Small-Diameter Holes — Runout and Edge Condition Decide the Result

As diameter drops, spindle runout, web strength, and chip evacuation dominate over brochure SFM. Specify the true Ø, depth, material, and whether the hole must be reamed. XRZ quotes fine carbide drilling and, where tolerance demands, a ream path (PCD only when the material fits). This page is the decision briefing—not a micro-drill supermarket.

PCD Reamer Solid Carbide Drill Bits Request Engineering Quote Custom Tool RFQ

SCALE CHANGE

When “small” changes the rules

Depth-to-diameter and stiffness matter more than a catalog SFM table.
Measured spindle/tool runout can consume the entire tolerance band.
Chip evacuation and web strength limit how aggressive a micro drill can be.

This page stays on scale. For tough-alloy hole severity (Ti, HRSA, mold steels), see Difficult Materials. Everyday larger general-mechanical holes → General Mechanical.

DRILL FIRST

Drill first — series vs custom

Start from a solid carbide drill path sized to material and depth. Use a published series when the feature fits; RFQ a custom fine drill when reach, neck, or edge prep must match an interference model. We do not invent off-the-shelf micro SKUs that are not on the product pages.

Primary entry: Solid Carbide Drill Bits.

REAM DECISION

Ream or stop at drill?

Ream when diameter, roundness, or finish is print-critical—not by habit.
PCD reamers apply when the material is suitable non-ferrous and life/finish economics justify the edge.
Default: do not specify PCD micro-reamers on steel.

Entry when ream is justified: PCD Reamer (material gate applies).

FAILURE MODES

Failure modes that dominate at small Ø

Walk / wander — centering and rigidity lose the axis before the drill even chips.
Breakage — web too thin for the load, or chip pack in a deep hole.
Oversize from runout — measured runout looks like a “bad drill.”
Burned corners / edge damage — heat and rubbing on a fragile micro edge.

RFQ