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Unusual occurence

I was grinding lathe bits today on my new grinding and sharpening mobile platform. I had it parked in the garage doorway, facing west, so the light would be better and the dust would blow out.

At one point I noticed a wisp of smoke coming out somwhere behind one of the grinders. Now I may be overcautious but I consider smoke and grinders an inherently undesirable combination.

I was puzzled: There was hardly any sparking, the bits were cool enough to hold bare hand. No strange noises. I looked and there on the brand new top was a burn - a linear scar, about 2 inches long, about 1/8" deep, about 1/4" wide with deeply charred edges. What could have caused this?

I moved my head and it became clear: The sunlight hit the grinder shield which has a lens in the middle. The lens was focussing the sunlight onto my bench top and burning it, judging by the length of the scar for a quite a while (for a sundialist it is tempting to calculate the exact time by measuring the length of scar exactly and estimating the amount of Earth's rotation from it but I am too lazy). Everytime I came to grind my head got in the way of the sunlight and the bright focus of light would disappear, leaving only the wisp of smoke as evidence of anything wrong. The burning would start again when I left the station to do things elsewhere.

I am sure that there are lessons here somewhere...In my defense I should say that we are not used to sunshine around here.

Reply to
Michael Koblic
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I was in the back of the shop one afternoon working on some small parts for a machine and was called up front to receiving to inspect some incoming material. As I walked into the early afternoon sunshine, I noticed the first pallet of unloaded boxes burst into flames. As I turned to shout for fire extinguishers, cars in the parking lot started exploding one after the other, all in a row. The work crew and I started to freak out until one of the guys, known for having a cool head under pressure, shouted for me to remove my magnifying visor that was tilted up on my head. It seems it was at just the right angle for the sunlight to turn it into a "Death Ray". We now have signs to reminding people not to wear their magnifying visors outside.

Reply to
Buerste

Sunshine in Campbell River! Now that is unusual!

Anywhere west of the Rockies, the sun is defined as a glowing spot on the clouds!

Reply to
Grumpy

Not that unusual an occurrence. A friend is a fire scene investigator and has said that about 4 or 5 fires a year, in the UK, are attributed to an object focusing sunlight and setting something on fire.

Reply to
David Billington

I've heard tell that a curved section of glass from a broken bottle can sometimes do that too.

Jeff

Reply to
jeff_wisnia

Yup. Kid I grew up with worked for the Forest Service. They had a problem with some people setting up broken bottles to cause fires at a later date. Some for a job, and some for kicks. The shop magnifiers had a sign warning about sunlight being focused.

Reply to
Calif Bill

I saw a car here that had a large burn mark across the inside part of roof that was caused by a compact mirror (concave) being left out on a seat or the dashboard. The char mark across the foam stuff was about a foot long.

Reply to
Cydrome Leader

Bottoms of broken bottles are a common forest fire cause.

Reply to
clare

On Tue, 30 Jun 2009 23:04:44 -0400, the infamous snipped-for-privacy@snyder.on.ca scrawled the following:

That happens here in the States far too frequently. I wish the fines the cops give to litterers would increase, including a chunk of money for firefighting. Forest fires are nasty and expensive.

-- Life is not about waiting for the storms to pass; it's about learning how to dance in the rain. --Anon

Reply to
Larry Jaques

If you say so.....

Reply to
Maxwell Lol

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