6/8 vs. 3/4

[sanfranciscian]

I am wondering why razor sizes are marked as 6/8 for 3/4 or say 4/8 for 1/2, is this because they are trying to differentiate between sizing for the blade and the level of grind ie. 6/8 razor with a 3/4 grind or 4/8 with 1/2 grind etc. it seems to be the case but i dunno?

Ian

 

[ouch]

I am wondering why razor sizes are marked as 6/8 for 3/4 or say 4/8 for 1/2, is this because they are trying to differentiate between sizing for the blade and the level of grind ie. 6/8 razor with a 3/4 grind or 4/8 with 1/2 grind etc. it seems to be the case but i dunno?

Ian

Straights are traditionally measured in 1/8" increments.

We don't need no steenking lowest common denominator.

 

[jtrops]

I am wondering why razor sizes are marked as 6/8 for 3/4 or say 4/8 for 1/2, is this because they are trying to differentiate between sizing for the blade and the level of grind ie. 6/8 razor with a 3/4 grind or 4/8 with 1/2 grind etc. it seems to be the case but i dunno?

Ian

I think you hit the nail on the head. It is difficult when the same language is used to describe two different aspects of the same razor. I can't think of a time when 1/2 didn't apply to the hollow grind, and 4/8 is the measurement in inches from the spine to the edge.

 

[huntmol]

It's just one of those things.

 

[Hawkeye5]

Mostly people not familiar with straight razors would refer to a 6/8ths as a 3/4.

 

[sanfranciscian]

it does seem logical to keep the two measurements separate to not confuse, i cant really buy in to the fact that they just use 1/8ths. because of sizes like 9/16,11/16, 13/16 because that would make 1/16th 4/8ths of an 1/8th. but it makes it fun none the less.

Ian

 

[LaughingAtFate]

Because we aren't measuring the razors in inches, We're measuring them in _eighths_ of an inch

So it's not half an inch, it's four eighths

Same again with the sixteenths...

 

[CraigJ]

Just to mess with us I think, some are puting the measurements in metric. It is probably some sort of conspiracy involving black helicopters and the Knights Templar.

 

[bonusmarple]

Mind games...

 

[StillShaving]

We don't need no steenking lowest common denominator.

Agreed. Ignoring the metric system for a moment, I wish wrenches (bolts) used the same approach. Instead of a 3/8 we could have a 6/16...or would that be a 12/32 Seriously, I would prefer to have a the denominator be the same either in 1/16 or 1/32 of an inch. Even if that meant having 6-1/2 /16 wrenches instead of 13/16.

 

[richmondesi]

A moment... We've been ignoring the metric system forever. FWIW, I wish I could speak with my teachers that told us the whole world would be using the metric system exclusively by now

 

[LaughingAtFate]

The interesting thing is, America (and England) still do use a form of Decimal distance... Admittedly it's an archaic form and confusing to most people.

The mile is a form of early Decimalised measurement, Only it doesn't use the Foot and inch as it's basis, it uses the Chain and the Furlong as it's structure (10 links make a chain, 10 chains make a furlong (1 chain x 1 furlong = 1 acre), 8 furlongs make a mile, etc)

So yeah, Archaic, but it explains why miles are such an odd number in foot distances.

Oh yeah, and to the other point, E'en though I was raised in the metric system, I still use Feet, inches and miles in my estimation of distance (though I can't wrap my head around pounds)

 

[richmondesi]

pounds are easy. They kick USD butt...

 

[drifwood]

An example from another field. If you buy unfinished hardwood lumber in Canada, the US (and some others too), the thickness is always given in 1/4's of an inch. If you ask for 2" maple, someone will say, "You mean 8 quarter maple." I quickly learned to accept this, even though I thought it was a bit silly.

Many years later I helped a friend who owns an small circular sawmill to cut out some lumber for a garage he was building. Once the slab is sawn off to make a flat surface, the log is moved closer to the blade by pulling a lever. Each pull advances it 1/4". So, 1 pull to allow for the thickness of the saw cut (the kerf) and 8 more (8/4) to yield 2" thick rough lumber. An indicator on a board would show you how many quarters you had set. And the light went on for me.

It is simplicity defined. No mathematical conversions or fractions required. 8/4 needs 8 pulls on the lever plus one (for the saw kerf). And this was a standard that applied all sawmills in operation for decades and decades. Even your dimwit cousin could master it. He didn't want to hear "four inches". 16/4 was just 16 + 1 pulls on the lever.

(This is also why we call 1 1/2" thick construction lumber 2" x 4", 6", etc. Before it was planed to final thickness, it came off the saw as 2" (8/4) rough lumber.)

Perhaps there was something similar in the cutlery business - the infeed table on the shear used to cut sheet steel to the proper width for blanks maybe.

I dunno, but I'm sure they didn't do it to make things more confusing. It was likely the exact opposite - a simple instruction to the guy running the machine. "Cut me 25 6/8 strips from this sheet stock, Johan."

It's just speculation, but I think the genesis of this measuring system came from some similar industrial standard.

Cheers,
Ian