Micrometer Info - And Other Key Tools

[robsryder]

It has been almost 50 years since I received training on the use of an analog micrometer. A micrometer is an essential tool for making highly precise measurements, such as for shim thicknesses. Of late I've been using digital micrometers, but I found the following videos to be very nicely done to explain the method to accurately read analog micrometers. Both inch and metric (mm) types of micrometers are covered. The cleaning and adjustment video was also nice. No point in trying to make a precise measurement with a micrometer that has a systematic bias or random error due to mis-calibration or a dirty anvil.

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[MCMXCIVRS]

Good basic instruction for those who are unfamiliar with these fine instruments. I've spent more than a few hours using micrometers in my time and am lucky to still have a set of high quality micrometers from my days rebuilding engines in a machine shop. There are some inexpensive types one can buy and those are pretty good tools for average use and will suit most needs for general motorcycle maintenance like checking shims, brake rotors and such. I have a couple of those as well for less refined work.

One note I'll add is on using the friction knob or ratchet knob. The video did touch on the reason for using it to ensure accuracy but even with it one can introduce variations depending on how you use it. The key is to use the same action every time, particularly with the ratchet type. If you calibrate the tool with say three clicks on the ratchet, every measurement should be done with three clicks as well. if you use more or less, the reading can be off by a few hundred thousands if that level of accuracy is needed. Also, for measuring small parts, it is usually easier to get accurate and consistent results by having the micrometer held in a micrometer stand or some other form of holding fixture. Just be sure that if you decide to clamp the micrometer in your vice to hold it, that you are very very gentle about it to not damage the tool or distort the frame.

 

[robsryder]

The following video provides some good info on some different types of torque wrenches and has some useful tips for novice mechanics. I did not agree with his explanation about beam deflection types of torque wrenches. It is the larger beam that deflects with force and the pointer remains stationary. It was also indicated that the torque wrench can become less accurate over time. Mis-use of a torque wrench can lessen the accuracy and it is useful to periodically recalibrate or check the calibration. A second video follows to illustrate a simple means to check calibration.

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I am adding a post "posting" caveat. The scale hook is shown as being placed at the very end of the handle. As demonstrated in subsequent videos placement of the force other than at the denoted location on the handle (detented area) will result in an incorrect torque delivered to the square head.

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[robsryder]

There are a number of videos that compare various torque wrenches. The results can be surprising. The less expensive torque wrenches can be as good as, and sometimes better than much more expensive units. In the second video testing included a non-scientific mis-use category. A very useful point to note was that exercising the "click-type" of micrometer torque wrench increases the accuracy, likely due to distribution of internal lubrication. The third video is done by the Project Farm guy; I find his tests to be more thorough and employ a reasonably scientific methodology.

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[20774]

Do I need to change the thread title to more than micrometers?

 

[robsryder]

I have come to like digital torque wrenches, mostly for the ease in which units can be changed. Torque is the product of force and distance. [A more complete definition is found here https://en.wikipedia.org/wiki/Torque ] Force is usually measured in pounds or newtons. Distance is usually in feet, inches, centimeters, or meters. One mis-perception comes from the relationship between pounds and kilograms. On earth this relationship is 2.2 pounds per kilogram. However, the pound is a measure of force, whereas the kilogram is a unit of mass. A kilogram is the same anywhere; the mass to create a pound force on earth is not the same on the moon or on mars. Force is mass times acceleration. Some torque wrenches use a unit of kg-cm; this is a non-sensical unit; the proper unit should be N-m. Since gravity on earth is about 9.8 meters per second squared one can approximate a kg-cm unit to N-m by dividing by 10 (I can do this in my head). Converting in-lbs to ft-lbs is a bit more challenging, but possible for single digit values of ft-lbs. Otherwise, I need a calculator. Thus, I like being able to quickly change the units on a digital torque wrench.

The following video compares several digital torque wrenches, including some that have the angle measuring capability. As some of you know, BMW uses angle torque criteria for some fasteners (e.g. oilhead head bolts).

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[robsryder]

Do I need to change the thread title to more than micrometers?

Yes, I have spun down the rabbit hole in looking at UTube videos on tools and measurement instruments. Next will come the big amazon bill!

 

[globalrider]

I don't buy CHEAP tools, especially measurement tools.

I have three Snap-On "click type" torque wrenches (1/4", 3/8" and 1/2") and one Precision Instruments 3/4" Split Beam torque wrench.

The way I look at it, if accuracy and precision (most people do not know the difference between those two) is a must as it should be with any measurement tool, I do not buy junk. That is not to say a cheap tool cannot do the job, but will it during its long life?

Some of my torque wrenches have been calibrated when I worked in a Standards Lab and got to use the mechanical side of the lab after hours (I worked in microwave calibrations 10 MHz to 40 GHz).

Well 17 years later, my 3/8" Snap-On "clicker" was repeatable from 5 to 75 lbf.ft. taking 5 readings at each major point: 5, 10, 15...70, 75. And it was good over the full range, not just the upper 80% of the range as is the usual in a "clicker". I also checked my 1/4" Snap-On "clicker" shortly after I bought it.

Important: look after your measurement tool and store it properly, don't lend it out and do not leave it is a humid environment. My 3/8" Snap-On clicker is now 48 years old and I trust it.

 

[robsryder]

Yet more info on clicker type torque wrenches

Following are links to three videos by an ozzie chap. The first has a comprehensive discussion about the operation of a "clicker" type of torque wrench. A unit is disassembled to illustrate the operation. I found these to be somewhat entertaining.

I am guessing that this bloke is an engineer or perhaps physicist [in the second video his t-shirt references the Schwarzschild radius, defining the event horizon for a non-rotating black hole - hence the "joke".] His language gets a bit salty as he seems to have little patience for some of his commenters. In the third video he does some measurements to illustrate his point about the relationship between hand position and torque activation on a clicker-type torque wrench.

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[Omega Man]

One of my key tools when I need to "see" what is going on electrically-

The Simpson 260.

https://simpsonelectric.com/products/test-equipment/vom-multimeters/260-8-260-8p/

OM

 

[robsryder]

I have a number of digital VOM devices, but sometimes it is really handy to have an analog scale. The price of a new Simpson 260-8 rivals that of a nice Fluke digital VOM.

https://www.globaltestsupply.com/product/simpson-260-8-analog-vom-meter-12388

https://www.fluke-direct.com/category/fluke-multimeters

I have obtained some used old Simpson 260 VOM units on the ebay. One issue is the failure of previous owners to remove the batteries. Some battery corrosion can
be corrected, sometimes not.

 

[Omega Man]

I have a number of digital VOM devices, but sometimes it is really handy to have an analog scale. The price of a new Simpson 260-8 rivals that of a nice Fluke digital VOM.

https://www.globaltestsupply.com/product/simpson-260-8-analog-vom-meter-12388

https://www.fluke-direct.com/category/fluke-multimeters

I have obtained some used old Simpson 260 VOM units on the ebay. One issue is the failure of previous owners to remove the batteries. Some battery corrosion can
be corrected, sometimes not.

I have two…… just in case

OM

 

[robsryder]

Continuing the discussion of hand position on click type torque wrenches

Following are two more linked Utube videos that discuss click-type micrometer torque wrenches. The first shows a disassembled click-type torque wrench and briefly discusses the importance of hand position.

The second video goes into more of the mathematical physics analysis of the static system.

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[Omega Man]

I wish this 800ftlb Snap-On one I have was a click type.

I bought it used for some bolts that I need to torque to 425ftlbs which means I need someone to read the gauge while I pull on the (3-piece for storage) handle.

OM

 

[robsryder]

Snap-On used to sell a version of their Torq-O-Meter (dial-type of torque wrench) that had an indicator light when the desired set point was reached. It was a simple set-up. The set point was adjusted to the desired torque setting. As torque was applied the indicator needle moved until contact was made with the set point. This contact closed a circuit (powered by a single battery) and a light illuminated. Very accurate. One just needed the keep an eye on the battery to avoid corrosion issues. One wonders if there could be a retro-fit to an existing dial-type of meter?

Here is an image of a similar one for sale on the ebay -

 

[robsryder]

It appears that Snap-On still sells these dial-type "torqometer" units with the indicator lights. See link (yikes!) -

https://shop.snapon.com/product/US-...ic-Models/TORQOMETER-U.S.-Light-Signal/TE25LA




I recently saw a motorcycle mechanic using a type of torque wrench with which I was unfamiliar. This was a deflecting beam type with a "click" feature. These are mostly from Warren and Brown, a fairly well-known Australian company.

https://wbtools.com.au/deflecting-beam-torque-wrench-12q-drive-30-300nm.html

 

[Omega Man]

Snap-On link rolls a “404” error. Possibly couldn’t believe the price either.

OM

 

[robsryder]

Here are other links to Snap-On torq-o-meter devices (the good news is that most are less than a set of tires)

https://shop.snapon.com/categories/US-Reading-Standard-2%-Accuracy-Basic-Models/675233

"https://shop.snapon.com/categories/US-Reading-Standard-2%-Accuracy-Basic-Models/675233"


https://shop.snapon.com/product/US-...METER-U.S.-Light-Signal-(with-Chart)/TE50FLAC

"https://shop.snapon.com/product/US-Reading-Standard-2%-Accuracy-Basic-Models/TORQOMETER-U.S.-Light-Signal-(with-Chart)/TE50FLAC"


I googled "snap on torqometer" to get to the snapon store. These links still show as bad. Don't know why. Cutting and pasting the quoted link worked. Is there some new security feature keeping our wallets intact???

 

[globalrider]

In the third video he does some measurements to illustrate his point about the relationship between hand position and torque activation on a clicker-type torque wrench.

I am having a tough time understanding that because the spring in the length of the handle is pre-loaded for a certain torque. Now if I grab it at the handle or 50% of the way from the pivot, I cannot see how that makes a different in that the whole length of the handle is being moved and the spring pre-load does not change as to where I hold it.

I would need a diagram showing how the insides work.

 

[robsryder]

I am having a tough time understanding that because the spring in the length of the handle is pre-loaded for a certain torque. Now if I grab it at the handle or 50% of the way from the pivot, I cannot see how that makes a different in that the whole length of the handle is being moved and the spring pre-load does not change as to where I hold it.

I would need a diagram showing how the insides work.

Take a look at the video with the mathematical physics explanation. I needed to follow that math to "get it".

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