Handwork: The Old-School Key to Reducing Spindle Time When Machining Plastic or Wood

At Accurate CNC, most of the parts we produce in our precision CNC machining services require some sort of edge treatment. One of the most common is a 45-degree edge chamfer that serves to make the assembly process easier and enhance safety when handling parts—those 90-degree edges can be very sharp.

While most machine shops would perform this operation on their machining centers, we often prefer to take a more manual approach and chamfer edges by hand when machining plastic or wood. Though it might seem counterintuitive, we’ve discovered that handwork can often be significantly more efficient, which translates to lower costs for our customers.

Why Not Just Chamfer Parts Using a CNC Machine? 

To add a chamfer to the edge of a part using a CNC mill or router, most machine shops use a process known as “stitching.” This is where you use a ball mill and repeatedly run it perpendicular to the edge of the part in order to form the desired radius. Depending on the length of the edge and the type of material, this can take hundreds or thousands of passes. 

Though using a ball mill is essentially mandatory for chamfering the edge of metal parts, when it comes to machining plastic or wood, it’s quite inefficient. Not only does using a mill or router involve surfacing the material to minimize variances in thickness, but cutting a chamfer can require a significant amount of machine time, adding to production costs. 

In fact, chamfering an edge can add up to two additional hours of spindle time for many of the large and long parts we manufacture. And when it comes to small parts, the time it takes to set up and program a machine can offset any potential efficiency gains. 

Handwork: Leveraging Manual Techniques for Accuracy and Efficiency

Machining chamfered edges may be standard practice for most shops; however, at Accurate CNC, we take a different approach for plastic and wood parts that call for a standard edge radius—we use a hand router instead of a mill. With this approach, we can often reduce the time it takes to cut a chamfered edge by up to 90% compared to stitching in a mill, ultimately achieving lower production costs for our customers. 

Using Handwork to Improve Quality when Machining Plastic

When machining open tolerance parts from plastics like UHMW, it’s common for the material to have thickness variations of ±10%. While this might not be very noticeable on small parts, many customers rely on our plastic machining and CNC wood router service for long parts like conveyor beds.

For projects like this, using a hand router allows us to control the amount of material we remove and make adjustments to maintain a more consistent edge profile. This means higher-quality parts with improved aesthetics and a better fit and finish.

Machining and Routing Chamfered Edges on Metal Parts

While handwork is a great way to drive efficiency within our plastic machining services, it has its limitations. Specifically, hand routing is largely limited to plastic machining and wood routing projects that call for standard chamfer profiles. We learned through experience that hand routers and metal parts don’t mix—the hot chips fall into the motor casings and burn out the router.

To cut custom chamfer profiles on aluminum or steel parts, we default back to our CNC router or mill. Though this may extend machine time, the higher-quality results and ease of assembly are worth the cost.

However, if only a small edge break is required, we can typically use an air chamfer tool to chamfer aluminum or steel parts that call for standard profiles. 

Accurate CNC: Plastic Machining and CNC Routing Services Tailored to Your Project

At Accurate CNC, our expertise in precision machining as well as manual processes enable us to develop simple yet creative solutions for our customers. Whether relying on tried-and-true manual techniques or leveraging advanced precision machining equipment, we take the most efficient and cost-effective approach for your project, resulting in parts that exceed expectations.

Are you looking to reduce the costs of a machining or routing project? We’d love to look over your designs and discuss your needs. Upload your part files and request a quote today, or contact our team to learn more about our custom machining and CNC router service at Accurate CNC.