A Beginner's Guide to CNC Milling and Turning for Custom Metal Parts

• A current drawing or CAD model, with its revision
• Material and quantity
• Critical dimensions, tolerances and surface finish
• Delivery date, plus any inspection or paperwork needs

FAQs

What is the difference between CNC milling and CNC turning?

In milling, the cutter spins and moves while the part stays clamped, so it suits flat, boxy shapes. In turning, the part spins in a lathe while the tool stays mostly still, so it suits round parts like shafts and bushings. Lots of parts need both. Knowing which saves time.

What does 5-axis CNC machining mean for a beginner?

This simply means that the machine uses five axes of movement such that the tool or workpiece can be tilted and rotated. This allows the tool to be brought into contact with various sides of a workpiece through a single setup, thus simplifying difficult shapes and achieving precision.

Which metals are easiest to machine for custom parts?

Normally aluminum. Aluminum cuts quickly, lasts longer, and the finish will be better. Brass is good as well. Stainless steel and titanium are more difficult to work with; they cut slowly and put strain on your tools. Metals that are easy to work with are cheaper to work with.

What tolerance should a beginner ask for on a CNC machined part?

The loosest one the part can live with. Tighter limits mean slower cutting and more inspection, and that costs money. Save the tight ones for fits, seals, and mating surfaces. Amtec Solutions Group lists ±0.005 inches or better, so send the drawing and ask the shop what's feasible.

Can one shop handle both a prototype and a production run?

Many can. Amtec Solutions Group says it covers one-off prototypes through higher-volume production. Telling the shop the first quantity and any repeat orders expected helps it plan setups and fixtures. That way, a prototype design doesn't need reworking when production starts. Ask early. Small detail, big difference.