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Day By Day© by Chris Muir.


Thursday, March 08, 2007

the beauty of averages

i do a lot of different things in the course of my job. one of the more esoteric things i have been certified for is using a high speed die grinder to to grind on exotic metals. metals that can catch on fire if you grind too hard, too fast, allow the burr shank to touch the metal while spinning, fail to keep a close eye on the chips to make sure they don't accumulate... blah blah blah. i got to go to portland oregon for training and certification a couple of years ago, so that was cool.
anyway, one of the biggest problems i have is with safety glasses. my prescription ones are clunkers, and the "over the glasses" type are really unwieldy. so what's a guy to do? why, look up "bifocal safety glasses" in my favorite catalog. here's the description, cut and pasted from the catalog:

Magnifying Wraparound Safety Glasses

* Our bifocal safety glasses bring items into focus while protecting your eyes
* Frame and temples are polycarbonate
* A rubber nosepiece and temple tips provide comfort
* Temple length is not adjustable; temple-to-temple width is 5 1/2"
* Lens is scratch resistant

To select the correct magnification level (also known as diopter), subtract 35 from your age and insert a decimal point between the two numbers. Choose the magnification level that is closest to that number.

did you catch how to figure out what diopter to order? optomotrists world wide must be rolling over wondering why they just got the cold sweats.
crazy thing is, i actually ordered using the formula, and i'll be damned if it isn't close enough to work. i have to get in close, around 12 to 14 inches to correctly focus, but that is the distance i need when i need the bifocals anyway.
so now i'm wondering if they sell other items using the same types of "rule of thumb" instructions. i'll have to poke around the catalog in my free time.
this just cracks me up..


Anonymous Park Dallis said...


I've been buying "cheaters" at the local Barnes and Noble and recently stepped up from 2.25 to 2.5.

I ran the formula and got 2.8!

Wouldn't have believed it.

3/9/07, 3:39 PM  
Blogger SonarMan said...

I'm surprised that a shooter like you hasn't heard of Wiley-X. They're the same outfit supplying safety glasses/goggles to our troops in Iraq.

They make shooting safety glasses, too, and will fit them to your prescription. I'm sure they would be suitable for the work you're describing.

They also make them for cyclist (pedalers and motorized). I have a pair myself. I'm not a biker, but the lok damn cool, and the anti-glare polarization is outa-this-world.

3/9/07, 4:07 PM  
Blogger bothenook said...

Park, the "thumb rule" just cracks me up. mainly because it works so well. at least in the now two cases i've heard of.
and sonardude, i looked into getting a pair of wiley's for shooting, but after getting the latest and greatest in progressive lenses, standard bifocals just don't cut it for me anymore when i go to the range. for work, bifocals are ok when grinding. for everything else, it's progressives, baby

3/9/07, 7:45 PM  

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