CNC Machining for Test and Measurement
Test and measurement equipment is judged on two things: whether the numbers it produces can be trusted, and whether it looks like a product somebody would pay for. Most of the machining sits right on that line — optical mounts, probe fixtures, enclosures, panel parts — and it is usually needed in small batches, once a design is frozen.
- Instrument enclosures, covers and panel parts
- Optical and lens mounts, breadboard adapters
- Probe and test fixtures, jig bodies
- Sensor housings and shielded enclosures
- Aluminium, stainless steel and engineering plastics
The short answer
Test equipment parts are rarely difficult individually. What makes them hard is that a position error on a mount becomes an error in the measurement, and a scratch on a front panel becomes a complaint. So the brief is different from a bracket: hold the geometry that sets the measurement, and treat the outside faces as finished surfaces.
We machine to your drawing with ISO 2768-m as standard and ±0.01 mm on the dimensions you mark critical — optical axes, datum faces, bore spacing, thread positions. Appearance faces get their own pass and their own protection before the part is packed.
Quantities are usually small: a handful of units for a build, then a repeat once the design is frozen. There is no minimum order quantity, and we keep the setup notes so the second batch matches the first. For ongoing batches of the same part, see CNC machining for industrial automation.
What we hold on automation parts
The numbers we quote against, and what they mean for the parts above.
General tolerance
ISO 2768-m
Applies to every dimension with no callout of its own. Most brackets and plates need nothing tighter.
Critical features
±0.01 mm
Held on bore fits, shaft fits, datum faces and hole patterns — the dimensions you mark as functional.
Milling envelope
1000 × 600 × 500 mm
3-axis and 4-axis work. Larger is quoted case by case.
Turning capacity
Ø 300 × 500 mm
Shafts, hubs, bushings and coupling parts, with Ø 42 mm bar capacity for small turned parts.
Materials
Al / SS / steel / plastics
6061-T6 and 6082, 304 and 316, 1018 to 4140, plus POM, PEEK, nylon and UHMW.
Finishing
On the same order
Anodising, passivation, zinc and nickel plating, black oxide and powder coating arranged with the machining.
Parts we machine for test and measurement equipment
What each part is usually made from, and what the cost actually hangs on.
| Part | Typical material | What usually matters |
|---|---|---|
| Instrument enclosures and covers | 6061-T6, 304 | Flatness at the seam, and how the outside faces look |
| Front and rear panel parts | 6061-T6, 6082 | Hole patterns for connectors and displays |
| Optical and lens mounts | 6061-T6, 303 | Bore concentricity and thread fit |
| Breadboard and rail adapters | 6061-T6, 1018 | Hole pattern matching the mating standard |
| Probe and test fixtures | POM, 6061-T6 | Locating features that put the part back in the same place |
| Sensor housings | 304, 6061 | Sealing faces and cable entry detail |
| Shielded enclosures | 6061-T6, 304 | Continuous contact at the joint faces |
| Calibration and reference blocks | 4140, tool steel | Stability, and flatness of the reference faces |
Have a drawing ready?
Send a STEP, IGES or DWG — you get a priced quote within 48 hours in the normal case, with tolerance and lead time stated on it.
Where measurement error actually comes from
On a test fixture the part that moves the number is usually not the expensive one. It is the bracket that holds the probe a few hundredths off where the model says it is. Errors like that come from geometry quoted loosely: a bore position taken from an outside edge instead of a datum, a shoulder height nobody called out, a thread centre that drifted with the tap.
Two habits fix most of it. Mark the datum that sets the measurement, and call out the dimensions that affect the result — everything else can run to ISO 2768-m and costs nothing extra. If you are not sure which ones matter, send the assembly and we will say what we would hold.
Appearance is the other half. Front panels, covers and bezels are the parts a customer touches and looks at. Say which faces are appearance faces on the drawing: they get a separate finishing pass, broken edges and individual protection in the box.
Processes behind these parts
Most automation parts use one or two of these. Where a job needs more than one, we run them on the same order rather than handing it back to you to coordinate.
POM · PEEK · UHMW
Insulators, wear strips and light tooling that metal cannot do.
Getting the drawing right the first time
Small decisions that save a rebuild on a fixture or a re-finish on a panel.
- Mark the datum that sets the measurement. Bore and slot positions quoted to that datum repeat; the same features quoted to an outside edge do not.
- Say which faces are appearance faces. They get a different pass, edge breaks and separate packing — cheaper to plan than to rework.
- Give the finish before the machining, not after. Coating adds thickness; a bore that must hold size after coating needs the allowance in the machining.
- For optical and probe mounts, send the mating part or the assembly. Position errors usually come from the interface, not from the single part.
- Say if the enclosure has to seal or shield. That decides gasket groove detail and whether joint faces are machined for continuous contact.
- Give the target date up front. Standard lead time is 2–4 weeks; rush orders are confirmed case by case.
Frequently asked questions
What test and measurement engineers ask before they send the first drawing.
Can you machine optical mounts and lens holders?
Yes. Send the bore sizes, the mount thread if there is one, and what the mount has to align to. We hold the bore and the thread concentric to the datum you mark, and we will say if a wall section is too thin to hold the thread properly.
Do you machine front panels and enclosures?
Yes — 6061-T6 and 6082 for most enclosures, 304 where the unit is washed down or used outdoors. Send the panel drawing with the connector and display cut-outs and tell us which faces are appearance faces.
Can you make a fixture that puts the part back in the same place every time?
Yes. Locating features — pins, nests, datum faces — are machined to the datum you mark, and we keep the setup notes so a second fixture is made the same way. Send the part model so the nest matches the part rather than a dimension.
How do you handle appearance faces?
Tell us which they are on the drawing. They get a separate finishing pass, consistent grain direction, broken edges and individual protection in packing. It is much cheaper to plan than to rework afterwards.
What about finishes that add thickness?
Powder coating adds all of its thickness on top; anodising adds roughly half outward. If a bore or a shaft has to fit after coating, say so and we allow for it in the machining — see anodising vs powder coating for the comparison.
What do you need to quote, and how long does it take?
A 3D model plus a dimensioned PDF, the material, the quantity including spares, and your target date. You get a priced quote within 48 hours in the normal case, with tolerance and lead time stated on it. Standard lead time is 2–4 weeks; rush orders are confirmed case by case.
Send us the drawing
Send a STEP, IGES or DWG model with a dimensioned PDF, the material, the quantity including spares and your target date. If the part sets a measurement, mark the datum that does it; if it is seen by a customer, mark the appearance faces. You get a priced quote within 48 hours in the normal case, with tolerance and lead time stated on it. If an NDA needs signing first, say so and we will do that before you send anything.
Ready to Start Your Project?
Send drawings in STEP, IGES or DWG. You get a priced quote within 48 hours in the normal case, with tolerance and lead time stated. Measurement geometry held to the datum, appearance faces finished as faces.