Four dimensions describe different parts of the drill
PCB drill cutting diameter, flute length, shank diameter and overall length are separate dimensions. The shank fits the holder; it does not tell you the hole size. Flute length describes the fluted section; it is not the end-to-end length of the tool.
| Dimension | Meaning | Why it belongs in the enquiry |
|---|---|---|
| Cutting diameter | Diameter specified for the cutting section. | Identifies the requested drill size; confirm any process allowance separately. |
| Flute length | Length of the fluted working section. | Must be reviewed against the working depth and setup. |
| Shank diameter | Diameter of the holder-engaging section. | Must match the intended holder or collet. |
| Overall length | End-to-end tool length. | Helps confirm seating and machine compatibility. |
Catalogue examples from the standard drill family
The standard PCB drill family lists a 3.175 mm shank and an overall length of 38.1 ± 0.1 mm. Cutting diameters and flute lengths vary within the family. These are catalogue references, not a universal specification for all PCB drills.
| Cutting diameter | Listed flute length |
|---|---|
| 0.075 mm | 0.8 mm |
| 0.10 mm | 1.5 or 1.8 mm |
| 0.25 mm | 4.0 mm |
| 0.50 mm | 8.5 mm |
| 1.25–3.175 mm | 12.0 mm in this catalogue group |
A 3.175 mm shank does not mean a 3.175 mm hole
Several different cutting diameters in the catalogue share the same shank diameter. Always write the cutting diameter and shank separately. If a supplier reference is ambiguous, request the drawing or a dimensioned description before ordering.
Do not select working length by a single rule
Review flute length with board thickness, the stack and the complete drilling process. A longer tool is not automatically a better match. This guide does not define a universal maximum stack height, because the correct limit depends on the tool and approved process.
Dimension questions
Are all PCB drills 38.1 mm long?
No. That overall length applies to the catalogue families identified on this site, not every PCB tool. Check the individual specification.
Can every diameter use every listed flute length?
No. The available combinations are diameter-specific. A family range must not be interpreted as all possible combinations.
What should I send when replacing an existing drill?
Send the cutting diameter, flute length, shank, overall length, current tool reference and board application. A drawing or clear photograph helps clarify geometry.
Continue with the complete PCB drill selection checklist or request a tooling quotation.
Discuss your application
Share the board material, tool dimensions and the issue you are seeing.
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