CNC Gear Hobbing for Brass Power Tool Gears

Power tool gears are small transmission components, but the dimensions that control shaft fit and rotation can be critical to the final assembly.
The brass gear shown here is manufactured for a U.S. power tool project. It is approximately 33 mm in outside size, with Module 0.5 external teeth and a precision center bore specified with a +0.01 mm dimensional requirement. The production quantity is 500 pieces.
For this project, our work combines CNC gear hobbing, precision bore machining and batch production control. The objective is not only to produce the required tooth geometry, but also to keep the critical mounting dimensions stable throughout the production run.
 

Project at a Glance

A Compact Gear Made to the Customer's Design

At approximately 33 mm, this gear is designed to work inside a compact power tool transmission.
The external teeth follow the gear specifications defined by the customer, while the center bore provides the interface with the mating shaft.
The gear uses Module 0.5 teeth. Other parameters—including tooth count, pressure angle, gear width and any specified gear accuracy requirements—are produced according to the engineering drawing.
This is an important distinction for custom gear projects.
We are not selecting a similar standard gear and modifying it. The component is manufactured around the customer's gear geometry, shaft interface and assembly dimensions.
 

From Brass Blank to Gear Hobbing

Before the teeth are generated, the brass material is prepared to the required blank geometry.
The blank machining stage establishes the dimensions and reference features needed for subsequent operations. The precision center bore is machined according to the drawing, followed by CNC hobbing of the external teeth.
A typical process is:

Brass Stock → Blank Machining → Precision Bore Machining → CNC Gear Hobbing → Deburring → In-Process Check → Final Inspection
The exact sequence depends on the complete drawing and dimensional relationships.
Keeping these operations within one manufacturing route also helps maintain a clear reference between the machined center features and the finished gear.
 

CNC Gear Hobbing for Module 0.5 Teeth

The external teeth are produced using CNC gear hobbing.
The hobbing setup follows the gear parameters specified on the customer's drawing. During machining, the hob and gear blank move in a controlled relationship to generate the repeated tooth profile around the circumference.
For this project, the module is 0.5.
Rather than adding unnecessary assumptions about tooth count or gear accuracy from the photograph, we manufacture the component according to the actual gear data supplied by the customer.
For a 500-piece order, hobbing also provides an efficient route from an approved setup into repeat production.
 

The Center Bore Is the Critical Dimension

The most notable precision requirement on this project is not the overall 33 mm size. It is the center bore.
The drawing specifies a +0.01 mm dimensional requirement for this feature.
The reason this matters is straightforward: the bore determines how the gear fits the mating shaft.
If the bore moves outside the specified range, the problem appears during assembly even if the external gear teeth themselves look correct.
For this reason, precision bore machining is treated as a key operation rather than a secondary hole-making process.
 

Holding the Bore Through a 500-Piece Run

The 500-piece quantity introduces another manufacturing consideration: repeatability.
Producing one part within the required bore dimension does not automatically mean that the same condition will remain unchanged throughout the complete production run.
Tool condition and machining variation can gradually affect a precision bore.
For this reason, the critical dimension can be checked during production at defined stages. This provides feedback while machining is still underway and helps identify dimensional movement before it affects a large portion of the batch.
For a production manager, this is an important difference between prototype gear machining and batch gear manufacturing.
The question is no longer only:

Can this dimension be made?
It becomes:

Can this dimension remain controlled throughout production?

Gear Teeth and Shaft Fit Are Evaluated Together

Although the teeth and center bore are produced through different machining operations, they belong to the same functional component.
The bore locates the gear on its shaft. The teeth transfer rotation to the mating gear.
Where the drawing specifies relationships such as runout or concentricity, these requirements need to be considered together rather than inspected as unrelated dimensions.
This is why a custom gear project benefits from manufacturing the blank, precision bore and gear teeth within one coordinated production plan.
 

Why Brass Works for This Component

Brass provides good machinability and corrosion resistance and is used for many small mechanical gears and transmission components.
Its machinability is useful for this part because both the precision center feature and fine external teeth need to be produced on a compact component.
The specific brass grade, however, should follow the customer's design.
Power tool operating load, speed, lubrication and mating materials can influence material selection. We therefore manufacture according to the specified alloy rather than assuming that one brass grade is suitable for every application.
 

Inspection Focused on What Affects Assembly

Inspection for this project follows the drawing rather than applying the same tolerance level to every dimension.
Particular attention is given to the precision center bore, while other checks can include:

• overall dimensions;
• gear width;
• drawing-defined gear characteristics;
• runout or concentricity where specified;
• burrs and edge condition.

For the 500-piece production run, in-process inspection provides dimensional feedback during manufacturing, while final inspection confirms the specified characteristics before shipment.
This keeps quality control focused on the features that matter to the actual power tool assembly.
 

Custom Power Tool Gear Production

YS Precision provides CNC gear hobbing services for custom power tool gears and other mechanical transmission components.
Depending on the design, we can combine:
Gear Blank Machining · CNC Turning · Precision Bore Machining · CNC Gear Hobbing · Secondary Machining · Deburring · Inspection
This U.S. project involves 500 custom brass power tool gears, approximately 33 mm in size, with Module 0.5 teeth and a critical center bore manufactured according to the customer's specified requirement.
The project demonstrates an important part of custom gear manufacturing: combining tooth generation with the dimensional control required for the gear to fit and function in the final assembly.
 

What We Need for a Gear Hobbing Quote

For a new CNC gear hobbing project, please provide the 2D engineering drawing and 3D CAD data where available.
Useful RFQ information includes:
Gear Type · Module · Tooth Count · Pressure Angle · Gear Width · Bore Specification · Material · Critical Tolerances · Quantity
If runout, concentricity, backlash, gear accuracy grade, heat treatment or surface finishing is required, please identify these requirements on the drawing.
This allows us to review the complete manufacturing process before quotation—not only the gear teeth, but also the precision features that affect assembly.