Quality control of finished parts — the check that every part goes through before it is allowed to leave for a client.
Tolerances, inspection and the measurement report
General tolerances. We work to ISO 2768-c by default, and to ISO 2768-m on request. A dimension that carries an explicit tolerance on the drawing always takes precedence.
How we check. The finished part is measured with a caliper; angles with a protractor. On rectangular parts we compare both diagonals as well.
We hold no certificate. Quality is proven by results, not by a certificate — which is why everything below tells you how to check us yourself.
A measurement report — on request, free of charge. One sheet: order, part, nominal dimension, measured dimension, both diagonals, who measured it, date. Ask for it when you send the enquiry.
Five checks that take two minutes, before you accept your parts
Most problems with cut parts are invisible on delivery. The part looks right, it measures right for length and width — and only at assembly does something turn out not to fit. By then, days have usually gone by.
We wrote this page because people come to us with exactly that story. The checks below take two minutes and need nothing but a tape measure. Run them on every supplier, including us.
1. Measure both diagonals
This is the most important check, and almost nobody does it.
Measure from one corner to the opposite one, then do the same for the other pair of corners. On a rectangular part the two diagonals are equal.
If they differ, the part is not a rectangle but a parallelogram — the sides can measure exactly right while the corners are not 90°.
What is normal: on a part around 500 mm, a difference of up to 0.1 mm is within the ordinary range. A difference of more than 0.3 mm means the machine is not squared up.
Why it matters: one degree of skew on a 500 × 300 mm part puts roughly 9 mm between the diagonals. The sides will measure correctly. The enclosure will not close.
2. Butt two parts together
Put two adjacent parts on a flat surface and push them together along the shared edge.
What to look for: a gap at one end. If the edge meets at the start and opens up towards the end, the corner is not square — or the edge is not straight.
Why it matters: with two parts the gap is visible. In an enclosure made of six, it can no longer be pulled out with fasteners.
3. Compare the first and the last part of the batch
Take two identical parts — one from the top of the stack, one from the bottom — and measure them.
What to look for: any difference between the two.
Why it matters: if the size drifted during cutting, the parts from the start of the run will fit and the ones from the end will not. That is particularly treacherous on a series, because the problem surfaces only once you have already installed half of it.
4. Measure holes from one and the same edge
Do not measure the distance between holes. Measure from one chosen edge to each hole.
What to look for: whether each distance, taken on its own, matches the drawing.
Why it matters: small errors between neighbouring holes accumulate. Five holes off by 0.3 mm each put the last one 1.5 mm out — and the bolts no longer go in.
5. Run a finger along the edge
No glove, along the full length.
What to look for: burrs, fuzz, scorch marks, a different roughness on different sides.
Why it matters: the edge tells you the condition of the tool and of the material. A frayed edge on wood-based panels usually means the part lifted during cutting. Fuzz and burrs mean a blunt tool or contaminated material.
Why it happens at all
A handful of causes, all of them mechanical, and none of them visible in a photograph.
The machine is not squared up. The gantry has to be exactly perpendicular to the rails. If it is not, everything comes out as a parallelogram — the machine cuts accurately, but in a skewed coordinate system.
Drift is not monitored through the day. On a gantry with two drives, either side can fall behind on its own. If that is not detected, the squaring done in the morning does not help the parts cut in the afternoon.
Tool compensation. A cutter has a diameter. If it is not accounted for correctly, holes come out undersized and outside dimensions oversized — by a full tool diameter, not by a little.
The material. Panels stored outdoors take up moisture, swell and warp. A warped sheet does not sit flat on the table and lifts during cutting. Acrylic and polycarbonate absorb moisture and can crack weeks later, already installed.
And finally — accumulation. One part with a 0.5 mm error passes. Six such parts in one enclosure do not go together, because the errors add up and twist.
How we work
We are not going to claim that errors do not happen here. We will tell you what we do so that they do not reach you.
We read the drawing before we cut. If a radius is smaller than the tool, if a tolerance is unrealistic for the material, if two parts are not going to meet at assembly — we say so before it has happened.
If any of the above sounds familiar, send us your drawing. We will tell you what we see in it — whether or not you end up ordering from us.