Metric meets imperial

[MarkAR]

1 hour ago, Gina said:

My dad was a toolmaker too (amongst other things).

Seems to have handed down the skills.

 

1 hour ago, KevS said:

Hope this clear things up🤣

Well it did, as before Mr Whitworth it was a case of make a nut to fit this bolt. There were all hand turned 🤨.

You missed, square, ACME, trapezoidal, buttress and of course all the left hand versions.😉

[Ibbo!]

39 minutes ago, johnturley said:

I remember the old Orgreave Coking Plant well, used to sample the effluent there initially on behalf of Yorkshire Water Authority, and then later the National Rivers Authority.

I expect that you also used to measure the strength of the caustic soda in degrees twaddle.

John  

I dont remember that, but remember having the short straw and having to go round and collect the cooling waters and effluent waters in the middle of winter.

The bug plant was IIRC the furthest away from the lab and kept the YWA fairly happy with our discharges.

Also the blood tests every 6 and then 3 months for the nasties like benzene.

[Corncrake]

6 hours ago, Gina said:

Cameras originally had 1/4" Whitworth

Good to know someone else remembers

Is "originally" significant ? They may still be Whit ?? who knows if they are now made to UNC, , , over the short length it matters not but would be an interesting excersise one winters evening to set about measuring a new camera ?

somewhere else someone mentioned the 3/8 tripod mount, - - time was when some cameras (one of mine) came with that as the mount (Leica standard?) and I had two 1/4 to 3/8 bushes in my bag for all eventualities.  That was back when the dinosaurs roamed wild

 

Edited June 11, 2020 by Corncrake

[Marvin Jenkins]

4 hours ago, vlaiv said:

This one is easy

Although not quite coherent. If you follow the graph from foot to nautical mile, you will conclude that:

nautical mile = 10 cable = 10 x (100 fathom) = 10 x 100 x (2 x yard) = 10 x 100 x 2 x (3 foot) = 10 x 100 x 2 x 3 x foot = 6000 x foot = 6080 x foot (if you go directly)

We have 80 feet (11520 poppy seeds) missing in our calculation - or about one shackle

 

I think most of theses diagrams are just made to con people out of what they think they are buying. I once worked for a guy, for a day that asked me how many hours I had worked? I said eight.
He started in UK pounds per hour, despite being in France. Converted it to Francs despite the recent move to the Euro. Then converted to Euros. I got ripped off at every turn, hence the one day I worked for the guy.

Wasn’t there a collaborative mission to one of the planets In the past that ended in failure because the US was working in their units and Europe was working in metric? Tried to land at 30,000 KLM’s an hour what ever that is in US miles.

M

[Tenor Viol]

8 hours ago, vlaiv said:

According to wiki (I had to look it up since this is the first time I saw that English and Imperial units are different thing), American units are further evolution of English units.

Therefore - not two steps behind, but two steps behind and one to the side

https://en.wikipedia.org/wiki/Comparison_of_the_imperial_and_US_customary_measurement_systems

The Victorians revised standards and created the 'Imperial' standard. This is when the pint moved from 16 to 20 fl. oz. The Americans retained the old English standard of 16 fl. oz. to a pint. This causes recipe problems as an American 'cup' measure (which does not really exist in the Imperial system) is half a pint i.e. 8 fl. oz. So if you don't twig that and use an Imperial half pint in your recipe... it's wrong, unless you've scaled everything else accordingly. 

It also means a US gallon (8 x 16 fl. oz. pints) is 4/5 of an Imperial gallon (8 x 20 fl. oz.).

I believe the US had everything to go metric in the early 70s but I think the Watergate scandal cause the legislation to get lost? Might be wrong... 🙃 

[JamesF]

7 hours ago, wimvb said:

So do plumbers

Oh, and let's not get into some pipes being specified by internal diameter and others by external diameter!

James

[JamesF]

6 hours ago, KevS said:

where the TPI were defined using a factor dependent upon the log of base 10 of the thread pitch in mm, although the outside diameters of the threads are imperial sizes

How we laughed...

James

[sploo]

6 hours ago, KevS said:

To avoid confusion: 

Mr Whitworth the inventor of the micrometer proposed that threads should be standardised to assist in the interchangeability of manufactured components, so we had BSW with a 55 degree thread angle. Once the engineering science was refined we discovered that we could apply a higher load to the same thread diameter by increasing the TPI of the thread so BSF came to the fore, again with a 55 degree thread angle. Meanwhile on the other side of the pond ANC and ANF (American National Coarse and American National Fine) (60 degree)  were utilised for the same reasons. There was a attempt to "unify" the thread types during the second world war, as a consequence a third thread type was utilised namely UNF & UNC (Unified National Fine & Coarse) with a 60 degree truncated thread form. However from around  1903 the British Association (BA) threads were already in use mainly on electrical equipment and to avoid confusion they had an included angle of 47.5 degrees, where the TPI were defined using a factor dependent upon the log of base 10 of the thread pitch in mm, although the outside diameters of the threads are imperial sizes. Although BA screws are predominantly manufactured in brass they should not be confused with BSB (British Standard Brass) that have 26 TPI on a 55 degree included angle regardless of diameter. These in turn should not be confused with BSC (British Standard Cycle) threads that over lap at 26 TPI as BSC threads have an included angle of 60 degrees (however a 26TPI BSC tap would be designated 26TPI BSB). Model engineering (ME) threads look similar to both of the former but are generally only available in 32 or 40 TPI sizes.  There was of coarse a necessity to thread pipe work together as a consequence BSP (British Standard Pipe) is utilised and the thread size is determined by the nominal internal diameter of "schedule 40" tube, dependent upon the application these threads are available in either taper or parallel thread forms of 55 degrees. However we have to be mindful that BSP threads look superficially similar to NPT (National Pipe Threads) that have a 60 degree internal thread angle. Both of these pipe threads should not be confused with ET (Electrical threads) which is applicable to non pressurised systems namely conduit and is similar to the PG 80 degree angle (so called Japanese designation) for conduit threads but as ever they are not interchangeable. 

Hope this clear things up🤣

Having rebuilt and restored numerous old bits of machinery, the above is particularly pertinent (and amusing). The old British Startrite table saws are great, but you'll find that the thread used for the rails on which the fence sits is a 1/2" 12 TPI (which was a curveball, as I'm more used to UNC... which just happens to be 13 TPI at that thread diameter - one of the few sizes where BSW and UNC differ). The side rails for the sliding table models are in metric, the grub screws that adjust the table insert plate are BA, and the threads in the fence are either BSW or metric, depending on the vintage.

The next machine I rebuilt was an Austrian made planer. Everything was in metric.

Oh, and don't even get me started on threads in Stanley hand planes... such as the not-available-anymore #12-20...

[sploo]

1 hour ago, KevS said:

...where the size of the hexagon was reduced to save metal, hence a 3/4 Whitworth spanner now fits a 7/8 bolt head...

Oh yeah - that's another good one; plus the differences in the hex sizes on BSW and BSF (whereby one spanner fits the other, but offset by one size).

[sploo]

2 hours ago, Marvin Jenkins said:

Wasn’t there a collaborative mission to one of the planets In the past that ended in failure because the US was working in their units and Europe was working in metric? Tried to land at 30,000 KLM’s an hour what ever that is in US miles.

Yep: https://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Encounter_with_Mars

I was working in the space industry at the time. The fact that non-SI units had been used anywhere (for that application) was just crazy.

[Tenor Viol]

2 hours ago, Corncrake said:

Good to know someone else remembers

Is "originally" significant ? They may still be Whit ?? who knows if they are now made to UNC, , , over the short length it matters not but would be an interesting excersise one winters evening to set about measuring a new camera ?

somewhere else someone mentioned the 3/8 tripod mount, - - time was when some cameras (one of mine) came with that as the mount (Leica standard?) and I had two 1/4 to 3/8 bushes in my bag for all eventualities.  That was back when the dinosaurs roamed wild

 

Having just bought a short dovetail plate to attach my cameras to, I realised that I needed a tripod head since there was no obvious way of adequately tightening the 1/4" bolt on the camera. So, I buy an iOptron tripod head. This takes the 3/8"-20 bolt. Fortunately, it comes with a 3/8 - 1/4 bushing... so screwed that in to the tripod head and then the 1/4" bolt through the dovetail plate and into the tripod head and all solved.  

[Tenor Viol]

There is the oddity that the Nautical Mile and Knot (1 Nautical Mile per hour) are SI units. This is because the NM is based on a 'sensible' definition of the distance subtended at the equator by one minute of arc.... 

[Guest]

Is it true that some SGL members are that old, that they used to use the cubit for measuring out distances?🤔🤣

[Corncrake]

45 minutes ago, JamesF said:

Oh, and let's not get into some pipes being specified by internal diameter and others by external diameter

Including waveguides - on this side of the pond and over yonder !

Or, "as well as waveguides", if you dont want to call them pipes

[Corncrake]

26 minutes ago, Tenor Viol said:

There is the oddity that the Nautical Mile and Knot (1 Nautical Mile per hour) are SI units. This is because the NM is based on a 'sensible' definition of the distance subtended at the equator by one minute of arc.... 

They are not SI base units, but they can be derived, I dont think they are named derived units though are they ?

(OT) I dont like named SI units. You can feel lbs/sq.in or kg/cm² but whats a Newton when its spread out ?

ducks

(/ot)

and dont get me started on cycles/sec, they just hertz.

Edited June 11, 2020 by Corncrake

[Guest]

7 minutes ago, Corncrake said:

and dont get me started on cycles/sec, they just hertz.

Hertz or just irritates?🤔🤣

[John]

It is odd when metric and imperial are mixed but I'm as guilty of that as anybody

I refer to 1.25 inch or 2 inch eyepieces and then give their focal lengths in mm and also to my scopes apertures in inches but their focal lengths in mm

I'm going to use cubits and palms from now on

 

[wimvb]

11 hours ago, Ken82 said:

Thanks to StubMandrel  I now have a converted ADM losmandy plate that fits my primalucelab scope rings. Isn’t it a pain the US work in imperial and Europe work in metric ! 

So what have we learnt from this?

That manufacturers can cut a losmandy plate any which way they like and it will be exactly 42 units long.

[wimvb]

2 minutes ago, John said:

It is odd when metric and imperial are mixed but I'm as guilty of that as anybody

I refer to 1.25 inch or 2 inch eyepieces and then give their focal lengths in mm and also to my scopes apertures in inches but their focal lengths in mm

I'm going to use cubits and palms from now on

 

And how many stone is the load capacity of your mount?

[John]

2 minutes ago, wimvb said:

And how many stone is the load capacity of your mount?

Limestone or granite ?

 

[Xplode]

2 minutes ago, wimvb said:

And how many stone is the load capacity of your mount?

Depends on the weight of the stones 🤣

[wimvb]

4 minutes ago, John said:

Limestone or granite ?

 

Limestone, I'm not taking anything for granite.

(That was all too easy)

Edited June 11, 2020 by wimvb

[Corncrake]

28 minutes ago, merlin100 said:

Hertz or just irritates?🤔🤣

Yes, you got it. A right royal   imperial pain in the , , but that would be impolite on a family forum let us just say ,, in the sensibilities.

 

[wimvb]

8 minutes ago, Xplode said:

Depends on the weight of the stones 🤣

According to wikipedia:

"The stone or stone weight (abbreviation: st.)[1] is an English and imperial unit of mass now equal to 6.35 kg (14 pounds).[nb 1]

England and other Germanic-speaking countries of northern Europe formerly used various standardised "stones" for trade, with their values ranging from about 5 to 40 local pounds (roughly 3 to 15 kg) depending on the location and objects weighed. "

[Corncrake]

1 hour ago, wimvb said:

 (roughly 3 to 15 kg) depending on the location

Gosh, I didnt know gravity could differ that much across the globe, even though I did start out in physics when its effect was measured in poundals**      ducks,   again.

Is it not being a bit pc, nay pedantic, for wiki to distinguish them as units of mass when it was a unit used by yokels weighing their allowance of gruel, and young school lads seeking distraction by reading the backs of their exersise books (< ok go on, who remembers those )

 

** or maybe 'Sir' just had an evil sense of humour

Edited June 12, 2020 by Corncrake