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Micrometers
In general (for what it's worth)


Mitutoyo 103-260 Outside Micrometer, Baked-Enamel Finish, Ratchet Stop, 0-1" Range, 0.0001" Graduation, +/-0.0001" Accuracy

Among all the manufacturers of measuring instruments there's bound to be one micrometer for every application. They typically have a range of one inch but can be gotten for any integer on the yard stick. The measuring faces are manufactured flat and parallel but again, there are specialty faces in the shapes of discs, points, blades; you name it.

You'll be able to find micrometers from super cheap throw-aways from China to heirloom investments from Switzerland. Which to buy? If the instrument will be used just a few times, go cheap. Why not? It probably won't wear out until it's been used for a while and then you can toss it. On the other hand, if it's going to get a work out, buy quality. You can tell quality by the price. Check your budget to see which is the better move. Also, beware of Chinese imitations of brand names, such as Mitutoyo. They look like the real thing until you discover that they only read to two decimal places, or that the certificates of calibration are absolute frauds. Always buy from authorized distributors in order to avoid getting these low priced rip-offs.

If you're buying quality, always aim for the possibility of repairs and that's assured if you buy brand names. Take a look at the section below and you'll see some of the problems you'll eventually run into. We also have a few things to say about digital (electronic) micrometers which you might want to consider. It's your money.

 

What will go wrong on a micrometer?

 

The carbide faces can be lapped flat and parallel (.00004") when they are worn from use or they can be replaced when severely chipped. The movements can be repaired with original manufacturer's parts which we import directly from the manufacturer.

Often enough, we'll get a micrometer for repair which has just about every one of the following problems. Fortunately they can all be fixed. If you've bought a solid, quality micrometer to begin with, you'll be able to count on it for years to come.

The following repair tips may be of interest:

The spindle turns hard or it's frozen. If it won't turn, don't force it. You might freeze it for good. We'll have to deal with this carefully. Send it in.

You can't read the numbers on the thimble anymore. A new thimble may be needed if cleaning doesn't help. Send it in.

The crystal on the dial micrometer is cloudy. You can replace the entire cover assembly on an Etalon, but it's expensive. It's trickier on other brands.

The hand on the dial micrometer is stuck. Maybe the crystal is pressing down on it. Maybe the movement is full of oil. Don't touch - send it in.

The red and blue markers no longer move. You can replace the cover assembly on an Etalon if you normally use these tolerance markers.

The carbide faces have a chip on the edge. This can be ground down and then lapped like new. Send it in.

One of the carbide faces fell off completely. New carbide faces can be brazed on. Send it in.

The blade of the blade micrometer is broken. New blades can be installed. Send it in.

The faces are scratched and no longer shiny. These can be lapped flat to a mirror finish of about 4 millionths. Send it in.

The spindle or anvil has play in its bushing. Maybe it can be fixed, but probably not. It's due to a lot of wear and tear. Consider buying a new micrometer.

The spindle lock won't work anymore. These can be replaced. You can probably do it yourself.

The zero doesn't line up on the thimble. A little wrench that came with the micrometer is used to line up the zero. Instructions probably came with the micrometer.

The ratchet or friction stop no longer function. We'll probably have to replace it with a new one. Send it in.

There are reading errors depending on where you measure. They're carbide faces, but they'll wear down eventually. This needs lapping. Send it in.

The faces are no longer parallel. Among other things, you may have bent the body. Maybe it dropped to the floor? Send it in.

The plastic "heat shield" is cracked or missing. It keeps the micrometer from expanding with body heat. It'll affect the readings. You can replace this yourself. We can help you get the part.

Of interest: even after your micrometer ceases to be accurate over its full range, you can still use it as a comparator—as long as you can get consistent, repeatable readings. Use the micrometer to measure your standard or master piece and then measure your work piece. The micrometer will tell you if you're off the mark.

 

Is it digital (batteries required)?

 

Digital (electronic) models change so frequently that they become obsolete in a matter of just a few years. You've bought other electronic stuff, so you know the score. They are not a good long-term investment. Chances are that repairs will be impossible. Plus, if it's made in China, it definitely won't be repairable.

They have several advantages: they will save time when many parts need to be measured because the display is faster to read; workers unskilled with vernier scale reading will be able to use these tools more reliably; and data can be collected for statistical control in large manufacturing situations; and it's easy to switch between inch and metric systems.

They have several disadvantages: the electronic component is simply one more element on the tool which can malfunction; there is no intuitive way of knowing whether the display reading is accurate; it's possible to make serious errors when the "zero" has been incorrectly preset; and oil and coolants are more likely to cause damage to these types of gages unless you pay extra for "coolant proof" models. Spare parts can be hard or impossible to get, depending on the age and make of the gage.

Only a few genuine manufacturers make their own digital micromters, all the others are generic Asian imports of questionable value.

Starrett digital micrometers are peculiar in their design. Just changing the batteries can be enough to turn your hair prematurely grey. Believe it or not, they actually have a plastic coil spring as a component. If you turn the thimble quickly (which you shouldn't do) the numbers will lag behind. There is no guarantee that all Starrett models are made in America. Check with a Starrett distributor for current information.

Mitutoyo digital micrometers have digital boards that can easily be replaced when they malfunction. Unfortunately, the boards aren't always in stock. These are probably our favorites for ease of use, reliability and repair. Models change very frequently which will make yours obsolete in a blink of an eye.

Brown & Sharpe (TESA) digital micrometers are aesthetically pleasing because the Swiss have an outstanding sense of design. The workmanship is good and solid. Unfortunately, spare parts can be almost impossible to identify and even harder to get a hold of.

Mahr provides excellent digital gages made in Europe, often with Swiss electronic components. Top-of-the line introductions include wireless data transmission. Check their web site or contact a Mahr distributor for current information.

 

Friction vs. ratchet

 

Friction and ratchet thimbles serve the same purpose. It's easy to fudge a reading by tightening the micrometer spindle a little more or less. The friction and ratchet thimble mechanism assures an even amount of tightening each time a measurement is taken. How to decide between the two? Select the type you're already used to (perhaps from your apprenticeship or trade school) and then be consistent with all the other micrometers in the shop.

 

Micrometer standards

 

You'll need to verify the accuracy of your micrometers, ideally before every time you use the gage.

Micrometer standards typically are cylindrical rods with 2 flat, parallel measuring surfaces or one face rounded, which is easier to use. Longer standards have plastic heat shields so your hands don't touch the bare metal.

You should have enough standards on hand to verify the accuracy of all your gages. Micrometer standards are available in 1-inch increments up to 23-inches; metric standards in 25mm increments up to 1.475 meters.

About once a year you'll want to send the standards to a calibration lab for certification. This lets you know that you're still working with accurate standards.

Certified gage blocks will perform the same function as standards. They can be assembled (wrung) to obtain the various lengths required to perform a micrometer calibration. This will be tricky work with anything much larger than 4 inches, as the stacks will likely tumble out of control and you may end up damaging the blocks. By all means, invest in rods for larger dimensions. (See calibration instructions on page 7)

 

Micrometer brands

 

As with any household appliance or electronic equipment, the manufacturer doesn't necessarily put its own name on the products. This is particularly true with the inexpensive models of micrometers which can appear in numerous different guises.

The big players have everything to lose if their products are sold under various names, so they've been careful to keep their brand identity. Mitutoyo, Starrett, Brown & Sharpe, Tesa and Etalon are among these.

The cheap stuff carries various names, some of them quite well known, such as SPI and Fowler. These respected resellers can give you the false impression that you're buying something of quality, even though you're paying only a fraction of the price. You ought to know better.

Major imports from China and Poland sell "by the boat load" according to one big catalog house. Another one counters that "Yes, and they arrive already rusty."

Polish micrometers either have no name on them, or the word Poland, or the brands Lincoln or VIS. Chinese micrometers can carry any name. Swiss Precision Instruments (SPI) sells these and one has to wonder what these micrometers have to do with Swiss and/or Precision?

The problem with unusual brands - even if they're very popular in their country of origin - is that parts are probably not available when repairs are needed. PAV (Präzisions-Apparatebau Vaduz) micrometers are made in Liechtenstein. If you want these repaired, you may have to plan a vacation abroad to that charming mountain principality. Not a bad business expense deduction, eh?

Mahr micrometers made in Germany are of very good quality and quite expensive. Parts are, or should be available from Mahr-Federal in Rhode Island but they have a high minimum purchase which can make these repairs problematic.

Swiss made Tesa, Etalon (and some Brown & Sharpe) micrometers are the cream of the crop and parts can be gotten through Long Island Indicator Service. If you can afford it, these would be the ones to get. Digital models, however, may not be economically repairable, regardless of their original cost.

American made Brown & Sharpe micrometers are made by S-T Industries (Brown and Sharpe no longer makes anything of their own). They very obviously lack the finesse of their European cousins.

Swiss-made Brown & Sharpe micrometers are the only ones we genuinely recommend. They'll cost a bit more but they'll last longer and you'll feel better. Designed for the professional. Forget all others.

Scherr-Tumico now goes by the name S-T Industries. They pioneered the "tubular" frame which allows for lighter weight micrometers of extremely large sizes. These American made micrometers tend to be on the cheap side and it often shows. However, you may have no other choice for a particular application such as enormous diameters.

Central Tool of Cranston, Rhode Island, makes micrometers aimed at the automotive industry. They're on par with the other American made micrometers.

Fowler sells some quality Swiss gages under the name Sylvac. Fowler also sells a lot of Asian junk. Polish indicating micrometers are also sold with the Fowler name on them. Spare parts are hard to get or not available and service is probably not possible.

Mitutoyo offers mechanical micrometers for all budgets and parts are easily available. The digital models won't be repairable if the models are obsolete, which happens about every 3 years. Mitutoyo is an innovator in digital measurement so if you're looking for the latest technology, look no further.

Mitutoyo indicating micrometers use epoxy to hold the anvil bushings in place. Unfortunately, this epoxy softens with time (and oil based solvents) and the micrometer will lose accuracy. Rubber bellows are supposed to keep the solvents away so don't remove them and replace the bellows if the rubber deteriorates..

Standard Gage is a brand name which you will now also encounter on inexpensive Chinese tools. It used to be one of the American stalwarts but has sadly been bastardized over the last decade.


436.1 Series Outside Micrometers - t436.1xrl-2 outside micrometer 1-2" range .0001
 

Starrett does not make a good quality micrometer although it's highly popular. Repairs sent to Starrett incur a high bench charge so it's probably more economical to find an independent repair shop to deal with these when the time comes.

Carl Zeiss made in Germany. Hefty construction but repairs probably won't be possible because of the lack of parts. The dial micrometer could be used in the upright position because the dial is at right angles to the spindle, unlike all the other indicating micrometers.

Etalon micrometers are the best Swiss-made OD micrometers available. This is an excellent micrometer which can be recommended. Experience shows that these have a long useful life (we encounter Etalon micrometers that are 60 years old and still worth repairing).

If we were to make one suggestion it would be to buy something as expensive as you possibly can afford. The quality of these items increases with the cost. If you plan on using it professionally, or over a long period of time, you'll have made the right choice.

Lastly, these are our own opinions based on years and years of repair work. The repair man knows what's under the hood and can't be fooled by advertising hype. Some manufacturers will be upset by these comments—they usually are—but we hope that it might spur them on to producing a better quality measuring tool for everyone's benefit.

 

Cleaning your micrometer

 

It may not be harmful, but we don't advocate the use of WD-40 because it tends to become tacky after a while. You're better off using any good 3-in-1 oil, if there is a reason to be concerned with rust. In general, it may be better to use nothing at all.

If your (mechanical) micrometers haven't been used for a long time, or if they seem dirty, you can remove the spindle, usually by unscrewing it, and wash it in mineral spirits or an organic cleaner. Make sure it's dry and then add a drop of 3-in-1 oil on the threads before reassembling. The rest of the micrometer can be cleaned with a cloth or soft brush and it can be coated in a bit of oil if it tends to get rusty.

When storing the micrometer do not close the spindle. The faces should not be touching unless you slip a piece of oiled paper between them. You will have noticed that new micrometers never ship with the spindle closed.

A word of caution about dealing with the spindle: if a chip gets into the threads, or there's a nick or burr on the spindle, then forcing the spindle to turn may freeze it up permanently. If you encounter any resistance... stop! and bring it to a professional.

The non-rotating spindles may not be designed to be removed at all. If they don't want to come out, don't force them either. You may shear off the guide screw. In this case, have a pro look at it.

Digital micrometers all have guide screws and are not designed for easy disassembly. Spraying WD-40 is a temporary solution; you're delaying the inevitable. Digital micrometers should not be tampered with.

And finally, perform any of these tasks over a desk and be on the lookout for any small parts which may suddenly drop out of the micrometer. You'll need to put them back in before you're done.

 

Indicating Micrometers - Dial Micrometers

 

There are two kinds of indicating micrometers: cheap and expensive. They are not intended to be used on the shop floor. They are inspection gages and belong in the inspection room. Shop-floor use will quickly lead to malfunctioning gages and expensive repairs.

It goes without saying that the cheap ones come from China and you will have to treat them as "throw away" gages because no one has repair parts.

The expensive ones are a long term investment and you should know which brands are readily repairable by experienced repair shops. These do not qualify as do-it-yourself projects.

We strongly suggest Etalon or Mitutoyo for their durability, workmanship and repairability.

  • Etalon (Switzerland) micrometers have changed little over the past 50 years and, in general, even the oldest models are all still repairable. These are the stalwarts of dial micrometers and, if you can afford them, should be your only option. Refer to page 16 for details.
  • Mitutoyo (Japan) sells at a more reasonable price, has undergone many changes, and older models may no longer be repairable. Their lower price makes for a good investment. Reading the graduations on the dial can be problematic because the thick bezel casts a shadow and partially hides the lines from view. Use in good lighting. Refer to page 54 for details.
  • Mahr (Germany) is also a high-end indicating micrometer, with an equally high-end price tag. It is of excellent quality but only the newest models can be repaired since parts are mostly obsolete for the older styles.


Mahr Federal 4151705 40EWR MarCator Wet Proof Digital Micrometer with Output, 0-1", Black/Red

By all means, avoid the Zeiss, Suhl, Polish or PAV Liechtenstein micrometers. Parts for these brands are generally not available in the US and you will be disappointed to find you have paid good money for gages that can't be repaired.

 

Fixed vs. rotating spindles

 


Mitutoyo 169-201 Disk Micrometer, Non-Rotating Spindle, Ratchet Stop, 0-25mm Range, 0.01mm Graduation, +/-0.004mm Accuracy

A rotating spindle, which is the standard form on micrometers, can damage sensitive surfaces. Disc micrometers, used to measure recesses and grooves, are usually available with non-rotating (fixed) spindles. The anvils do not turn, there is no rubbing against your measured surface and nothing is scratched in the process. This is the preferred spindle style in these situations.

 

More information

 

  • Micrometer repairs: Etalon, Tesa, B&S, Starrett, Mitutoyo, Mahr and some others.
  • Micrometer sales: Etalon, Tesa, B&S, Mitutoyo and that's about all.

Please refer to our index page for these and other topics.



The above items constitute advertisements on behalf of Amazon.com and are not to be construed as endorsements by Long Island Indicator Service. We strongly believe in buying quality tools and gages, and urge customers to check carefully before making a purchase. If the prices appear unusually low, we suggest proceeding with caution.

 

LONG ISLAND INDICATOR REPAIR MANUALS

BesTest and TesaTast Indicator Repair Manual … page 177
Starrett 711 Last Word Indicator Repair Manual … page 199
Interapid Indicator Repair Manual … page 208
Compac Test Indicator Repair Manual … page 194
Mitutoyo Test Indicator Repair Manual … page 102
 

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14 Sarah Drive — Hauppauge NY 11788 — USA


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This page's most recent revision: 31 AUGUST 2017
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Original photographs and content copyright 2017 by JWGrum

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