01
Tolerance stack nobody checked
A bore is called at ±0.01 mm, the mating pin at ±0.01 mm, and the assembly only has ±0.02 mm to give. The parts pass incoming inspection and still will not go together. We ask for the mating callout before quoting.
Machinist Resources
Machinist Resources
Reference material written for the shop floor: tolerance charts, G-code and M-code notes, deburring and finishing guides, plus the 5-axis capacity behind them. Use it to check a design before you cut metal.
±0.005 mmRa 0.2–0.8 μm127 CNC machinesNo MOQ
15 yearsMachining since 2011
127High-precision CNC machines
±0.005 mmAchievable tolerance
99.99%Qualification rate
Where quotes stall
Four problems that come from thin reference data
Most rejects start at the drawing, not the spindle.
02
Burrs that show up at assembly
A 0.2 mm rollover on a cross-hole edge jams an automated feeder. Deburring is not a line item on the drawing, so it gets skipped. Add an edge condition note and the cost becomes visible early.
03
Finish called out as a symbol only
Ra 0.8 μm on a 4,000 mm face and Ra 0.8 μm on a Ø12 mm bore are two different operations. Calling both the same way adds polishing time you did not budget for.
04
Prototype process copied to production
A 3-axis setup that worked for five pieces can double cycle time at 10,000. The fixture, not the machine, becomes the bottleneck.
How we work
Reference data you can check, then a shop that matches it
Two things decide whether a part comes out right: the numbers on the drawing and the setup that holds it.
Tolerances
Set tolerances by function, not by habit
A general tolerance block of ±0.1 mm covers most features on a machined part. Tightening everything to ±0.005 mm adds inspection time and scrap risk without improving function. We mark the two or three features that actually locate the part and leave the rest loose.
On a 4,000 mm part, thermal drift and workholding deflection matter more than spindle accuracy. For long parts we plan roughing and finishing in separate setups so the material settles before the final pass.
- 1±0.005 mmReachable on located features with the right setup
- 2±0.0002 inSame figure for drawings written in inch
- 3Ra 1.6–3.2 μmAs-machined finish, fine for most non-sealing faces
Setup and code
Read the G-code before you blame the tool
G-code tells the machine where to move. M-code tells it what to switch on: spindle, coolant, tool change, pallet. When a part comes out short on one side, the cause is usually a work offset or a tool length that was set against the wrong face.
For five-sided parts we post from the CAM model and verify the rotary table position offline. A Ø400 mm rotary table gives enough swing for most housings, and the 16 simultaneous 5-axis centers handle undercuts that would need three setups on a 3-axis machine.
- 1G41/G42Cutter compensation, check the lead-in length
- 2M08Coolant on; starving a deep pocket burns the insert
- 3M00Optional stop for in-process measurement
Selection table
Pick the process by feature, not by habit
Start from the geometry and the quantity.
| Feature | Process | Step-over / feed | Watch for |
|---|---|---|---|
| Deep pocket, L/D over 4 | 3-axis with long reach | Light radial, 0.1 × D | Tool deflection and chatter |
| Five-sided housing | 5-axis simultaneous | 0.3 × D radial | Rotary table clearance |
| Ø6 mm or smaller bore | Micro machining | 0.05 mm step-over | Heat build-up in the tool |
| Long shaft, Ø25 mm | Swiss / mill-turn | Bar feed, steady rest | Bar whip above 3,000 rpm |
| Thin wall under 1 mm | 4-axis with support | Finishing pass 0.2 mm | Spring-back after clamping |
What we run
Services behind these machinist resources
One shop for the prototype and the production run.
01
5 Axis CNC Machining
16 simultaneous 5-axis centers for undercuts, angled faces and housings that would need multiple fixtures on a 3-axis machine. One setup means one datum, which is where accuracy usually comes from.
02
3 and 4 Axis Machining
27 three-axis machines and 12 four-axis mills handle plates, brackets and prismatic parts. Good choice when the geometry is open and the volume is high.
03
CNC Milling & Turning
16 mill-turn centers cut shafts, fittings and threaded parts in one cycle. Less handling means fewer re-datum errors between the milled flats and the turned diameter.
04
Rapid Prototyping
From a single piece to a 10,000+ run with no minimum order quantity. Useful when you need to test fit before committing to hard tooling.
05
Sheet Metal Fabrication
Bent and formed enclosures, brackets and panels. We keep the flat pattern and the formed part under one drawing revision.
06
Part Surface Finishing
Anodizing, plating, powder coating, bead blasting and polishing. Laser marking down to 1.5 mm character height for traceability.
Cutting envelope
Machine range and what fits
Match the part to the travel before you send the file.
| Machine group | Travel | Typical parts |
|---|---|---|
| Large gantry | 4,000 × 400 × 150 mm | Long beams, rails, tooling plates |
| Medium 5-axis | 750 × 1,150 × 550 mm | Housings, manifolds, brackets |
| Medium 5-axis | 600 × 600 × 600 mm | Enclosures, covers, plates |
| Compact 4-axis | 500 × 500 × 450 mm | Fittings, connectors, small bodies |
| Mill-turn | Ø400 mm rotary table | Shafts, bushings, threaded parts |
Why GreatLight
Numbers we work to
Every figure below is a shop specification, not marketing copy.
15Y
Machining since 2011
Three wholly-owned plants and 7,600 m² of manufacturing space in Dongguan, plus a factory in Singapore at No.3 Joo Koon Circle.
127
CNC machines on the floor
16 simultaneous 5-axis centers, 12 four-axis mills, 27 three-axis machines and 16 mill-turn centers, run by 150 technicians.
±0.005
Tolerance in millimeters
Equivalent to ±0.0002 in. Held on located features with the right workholding, not on every face of the part.
Ra 0.2
Finest controlled finish
Ra 0.2–0.8 μm when the drawing calls for it. As-machined parts sit at Ra 1.6–3.2 μm.
12 h
Quote and DFM turnaround
Quotation plus free DFM analysis within 12 hours. Production can start within 24 hours of approval.
0
Minimum order quantity
From one prototype to 10,000+ part runs. Uploads stay confidential and an NDA is available on request.
7,600 m²Manufacturing space
150Technicians
3–5 daysParts ship in
100%Inspection before shipment
Industry requirements
What each sector asks for, and what we deliver
Aerospace brackets
Traceable material and documented inspection for structural parts.
- ±0.005 mm
- ISO 9001:2015
- Full inspection report
Automotive and EV housings
Process control that holds across a production run, not just the first article.
- IATF 16949:2016
- 99.99% qualification
- 10,000+ runs
Medical instrument bodies
Clean deburring, controlled finish and material certificates on file.
- ISO 13485:2016
- Ra 0.8–1.6 μm
- Deburred edges
Robotics and automation parts
Repeatable datums so the second unit bolts into the same fixture.
- 5-axis
- 4,000 mm max
- 100% inspection
FAQs
Questions from engineers and buyers
What tolerance should I put on a general machined part?
Start with ±0.1 mm for non-critical features and tighten only where the part locates or seals. A drawing with two tight features is cheaper to make and easier to inspect than one with twenty.
We can hold ±0.005 mm on located features. If you are unsure which ones matter, send the mating part and we will mark them in the DFM report.
How do I decide between 3-axis and 5-axis?
If every feature can be reached from one direction, 3-axis is enough and usually faster per part. Angled holes, undercuts and five-sided housings push you toward 5-axis because they avoid a second or third setup.
Each extra setup adds a datum shift. On parts with tight position tolerance between faces, fewer setups matter more than spindle speed.
When is deburring a separate operation?
Cross-drilled holes, threaded entries and milled edges that touch a mating surface all need an edge condition. If the drawing says nothing, the machinist decides, and that decision changes from operator to operator.
Write the edge callout as a note, for example 0.1 mm max edge break. Then deburring becomes a measurable step instead of a surprise at assembly.
What finish can I get without a separate polishing step?
As-machined surfaces land around Ra 1.6–3.2 μm. That is fine for brackets, covers and most non-sealing faces.
For Ra 0.2–0.8 μm we add a finishing pass with a smaller step-over, and sometimes bead blasting or polishing. It costs time, so call it out only where a seal, a bearing or a sliding fit needs it.
How do I read G-code and M-code without a machine in front of me?
Read the block sequence first, not the individual words. G00 and G01 set the motion mode, G41 and G42 bring cutter compensation in and out, and M08 controls coolant. An M00 in the middle of a cycle usually means the programmer wants a measurement.
If a feature is consistently off, check the work offset and tool length before editing the program. The code is rarely wrong on a proven post.
What should I check before sending a file for quote?
Confirm units, datum scheme and thread callouts. Mixed metric and inch dimensions on one drawing cause more scrap than any machining error.
Include the mating part or the assembly fit where it exists. It tells us which tolerances are functional and which are decoration.
Do you handle both prototypes and production runs?
Yes. There is no minimum order quantity, so one prototype and a 10,000+ run go through the same shop. The setup changes between them, and we say so in the quote.
For production we usually add a fixture that the prototype did not need. That is where cycle time and repeatability come from.
How fast can I get a quote and parts?
Quotation and free DFM analysis come back within 12 hours. Production can start within 24 hours of approval, and parts ship in 3–5 days.
Every part is inspected before shipment: raw material check, in-process monitoring and final inspection. Reports are available on request.
Send the drawing, get a real answer
Upload your file and we will return a quotation with free DFM analysis within 12 hours. No minimum order quantity, from one part upward.
12-hour quote100% inspectionNo MOQNDA on request
