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A micrometer screw gauge measures outside measurements like diameters. They are designed for taking extremely precise, accurate measurements at sizes too small for the naked eye. Some examples include the thickness of paper, plastic bags and automotive brake wear. They are used for domestic hobby and DIY uses such as handloading bullet shells and making things with a lathe. Bigger users include manufacturers, scientific researchers, forensics, metalworking, machinists etc. Other types of calipers measure internal measurements like inside a pipe or the depth of an object like a groove. This review covers micrometer screw gauges, which are for outside measurements.
Don’t confuse a micrometer screw gauge with a so called micrometer caliper. They are two different tools, very similar in appearance and purpose, but it’s not hard to quickly learn how to distinguish between the two. With micrometer screw gauges as reviewed here, they have an appearance similar to a G-clamp. It’s almost possible to mistake them for small G-clamps, if they are manual micrometers i.e. no digital or analogue displays. There’s a manual micrometer reviewed here, and an analogue, and mostly digitals. Electronic and digital aren’t synonymous, some analogue devices do have LCDs.
Carbide is commonly used at the clamping points to preserve the perfect flatness for accurate clamping, so measurements can be repeated more precisely. America’s Starrett and Japan’s Mitutoyo, are the big names for expensive premium quality for both micrometers and calipers. Mitutoyo provides buyers with a certificate of quality control, and a one year warranty. Usually digital devices rapidly dominate amongst modern devices, but surprisingly this is currently not the case in the world of micrometer screw gauges. All of the micrometers reviewed here in the top five, including the cheap brands: iGaging and Anytime Tools, have carbide clamping surfaces.
iGaging 0-1″ Digital Electronic Micrometer
This digital micrometer has a large LCD, and measures in the metric and imperial systems, in either increments or absolute. The resolution is 0.00005 of an inch, with a deviation of only 0.00016 inches. Repeatability seems around a deviation of 0.0002. But compared with other cheap micrometers it seems this one is more accurate, and better value for money. It’s not as precise as the expensive premium micrometers from makers like Japan’s Mitutoyo, but it’s still a good bargain. So with mission critical jobs you might like a more expensive higher quality micrometer in the hundred or more dollar range.
There’s a useful clicking noise after the device is tight enough on an item being measured. Items are held by carbide tipped clamps for longer lasting flat precision. It has a USB output port, which requires additional expansion gear to utilize. The micrometer automatically switches off to save you from the frustration of a dead battery on your next use. Most were satisfied, but few were not. A lot of budget products would benefit from much better quality control. It seems some manufacturers like iGaging, mostly make good quality produce, with only around 9% of rejects ending up with consumers.
Anytime Tools Premium 0-1″ MICROMETER Precision Machinist Tool
This is a very good value for money micrometer with old fashioned manual readings. Transparency is an advantage with manual readings, unlike digital and analogue micrometers, which hide the details of how they came to a numbered conclusion. The readings are decimal based for inches. It measures up to 1 inch, with accuracy around 0.0001 of an inch. It intentionally doesn’t have a shiny coat to avoid glare, which is very important for a manually read micrometer. The anvils are thick and made of carbide. The spindle is made of hardened metal that has been threaded by being carefully carved.
This micrometer comes with a special calibration spanner. But be careful not to lose it, else you might as well buy a new set. You need to use the right oil, and keep the micrometer clean in its’ protective case. Free online resources, show you how to use it. A clicking noise tells you when the clamps are tight enough to take a measurement reading. It seems they had reasonably good quality control with this device. Accuracy is good enough for general use, but for high precision critical uses, you might want to rely on a premium micrometer from Mitutoyo.
Mitutoyo 293-340-30 Digital Micrometer
Those experienced with micrometers should be all too familiar with Mitutoyo for Japanese premium quality at a nice price. This one has a very high resolution at 0.00005 of an inch, and very high accuracy at a deviation of 0.00005 of an inch. In a nutshell it can give you better precision than the other brands in the top five reviews here. If you need the best precision and reliability at the lowest price, Mitutoyo is the one. It isn’t the cheapest, but it is the lowest price for top precision and reliability.
This micrometer does imperial and metric measurements. The unit also measures up to 1 inch in sizes. It is digital with an LCD screen. The clamp surfaces are made of carbide, for long lasting quality. It has a certified IP65 rating for resistance from harm caused by water and dust. It automatically powers off to save your battery when for whatever reason, you don’t switch it off. There were no complaints about quality for this micrometer, the only known complaint was for a missing calibration tool. Mitutoyo really does live up to the finest quality expectations.
Anytime Tools 1″ Digital Outside Micrometer
Another affordable entry from Anytime Tools, this time (pun not intended) it’s an analogue micrometer for just a few bucks more. Their more popular micrometer was not analogue, but completely manual. This analogue device displays numbers not by a gauge, but by a digit counter. The spindle is made of hardened metal that has been precision threaded by carving. As with all the other micrometers reviewed here, the clamp ends have carbide to help prevent them from losing shape. But it only measures in inches, and no more than 1 inch in length, with accuracy around 0.0001 of an inch.
There is a locking nut, and handles that are both regular and ratchet types to help you apply the same clamping pressure to improve repeatability of measurements. It has its’ own calibration spanner, which is included in the cushioned protection case. Accuracy is very good compared with other budget competitors around the same price, but beyond general use if you need specialist precision quality, you can’t expect that with this price. It’s like only around 1/6 the cost of the Mitutoyo micrometers reviewed here. Quality control doesn’t seem perfect, and it only comes with a 30 day standard returns guarantee.
Mitutoyo 293-340 Digimatic Outside Micrometer
This is just like the other Mitutoyo micrometer ranked in third place just above. It comes with a long lasting silver oxide battery. It has an automatic power off function. It can withstand a low pressure water spray, without ruining the electronic components. You should take the battery out of the device, if you’re not going to use it for more than 3 months. Unfortunately without the battery, this micrometer will lose its’ zero calibration. There were no complaints about quality. One person claimed that they received a fake Mitutoyo from China, which looked different, and wouldn’t calibrate to zero.
Mitutoyo micrometers are such good quality that if you take care of them properly, do not be surprised if they last for decades.
What to Look For
Accuracy and precision are the most important perks for a micrometer screw gauge. They measure such ridiculously microscopic sizes, so it’s understandable that this nature of measuring is sensitive to corruption. Repeatability is actually measured as a number by micrometer makers. Different people should be able, to get the exact same measurement of the same thing, every single time. The device needs to accurately start at zero with every new measurement, unless the user wants otherwise.
Reliability is the next most important perk. A low quality piece of junk that won’t take a measurement, is something you need to balance, with how important your work is. Sometimes a micrometer can be unreliable, not always due to poor quality, but because of an inefficient or flawed design weakness. Such could be a dead battery caused by reasons such as power drainage from a silly design that causes the micrometer to power up when it senses small vibrations like aftershocks or animals. Is it really such a big deal to have a power button and auto off for safety?
All were budget choices in two categories: general users and critical users. The latter category was dominated by Japan’s Mitutoyo, established in 1934. Mitutoyo makes outstanding quality micrometers at a great price. America’s Starrett, established in 1880, also makes great micrometers, but none were in the top five. The micrometers for general use were significantly cheaper by almost 1/6th of the cost. But they were not as fine-tuned for such microscopic precision. Quality was not exactly premium with generally around 10% of customers having problems. Mitutoyo had no complaints over quality and was showered almost entirely with the biggest praises.