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A pair of sunglasses and ultraviolet rays protection

by HarryColemanHarryColeman 10 May 2018 03:53

<p>Sun glasses are protective devices that prevent eyes damaging and discomfort by reducing bright light and UV rays (Partridge, Eric The New Partridge Dictionary of Slang and Unconventional English). In the early 20th century, they were also known as sun cheaters (American slang).</p>
<p>From 10 a.m. until 2 p.m. the sun is high and Ultraviolet light is the strongest The closer you are to the earth’s equator; the higher altitude, and the more reflective the surface, the stronger it is. UV rays pass through clouds, so don’t be fooled into thinking protective eyewear isn’t necessary when the sky is cloudy. Even though shaded areas reduce Ultraviolet exposure, your eyes can still be exposed to rays that bounce from buildings, roads and other surfaces.</p>
<p>When choosing sunglasses, better to invest in wraparound frames, they limit sunlight more effectively; protection of UVA and UVB rays should be 99 to 100%; gray or brown are the best for color recognition. It is important to understand, that UV protection and darkness are not the same. A pair of sunglasses are especially necessary for people with macular degeneration, cataracts, etc.</p>
<p>Shades should protect your eyes from potentially damaging UV rays as well as the glare of the sun. If UV light passes through the sunglasses, it causes more damage then eyes without sunglasses at all. Eyes behind glasses dilate and more UV light reach the retina, unprotected exposure to UV light can lead to serious eye problems. So when buying shades, look for the percentage marking of UV blocking. Most sun lenses will have a sticker or a tag as well showing that they filter out 99% or 100% of ultraviolet.</p>
<p>The United States Environmental Protection Agency (EPA) developed the UV Index, and to protect your eyes from harmful solar radiation, sunglasses should block up to 100 percent of UV rays. A pair of $5 sunglasses may filter out 100% UV rays just as well as a $200 dollar pair. Generally, more expensive lenses have higher quality and provide a sharper, clearer image with less distortion. The sun radiates Ultraviolet that arrives on Earth in wavelengths 320-400nm (UVA) and 290-320nm (UVB), both UVA and UVB can be dangerous to your eyes.</p>
<p>Polarized shades are coated with a special film that helps reduce glare. Having this chemical film on polarized shades, you are able to see more clearly. Polarized sunglasses have been popular for years with boaters and fishermen who need to reduce reflected glare from the water surrounding them.</p>

My name is Harry Coleman. I am an automotive technician.
Since I was born, I just broke toys, picture frames, etc, all accidentally, of course. With the time I started to take them apart purposefully. As I grew older I realized I should probably put some things back together. I still haven’t gotten that clock to work.

In my blog I'll share my experience and ideas with brothers-technicians. And feel free to comment my posts and share your thoughts too.


When drilling holes in steel sheets, there are two main problems.
1. Complexity of alignment, at the beginning of the rotation, the cutting edges are shifted.
2. The shape of the hole is not round, but triangular, bending of the surface (often with it the detachment of the paint), need for subsequent revision of the round file. In addition, during the drilling, at the moment of biting the edges of the material, a sharp jerk takes place, which either turns out the hands or deforms the workpiece.

Advantages of the best spade bits.

- One tool for different diameters. For example, the Yato YT-44740 can replace 12 sizes in the range of 6 to 38 mm and fix the defective hole after the spiral.
- Special sharpening of the cutting edges of the first stage. Allows you to self-center without moving away.
- The massive base does not allow to bend under critical overloads.
- When passing the next step, the next, removes the bevel by removing the burrs.
- Production of holes up to 38 mm in diameter with the possibility of clamping the shank into the holder of an electric drill or a drilling machine calculated up to 10 or 13 mm.
- Fast visual identification. Inside the groove, opposite to each step of the drill, carrots are dimensioned, which allows them to orientate themselves in them without a caliper.
- Possibility of repeated re-sharpening with weakening cutting ability.
Are there any shortcomings in this tooling?

- If you often have to work with small diameters, then when they become blunt, work on steel becomes big.
- Drilling sizes of more than 20 mm requires a drive more powerful than 800 watts.
- During the passage of the last maximum step and the failure of the tool through the steel sheet, difficulties arise with its removal. To facilitate pulling out, some manufacturers from the end of the wide part perform a chamfer.
- On some models of inexpensive Chinese step drills, the diameters of the steps may be several tenths of a millimeter, usually in the minus, different from the exact size.
- When you are in one drawer or bag with another tool, in contact with it, the first cutting step, due to the high hardness, can break off, and if you fall on a hard surface, the drill itself may also burst.

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