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How to Use a Dial Caliper

How to Use a Dial Caliper:

Learning how to use a dial caliper has never been easier.  The dial caliper is one of the fastest, and easiest, to use of the precision measuring tools.  It takes linear measurements; Inside diameter(ID), outside diameter(OD), and depth readings.  Although the dial caliper is not as accurate as a micrometer, it is much more precise than a tape measure(Learn More: Micrometer).  A micrometer is somewhat slow to use, and requires a bit of a learning curve in order to use.  However, the dial indicator is very fast to use, and very easy to learn.  Best part is, the inexpensive models work great for many applications/projects.  In fact, given the choice between a high dollar model, and an inexpensive base model, I’d use the cheap model nine(9) times out of ten(10).  I’ll explain this, in greater detail, further into this article…


Different Projects Require Different Tools:

A carpenter would not use a yard stick when measuring wood for a bird house, prior to cutting it.  Nor would he/she use a dial caliper, as it’s not large enough to make those kind of measurements.  However, the carpenter would likely use a tape measure.  Furthermore, an engine builder/transmission builder would not use a tape measure when assembling their automotive project.  He/she would use a dial caliper, micrometer, and the like…as they are designed for reading smaller, finer, measurements.

Dial Caliper Uses:

As previously mentioned, this tool isn’t the most accurate…especially if you purchase an economical one(Starting around $30).  The great news is, an inexpensive dial caliper works great for a lot of uses.

Dial calipers are great for measuring the following:

  • Automatic Transmissions:
    • Front unit end-play.
    • Pump gear thickness.
    • Pump gear-to-stator clearance.
    • Pump & valvebody valve/sleeve OD(outside diameter).
    • Depth of installed bushings.
      • This is an important measurement that you need to take…before removing the old bushings!
    • Clutch thickness.
    • Steel plate thickness.
    • Selective washer thickness.
    • Selective snap ring thickness.
    • Etc.
  • Engines:
    • Cylinder bores:
      • This is only for a rough measurement.
      • This is helpful when identifying if a cylinder has been bored-out(enlarged).
    • Cam Lobes:
      • Rough measurement only.
        • Base circle measurement.
        • Lobe lift.
    • Modeling clay(Yes, Play Dough).
      • Modeling clay is used to identify running clearances inside an assembled engine.
        • Deck height clearnce.
        • Piston-to-valve clearance.
      • The modeling clay gets squished by the moving engine parts.
      • The squished clay is then gently measured with the dial caliper.
    • Etc.
  • Miscellaneous:
    • Thickness of a feeler gauge(aka feeler blade).
      • This is especially helpful if the numbers have worn off of your feeler gauges.
    • Bolt length.
    • Bolt washer ID(inside diameter).
    • Drill bit diameters.
    • Gunsmith Needs:
      • Bullet diameters.
      • Shell casing diameters.
    • Etc.

Are There Different Types of Calipers?

Yes, there are different types of calipers.

  • Vernier Calipers:
    • The slowest to use, and require a learning curve.
  • Dial Calipers:
    • Very fast to use, and easy to learn.
    • Can be very economical.
    • Come in different readouts on dial:
      • 0.010″. (ten-thousandths of an inch)
      • 0.001″. (one-thousandth of an inch)
  • Digital Calipers:
    • Very fast to use, and the easiest to learn.
    • Can easily read both standard, and metric, sizes.
      • Makes converting between standard & metric readings a breeze.
    • Most expensive.
    • Requires batteries.

0.010″ vs 0.001″:  Part 1 of 2.

In order to learn how to use a dial caliper, you must know how your dial caliper is configured.  Dial calipers come in two(2) different types of configurations, or measurements:

  • 0.010″
  • 0.001″

You may be wondering, what is 0.010″?  What is 0.001″?  How does this apply to me, and my engine/transmission project?  Are all of these zeros really necessary??  First of all, let’s discuss the nomenclature, or the language.  Knowing, and speaking, the right language makes life a lot easier for all involved.  So, let’s start off on the right foot.  Below is a crash course on precision measurements.  If you’d like, you can read the whole article on this topic(Learn More: 0.010″ vs 0.001″ vs 0.0001″).

Learning the Language:

  • 0.001″ is pronounced, “One thousandth of an inch.”
  • 0.010″ is pronounced, “Ten thousandths of an inch.”
  • 0.100″ is pronounced, “One-hundred thousandths of an inch.”

Tape Measure:  Something that we’re all familiar with…

1.000″ is pronounced, “One inch(1″).”

0.500″ is pronounced, “Five-hundred thousandths of an inch…or, half inch(1/2″).”

0.250″ is pronounced, “Two-hundred & fifty thousandths of an inch…or, quarter inch(1/4″).”

0.125″ is pronounced, “One-hundred & twenty-five thousandths of an inch…or, one-eighth of an inch(1/8″).”

Pulling Out Your Hair:

Okay, after reading through the last section, we can see now how a dial caliper, and a tape measure are related.  Now we diverge…

For the next example, I measured a hair on my arm with the dial caliper.  It measured roughly 0.001″.  Say what??? ha  Once again, this is pronounced, “One thousandth of an inch.”  Now we have something to work with, in order to start to make sense of thousandths of an inch.  Have you ever tried measuring the thickness of your hair with a tape measure?  I don’t care how good your vision is…it would be impossible to identify the thickness.  Believe it or not, some engine measurements require precision that’s even finer than the thickness of human hair.  Now we are talking about less than 0.001″.  We need to stay on track with this article.  If you’d like, you can read the whole article on the topic of precision measurement(Learn More: 0.010″ vs 0.001″ vs 0.0001″).

0.010″ vs 0.001″:  Part 2 of 2.

As previously mentioned, dial calipers come in two(2)types of measurements; 0.010″ & 0.001″.  I wouldn’t waste my time with anything less accurate than 0.001″.  Having this amount of detail helps to eliminate a lot of guesswork.  Let’s look at an example.

Take a look at both images shown below.  The top image has two(2) sets of measurements.  Only pay attention to the measurements in the blue ring.  Now take a look at both images.  Which dial caliper has a greater/larger reading?

How to use a dial caliper: Set at 0.050"(fifty thousandths of an inch).
How to use a dial caliper: Set at 0.050″(fifty thousandths of an inch).

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