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Metric V Imperial Measurement

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Ray Lyons07/02/2020 20:22:35
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Went to the hospital recently to see a consultant. On arrival, was taken into a side room for measurement, weight, height, blood pressure etc. Height came in at something like 1.7 and weight at 70. I soon got the brush off when I asked what these figures meant in British money. After all don't they quote baby's weight in pounds and ounces and the police give heights in feet and inches when describing a person. I wonder if Brexit will mean a return to British standards such as BSW and BSF.

on a more serious note, I have to change some storage cupboard doors to flush mahogany ply. The fitted doors are a little wider than the new ones so I glued some extra lipping strips on to make up the width with the intention of trimming the excess overlap ( an excuse to buy a new palm router)

Ordered a router advertised as fitted with 1/4", 3/8" and 1/2" collets. After a few weeks, I bought a 1/4" shank trimming cutter and today decided to try it out on a piece of scrap timber. The cutter would not fit so I checked the sizes of the collet and the cutter. Collet is .236in (6.4mm) and the cutter is .246in.

The collet appears to be hardened so I think the best way out is to grind the bore using a small grinder in the lathe. If anyone has any experience of grinding a collet I would appreciate your advise.

Brian H07/02/2020 20:28:24
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My hospital (Kings Mill in Mansfield) keep conversion charts and are only too happy to quote measurements in English.

Brian

JasonB07/02/2020 20:30:46
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Posted by Ray Lyons on 07/02/2020 20:22:35:

Collet is .236in (6.4mm) and the cutter is .246in.

The collet appears to be hardened so I think the best way out is to grind the bore using a small grinder in the lathe. If anyone has any experience of grinding a collet I would appreciate your advise.

I think you will find 0.236" is 6mm give or take a nats.

Better to buy a 1/4" collet for your router or get a 6mm bit. I'd opt for the collet as 1/4" shank tools are still far more common here in the UK than 6mm

What make is the router, 1/2" capacity sounds massive for a small palm router.

Edited By JasonB on 07/02/2020 20:38:45

Derek Lane07/02/2020 20:40:04
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Contact the seller and ask for the correct collets as it is advertised as imperial

lfoggy07/02/2020 21:08:08
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Medicine and science in the UK have been fully metric for decades (certainly long before I qualified in the late 1980s). Even in the USA, the last bastion of of Imperial weights and measures, medicine and science largely abandoned pounds and ounces years ago. If you do want quick conversion though, there are many simple charts and apps to assist.

Curiously, we still measure blood pressure in the archaic units of mm mercury (mmHg).

Vic07/02/2020 22:41:48
2912 forum posts
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I bought a router recently that came with 1/4” and 3/8” collets as standard. I also bought 6mm and 8mm collets for it though at the same time. All the new router bits I’ve bought for it are 6mm but I do have plenty of old 1/4” ones as well.

Steviegtr07/02/2020 22:56:00
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Wouldn't it be awesome if we went back to imperial. Stuff the rest of the world. Rule BRITANNIA. Britannia rules the waves.

Steve.

not done it yet07/02/2020 23:26:25
6321 forum posts
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Curiously, we still measure blood pressure in the archaic units of mm mercury (mmHg).

Archaic to be in mercury, but metric, nevertheless. Was it ever measured in inches of mercury? Or even inches water gauge?

Steviegtr07/02/2020 23:32:08
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Posted by not done it yet on 07/02/2020 23:26:25:

Curiously, we still measure blood pressure in the archaic units of mm mercury (mmHg).

Archaic to be in mercury, but metric, nevertheless. Was it ever measured in inches of mercury? Or even inches water gauge?

You may have a point. Metal pipe fittings are still in BSP.

Steve.

Ian P07/02/2020 23:32:23
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2524 forum posts
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On Wednesday this week I had an X-ray scan at a local hospital where my weight and height were measured in cm and Kg, The radiographer then looked at the two conversion charts on the wall and entered in the imperial values on her paperwork!

I was somewhat surprised but she assured me that how it was always done (maybe she meant thats how she had always done it)

I bet whoever interprets the images and processes the paperwork has conversions charts at their desk to convert to metric units!

Ian P

Steviegtr07/02/2020 23:32:24
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Oh & MPH

Mike Poole08/02/2020 00:30:21
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If drawings are dimensioned in thousandths of an inch then machining and measuring are easy unless you prefer a ruler. Drawings dimensioned in fractions of an inch are a pain as machines do not have dials in fractions. Metric is no problem if you think a millimetre is 40 thou. Metric is the way forward even if like me you are familiar and comfortable with both systems.

Mike

Bill Pudney08/02/2020 01:38:27
563 forum posts
24 photos

For what it's worth, in the mid 70s I was fortunate enough to be working as a ships draughtsman on the T22 frigate which became HMS Broadsword. This ship was all metric, and I was told that it was the first ship classified as "metric" to be designed and built by the MOD(N)

Since then I have been happy using either imperial or metric, although my preference is for metric, so much more logical than basing a system of measurement on the length of a random thumb, or forearm or whatever!!

cheers

Bill

S.D.L.08/02/2020 03:53:26
236 forum posts
37 photos
Posted by Steviegtr on 07/02/2020 22:56:00:

Wouldn't it be awesome if we went back to imperial. Stuff the rest of the world. Rule BRITANNIA. Britannia rules the waves.

Steve.

NO

Steve

Speedy Builder508/02/2020 07:20:59
2407 forum posts
191 photos

As my Dad used to say - Can you imagine a simple plate 1m x 1m, now put 1Kg load on that and slip your hand under one corner of it. No Can't imagine that. Now, take a simple plate 1ft x 1ft, place 1lb on the plate and do the same - yes, I could imagine that. But we move with the times.

JasonB08/02/2020 07:27:44
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Posted by Steviegtr on 07/02/2020 23:32:08:
pipe fittings are still in BSP.

Depends where you are getting them, most of the metric world works with "G" threads now wink

Brian G08/02/2020 08:08:50
782 forum posts
34 photos
Posted by JasonB on 08/02/2020 07:27:44:
Posted by Steviegtr on 07/02/2020 23:32:08:
pipe fittings are still in BSP.

Depends where you are getting them, most of the metric world works with "G" threads now wink

First class stirring.

I love the fact that there is no longer any connection between the BSP/G size and that of the pipe. It shows that sometimes practicality is allowed to override order.

Brian G

Robert Atkinson 208/02/2020 08:25:42
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1086 forum posts
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Aviation is still mostly imperial but is slowly coming round to metric, It can't come soon enough. On pipe fittings, SMC pneumatcs came up with Unithread male fitting with a special thread form that fits G Rc, NPT or NPTF female. Sealing is by a captive gasket.

Robert G8RPI.

JA08/02/2020 09:01:39
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1222 forum posts
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Some years ago, looking through a German table of metric threads, I found this (from memory) -

M6,35 x 1,25 x 55degrees.

In the drive to replace non-metric threads they had to admit defeat when it came to the universal camera mounting thread.

JA

Chris Evans 608/02/2020 09:19:11
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1959 forum posts

I spent my 50 years working life in toolmaking. About half using imperial and half metric, no problem using either. My home machinery is metric as that is what I found when needing machines. Tinkering around with old British bikes I mainly work with imperial measurements without problems. I do stop and think when sizes come up in centimetres and quickly multiply by ten. Post Brexit will we buy petrol by the gallon again ? Nudging £6 a gallon will make folk stop and think !

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