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# how to use screw gauge

From Wikipedia

A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread. More screw threads are produced each year than any other machine element.

The mechanical advantage of a screw thread depends on its lead, which is the linear distance the screw travels in one revolution. In most applications, the lead of a screw thread is chosen so that friction is sufficient to prevent linear motion being converted to rotary, that is so the screw does not slip even when linear force is applied so long as no external rotational force is present. This characteristic is essential to the vast majority of its uses. The tightening of a fastener's screw thread is comparable to driving a wedge into a gap until it sticks fast through friction and slight plastic deformation.

## Applications

• Fastening
• Moving objects linearly by converting rotary motion to linear motion, as in the leadscrew of a jack.
• Measuring by correlating linear motion to rotary motion (and simultaneously amplifying it), as in a micrometer.
• Both moving objects linearly and simultaneously measuring the movement, combining the two aforementioned functions, as in a leadscrew of a lathe.

In all of these applications, the screw thread has two main functions:

• It converts rotary motion into linear motion.
• It prevents linear motion without the corresponding rotation.

## Design

### Gender

Every matched pair of threads, external and internal, can be described as male and female. For example, a screw has male threads, while its matching hole (whether in nut or substrate) has female threads. This property is called gender.

### Handedness

The helix of a thread can twist in two possible directions, which is known as handedness. Most threads are oriented so that a bolt or nut, seen from above, is tightened (the item turned moves away from the viewer) by turning it in a clockwise direction, and loosened (the item moves towards the viewer) by turning anti-clockwise. This is known as a right-handed (RH) thread, because it follows the right hand grip rule (often called, more ambiguously, "the right-hand rule"). Threads oriented in the opposite direction are known as left-handed (LH).

To determine if a particular thread is right or left-handed, look straight at the thread. If the helix of the thread is moving up to the right, it is a right-handed thread and conversely up to the left, a left-handed thread. This holds whether the thread is oriented up or down.

By common convention, right-handedness is the default handedness for screw threads. Therefore, most threaded parts and fasteners have right-handed threads. Left-handed thread applications include:

• Where the rotation of a shaft would cause a conventional right-handed nut to loosen rather than to tighten due to fretting induced precession. Examples include:
• In some gas supply connections to prevent dangerous misconnections, for example in gas welding the flammable gas supply uses left-handed threads.
• In a situation where neither threaded pipe end can be rotated to tighten/loosen the joint, e.g. in traditional heating pipes running through multiple rooms in a building. In such a case, the coupling will have one right-handed and one left-handed thread
• In some instances, for example early ballpoint pens, to provide a "secret" method of disassembly.
• In mechanisms to give a more intuitive action as:
• The leadscrew of the cross slide of a lathe to cause the cross slide to move away from the operator when the leadscrew is turned clockwise.
• The depth of cut screw of a "Stanley" type metal plane (tool) for the blade to move in the direction of a regulating right hand finger.

The term chiralitycomes from the Greek word for "hand" and concerns handedness in many other contexts.

### Form

The cross-sectional shape of a thread is often called its form or threadform (also spelled thread form). It may be square, triangular, trapezoidal, or other shapes. The terms form and threadform sometimes refer to all design aspects taken together (cross-sectional shape, pitch, and diameters).

Most triangular threadforms are based on an isosceles triangle. These are usually called V-threads or vee-threads because of the shape of the letter V. For 60Â° V-threads, the isosceles triangle is, more specifically, equilateral. For

Rain gauge

A rain gauge (also known as a udometer or a pluviometer [Pluviograph ] or an ombrometer or a cup) is a type of instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation (solid precipitation is measured by a snow gauge) over a set period of time.

## History

The first known records of rainfalls were kept by the Ancient Greeks about 500 B.C. This was followed 100 years later by people in India using bowls to record the rainfall. The readings from these were correlated against expected growth, and used as a basis for land taxes. In the Arthashastra, used for example in Magadha, precise standards were set as to grain production. Each of the state storehouses were equipped with a standardised rain gauge to classify land for taxation purposes.

While some sources state that the much later cheugugi of Korea was the world's first gauge, other sources say that Jang Yeong-sil developed or refined an existing gauge. In 1662, Christopher Wren created the first tipping-bucket rain gauge in Britain.

## Principles

Most rain gauges generally measure the precipitation in millimeters. The level of rainfall is sometimes reported as inches or centimeters.

Rain gauge amounts are read either manually or by AWS (Automatic Weather Station). The frequency of readings will depend on the requirements of the collection agency. Some countries will supplement the paid weather observer with a network of volunteers to obtain precipitation data (and other types of weather) for sparsely populated areas.

In most cases the precipitation is not retained, however some stations do submit rainfall (and snowfall) for testing, which is done to obtain levels of pollutants.

Rain gauges have their limitations. Attempting to collect rain data in a hurricane can be nearly impossible and unreliable (even if the equipment survives) due to wind extremes. Also, rain gauges only indicate rainfall in a localized area. For virtually any gauge, drops will stick to the sides or funnel of the collecting device, such that amounts are very slightly underestimated, and those of .01&nbsp;inches or .25&nbsp;mm may be recorded as a trace.

Another problem encountered is when the temperature is close to or below freezing. Rain may fall on the funnel and freeze or snow may collect in the gauge and not permit any subsequent rain to pass through.

Rain gauges should be placed in an open area where there are no obstructions, such as building or trees, to block the rain. This is also to prevent the water collected on the roofs of buildings or the leaves of trees from dripping into the rain gauge after a rain, resulting in inaccurate readings.

## Types

Types of rain gauges include graduated cylinders, weighing gauges, tipping bucket gauges, and simple buried pit collectors. Each type has its advantages and disadvantages for collecting rain data.

### Standard rain gauge

The standard rain gauge, developed around the start of the 20th century, consists of a funnel attached to a graduated cylinder that fits into a larger container. If the water overflows from the graduated cylinder the outside container will catch it. When measurements are taken, the cylinder will be measured and then the excess will be put in another cylinder and measured. In most cases the cylinder is marked in mm and in the picture above will measure up to 25&nbsp;mm (0.98&nbsp;in) of rainfall. Each horizontal line on the cylinder is 0.2&nbsp;mm (0.007&nbsp;in). The larger container collects any rainfall amounts over 25&nbsp;mm that flows from a small hole near the top of the cylinder. A metal pipe is attached to the container and can be adjusted to ensure the rain gauge is level. This pipe then fits over a metal rod that has been placed in the ground.

### Weighing precipitation gauge

A weighing-type precipitation gauge consists of a storage bin, which is weighed to record the mass. Certain models measure the mass using a pen on a rotating drum, or by using a vibrating wire attached to a data logger. The advantages of this type of gauge over tipping buckets are that it does not underestimate intense rain, and it can measure other forms of precipitation, including rain, hail and snow. These gauges are, however, more expensive and require more maintenance than tipping bucket gauges.

The weighing-type recording gauge may also contain a device to measure the quantity of chemicals contained in the location's atmosphere. This is extremely helpful for scientists studying the effects of greenhouse gases released into the atmosphere and their effects on the levels of the acid rain.

### Tipping bucket rain gauge

The tipping bucket rain gauge consists of a funnel that collects and channels the precipitation into a small seesaw-like container. After an amount of precipitation equal to 0.2&nbsp;mm (0.007&nbsp;in) falls, the lever tips, dumping the collected water and sending an electrical signal. The recorder consists of a pen mounted on an arm attached to a geared wheel that moves once with each signal sent from the collector. When the wheel turns the pen arm moves either up or down leaving a trace on the graph and at the same time making a loud click. Each jump of the arm is sometimes referred to as a 'click' in reference to the noise. The chart is measured in 10 minute periods (vertical lines) and 0.4&nbsp;mm (0.015&nbsp;in) (horizontal lines) and rotates once every 24 hours and is powered by a clockwork motor that must be manually wound.

The tipping bucket rain gauge is not as accurate as the standard rain gauge because the rainfall may stop before the lever has tipped. When the next period of rain begins it may take no more than one or two drops to tip the lever. This would then indicate that 0.2&nbsp;mm (0.007&nbsp;in) has fallen when in fact only a minute amount has. Tipping buckets also tend to underestimate the amount of rainfall, particularly in snowfall and heavy rainfall events.. The advantage of the tipping bucket rain gauge is that the character of the rain (light, medium or heavy) may be easily obtained. Rainfall character is decided by the total amount of rain that has fallen in a set period (usually 1 hour) and by counting the number of 'clicks' in a 10 minute period the observer can decide the character of the rain. Correction algorithms can be applied to the data as an accepted method of cor

From Encyclopedia

Pressure Gauge Pressure Gauge

Question:a thin wire is wounded around a pencil.The total length of the wire that wounds the pencil is 2 cm,what is the diameter of the wire?

Answers:2 cm is the circumference (C=pi*OD), and from that value you can calculate the outside diameter which is the sum of the diameter of the pencil and 2x the diameter of the wire (OD= y + 2x where y is the D of pencil an x the D of wire). You can't still solve it because the diameter of the pencil is not given. ;-)

Question:On a Circuit breaker or sub panel terminal lug, how tight do you go when you screw the wire down? Do you "fan" the wires out or let the screw flatten it for you.

Answers:As tight as you can get with your screwdriver. Loose wires are bad. The tighter the better (within reason).

Question:I was wondering how you hook up an Air Pressure Gauge to a potato gun's combustion chamber to see how much pressure is built up in the chamber. (that way i can avoid going to high and blowing the gun up). Do i just need to buy one and then screw it into the PVC pipe or is there a certain procedure and adapter that i need to get an accurate reading. i would like to have a gauge i could hook up to a combustion potato gun (preferably) and a pneumatic gun also, so i could use it for testing purposes. i have NO experience in hooking up pressure gauges so please be as detailed as possible. thank you.

Answers:You could thread it straight into the combustion chamber or give yourself some slack by threading on an extension tube. If you use tubing make sure that it is designed for high pressure or your pressure reading could have substantial loss. Use a gauge that allows the arrow to stick at max pressure since you are measuring a dynamic system. Remember that since you are drilling a hole into the combustion chamber, you are creating a weak spot in the material which could allow material fatigue or failure to occur. You can reinforce the hole with some kind of flexible, PVC compatible glue or use a combustion chamber with adequate thickness. If you are really cheap you can wrap some duct tape around the chamber so that if it does explode shrapnel hopefully won't fly into your face. Since potato guns are illegal in some counties, everything I have written is for entertainment purposes only and should never be attempted by anyone :) .

Question:most screw catalogues use gauge sizes for the size of the screw eg 8 x 1inch but some catologues use the diameter of the screw in mm eg 4.0 x 25mm what is the metric equivalent for a 10 guage x 1inch wood screw?

Answers:5mm x 25 This chart has the metric conversion you asked for, not just the imperial ones as above: http://www.diydoctor.org.uk/projects/screwsize.htm The link is better formated, but the cut 'n' paste below gives you the idea: Metric/Imperial Conversion Chart GaugeLengthImperialGaugeLengthImperial mmmmSizemmmmSize 3124 x 1/23.5126 x 1/2 164 x 5/8166 x 5/8 204 x 3/4206 x 3/4 254 x 1256 x 1 304 x 1 1/4306 x 1 1/4 404 x 1 1/2406 x 1 1/2 4128 x 1/24.5259 x 1 168 x 5/8309 x 1 1/4 208 x 3/4359 x 1 3/8 258 x 1409 x 1 1/2 308 x 1 1/4459 x 1 3/4 358 x 1 3/8509 x 2 408 x 1 1/2609 x 2 3/8 458 x 1 3/4709 x 2 3/4 508 x 2759 x 3 608 x 2 3/8 708 x 2 3/4 52510 x 163012 x 1 1/4 3010 x 1 1/44012 x 1 1/2 3510 x 1 3/85012 x 2 4010 x 1 1/26012 x 2 3/8 4510 x 1 3/47012 x 2 3/4 5010 x 27512 x 3 6010 x 2 3/88012 x 3 1/4 7010 x 2 3/49012 x 3 1/2 7510 x 310012 x 4 8010 x 3 1/411012 x 4 3/8 9010 x 3 1/213012 x 5 1/8 10010 x 415012 x 6