Contract manufacturing companies like ours spend a great deal of time talking to customers about the hole sizes in their CNC machined parts.
You might assume these discussions are relatively objective and straightforward, but in many cases the opposite is true. In fact, it’s quite common for manufacturers and customers to take conflicting measurements of the same holes when it comes time for part inspection.
These discrepancies most often occur when each party is using their own measurement systems, with tools that measure to differing accuracy and techniques.
Common Hole Measuring Tools for CNC Machined Parts
There are many different tools available for measuring hole diameters and other dimensions in CNC machined parts. Some tools take more accurate measurements than others. Here are several of the most common measurement tools.
- Air gauge
- Bore gauge
- Deltronic pins
- Myers pins
- Coordinate Measuring Machine (CMM)
Customers commonly rely on some or all of these methods to measure hole diameter during part inspection. However, if your hole tolerance is 0.005” or less, calipers may not be capable of providing accurate measurements.
Air gauges, on the other hand, provide the most accurate measurements for parts with extremely tight tolerances. But using an air gauge requires an investment in custom tooling, which can add to the cost and lead time of a project and in most cases it’s overkill for the information required.
Best Practices for Measuring Holes in CNC Machined Parts
While there is no “right” or “wrong” tool for measuring holes in CNC machined parts, there are some best practices to keep in mind that will help your project run efficiently.
The single most important action you can take to keep your project moving smoothly is to clearly communicate which measuring tool you prefer your contract manufacturing company to use before your project begins.
Conveying your expectations up front streamlines communications. It reduces or eliminates back-and-forth phone calls and emails regarding hole size discrepancies. Most importantly, it prevents having to scrap parts and start over.
If you’re not sure which tool you should use to measure the holes in your part, we generally recommend using a bore gauge, Myers pins, or Deltronic pins, depending on diameter size and tolerance requirements:
- Bore gauge. For hole diameters larger than 1”, bore gauges are the most universally accepted method of measurement.
- Myers pins. For hole diameters 1” or less and tolerances greater than or equal to 0.002”, Myers pins provide highly accurate functional measurements.
- Deltronic pins. For hole diameters 1” or less and tolerances less than 0.002”, Deltronic pins are generally the best functional measuring tool. Deltronic pins must be purchased specifically for a given hole size, so be sure to communicate this requirement before the project begins to minimize disruptions in lead time.
Pins are almost always a great choice because they incorporate an additional layer of assessment for functional accuracy. The pins move in and out of a hole in a way that closely mirrors how the hole will function in its end-use application. The only drawback to pins, is that they can’t measure a taper or roundness inside the hole.
When you need contract manufacturing services, trust Reata to measure your parts accurately. Reach out to us for a fast quote today!