Tools of the Trade – Calipers and Micrometer

Tools of the Trade – Calipers and Micrometer

In the olden days of apprenticeships, your status in the world was built on your set of tools. While you were an apprentice, you started saving your money and acquiring your collection of tools, and when you had a full set and were ready to start your own practice, you launched on the foundation of the tools you brought with you.

The set of tools you needed was directly related to your field – cobblers needed shoemaking tools, blacksmiths needed forging tools. If you allow the analogy to stretch, even the young women of the time built a collection of tools – they filled hope chests with linens and tablecloths as a dowry for when they got married.

And I think to some extent, this tradition of building a set of tools persists today. Machinists and auto shop guys still take great pride in their toolboxes, carpenters take loving care of their chisels, and electricians wouldn’t be caught without at least the essential wiring tools. Even occupations that aren’t traditionally blue-collar come with tools. Lawyers may need bookshelves full of reference volumes, and teachers may have cabinets full of visual aids.

So what tools of the trade do you use, readers?

I do keep a Craftsman toolbox in my bedroom, but sadly those tools I don’t use in my grad student lab career. I think the best answer for myself is simply to look at my desk. Of course I use many tools in my research, but the two that get constant use are my calipers and my micrometer. I keep them readily on hand, on my desk and in lab.

Calipers are used to measure distances. In the photo above, the top tool is a digital caliper. You spread the jaws open to encompass the distance you are interested in (the diameter of a pipe, perhaps, or the length of a screw, or the spacing between holes), and the distance is displayed on the digital readout. The nice thing about a digital caliper is that you can easily choose inches or millemeters as the display output.

Micrometers are a subset of calipers – still used to measure distances, just smaller and more precise ones. (The bottom tool in the picture.) Calipers will generally measure 6″ or 8″ maximum, and will have an accuracy of perhaps .001″. Micrometers, on the other hand, have a typical accuracy of .0001″, but will only measure a maximum of about 1″. I’ve actually never seen a digital micrometer, so mine is an old-school Vernier model, in standard English units, so if I need metric I have to convert later.

What tools have you collected over the years to do your job? Sound off in the comments!


My first instrument was an Amp/Volt/Ohm meter, analogue with a four inch needle and reflecting strip for accurate measurement. Not a true AVO (I couldn’t afford one of those) but the next best thing. Next came a ‘scope the shape of a medium sized suitcase, on a trolley because you needed two people to lift it. Their modern replacements are still indispensable even in these days of integrated circuits.
The scope glowed its last many moons ago amid sparks and a nasty smell. The ‘AVO” still works fine although it is getting harder to buy the battery used for the Ohms range, the probes are far too big for general use and you have to remember the impedance on the voltage ranges is only a few 10’s of K. It makes a very fine bookend though.

This statement by MISS OUTLIER really illustrates the situation in this country concerning engineering:

“so if I need metric I have to convert later.”

95% of the earth’s population uses the metric system. Every country except the United States (Liberia and Myanmarr are engineering approximations to zero) I changed over to metric in my practice and stubbornly refuse to use the “metric inch.” All of us pay approximately $10.00 per day per person in the US because we hang on to an irrational set of units that only exist because they are defined by the metric system. If any of you do catch up with the 19th century and use the metric system, please…don’t use centimeters, only millimeters. All of my rulers, obtained from Australia have only millimeters. It made quite a difference compared to the Canadian ones I used with cm on them. Yes–their is a “best practice” for using the metric system, but we have never changed over to even debate that point.

In Australia they have 90 mm bricks with 10 mm mud so you know each length is 100 mm. Count the bricks, know the height. Engineers seldom complain about this measurement handicap we live under. I finally bought a tool chest for nothing but metric tools. I banished my old tool box to another storage room. Only when I’m forced to use an English/Traditional American/Standard?/Imperial “System” measurement do I dig one out.

Now that I’ve been using metric exclusively for about 2-3 years I’ve been amazed at how much simpler and straightforward my engineering work is. For any of you that have an interest in breaking the yoke of the barbaric measurements forced upon us by the population at large I recommend you check out Pat Naughtin’s website (Metrication Matters). His lecture at Google is of great importance to understanding the situation we are in:

His website:

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I keep calipers, a precision ruler, sharp pencils, hex keys, and a salvaged old Tektronix 455 oscilloscope on my workbench too. But without a doubt the most important ‘tool’ in my ‘toolbox’ is my laptop, a Thinkpad W500. That does my CAD work, spreadsheets, numerical analysis, word processing, programming, and of course, e-mail. It holds most of my catalogues, textbooks, drawings, datasheets, contacts, and reference manuals. I take as reverential care of it as I do my other prized tools, and would be hard-pressed to get much done without it!

I have been involved in several startups over the years and have collected many tools. I have an electronics lab which includes a Tek 7854 scope and a HP 1630G, as well meters, signal generators and supplies. I have a machine shop which includes a 9×42 Bridgeport J-head mill and a model A south bend 9 lathe. (These tools take a lot of tools). I have a metal fabrication shop that includes a Lincoln wire feed welder and a Lincoln buzz box, an acetylene torch a small compressor and a horizontal band saw. I have set up recently to do Al anodizing. In case I need to make castings of Al or Brass I have a small foundry shop. In the same garage I have a bunch of wood working tools including a 10″ table saw, a disc/belt sander, a s10″ thickness planer and a 10″ compound miter saw. I use a desktop computer running Alibre for mechanical design, open office for bookkeeping etc, Eagle PCB for electronics design. This is a shortened list but goes to show what you want when you need to do it all yourself.

Miss Outlier,

I appreciate your dream. I have always liked building things. I was raised on a farm and I always had access to tools and my father taught me a reverence for tools and craftsmanship. I have a love for tools, there is something magic about watching a piece of metal being carved by a precise machine with what appears to be no effort. But it is more than that, it is the idea, the design then the execution. There is also the knowledge of what is possible. You gain that through experience and tutelage, stick with your studies and take advantage of the opportunity’s you have access to, with that focus your dream will be realized.

That being said, if your shop is small make sure to buy wheels for your tools so you can move things around to make room.

The most used tool is my computer mainly for simulation and report writing. There are several programs that I use to keep that in shape but I guess that this is hardware (e.g. ccleaner).
I have a vernier calipers used for measuring diameters typically and also a tape measure. I take nothing else between jobs having the ability to order the required tools if necessary. Pipe cutters large and small, torque wrenches and spanners are all things I use regularly.
In terms of equipment in the lab or on site, my most used are condensors. My biggest brute is a large glycol chiller.

I am a third year EE student, but currently work in the auto repair industry as an instructor. Because I’m coming from the auto industry, I already have at least $125K in tools. It sort of gives me a head start.

Included in those tools are 7 oscilloscopes (Tektronix TDS 2012, Fluke 99B Series II, Pico 4223 PC scope, and a few others built specifically for auto repair by companies like Snap-On). I also have 3 inductive current probes (PDI: 0-60A, Fluke 80i-110s: 0-100A, and Fluke i1010: 0-1000A), two pressure transducers (Pico WPS 500X and Fluke PV350), 2 function generators, 2 soldering irons, thermocouples, and about every type of test lead and probe known to man. Of course, there are a ton of other electrical diagnostic or repair tools that are aut0-repair specific. I won’t bore you with those details.

In addition to all the electrical test tools, I also have about any pneumatic or hand tool necessary. My pneumatic tools include impact wrenches/ratchets, die grinder, impact hammer, and drill. There are too many hand tools to list, but they include socket sets (standard and deep, impact, metric and imperial), ratchets, wrenches, screwdrivers, pliers, and a bunch of other tools that would likely bore you to death if listed. Of course, just like Miss Outlier, I too have calipers and micrometers.

The electrical test tools are obviously more important to me as an EE student, but I plan to still keep all the other tools as well. I’ve considered minoring in ME, so you never know when they might come in handy.

My favorite tool is a HP 32SII calculator. For me, it’s ideal without being overcomplicated. I don’t know what I would do without it. In fact, I own 3 of them. One for the office, one for the backpack, and one for the home office.

What really worries me nowdays is when there’s a blackout and all of the computers in the office are dead. It’s amazing how everything comes to a grinding halt.

Do any of you youngsters know how to use a slide rule? Don’t need any batteries. A novel thought

In my back pack I keep my high end Littman Stethoscope and two Post Versalog slide rules (one for when my hands are icky and one for clean). The ‘scope for listening to lungs, the slide rule for dosage calculations. Who needs calculators?

Great tool to measure, I remember the day when I was introduced to micrometer, though I had difficulty in measuring the least count and little bit confused of circular head and main head reading but not now, as it is our day to routine.

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