#10 screw and 3/16 screw

[Paul Alciatore]

Just to add a bit of interest to our lives...the tapped holes in those aluminum 19" server/relay/telecom racks full of high tech equipment are usually#12-24.

Only the computer nerds and the telephone people are stupid enough to use racks with 12-24 holes. The radio and TV industry uses 10-32. I have bought dozens of the racks and thousands of the screws. Always 10-32.

[DATo]

The switch from Inch to Number measuring for "small" threads produced some
wierdcases. These are generally threads less than 1/4"
In Number Screw sizes, You start with .060 as a base and it is a 0-80 thread, or 0-72 etc.
( Please note that .0625 is 1/16 , so " )" is close to that fraction benchmark)
Each sequential thread size grows by .013" and gains one digit.
A 1-72 for example is .073" and a 2-56 is .086 in the "Major Diameter" measurement.
A 10-32 is .060 PLUS .130 ( 10 x .013) or .190
Your old 3/16 thread is .1875"
The only "exact" one is 1/8-40 (ie.) as it meets a 5-40 (.060+.065) at .125 dead on.

Real confusion is with the #14 threads (.060 + .182) as its .242
So if you have a 1/4 -20 bolt, it will not fit a 14-20 hole !

Old machines and hardware still use the old standard of 100 ago

Its a lot easier, to refer to numbers than fractions.
Can you imagine doing a 5/64-72 or a similar ?
It was an attemp to make the range smaller than 1/64's
Of course it doesn't get a simpler than Metric..but I won't go there

Rich

Excellent post Rich !

Don't mean to nitpick but I just wanted to mention that the number series screws actually start with "quad-aught" 160's (0000-160) which have a major diameter of only .021" dia. The smallest I have ever seen are triple aught 120's with an O.D. of .034" and we actually have them as well as the taps in our shop. I can no longer see the threads without a magnifying glass. To be honest I can't remember the last time we used them though but we have used them - it's been probably literally decades ago as near as I can recall.

[WhatTheFlux!]

"Uh this machine is set to metric, how do I set it back."

"You can't it's Canadian."

"Ok, so what's 310 in F then?"

"Hot enough to melt nylon."

"...Yeah but I need to know what it is in F."

"No you don't. Just go with it."

"And what the hell is BAR? And everything is in MM. I can't run this."

"We've run it for three years without issue, maybe the problem is you?"

"No the problem is the machine uses non-standard measurments that I don't understand and I'm not about to learn. THIS IS AMERICA the rest of the world should be using our measurment system... not some system invented in France. What the **** is wrong with that picture? That's right, FRANCE. I REFUSE to use anything produced by the French or invented by the French."

"Ok... you're fired. Plain and simple. No one else had a problem with this, and on top of that while I have no great love of France or French culture we do have French and French-Canadian customers. Can't have you badmouthing the folks who pay us."


----
This happened about six weeks ago. His attitude changed real quick, started backpeddling real fast when I threatened him. Now he's "down" with metric.

I never had any issue switching from one to the other, and I can think in metric just fine. Never had a issue. Only time problems cropped up for me was during conversion. That's when I decided to just think in metric for those applications rather than screw around with numbers.

[Shade]

The best reason NOT to use the Metric system... it's French...

[WhatTheFlux!]

Hating on the French is soooooo 10 years ago. Get with the times man.