Why use a micrometer?
This guide is meant as a best digital micrometer and caliper for hobbyist use primarily. If you have never used a digital micrometer or caliper before you will probably be quite impressed with how good the cheaper hobby devices actually are and how useful they become. Once you’ve mixed up your PCB drill bits you are usually left to guess work for which is which. Not with a micrometer. You can tell your .6mm, .8mm and 1mm apart.
You can use a micrometer to measure much more accurately than with anything else.
What do you use a micrometer for?
Basically anything you want to measure accurately and specifically things that are small. I used to use a micrometer at a printers for measuring the thickness of paper and cardboard. You obviously can’t use a ruler to measure how thick paper is.
I use a micrometer in my electronics hobby. I don’t know how I managed without one to be honest. You can use a micrometer to measure things that you wouldn’t otherwise be able to measure. You can measure how thick printed circuit boards are. I frequently use a micrometer to check how thick wire is.
What’s the difference between a micrometer and a caliper?
A micrometer is more accurate than a caliper. It’s designed to measure very small distances. A caliper measures over a larger range and so even though it can measure smaller distances its not quite as good as a micrometer for smaller things.
A micrometer can usually measure up to an inch maximum and can usually only measure outside dimensions, such as the outside size of the thickness of wire or cardboard.
They can also typically measure to a hundredth of a millimeter.
A caliper can typically measure up to fifteen centimeters but only to a tenth of a millimeter resolution. They can usually measure outside and inside measurements and sometimes depths too.
Digital micrometers and calipers
I personally prefer digital micrometers. I used to use an analogue micrometer and it’s more difficult to read. You revolve the end and it moves on a thread. It has a type of ratchet on it. This is so you don’t over tighten it and squash what ever you are measuring. You then read the measurement like you would with a ruler.
A digital micrometer has a sprung lever that you operate with your thumb. First you press “zero” to unsurprisingly zero the device. Then press the lever with your thumb which opens up the gap. Put the item you want to measure in the gap and release your thumb on the lever. It then closes on the item and the digital display tells you what the measurement is.
Calipers vs micrometers
As they measure different distances I’m surprised this question gets asked as often as it does. Ideally you really need both. I’m sure most people who own both would agree that they use a micrometer as well as a caliper.
Resolution and calibration
Don’t get calibration and resolution muddled up. Very accurately calibrated micrometers cost a lot of money. If you measure say for instance a sheet of paper, your micrometer may say its .43mm thick. Another sheet may measure .55mm. Even if your micrometer isn’t correctly calibrated the second sheet will be very near to .08mm thicker. If you know someone with an expensive calibrated micrometer measure a few things with it and check with yours. You might find that it measures .05mm larger consistently compared to the expensive calibrated one. Bear that in mind and just take off .05mm from what you measure. A useful tip if you have an inexpensive micrometer.
I’m not saying that it’s now as good as the expensive calibrated one but its worth knowing for future use.
Expense and accuracy
It wont come as any surprise if I tell you that the more accurate tools are the most expensive.
It may not surprise you if I mention it is also a law of diminishing returns.
That basically means that a micrometer that’s twice as accurate as another will cost a lot more than twice its cost.
The most accurate devices will also be much more sensitive to things like temperature and being dropped!
The good news is that even budget devices are pretty useful. To be honest I’m not sure how accurate my devices are. They can be claimed to be to within what ever they want as I can’t really test what they say. I can say though that I’ve found both my devices to be so useful that I’d say I couldn’t do without them now.
Using micrometers
I bought both my devices after I started building a CNC machine. I was amazed at how good my machine was as a first attempt. It could easily move at .1mm intervals but I couldn’t measure .1mm. Believe me, I actually tried with a ruler and magnifying glass. I laugh at this now but you can see I defiantly needed a micrometer and caliper.
The micrometer is used to measure the thickness of the material that I cut and the diameter of cutting tools. This is especially useful when you have a few different cutting tools out and muddle up your 1.2mm and 1.4mm ones.
The micrometer also comes in useful when you measure the thickness of the material. Sometimes you find that 2mm thick sheets are really only 1.8mm thick. Sometimes you find that it might be 2mm at one end and 1.9mm at the other end of the sheet.
These things make understanding problems a lot easier. I thought my machine was cutting too deep in places but it was the material that was varying in thickness.
Although I bought a micrometer to help me with my CNC machine it gets used for loads of other hobby electronic use’s.
Using calipers
The caliper is as useful to me as the micrometer is. It’s about the only way to calibrate your CNC machine.
Make a design of a 100mm square and get your CNC machine cut it out. Then measure it with your caliper. You can then set the calculation to set your machine. This enabled me to get my CNC machine working to .1mm, an accuracy I’d never have been able to work to or check. Before I got my caliper I measured with a steel ruler so you can guess how far off I was!
I can now measure square holes and panel cutouts for switches and meters. This was always trial and error before.
The Best digital micrometer
The number one choice in this buyer’s guide is the Mitutoyo 293-832-30 Digital Micrometer. It’s not often that something is such a clear winner but there’s really not anything else around as good as this at the moment.
Mitutoyo has a very good and long reputation in this industry. As I mentioned this guide is really aimed more for the hobbyist user but this is so good it is used by professionals. It’s not that surprising when you look at the specifications.
It has a resolution of 0.001mm and an accuracy of .002mm. You can measure up to 25mm with it. It has a good battery life, the manufacturers say over a year and if you leave it turned on by mistake it will auto power off after twenty minutes. It also comes in a protective case to keep it safe.
What about the cost?
The cost is probably the only thing that will stop you buying this micrometer. What you are paying for though is something that is extremely accurate. This is basically a top of the range device and for a little over a hundred pounds this will be in a lot of people’s budget and you really are getting the best. If you are an Amazon Prime member you can get it next day for no extra cost.
If the Mitutoyo is something you can’t stretch too then the other model I recommend is the Bestlands one. The specifications are similar to the Mitutoyo but it isn’t as well built or as solid. You are still getting a very good measuring device but I don’t think many professionals would use this. As you can’t really compare the price you can’t really compare the performance.
For hobbyist use, I don’t think you can complain and this device is a step up from the £20 ones.
Final thoughts on the best digital micrometer
It’s not often that to find a product that is so easy to recommend. There are usually a lot of considerations and price brackets to take into account.
There are some cheap digital micrometers for around £10-£20. I don’t think it will come as much of a surprise if I tell you the performance of these isn’t great. If you don’t have anything better than a ruler you’ll probably be impressed with what you can do with something so cheap, however, if you can stretch to buying the Mitutoyo, you’ll probably never have to think of buying another micrometer ever again.
It’s that good, and I’m not alone in thinking that. There are many great reviews for this device and when you consider the price it’s really worth stretching to it.
If you can’t then the Bestlands is the best of the rest for the price.