thickness:
| Sheet thickness | Minimum hole Ø |
|---|---|
| 1 mm | Ø 1.02 mm |
| 1.5 mm | Ø 1.02 mm |
| 2 mm | Ø 1.2 mm |
| 2.5 mm | Ø 1.35 mm |
| 3 mm | Ø 1.5 mm |
| 4 mm | Ø 2 mm |
| 5 mm | Ø 2.5 mm |
| 6 mm | Ø 3 mm |
💡 Rule of thumb: from 2.5 to 6 mm thick, the minimum diameter is about half the thickness.
In a 3 mm blank, a Ø 3 or 4 mm pin hole, a Ø 5 mm lanyard hole or a Ø 10 mm thumb hole are no problem (minimum 1.5 mm). A Ø 1 mm hole, however, would only be marked: it will have to be drilled.
Need a hole smaller than the limit? Contact us before ordering: [email protected]
5 Tips Before Sending Your DXF
- 1Draw in millimeters, at 1:1 scale, and export as DXF (R14 or R2000). The dimension you draw is the dimension you want to get: no need to adjust it yourself to "compensate" for the laser.
- 2Close every outline and draw nothing twice. Two overlapping lines mean an extra laser pass (and a line counted twice in the quote).
- 3Check your hole diameters. In 3 mm material, do not go below Ø 1.5 mm (see the table): below that, the hole is only marked.
- 4Keep about 0.2 mm of clearance between parts that fit together: each part can be off by up to ±0.10 mm.
- 5For a tight fit (pin, tang in a handle), draw the hole slightly smaller and ream it afterwards: you set the exact fit by hand.
Frequently Asked Questions
What is the laser cutting tolerance on a 3 mm stainless steel knife blank?
±0.10 mm for a part up to 300 mm long, and ±0.15 mm between 300 and 1,000 mm.
What is the smallest hole the laser can cut in 3 mm stainless steel?
The minimum diameter is 1.5 mm. Below that, the hole is only marked by the laser, not cut through.
Do the tolerances change with thickness?
From 0.5 to 6 mm, no: they depend only on the part length. Above 6 mm they can widen slightly, but those thicknesses are rare in knifemaking.
Does heat treatment change the part's dimensions?
The stated tolerances apply to cutting. Heat treatment, above 1,000 °C, can distort a thin part slightly: that is why straightening and final grinding are part of the process.
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