How to measure the caliper of a tree

Specifications for trees - RCW Nurseries

Trees get grades?

          Trees, like many other commodities, have standards and grades. Trees are measured in several ways. 

  1. Pot size, which is usually measured in gallons. RCW uses a   #   sign instead of the word gallon.
  2. Height is the real height of the plant…and NEVER includes the soil in the pot. 
  3. Spread is the average width of the branches. 
  4. Caliper is the diameter of the trunk, measured at 6 inches above the  soil line, on trees that measure 4″ caliper or smaller.  Over 4″ caliper trees are measured 1 foot from the soil line.
  5. Grade is a level of plant quality that meets minimum standards.  Over all shape, how straight the trunk is for some species, large gaps, weak unions or crotches and damage to the trunk are the types of things that affect grade. Grade #1 trees are the best. Trees that are graded at #1 1/2  have issues that they may be able to over come if you know what they need and take care of it. If you just need a bunch of cheap trees, #2 grade may work for you.

    The chart below, provides the standard information you need to when picking out trees. If the tree you’re looking at is far larger than these guidelines, it may have been in the pot too long and have problems down the road. If the tree is far under these standards, you may not be getting what you paid for. That said, there are always exceptions to the rules. Understanding the nature of the variety you’re looking at, is important.   For instance, a #15 Texas Mountain Laurel will be very short…perhaps 4 feet tall. They grow VERY slowly. A #15  Sycamore will be at the high-end and probably seem  to be over sized, but will have a smaller caliper.     


       Shade and Ornamental Trees

POT SIZE                                 CALIPER             HEIGHT         SPREAD            

 #15 1 1/4-1 1/2 6′-8′ 2 1/2′-3′  
#30 2″ – 2 1/2″ 8′ -10′ 4′ –  5′   
#45 2 1/2″ – 3″ 10′ – 12′ 5′ – 6′  
#65 3″ – 3 1/2″ 12′ – 14′ 6′ – 7′  
#95 4″ – 4 1/2″ 14′ – 16′ 7′ – 8′  



         Flowering Ornamental Trees

 POT SIZE                                CALIPER            HEIGHT          SPREAD            

# 15  1″ – 1 1/4″ 5′ – 7′ 3′ – 4′  
#30 1 1/2″ – 2″ 6 ‘- 8’ 4′ –  5′   
#45 2″ – 2 1/2″ 8’+ 5’+  


     Clump or Multi-cane Trees

Pot Size Height Spread      
# 15  6 ‘- 8’ 2 1/2′ – 3′      
#30 8′ -10′ 4′ –  5′       
#45 10′ – 12′ 5′      
#65 12′ – 14′ 6’+      

Information provided by the Southeast Texas Nursery Growers’ Association

Filed Under: Gardening tips, Landscaping, Uncategorized

Tools for measuring tree diameter

Tools for measuring tree diameter
Tools for measuring tree diameter
Forest Measurement and Modelling.

  • [Within reach]
  • [Above reach]
  • [Ranking]
  • Bole size

Fiberglass tape: A girth tape measures diameter indirectly. The tape is wrapped around the tree to measure circumference. This value is divided by PI (3.1415....) to estimate diameter. Often the tape will have normal units (mm and cm) on one side and PI units on the other side.

The tape should be held relatively firmly (but avoid stretching). The tape should also be wrapped around the bole in a perpendicular plane to the stem axis. Keeping the tape numbers right side up (as in the photograph) reduces the chances of incorrectly reading the scale - when upside down errors like x. 4 being recorded as x.6 are common.

Calipers: Calipers are comprised of a fixed arm, scale and moveable arm. The fixed arm is placed along one side of the tree at the desired height. The moveable arm is then placed flush against the other side of the tree and the scale is read directly. The calipers must be located perpendicular to the stem axis.

The length of the caliper arms must be at least half the diameter of the tree. Biased estimates (underestimates) of the diameter will result if the arms are less than half the tree diameter. This limitation may restrict the use of calipers to smaller trees - the large diameter trees often found in natural eucalypt forests would require calipers arms in excess of 1 m which would be inconvenient.

There are a wide variety of calipers available. The most widely used type is the light, hardwearing, metal alloy caliper.

Spiegel Relaskop (Relascope): Commonly referred to as a Relaskop. A sophisticated, compact and robust device for measuring range, tree height and diameter, and stand parameters. It is relatively expensive.

Telerelaskop: A research quality instrument that is no longer in production. The Telereskop is similar in principle to the [Relaskop] except that it includes 5 x optical magnification.

Criterion Laser: A heavy height, diameter and range measuring instrument. The Criterion uses laser light to determine distance from a tree. The user enters numbers read from a rifle-scope and a simple computer chip calculates diameter.

Pentaprism: A medium weight and cost instrument for measuring tree diameter. The Pentaprism uses a moveable prism to superimpose an image of the tree bole over an original image. When the sides of the superimposed image line up with the original image, the diameter can be read directly from a scale which measures displacement of the moveable prism.

Many users experience difficulties with the Pentaprism. They have difficulties lining up the sides of the tree for the two images.

Ranking tools for ease, effectiveness and cost

I have ranked the above tools used for measuring diameter at heights not within easy reach. My interpretation of 5 main factors:
  • price
  • precision
  • robustness
  • ease of sighting
  • speed of use
  • compactness

[toolsd.htm] Revision: 6/1999
Cris. [email protected]

How to use a caliper, a micrometer, a ruler

The home master has to deal with measuring length, width and height all the time. An angle of 90 ° or 45 ° is also often necessary to maintain. Otherwise, high-quality repair of the apartment or the manufacture of homemade products cannot be performed. Accuracy when performing linear measurements of 1 mm in the vast majority of cases is sufficient, and a tape measure or a simple ruler is suitable for them.

Often tape measures have an additional bubble level, which allows you to set furniture, refrigerator and other items horizontally. But the accuracy of this level is not high due to the small length of the tape measure reference plane. In addition, the cone with an air bubble in tape measures is often not set exactly, which does not ensure horizontality and the work done.

A wide range of laser measuring devices is available for sale for measuring linear dimensions, but, unfortunately, due to the high price, they are not available to non-professionals.


for the use of calipers (Columbus)

Caliper is a linear measuring tool used to measure the external and internal dimensions of parts including depth, with an accuracy of 0.1 mm.

It is not possible to measure the diameter of a drill, self-tapping screw and the dimensions of other small parts with sufficient accuracy with a ruler. In such cases, you need to use a caliper, which allows you to measure linear dimensions with an accuracy of 0.1 mm. Using a caliper, you can measure the thickness of sheet material, the inner and outer diameters of the pipe, the diameter of the drilled hole, its depth and other measurements.

Vernier calipers are available with a ruler and vernier reading, a dial and a digital indicator. A variety of calipers with a ruler for measuring the depth of holes are also called "Columbus" by professionals.

Affordable, highly reliable is a vernier caliper type ШЦ-1 with a measurement range from 0 to 125 mm, which is quite enough for most cases. Caliper ShTs-1 additionally allows you to measure the diameter of holes and depth.

A digital plastic caliper made in China under $4 is now on sale, pictured below.

Caliper made of plastic, although its jaws are made of carbon, it is difficult to call it a measuring tool, since it is not certified and therefore the accuracy of 0.1 mm readings declared by the manufacturer is not guaranteed. In addition, with frequent use, the plastic will wear out quickly, and the reading error will increase.

A plastic caliper, if its readings are accurate for rare home measurements, is quite suitable. To check the caliper, you can measure the shank of the drill, which is stamped with the size or diameter of the pin of the electrical plug.

The device and principle of operation of the vernier caliper

The classical caliper is arranged as follows. A movable frame is installed on the measuring rod with the help of grooves. In order for the frame to sit tightly, a flat spring is installed inside and a screw is provided for its rigid fixation. Fixing is necessary when carrying out marking work.

The shaft is marked with a metric scale in 1 mm increments and centimeter divisions are indicated by numbers. The frame has an additional scale with 10 divisions, but with a step of 1.9 mm. The scale on the frame is called a vernier in honor of its inventor, the Portuguese mathematician P. Nunis. The stem and frame have measuring jaws for external and internal measurements. A depth gauge ruler is additionally fixed to the frame.

Measurements are made with a clamp between the workpiece jaws. After clamping, the frame is fixed with a screw so that it does not move. The number of millimeters is counted on the scale on the bar to the first vernier risk. Tenths of millimeters are counted by vernier. What stroke on the account from left to right on the nonius coincides with any of the scale marks on the bar, so many tenths of a millimeter will be.

As you can see in the photo, the measured size is 3.5 mm, since from the zero mark of the scale on the bar to the first mark of the vernier there were 3 full divisions (3 mm) and on the vernier it coincided with the mark of the bar scale of the risk of the fifth division of the vernier (one division on the vernier corresponds to 0. 1 mm measurements).

Measurement examples with calipers

To measure the thickness or diameter of a workpiece, open the jaws of the caliper, insert the workpiece into them, and bring the jaws together until they come into contact with the surface of the workpiece. It must be ensured that the planes of the jaws when closing are parallel to the plane of the measured part. The outer diameter of the pipe is measured in exactly the same way as the size of a flat part, only it is necessary that the jaws touch diametrically opposite sides of the pipe.

In order to measure the internal dimension in a workpiece or the internal diameter of a pipe, the caliper has additional jaws for internal measurements. They are brought into the hole and pushed all the way into the walls of the part. When measuring the inner diameters of the holes, the maximum reading is achieved, and when measuring parallel sides in the hole, the minimum reading is achieved.

In some types of calipers, the jaws do not close to zero and have their own thickness, which is usually stamped on them, for example, the number "10", although the first vernier mark is at zero. In the case of measuring internal holes with such a vernier caliper, 10 mm is added to the readings on the vernier scale.

Columbus type caliper with movable depth gauge can be used to measure the depth of holes in workpieces.

To do this, fully extend the depth gauge ruler from the stem, insert it into the hole as far as it will go. Bring the end of the caliper bar to the stop against the surface of the part, while preventing the depth gauge ruler from leaving the hole.

In the photo, for clarity, I demonstrated the measurement of the depth of the hole by attaching the ruler of the caliper depth gauge to the outside of the pipe section.

Examples of marking parts with a caliper

The caliper is not intended for drawing marking lines on materials and parts. But if the caliper jaws for external measurements are sharpened on a fine-grained emery wheel, giving them a sharp shape, as shown in the photo, then marking with a caliper will be quite convenient.

It is necessary to remove excess metal from the jaws very carefully and slowly, avoiding discoloration of the metal of the jaws from strong heating, otherwise they can be damaged. To speed up the work, to cool the sponges, you can periodically dip them for a short time in a container of cold water.

In order to measure a strip of sheet material with parallel sides, you need to move the caliper jaws apart, focusing on the scale to a given size, with one jaw to lead along the end of the sheet, and the second to scratch the line. Since the caliper jaws are hardened, they do not wear out. You can mark both soft materials and hard ones (copper, brass, steel). There are clearly visible risks.

The sharply ground caliper jaws make it easy to mark a circle. To do this, a shallow hole with a diameter of about 1 mm is made in the center, resting against one of the sponges, the second draws a circle line.

Thanks to the refinement of the shape of the caliper jaws for external measurements, it became possible to accurately, conveniently and quickly mark out parts for their subsequent machining.

How to measure with a micrometer in practice

You can obtain the size of products with an accuracy of 0.01 mm by measuring with a micrometer. There are many modifications, but the most common is a smooth micrometer of the MK-25 type, which provides a measurement range from 0 to 25 mm with an accuracy of 0.01 mm. With a micrometer it is convenient to measure the diameter of the drill, the thickness of the sheet material, the diameter of the wire.

The micrometer is a bracket, on one side of which there is a support heel, and on the other side there is a stem and a high-precision thread into which the microscrew is screwed. There is a metric scale on the stem, according to which millimeters are counted. The microscrew has a second scale with 50 divisions, according to which hundredths of a mm are counted. The sum of these two values ​​is the measured size.

To make a measurement with a micrometer, place the part between the heel and end of the micrometer screw and turn the ratchet handle (located on the end of the micrometer screw barrel) clockwise until the ratchet makes three clicks.

The stem has two scales in 1 mm increments - the main scale is digitized every 5 mm and an additional one, shifted relative to the main one by 0.5 mm. The presence of two scales improves the accuracy of measurements.

Reading is performed as follows. First, they read how many whole millimeters, uncovered by the drum, turned out according to the digitized, lower scale on the stem. Next, check on the upper scale the presence of risks located to the right of the risks of the lower scale. If the risks are not visible, then proceed to take readings from the scale on the drum. If the risk is visible, then another 0.5 mm is added to the integer number of millimeters received. The readings on the drum are measured relative to a straight line drawn along the stem between the scales.

For example, the size of the measured part is: 13 mm on the lower scale, on the upper scale there is an open mark, to the right of the open mark on the lower scale there is no need to add 0. 5 mm, plus 0.23 mm on the scale of the drum, as a result of addition we get : 13mm+0mm+0.23mm=13.23mm.

Micrometer with digital reading of measurement results is more convenient to use and allows you to measure with an accuracy of 0.001 mm.

If, for example, the battery is dead, then you can measure with a digital micrometer in the same way as with a smooth MK-25, since there is also a reference system for divisions with an accuracy of 0.01 mm. The price of micrometers with a digital reading of the measurement results is high and unbearable for a home master.

How to measure large diameter pipe

Caliper jaws with a measuring range of 0 to 125 mm are 40 mm long and can therefore measure pipes with an outside diameter of up to 80 mm. If it is necessary to measure a pipe of a larger diameter or if there is no caliper at hand, you can use the folk method. Wrap the pipe around the circumference with one turn of non-stretching thread or wire, measure the length of this turn with a simple ruler, and then divide the result by the number Π = 3. 14.

Online calculator for calculating the pipe diameter along its circumference
Total winding length, mm:
Number of turns:

Despite its simplicity, this method of measuring the pipe diameter allows for an accuracy of 0.5 mm, which is quite enough for a home master. For a more accurate measurement, you need to wind more turns.

How to measure an angle

To obtain a given angle when marking, you can use a protractor, which everyone met at school in geometry lessons. For measuring in everyday life, it is quite enough accuracy.

The photo shows a plastic ruler in the form of a triangle with 45º and 90º angles, with a built-in protractor. With it, you can mark up and check the accuracy of the resulting angle.

When marking metal parts, a locksmith's metal square is used, which provides higher measurement accuracy.

How to use the miter box

To obtain a straight or 45º angle without marking, it is convenient to use a device called a miter box. With the help of a miter box, it is convenient to cut platbands for doors, moldings, plinths and much more to size at an angle. The cut is obtained with the required angle automatically.

It is enough to measure the length, insert a strip of material between the vertical walls of the miter box and, holding it with your hand, make a cut. To obtain a high-quality end face of the board, a saw with fine teeth should be used. A hacksaw works well for metal. It is possible to saw even varnished boards without varnish chips.

Angle 45 0 When sawing with a miter box, it is just as easy as a straight cut. Thanks to the high guides of the walls of the miter box, it is possible to saw boards of different thicknesses.

The miter box can be bought ready-made, but it is not difficult to make it yourself from improvised material. It is enough to take three boards made of wood or plywood of a suitable size, and screw the other two to the side ends of one of them with self-tapping screws. Make guide cuts at the required angles and the miter box is ready.

device device, how to use and store

Vernier caliper is a universal tool for measuring the external and internal dimensions of parts, the depth of holes, etc. It is widely used in the technical field and is easy to use, along with a micrometer and inside gauge. The mechanical structure makes the device almost invulnerable, with an unlimited service life. Despite the simplicity of its device, it is necessary to know how to measure various parameters with a caliper and obtain accurate data.

  • Design and function
  • Measuring different surfaces
  • Measurement Method
  • How to store the
  • instrument

Design and principle of operation

Measurements are carried out not only in industry, but also by private users, since the device is small in size. A characteristic feature is the vernier scale, which allows you to determine even tenths of a millimeter .

To use the caliper, no special training is needed, you can start working after a brief familiarization with the structure. The design provides for fixing the elements to prevent errors.

The name of the tool comes from the bar on which the main scale is located. Nonius is classified as an additional element, with its help you can track tenths or hundredths of a millimeter, if necessary. Attachment consists of :

  • rod;
  • moving frame;
  • measuring sponges on the inside;
  • outside measuring sponges;
  • depth gauge;
  • vernier;
  • screw clamping the frame.

Some versions have a double scale displaying data in inches. When the moving parts move, the control division part also moves, which will display the information. Regardless of the type of measurement, the displacements are the same, only the control end measures differ. The depth gauge rests against the bottom of the measurement object. For normal measurements, parts are fixed with internal or external jaws. You can use the vernier to get the most accurate values. There are several rules regarding0147 how to use the caliper correctly :

  1. Avoid situations in which the jaws of the device can be distorted. After approaching the required position, they are fixed by means of a locking screw.
  2. Shtangel hold exactly at eye level, reading the information.
  3. It is necessary to observe safety precautions during operation, as the jaw ends are sharp and can be injured by negligence.
  4. Store the device away from sawdust, shavings, water, dust or other liquids.
  5. Wipe the caliper with a clean cloth before and after work.

Measuring different surfaces

To measure the external dimensions of products, they are fixed in the lower jaws of the tool. It is bred so as to cover the measured workpiece, and then reduced to the stop. Readings can be taken both from the main scale and from the additional one.

To determine the internal parameters, the tool is set to zero position, then the internal measurement jaws are placed in the workpiece parallel to the measured planes. Then they are bred to the stop - to fix the position and prevent a significant error. In this way, the diameter of the components can be determined.

Depth is measured with depth gauge . The end part rests against the end of the part, and the depth gauge plunges into the other end. When the desired point is reached, readings are taken from two scales. Many people understand how to use a barbell, but not everyone knows that marking can also be done with this tool. It is applied with direct risks, using the base edges of the device as a guide, placing them parallel to the surface of the workpieces. Also, if necessary, circles are drawn or serifs are made.

Measuring method

It is not enough to know how to measure something with a caliper. Another problem is determining the exact results and using the additional features of the instrument. It’s easy to figure out the external parameters, since they are easy to remove, but you have to master two scales even for this purpose. The first of them - the main one, displays whole fractions of a millimeter. In order not to go astray during calculations, the device is fixed at the control point. Only then can it be taken from the workpiece, the data will remain unchanged.

Vernier is used for more precise measurements. It has ten divisions corresponding to a fraction of a whole. If the first division coincides with the value on the main scale, equal values ​​are obtained. If the second has some trait, then 0.1 is added to the whole, 0.2 to the third, 0.3 to the fourth, and so on.

Nonius modern devices can show even hundredths of a millimeter.

Learn more