CNC machining and waterjet cutting: what to know

What the job involves, what changes the price, and what to ask a pro.

What cnc machining and waterjet cutting is

CNC machining and waterjet cutting turn a drawing into a finished part, sign or decorative piece in metal, plastic, stone or glass. People usually need it when a part is no longer sold, a repair needs a custom replacement, or a project calls for shapes that a hand saw or torch cannot hold accurately.

Signs you need it

  • A broken or worn part has no replacement on the market, and you can measure it or have a drawing of it
  • You need flat metal, plastic or stone pieces cut to exact outlines, such as brackets, gussets, base plates or a sign panel
  • A design has curves, holes, slots or lettering that must line up with other parts
  • You need several identical pieces, such as a set of mounting plates, and they must all fit the same
  • You want an intricate stone or tile medallion or inlay, and the material is too hard or brittle for hand tools

What the pro does

  • The shop reviews your drawing or sketch and checks the dimensions, the material and whether the design can be cut as drawn
  • They pick CNC milling, routing or waterjet based on the thickness, the edge quality you need and how much heat the material can take
  • They program the cutting path and set up clamps or fixtures so the stock cannot shift during the cut
  • They cut a first piece and check it against your dimensions before running the full order
  • They deburr, clean and inspect each part, then pack them so the edges are not chipped in transit

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Material type and thickness, since hard metals and thick stone slow the cut and wear tools or abrasive faster
  • Whether you supply a usable drawing file or the shop has to redraw the part from a sketch
  • Number of pieces and whether the same program can repeat across the run
  • Tight tolerances and smooth finish requirements on faces that must seal or mate with another part
  • Secondary work such as tapping holes, countersinking, bending or polishing edges
  • Whether the shop must buy stock that is not on hand before it can start
  • Turnaround timing, since a rush order can pull the shop off other work

What a written quote should spell out

  • Material grade, thickness and the stock size being cut from
  • Cutting method, such as CNC milling, routing or waterjet, and the reason it was chosen for this material
  • Number of pieces, with any program or setup work shown on its own line
  • Tolerances and edge finish you asked for, and how the shop will check them
  • Secondary operations like drilling, tapping or deburring, listed separately
  • How the parts will be packed and shipped, and who handles breakage in transit

Questions to ask before you hire

  • Can you cut this from my drawing as supplied, and will you tell me now if any feature cannot be made as drawn?
  • Which cutting method will you use for this material and thickness, and what edge will it leave?
  • Will you send a first piece or a measured check before you cut the full order?
  • What tolerance can you hold on the holes and slots I have marked?
  • What file format do you need, and do you charge to clean up or convert a drawing?
  • Do you have this material in stock, or does it have to be ordered and how long does that add?
  • If a piece comes out wrong, who pays to remake it and how fast can it be done?

Red flags

  • They will cut a part that has to fit something without asking for the mating part or measurements
  • They cannot explain why they chose waterjet or milling for your material
  • They refuse to show a sample of their edge work on the same material type
  • They change your drawing without telling you and do not show you the revised version before cutting

What you can do yourself

Measure the part carefully, sketch it with dimensions, and note the material, thickness and quantity before you call. Do not use a torch, abrasive saw or hand router to make a part that holds weight or must fit tightly, because the fit and strength will not be reliable. Call a shop when the job needs repeatable accuracy or a run of identical pieces.

Licenses and permits

Machine shops and waterjet cutters are usually run as ordinary businesses, but some work for structural, pressure or safety parts requires certification or inspection records. Check with your state or local licensing or business registration office for what your project needs.

CNC machining and waterjet cutting questions

Can a shop cut a part from a photo?

A photo alone rarely gives enough detail. Send a sketch with dimensions, the material, the thickness and any hole or thread specs. If the part must fit existing hardware, send the actual part or a measured sample too.

Which is better, waterjet or CNC?

It depends on the material. Waterjet cuts most materials without heat, which suits stone, glass and many metals. CNC milling or routing gives tighter holes and cleaner pockets in plastic, wood and many metals. Ask the shop which one fits your part and why.

How do I make sure the parts will fit?

Ask for the dimensions and tolerances in the quote and for a first-piece check before the full run. Keep your drawing revisions in writing so the shop cuts the version you approved.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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