Quick Answer An O-ring groove should be designed around the complete sealing system, not only the O-ring diameter. The groove must provide: The correct amount of squeeze Enough volume for the elastomer Suitable width and depth Controlled corner radii Acceptable extrusion clearance A surface finish compatible with the seal Reliable installation and inspection [...]
Quick Answer A threaded insert should replace a directly tapped hole when the parent material may not provide enough durable thread engagement, when the fastener will be installed and removed repeatedly, when the part needs thread repair, or when the design requires a more wear-resistant internal thread. Direct tapping is often the simpler [...]
Quick Answer To dimension a CNC blind hole correctly, separate the required straight cylindrical depth from the additional depth occupied by the drill point. The drawing should state: Hole diameter Usable cylindrical depth Total drilled depth or bottom condition Required tolerance Functional requirement The drill-point clearance is not a universal fixed value. It [...]
Quick Answer For many conventional CNC-drilled holes, a depth-to-diameter ratio of approximately 3×D to 5×D is a practical starting point for design review. Here, D means the drill diameter. For example, a 5 mm drill producing a 25 mm hole has a ratio of 5×D. This is a planning guideline, not a universal [...]
Quick Answer Standard drill sizes can reduce the cost of machined holes because they are more likely to be available in a supplier’s existing tool inventory. Using a commonly stocked drill can reduce: Special-tool purchases Tool-change time Setup complexity Programming effort Quotation uncertainty Replacement-tool delays This does not mean every hole should be [...]
Quick Answer Undercuts justify custom tooling in CNC milling when the feature is functionally necessary, cannot be redesigned without compromising the part, and will be produced in enough quantity to support the additional tooling cost and setup work. For a one-off prototype, redesigning the geometry or adding a standard relief is often more [...]
Quick Answer External corner radii should be designed to remove sharp exposed edges, reduce stress concentration, improve tool access, support safer handling, and match the part’s functional requirements. The correct radius depends on the material, part size, machining method, available tooling, assembly conditions, and whether the edge is structural, cosmetic, or used for [...]
Quick Answer Delrin parts can be designed to minimize dimensional instability by keeping wall thickness uniform, avoiding heavy unbalanced sections, adding generous radii, controlling moisture and temperature exposure, using realistic tolerances, and planning machining and inspection around material movement. A 3D model is useful, but a complete drawing should also define critical dimensions, [...]
PEEK is often considered when a metal CNC component becomes too heavy, too conductive, too prone to corrosion, or unsuitable for a specific working environment. As a high-performance engineering plastic, PEEK can offer a useful combination of strength, thermal stability, chemical resistance, low friction, and electrical insulation. However, PEEK should not replace metal automatically. [...]
Free-machining stainless steel is often selected when a CNC part needs the appearance and corrosion resistance of stainless steel, but also needs better machinability, shorter cycle time, and more stable chip control. For many precision CNC components, material selection is not only about strength or corrosion resistance. It also affects tool life, machining cost, [...]
