DRAWING DETAILS / CNC MACHINING INSIGHTS
A blind hole is defined by more than its diameter. The drawing must establish the controlled depth, the function at the bottom of the hole, and whether a fastener, pin or mating component uses the feature. Those notes give an RFQ review a clear functional target.
State what the depth controls
A blind-hole depth might create clearance, limit a fastener, locate a pin or protect material on the opposite side. Identify which of these applies. If the bottom condition affects assembly, show the related mating geometry or explain the clearance requirement in the controlled drawing.
For threaded blind holes, thread designation and usable depth should be clear alongside the hole callout. Our CNC thread specification guide covers the drawing information that prevents a thread note from being incomplete.
Separate the main hole from its bottom condition
| Drawing detail | Why it matters | Useful note |
|---|---|---|
| Hole diameter | Defines the feature opening or fit. | Dimension it from the relevant drawing references. |
| Controlled depth | Sets the functional reach into the part. | State whether the depth is measured from the entry face and identify the reference. |
| Bottom condition | May affect pin seating, clearance or contact. | Show whether a flat contact area, clearance or another condition is functionally required. |
| Entry side | Determines which face receives the feature. | Make the side clear in the view or section. |
A section view is often the most direct way to communicate the entry surface, depth and remaining material around a blind feature.
Link the hole to its mating part
If a blind hole receives a pin, screw or another component, include the relevant mating information. A reviewer should be able to understand whether the feature locates, retains or simply clears the companion part. Our assembly-fit guide outlines the context that is helpful to provide with an RFQ.
Do not leave inspection priorities implied
When depth, location or a seating condition affects the assembly, identify that requirement before production release. Not every blind hole needs the same attention; focus on the dimensions that control function. See our CNC inspection requirements guide for a practical way to connect a critical feature to an inspection expectation.
Questions to answer before release
- Is the feature through or blind, and which face is the entry side?
- What dimension controls depth, and from what reference?
- Does the bottom contact, clear or limit a mating component?
- Is the hole threaded, and what thread requirement applies?
- Which dimensions need confirmation because they affect fit or function?
Make the bottom condition clear
ExactMach coordinates drawing-defined CNC milling, CNC turning, prototypes and custom parts around Shenzhen and Dongguan for international orders. A complete blind-hole callout helps the review team understand the released functional requirement before production begins.