【HaiChuan Discussion】A small error can lead to big consequences – have you ever encountered tape measures with different scales?

It seems I need to buy a few more rulers to compare them. However, there’s no problem with those knives in your diagram, because the way you arranged them at the beginning already contained an error; it’s only natural then that there are errors later on as well.

What to do if several rulers have errors? ? ? ? ? Which one is the correct one? ? ?

Before the liberation, the landlords would take from large containers and give back from small ones.

A ruler also works by taking multiple measurements and averaging them, right? On another picture, 0.9m is shown as 1m – without a ruler to compare with, how can one know whether what’s being measured is 0.9 or 1?

It still isn’t based on a calibration scale

Why is it required that measuring instruments be calibrated? The box calipers used by workers are accurate to the millimeter level; just adjust them at your own workplace. When buying a regular box ruler, don’t seek the cheapest option; also, sellers are aware of the accuracy levels of these rulers, so you can ask them directly.

When using a steel tape measure, it is first necessary to check all its parts: for self-winding and brake-type tape measures, the tape should extend and retract smoothly and flexibly, without any sticking； The button mechanism of a brake-type tape measure should be able to effectively control the reeling in of the tape, with no obstruction or malfunction occurring ； Box and rack type tape measures should be flexible when rolling them out ； The surface of the scale band must be free from rust, obvious spots, or scratches, and the markings should be clear. When using a tape measure, the \"0\" end should be used as the reference point for measurement, which makes reading easier. When using a non-zero point as the measurement reference, special attention should be paid to the numbers on the lines at the starting end to avoid misreading. When using a tape measure, just like a metal ruler, it must not be tilted in any direction, and the measuring strip must be stretched tight. The tape of a steel tape measure is usually coated with chromium, nickel, or other coatings; therefore it needs to be kept clean. During measurement, avoid letting it rub against the surface being measured to prevent scratches. When using a self-winding or braking tape measure, do not pull the tape out too forcefully; instead, pull it out slowly, and also let it retract slowly after use. For a braking tape measure, press the brake button first, then slowly pull out the tape. After use, press the brake button to automatically rewind the tape. A tape measure can only be rolled, not folded. It is not allowed to place the tape measure in humid areas or those with acidic gases to prevent rust. To facilitate use at night or in low-light conditions, the scale surface of some steel tape measures is coated with a luminous substance that emits light in darkness, allowing the scale markings and numbers to be seen clearly. It is important to take care to protect this coating during use. In addition to measuring length, steel tape measures are also commonly used to determine the diameter of cylindrical components such as cylinders and end caps. Before making a measurement, it is necessary to select a steel tape measure with an appropriate measurement range based on the diameter of the component being measured. When measuring the outer circumference, a flat steel tape should be used. The steel tape measure in use must be free of any defects that could affect its performance; the surface of the workpiece being measured as well as the working surface of the tape measure should be cleaned thoroughly. The usage method is to wrap the tape measure around the circumference of the radial cross-section of the workpiece being measured, pull the tape tight with both hands, slide it back and forth along the surface of the workpiece several times, and then take the reading. The method for reading a steel tape measure is the overlapping method: when the tape is wrapped around the object to be measured, the ends of the tape overlap. The value indicated by the markings at the point where the tape ends overlap is the measurement result, which represents the outer circumference of the cylindrical object being measured. By dividing the measured outer circumference value by π, it is possible to convert it into the outer diameter value of the cylindrical workpiece being measured (such as a cylinder or a closed end). If using a steel tape measure to measure small-diameter cylindrical workpieces, the measurement can be carried out directly ； When measuring large-diameter cylindrical workpieces and the operation is to be carried out by a single person, it is necessary to use magnet blocks to press the tape against the workpiece (this is only applicable when the workpiece is made of a ferromagnetic material) in order to conduct the measurement, or two people must work together for this purpose. When using a steel tape measure, special attention should be paid to whether it has passed calibration; there have been many cases of problems arising from the use of low-quality tape measures with large errors. Secondly, when measuring the length of the same workpiece multiple times, the same steel tape measure must be used.

On the morning of January 24, reporters went to the New Era Building Materials Market in Weicheng District, where there is a shop selling tape measures at its east entrance. When the reporter asked about non-standard tape measures, the clerk said they had heard of such tape measures and that occasionally people would come in to inquire about them, but their store did not sell them. At Weifang Commodity City, many of the shops on display sell tools such as tape measures. In response to journalists’ specific need to purchase non-standard tape measures, the owner of one store said that such products were sold in the past, but after the supplier was investigated, they became unavailable. After conducting investigations, the reporter found that the shops were selling mainly standard tape measures; one or two of them refused to provide relevant information after attempting to verify the reporter’s identity. Subsequently, the reporter went to Baihui Market in Hanting District and visited seven or eight shops. The staff at most stores said they were unaware of the situation and recommended purchasing online. Only the staff at one store said they could help arrange to get the goods. Journalists logged onto e-commerce platforms such as Taobao and JD.com and entered “non-standard tape measures” as a search term; the result was “no relevant products found.” However, after splitting the keywords and searching again, it was discovered that some merchants were selling such products. These merchants said that after the issue of \"non-standard rulers\" became a trending topic on Weibo, e-commerce platforms took action to rectify the situation; most of those products were removed from sale, and the manufacturers were also affected. As a result, there is currently a shortage of supply, and those products will be made available again depending on the circumstances. Are non-standard tape measures really unavailable? The reporter contacted local renovation professionals and learned that such tape measures with large errors are available not only online but also in physical stores. At the recommendation of a person in the decoration industry, the reporter purchased a non-standard tape measure from a hardware store in the urban area on the 25th for 50 yuan. This brand-new tape measure has an English label indicating a length of 5 meters; it looks no different from ordinary tape measures, but the scale indicated on it hides a secret. Actual tests showed that the error per meter was 20 centimeters, which is 500 times higher than the allowable limit. The reporter gave the non-standard tape measure purchased to a professional renovation team, and compared it with a standard steel tape measure. The results showed that when the reading on the standard scale was 1 meter, the reading on the non-standard scale had reached 1.2 meters ； When the reading on the standard scale is 2 meters, the reading on the non-standard scale has reached 2.4 meters. This non-standard tape measure, labeled as 5 meters long, actually has a length of only 4 meters; the error is 1 meter, resulting in an error rate of as high as 25%. Upon reviewing relevant information, the reporter found that according to China’s QBT2443-2011 standard for steel tape measures, the error tolerance for such measures is divided into two grades: first grade and second grade. Taking a nominal 5-meter steel tape measure as an example, the allowable positive and negative error for grade 1 standards must not exceed 0.2 millimeters per meter, while for grade 2 standards it must not exceed 0.4 millimeters per meter. Based on this calculation, a non-standard tape measure with an error of 20 centimeters per meter has an error that is **500 times higher than the allowable value for class II standard errors, which is far beyond the acceptable limit. According to industry insiders, the non-standard tape measures available on the market come in different sizes; they can not only be extended from 0.8 meters to 1 meter but also compressed from 1.2 meters to 1 meter. Some sellers simply call it a “error scale” or “shrinkage scale”. It’s difficult to find it regularly; it’s only available in some unregulated shops, and supplies are provided through connections with renovation teams. Some people use them in concealed work, taking advantage of the \"errors\" in non-standard tape measures to make profits. When homeowners and contractors inspect renovation projects, steel tape measures are one of the main tools used, while non-standard tape measures become tools for unlicensed renovation teams to earn illegal profits. According to industry insiders, renovation crew supervisors usually have two types of tape measures: a standard one and a non-standard one. They choose which one to use depending on the situation; if it’s likely to be noticed by the homeowner, they use the standard tape measure ； For things that are not easy to detect, such as concealed works, non-standard tape measures are used. “Intentionally misreporting the renovation area can allow one to claim more payment for the renovations. Some finished construction products are too large and do not meet the acceptance standards; as a result, some people resort to using ‘shrinkage scales’ to cheat their way through and pass inspection. ”An industry insider said that these two types of non-standard tape measures are mainly used in renovation projects and carpet sales, etc. Depending on the agreements reached with homeowners during renovations, it is possible to make significant profits by either deliberately overreporting the dimensions or underreporting them. In addition, there is another type of standard with non-standard features in the latter part; in this case, custom molds are required, resulting in higher purchase costs. When pricing is based on non-standard measurements, how much do homeowners actually lose? A professional in the decoration industry did some calculations for the reporter: if the error rate due to non-standard measurements is 25%, then the \"amount of work required\" increases by 25% as well. Taking hydropower projects as an example, for a house with an area of 100 square meters, the labor cost is around 4,000 to 5,000 yuan; when non-standard measuring tapes are used, the homeowner has to pay the workers an additional 1,000 yuan ； If the work and materials are included in the contract, the total cost doubles, resulting in a loss of around 2,000 for the owner ； If one encounters an untrustworthy renovation company, the homeowner will suffer losses of over 3,000 yuan due to the relatively high overall cost. Since the emergence of these \"non-standard rolls\" in recent years, they are generally used only by unregulated small renovation companies, mostly for measuring tasks such as tile laying and balcony enclosures. According to lawyers, the production and sale of non-standard tape measures are illegal. On this matter, Wang Xiaoqian from Shandong Haode Law Firm states that if someone deliberately purchases and uses non-standard tape measures in order to deceive consumers, thereby violating the Consumer Rights Protection Law, they must compensate the consumers twice for the losses suffered, with the amount of additional compensation being three times the price of the goods purchased or the cost of the services received. If construction workers use non-standard tape measures, resulting in damage to the building or even casualties, the manufacturers, sellers, and users will be held criminally liable. Producing and selling \"non-standard tape measures\" violates the Metrology Law and constitutes an illegal act. Articles 14 and 16 of the Metrology Law stipulate that no entity or individual shall, in violation of the regulations, manufacture, sell, or import measuring instruments using non-legal units of measurement. When using measuring instruments, their accuracy must not be compromised, nor must the interests of ** and consumers be harmed. Article 27 stipulates that those who manufacture, sell, or use measuring instruments intended to deceive consumers shall have such instruments and any illegal gains confiscated, and shall be fined. In cases of serious circumstances, the individuals or entities responsible shall be held criminally liable in accordance with the relevant provisions of the criminal law. If consumers encounter practices similar to using non-standard tape measures to underweight goods, they can call 12315 to file a complaint. “In fact, during the renovation process, some homeowners questioned whether there were irregularities in the cost calculation, but they often failed to find any flaws. When the owner and the contractor conduct the inspection and settlement, it is essential to make sure that the rulers used are legitimate. ”Wang Xiaoqian said that proper steel tape measures come with trademarks and corresponding label information, while those without such markings are considered \"products without proper identification.\" Even if their appearance is similar to that of genuine products, the brands associated with them are usually obscure. Additionally, it is recommended that owners bring a standard ruler to the construction site during the inspection and settlement process, which can also help prevent the contractor from cheating.