Metric or imperial ?

[normspanners]

I can work in Fahrenheit and Centigrade no bother.

So can I, but prefer it to be about 20 C

 

[Spark plug]

Degree's are the only unit I can think of that are standard ware ever you go.

But I always struggle with minutes and second of a degree.

 

[Paul.]

Degree's are the only unit I can think of that are standard ware ever you go.

But I always struggle with minutes and second of a degree.

Never used radians in a calculation then..

 

[Turbo]

I was only ever taught metric at school and I when doing metalwork it's what I still use. But my lathe is imperial & I'm starting to have to think in thou's as well. As for the lathe, a myford ML7, There are 6 different threads used on it, a nightmare when it comes to restoration. There's unf, unc, bsf, whitworth, BA and metric and the parts list isn't very accurate either. The introduction of metric threads was a good idea to simplify things if only everyone would use them.

When it comes to woodwork I would tend to use imperial. As others have said, fractions are so much easier to divide up without ending up at an awkward figure and timber is mostly still sold in feet and inches.

I have 2 boxes of imperial drill bits but whatever way my brain is wired I have to convert the size to metric when drilling holes. Where I used to work we only used imperial bits because our boss reckoned they are better sized when drilling pilot holes for tapping and clearance holes for bolts without buying expensive in 0.1 mm metric sets.

 

[langy]

Leyland trucks still used a mixture of all the different threads even up until around the millennium.

for some crazy reason seat belt bolts are 7/16 unf and will screw into suspension mounts in mitsubishi evo 9-10 suspension mounts that use 11mm (and maybe others) they feel perfect and screw in by hand until they are stressed and the thread rips out !!

Why would you screw a 7/16 unf fitting into a metric thread ???

 

[langy]

Metric bolts are much cheaper than imperial bolts

 

[taycat]

had one of my schools projects graded lower cos i did it in imperial teacher was struggling to work it out.
was what i was brought up using, only do metric when necessary.
Tay is like me and can flip between the two.

 

[premmington]

I am aged 48, I do everything in metric! Measurement wise!

I even weigh myself in kilos! And my height is in cm.

I look at fluid in litres not gallons, even beer in 1/2 litres!


But I still travel 2 miles to work! At 30MPH

Km and Kmh means nothing to me! Nothing at all.


.

 

[normspanners]

Why would you screw a 7/16 unf fitting into a metric thread ???

Because it happens ---
It has happened on a few of the cars i was involved with when the cars where stripped to go for acid dipping, all the bolts not used would get thrown into the spare various bolts bin, but they thought all the bolts would all be metric. because it was jap.
Then somebody would go looking for a few particular bolts and found one that would screw in because 11mm is not a common size, and thought that the bolts where correct because they screwed in with your fingers no problem.
I was just making the point that some threads are VERY close and appear to work until stressed
as per an uk airliner thats windscreen was bolted in, the engineer guy replaced the seal and used new bolts but found metric not unf, it was fine until it got to 17,000ft then the screen blew out taking the captain with it.

Investigation[edit]
Accident investigators found that a replacement windscreen had been installed 27 hours before the flight, and that the procedure had been approved by the shift maintenance manager. However, 84 of the 90 windscreen retention bolts were 0.026 inches (0.66 mm) too small in diameter, while the remaining six were 0.1 inches (2.5 mm) too short. The investigation revealed that the previous windscreen had been fitted with incorrect bolts, which had been replaced on a "like for like" basis by the shift maintenance manager without reference to the maintenance documentation, in order to save time as the plane was due to take off soon and there was a tight schedule.[5] The air pressure difference between the cabin and the outside during the flight proved to be too much, leading to the failure of the windscreen. The incident also brought to attention a design flaw in the aircraft of the windscreen being secured from the outside of the aircraft, putting a greater pressure on the bolts than if they were secured from the inside.

Investigators found the British Airways Birmingham Airport shift maintenance manager responsible for installing the incorrect bolts during the windscreen replacement and for failing to follow official British Airways policies. They also found fault with British Airways' policies, which should have required testing or verification by another individual for this critical task. Finally, investigators found the local Birmingham Airport management responsible for not directly monitoring the shift maintenance manager's working practices.

 

[normspanners]

Why would you screw a 7/16 unf fitting into a metric thread ???

http://honda-tech.com/honda-civic-del-sol-1992-2000-1/m11-1-25-bolt-where-can-i-find-them-1979336/
read this mainly post 8 it might explain why someone would !!

 

[Pete.]

That windscreen story is scary!

This kind of thing is why I always grab hold of any non-standard metric pitch tap or die I find. I once had to make the bolt below for a guy to hold the generator on the end of an old MZ motorcycle crankshaft (M7 x 1.0). Lucky for him I had a M7 die.

 

[doubleboost]

I use both
Now that I have a metric lathe , I am using metric more
Strange that on most hydraulic / air fittings they still use BSP
Camera mount threads are ether 1/4 or 5/16 Whitworth

 

[normspanners]

Strange that on most hydraulic / air fittings they still use BSP

Toyota forklifts use standard bsp hydraulic fitting thread but reverse flange IE similar to jic with the cones the other way.

Just to be awkward IMO

 

[ronan]

The worst thing are proprietary threads, eg threads that only one maker produces. One that springs to mind are the tiny screws that are used to hold tct tooling to shanks or boring bars etc. They charge you a fortune for a tiny little screw if you drop it on a lathe or mill and cannot find it.

 

[Gareth J]

I think most people (and it is reflected in many of the replies above) use the measurement that implies the level of accuracy they working with best.

"I'm 10.5 stone" to say "I'm 66kg" is too accurate. A sturdy bowel movement or a heavy pair of jeans could throw you way into the next kg.

Also, it's legacy. If a 12' gate fits in a 12' gate place, you're not going to measure it up in mm.

But the thickness of plyboard for example is better suited to mm, no need to get involved with fractions and the size of increment iis appropriate for the job, way more so than the inch.

By using both we can fit in with things that already exist, stick to nicer, round numbers and imply a level of tolerance/accuracy.

 

[ronan]

Various threads from my 1918 "machinery's screw thread book" (i must remember to buy some war bonds)

whitworth standard
whitworth small
british standard fine
british association threads
standard brass threads
admiralty fine thread
standard pipe thread
cycle engineers institute threads
standard automobile threads
royal microscopical society's threads
royal photographical societys threads
threads for hydraulic piping
copper tube screw thread
model engineers standard thread
sparking plug threads
standard threads for steel conduit
lowenhertz thread
french standard threads
united states standard threads
united states society of automobile engineers thread
cadillac screw thread
waltham watch screw thread
acme screw threads
briggs standard pipe thread
standard worm thread
square thread
buttress thread
harvey grip thread
Finally metric threads.

maybe it was a good idea to try and standardise threads and reduce the amount of different ones used ?

 

[ronan]

Never used radians in a calculation then..

2 x pi ? Yeah i remember them from starting maths in college, never heard of them previous, or coulombs or a henry.

 

[brightspark]

is gas thread on that list

 

[Pete.]

Details of gas threads can be found here...

 

[doubleboost]

Details of gas threads can be found here...

LOL
Automotive oil pressure switches are normally 1/4 gas