Design guidelines for tapped parts
Following a few basic design guidelines will help ensure your parts are properly tapped and pass SendCutSend review.
Sheet metal tapping guidelines
Sizing & hole requirements
Sizing limits apply to flat parts before bending for sheet metal
| Min part size (flat) sheet metal | 1″ x 1.5″ |
| Max part size (flat) sheet metal | 36″ x 46″ |
- Tapping direction is perpendicular to the main surface only
- All threads are right-hand
- Verify min hole sizes for your material in the Material Catalog
- Keep the center of any tapped hole at least this distance from other cut features:
(tap hole size ÷ 2) + minimum tap hole-to-edge distance for the material - The minimum tap hole-to-edge distance varies by material and thickness. Find it on each material info page.
- Tapped holes near bends: Place tapped holes at least ½ the full die width away from the bend line. See bending guidelines.
What to expect with tapped parts
- Parts may have light oil residue
- Some deburring may be needed
- Tapped holes near bends may distort and need chasing
- All threads are right-hand
Choosing a thread type and size
UNC (Unified National Coarse) — Standard for most applications. Easier to tap, stronger in thinner materials, more resistant to stripping in soft metals.
UNF (Unified National Fine) — Better when space is limited or when working with harder materials that can support more threads per inch.
Metric (M) — Based on ISO standards. Choose if your project already uses metric hardware.
Rules of thumb:
- Larger taps for thicker parts or higher load capacity. Smaller taps for thinner sections or tight spaces.
- Thread engagement beyond ~1–1.5× the bolt diameter doesn’t significantly increase strength.
- Keep thread depth ≤ 3× the tap diameter (3XD).
Available tap sizes for sheet metal and plastic
Model your hole at the size listed below for the tap you want. We automatically resize laser cut holes to the correct drill size.
| Thread/Tap Size | Hole Size (in) | Hole Size (mm) |
| 4-40 | 0.091″ | 2.32 |
| 6-32 | 0.116″ | 3.00 |
| 8-32 | 0.138″ | 3.51 |
| 10-32 | 0.164″ | 4.17 |
| 1/4-20 | 0.209″ | 5.31 |
| 1/4-28 | 0.221″ | 5.62 |
| 5/16-18 | 0.266″ | 6.76 |
| 5/16-24 | 0.278″ | 7.07 |
| 3/8-16 | 0.323″ | 8.21 |
| 3/8-24 | 0.341″ | 8.67 |
| 1/2-13 | 0.435″ | 11.05 |
| 1/2-20 | 0.459″ | 11.66 |
| M2 x 0.4 | 0.065″ | 1.66 |
| M2.5 x 0.45 | 0.083″ | 2.11 |
| M3 x 0.5 | 0.102″ | 2.60 |
| M4 x 0.7 | 0.134″ | 3.41 |
| M5 x 0.8 | 0.170″ | 4.32 |
| M6 x 1.0 | 0.203″ | 5.16 |
| M8 x 1.25 | 0.274″ | 6.96 |
| M10 x 1.5 | 0.344″ | 8.74 |
Additional tapping resources
If you’re designing parts for tapping, these resources may help:
Pre-flight checklist for sheet metal and plastic
- File is in a format that we accept (2D: .dxf, .dwg, .ai, .eps; 3D: .step or .stp)
- All holes and cutouts are at least 50% material thickness for laser cut parts
- All holes and cutouts are no less than 0.070” for most waterjet cut parts
- All holes and cutouts are no less than 0.125” for all CNC routed parts
- File is built at a 1:1 scale, preferably in inch or mm units
- 2D files: all objects on the same layer, text converted to outlines, no open contours, all shapes united or merged, floating interiors bridged or stencilized
- 3D files: single solid sheet metal body, uniform thickness with a face at every edge, modeled at stock thickness with matching bend specs
- All stray points, duplicate lines, empty objects and text areas have been removed