Custom Brass CNC Turning for Electrical Hardware Components

This small brass component was made for an electrical product and supplied to a customer in Germany.

The part is only about 15 × 4.5 mm, but there is quite a lot happening along that short profile: several stepped diameters, narrow circular features and a machined center hole.

The customer provided both a 2D engineering drawing and 3D model. According to the drawing, the hole has a +0.02 mm tolerance, while the relevant outside diameter is controlled to -0.05 mm.

The order was approximately 8,500 pieces.

This is not a standard brass fitting or catalogue item. It is a custom CNC turned part, so the dimensions, tolerance limits and geometry all come from the customer's design. At this quantity, the turning process also needs to be practical enough to repeat thousands of times.

Project Specifications

A Short Part with Several Turned Features

At first glance, this looks like a straightforward lathe part.

Most of the geometry is rotational, which makes CNC turning a natural process. Look more closely, though, and several diameter changes are packed into a very short body.

That affects how the turning sequence is arranged.

There is little value in adding secondary machining when the required geometry can stay on the lathe. For an order of 8,500 pieces, keeping the process direct also reduces handling and unnecessary cycle time.

A few extra seconds on one part may not sound important. Repeated thousands of times, they are.

The Hole and OD Are Not Controlled the Same Way

The 2D drawing gives us one of the more useful details about this component.

The specified hole is controlled to +0.02 mm, while the relevant OD carries a -0.05 mm tolerance.

These are one-sided tolerance requirements, so we do not treat them as generic ± dimensions or simply aim at the nominal value.

During machining and inspection, each feature has to remain within its own permitted tolerance zone.

This is also why the 2D drawing remains important even when a complete 3D model is available. The model shows the geometry very clearly, but the drawing tells us where the dimensional limits are.

For a small custom turned component, those limits often tell us more about the machining job than the overall size does.

Keeping the Process on the Lathe

The customer specified brass for this component, and the part geometry is well suited to turning.

The stepped outside profile, narrow circular features and center hole can be produced without introducing an unnecessarily complicated machining route.

That simplicity becomes useful at production quantity.

Every additional setup means more handling. Every unnecessary tool movement adds time. Neither is particularly important for one prototype, but both become worth considering when the same component needs to be produced 8,500 times.

For this part, the sensible approach is straightforward: keep the rotational work on the lathe and make the turning sequence as stable as possible.

What Changes When the Order Reaches 8,500 Pieces

The first few parts tell us whether the setup works.

The rest of the order tells us whether the process works.

During a longer production run, tool wear develops gradually. On a small component like this, dimensional drift may begin to show in the hole or OD before anything looks obviously wrong at the machine.

The closely spaced profile features also need to remain clean as production continues.

So the useful question is not simply whether the machine is still cutting parts. It is whether the parts coming off later in the run are still following the same drawing limits as the earlier ones.

That is where in-process dimensional checks become part of normal production rather than something left until the complete batch is finished.

Why We Need Both the 2D and 3D Files

For custom CNC turning from customer drawings, the 2D and 3D files serve different purposes.

The 3D model helps us understand the complete form quickly, especially when several small profile changes sit close together.

The 2D drawing carries the manufacturing information: tolerance directions, dimensional limits and other notes that need to be checked during production.

For this part, the distinction is particularly clear.

A 3D model can show us a 4.5 mm diameter. The 2D drawing tells us whether that diameter is allowed to go above nominal, below nominal, or both.

That information affects how the component is machined and inspected.

Where This Fits in Our Custom CNC Turning Work

YS Precision provides custom CNC turning services for drawing-based metal components rather than only standard hardware.

Our turning work includes small brass parts like this one, as well as pins, shafts, sleeves, bushings, spacers, threaded parts and other rotational components.

Depending on the customer's design, machining can include OD/ID turning, drilling, boring, grooving and threading. Parts with cross holes, flats, slots or other non-rotational features can also move into secondary milling or turn-mill machining when the drawing requires it.

We work with brass, stainless steel, aluminum and other specified materials for electrical equipment, automation, medical devices and other industrial applications.

The machining route is decided after we see the drawing—not before.

Small Part, Production-Level Thinking

There is no reason to make this brass component sound more difficult than it is.

It is a 15 × 4.5 mm custom turned part with a center hole, several closely spaced diameters and clear tolerance limits. CNC turning is exactly the process we would expect to use.

What changes the job is the quantity.

At 8,500 pieces, small decisions in tooling, machining sequence and inspection are repeated often enough to matter. The +0.02 mm hole and -0.05 mm OD also give us clear dimensions to watch as the batch progresses.

That is the part of the project we find most useful: not proving that one small brass component can be machined, but setting up the work so that thousands of them can be produced from the same customer drawing without making the process more complicated than it needs to be