Our shop has 3-axis CNC mills on one side and conventional mills and grinders on the other. We keep the manual machines because some jobs are faster and cheaper on them, while for others it would waste the customer’s money not to use CNC. We make that call every day, so here is how we make it.

What CNC does well

Repeatability comes first. Once a program is proven, the fiftieth part matches the first. For any real quantity, like a batch of bushings, a set of fixture plates, or spare parts a customer will reorder next year, CNC is the clear choice. The program stays on file, so the next batch starts from a known process instead of someone’s memory.

It also handles complex shapes. 3D contours, pockets with small corner radii, a plate with forty precisely located holes: these are routine on a CNC mill. Doing that hole pattern by hand means forty chances to misread a dial.

The machine also runs without someone at the handwheels. During a 40-minute cycle, the operator can set up the next job or deburr the last one. On a manual machine, every minute of cutting is a minute of someone’s time.

What CNC costs

The machine is expensive, but it’s only one of the costs. There’s CAM software, tooling, workholding, and people who can program and set up. Good CNC programmers in the Philippines are hard to hire and hard to keep.

Then there’s the cost of the first part. Modeling, programming, setup and a careful first run can take hours before any cutting starts. Spread across a hundred parts, that’s small. On a single part, it can double the price. That’s why one-off quotes sometimes surprise people: most of the cost is in preparing the job.

Why we still use manual machines

Give a skilled machinist a shaft that needs one shoulder taken down 0.5 mm and it’ll be done before a CNC setup is finished. For single, simple operations like facing a plate, opening up a bore, or modifying an existing part, manual is quicker from start to finish.

Repair work also tends to go manual. Worn parts rarely match their drawing, if there is a drawing at all. A machinist can measure as they go, creep up on a fit, and match a mating part with a micrometer. That’s hard to program in advance.

Some processes stay manual in our shop. Our surface grinding is done on conventional machines, and it gives a flatness and finish our mills can’t.

The drawbacks of manual work

Consistency depends on the machinist. A good one holds tight tolerances all day, but over a batch of twenty parts there will be some variation, and there’s no program to fall back on if that person is on leave.

Manual machining is also slow for volume. Making the fifteenth identical part on a manual mill is tiring and expensive, and sooner or later it leads to a scrapped part.

How we decide

Our rough rules:

One part, one simple feature: manual.
Ten or more parts, or one part with 3D shapes or a large hole pattern: CNC.
Anything the customer will reorder: CNC, so the program is saved.
A worn part that has to match what’s there rather than a drawing: usually manual.

Customers don’t sort their jobs by machine type before sending them, which is why we run both.