Part 1 covered the basics. Part 2 covers how the tool actually reaches your geometry. Design restrictions, minimum wall thickness, hole depth, thread callouts and tolerance choices that decide whether a part machines clean on the first run.
Most failed parts trace back to one line in the model, not to the machine.
You modeled a sharp internal corner at the base of a pocket. A rotating cutter leaves a radius equal to its own radius, so a 6 mm end mill leaves R3. If the corner stays sharp on the print, the shop either adds a radius, sinks an EDM electrode, or quotes the part at a higher price. Draw the radius you can live with.
A pocket 60 mm deep and 8 mm wide forces a cutter with a 7.5:1 length-to-diameter ratio. That tool deflects, chatters, and leaves taper on the wall. Depth-to-diameter above 4:1 starts to cost real money. Above 10:1, expect step-downs measured in fractions of a millimeter.
A blanket ±0.01 mm on every dimension looks safe on a drawing. It is not. Each tight callout adds an inspection step and a slower finishing pass. On a 200 mm aluminum part that is stable, ±0.005 mm is reachable. On a thin 304 stainless bracket, it is not, and the quote reflects the risk.
A 0.8 mm wall on a 100 mm long aluminum housing looks fine in CAD. The cutting force pushes it, the material springs back, and the wall measures different at each end. Below 1 mm in aluminum, wall thickness becomes a fixturing problem, not a machining problem.
Five design restrictions decide your part more than any material choice.
A milling cutter removes material by spinning. That single fact sets the geometry you can produce. Internal corners come out with the tool radius. Floors come out flat only if the cutter can pass over them. Undercuts need either a smaller tool, a different setup angle, or a different process entirely.
Before you finalize a pocket, ask which direction the tool enters and where it exits. If the answer is 'from the side', the feature is a slot, not a pocket, and the cutter will be unsupported for part of the cut. On a 5-axis machine we can tilt the tool to reach a wall that a 3-axis setup cannot, which often removes a second operation.
Workpiece stiffness and tool stiffness are two sides of the same cut. A long end mill flexes and cuts oversize. A thin wall flexes and cuts undersize. Both show up as a dimension that drifts along the part, and both are solved before the first chip, not after.
Wall thickness is the usual culprit. In aluminum, 1.0–1.5 mm is a practical floor for a machined wall, and 0.8 mm is possible only with light finishing passes and custom soft jaws. In stainless and titanium, the floor is higher because cutting forces are higher. Holes and slots that run parallel to a thin wall need extra stock left for a finishing pass.
Starting values for the features that drive most quotes.
| Feature | Practical limit | What changes when you cross it |
|---|---|---|
| Internal corner radius | ≥ tool radius (R1.5 typical) | Sharp corner needs EDM or a smaller tool |
| Pocket depth / width | ≤ 4:1 | Long reach tool, slower step-down, higher cost |
| Minimum wall, aluminum | 1.0–1.5 mm | Custom soft jaws, light finishing passes |
| Minimum wall, stainless | 1.5–2.0 mm | More passes, more heat, more risk |
| Hole depth / diameter | ≤ 10:1 drilled | Deep hole drilling cycle or gun drilling |
| Thread engagement | 1.5 × diameter in steel | 2 × diameter in aluminum and plastics |
| Tall unsupported feature | ≤ 4 × feature width | Added support ribs or a second setup |
| Standard tolerance | ±0.05 mm | Below that adds inspection and finishing time |
One shop for the prototype and the production run.
16 simultaneous 5-axis centers reach angled faces, deep pockets and contoured surfaces in one setup. Useful when a design has features on four or five sides and the tolerance stack between setups would otherwise eat the budget.
27 three-axis and 12 four-axis machines handle prismatic parts, plates, housings and brackets. Most parts that fit a 3-axis setup should stay on one, because fewer axes means a simpler quote and a shorter lead time.
16 mill-turn centers combine turning and milling in one cycle for shafts, bushings, connectors and cylindrical housings. Live tooling cuts cross holes and flats without re-chucking the part.
When a design is still moving, machining a prototype in the final material answers fit and function questions that a printed model cannot. Same tolerances as production, no tooling cost.
Anodizing, plating, powder coating, bead blasting and polishing. Finishes change dimensions, so we mask threads and bores where the fit matters. Laser marking holds a minimum character height of 1.5 mm.
100% inspection before shipment with raw material check, in-process monitoring and final inspection. Dimensional reports on request, which matters when your own quality system needs the paper trail.
What the shop floor can take on.
| Category | Range | Notes |
|---|---|---|
| Aluminum | 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075, ADC12 | 7075 for strength, 6061 for general work |
| Stainless | 303, 304, 316, 316L, 420, 430, 431, 440C, 17-4PH | 303 machines best, 316 for corrosion |
| Steel | 1018, 1045, 4130, 4140, 4340, A36, tool steel | 4140 and 4340 need pre-hard or annealed stock |
| Titanium and special | TA1, TA2, TC4 (Ti-6Al-4V), Inconel, magnesium AZ31B / AZ91D | Sharper tools, lower speeds, more coolant |
| Copper and brass | C101, C103, C110, beryllium copper, C27400, C28000, C36000 | C36000 is the free-machining grade |
| Plastics | ABS, PC, PMMA, POM, PA, PEEK, PP, HDPE, carbon fibre | PEEK and carbon fibre need sharp tooling |
| Maximum part size | 4,000 mm travel on large machines | 750 × 1,150 × 550 mm and 600 × 600 × 600 mm also available |
| Finishes | Anodizing, plating, powder coating, black oxide, blasting, polishing | Laser marking minimum character height 1.5 mm |
We give the same answers on the quote as we do on the floor.
Send a STEP file and a drawing. You get a price and a written list of the features that will drive cost, before you commit to a revision.
Reachable on stable geometry up to 200 mm. We tell you when a callout is not realistic for the material and wall thickness in front of us.
Inspection runs on every batch, not on a sample. Reports are available when your quality system needs them.
One prototype and a 10,000-part run go through the same process plan. The second setup is already proven.
Dongguan, China and a Singapore factory (No.3 Joo Koon Circle). 7,600 m² of manufacturing space and 150 technicians.
Once the drawing is frozen and material is on hand, production can start within 24 hours. Standard parts ship in 3–5 days.
Pocketed ribs and thin webs where weight drives every wall. 5-axis setups cut the tolerance stack that comes from flipping a part four times.
Sealing faces and mounting holes that have to line up across a long part. IATF 16949 process control, inspection reports on request.
Joint housings with bores on multiple axes. Mill-turn removes a re-chuck step and keeps the bore concentric with the mounting face.
Small features, blunt edges and cleanable surfaces. ISO 13485 process control, passivation and bead blasting before packing.
Depth-to-diameter is the number that matters, not depth alone. Up to 4:1 the cutter is rigid and the cut is fast. Between 4:1 and 10:1 you need a longer tool, smaller step-downs and a slower feed, so the cycle time climbs.
Past 10:1, the tool is long enough that chatter becomes likely. If a design needs an 80 mm deep, 6 mm wide slot, we will usually suggest opening the width, adding a draft, or splitting the part.
1.0–1.5 mm is a practical floor for a machined aluminum wall, assuming the wall is short and supported. At 0.8 mm we can still cut it, but only with light finishing passes and soft jaws that support the wall along its length.
Below that, the part becomes a fixturing problem. The wall will measure differently at each end unless the whole cut is planned around supporting it.
Model them. A radius that exists in the model is a radius we can machine and inspect. If the drawing says sharp and the model says sharp, we either add a note asking which radius is acceptable or quote EDM for that corner.
A good default is to size the internal radius to the largest cutter that fits the pocket. An R3 corner in a 20 mm pocket lets a 6 mm cutter do the work in one pass.
It depends on geometry and material more than on the machine. A stable aluminum part up to about 200 mm, with no thin walls and no deep pockets, holds ±0.005 mm without special effort.
A thin stainless bracket, a long part with a big temperature swing, or a wall under 1 mm will not. We flag those callouts in the DFM report so you can decide whether the tight tolerance is functional or just drawn by habit.
Threads are cheaper cut with a tap or a thread mill than modeled as a helix in the CAM file. Give us the thread callout (M6 × 1, 1/4-20 UNC) and the depth, and we will pick the tool.
Engagement matters more than the callout. In steel, 1.5 × diameter is enough for full strength. In aluminum and plastics, plan for 2 × diameter because the threads are softer and strip earlier.
Yes. Sixteen simultaneous 5-axis centers handle angled faces and contoured surfaces without flipping the part. That removes the tolerance stack you get when a feature is cut in a second or third setup.
Not every part needs it. A prismatic plate that fits a 3-axis vise should stay on a 3-axis machine, because the setup is simpler and the quote is lower. We will tell you which one your part is.
A STEP file for the geometry and a PDF drawing for tolerances, threads, finishes and critical dimensions. If the drawing and the model disagree, we ask before quoting.
Uploads are kept confidential and an NDA is available on request. A quotation with free DFM analysis comes back within 12 hours.
Finishes change dimensions. Anodizing builds a few micrometers per surface; plating adds more. If a bore has a press fit and also gets plated, the bore will close up unless we mask it or cut it undersize.
Tell us the fit and the finish together. We mask threads and critical bores as standard when the drawing calls for both.
Upload a STEP file and a drawing. Within 12 hours you get a price and a written list of the features that drive it, from a shop that has been cutting metal since 2011.
12-hour quote100% inspectionNo minimum order quantityNDA on request
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Upload your 3D model or 2D drawing and get a quotation with a free DFM analysis. Maximum processing size 4,000 mm.
CNC Metals 13 grades
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