This is an honest Proster micrometer review of the 6-piece outside metric set (£126.13) for one specific job: checking parts before they leave a small workshop. If you run a garage CNC or lathe side-line and a customer has just quoted ±0.02 mm, the question is whether this set is trustworthy enough to sign off external sizes — and where it is not.
What you get for £126.13
Six frames covering 0–150 mm in 25 mm steps, carbide measuring faces, a ratchet stop and spindle lock, a setting standard per frame and a case. It is a mechanical set — sleeve and thimble scales, no LCD — resolving 0.01 mm. Buying those six ranges as single tools would cost considerably more, and premium trade brands such as Mitutoyo cost more again.
Repeatability versus a caliper
The reason to own it is repeatability. The ratchet applies the same pressure every time, so the same part reads the same number — which a digital caliper, with its flexing jaws, will not reliably do. For a side-line that lives on its reputation, that matters: one returned part for being out of tolerance can wipe out the profit on three orders, plus the hit to your store rating. If tolerance uncertainty has stopped you quoting the ±0.01 mm jobs, a repeatable external check is what lets you take them on.
Where it fits a small workshop
It is a strong quick-check tool for external QC before dispatch — shafts, pins, turned diameters and bar stock. Pair it with a bore tool for internal features (see internal micrometer), and use the outside micrometer guide for technique. Next-day UK stock helps when an order has a deadline.
Who should look elsewhere
- Anyone who must provide UKAS-traceable certificates out of the box — this set is not supplied calibrated to a certificate;
- Internal-bore-only work — buy a dedicated bore tool instead;
- Sub-0.001 mm resolution for aerospace-grade inspection.
Verdict
For external workshop QC it is honest value: repeatable to 0.01 mm, mechanically reliable with nothing to go flat, six ranges in one case and quick UK availability. It is not laboratory metrology and it does not pretend to be — judged as a working man's set for checking parts before they ship, it earns its place. Still deciding how to choose? See the micrometer buying guide.
PROSTER Outside Micrometer — 6-Piece Metric Set
Six metric frames covering 0–150 mm in 25 mm steps, carbide measuring faces and a ratchet stop, with free UK delivery, 30-day returns and a 12-month guarantee.
Frequently asked questions
Is the PROSTER micrometer set good enough for CNC part inspection?
For external sizes to about 0.01 mm it is a sound quick-check tool; for traceable sign-off a customer may still require accredited calibration.
Is it digital?
No, it is a mechanical 6-piece outside set with sleeve and thimble scales and a ratchet stop.
Is it better than my digital caliper for tolerance work?
For external measurements yes, because the ratchet gives repeatable pressure a caliper cannot; keep the caliper for internal and depth checks.
Who should not buy it?
Anyone needing internal-bore micrometers only, sub-0.001 mm resolution, or UKAS-traceable certificates out of the box.