What did you do Today 2018

My plan is to put the fire out by throwing petrol at it!

Only criticise the Newton if you understand the difference between a Pound(force) and a Pound(weight) and use the Imperial system's Slug.

After wrestling with Slugs for 5 minutes the logic of SI might win a few converts. If not do some calculations in Slinches.

Go to the bottom of the class if you love imperial and can't explain what a Blob is...

Dave

That's me to the bottom of the class then!

I started using metric (and Imperial) as an apprentice with a company making large diesel and gas engines. They decided to build a French engine under license and equiped a department with all metric tooling with the instruction that no conversions would be allowed, if you had your own measuring equipment then it must be metric.

Nowdays I model mid 19th century traction engines and I'm blowed if I'm going to convert everything to mms.

Brian

It's an in joke here, mitre bond is basically a huge bottle of superglue plus a big activator spray. You can use it to glue anything to anything, even bishops.

Neil

I was trained in both imperial and metric and am happy to work in either - but only came across slugs and blobs last month while studying 'Design of Machinery'.

You learn something new every day - whether it's useful or not remains to be seen

Lionel

Edited By Limpet on 04/02/2018 21:48:45

1 slg is the mass that accelerates at 1 ft/s/s when acted on by a force of 1 lbf.

But we should use the Poundal.

1 pdl being the force that accelerates a mass of 1 lb at 1 ft/s/s.

To complete the set, 1 lbf accelerates a mass of 1 lb at 1G.

My problem is that the slug has lbf in it's definition so it should be measured at Greenwich to be truly Imperial.

But if the lb is defined against the standard kg maybe you measure it at Paris.

Instead it is usually defined at the Equator which is neither here nor there.

My brain hurts.

The change to SI units came when I was struggling with thermodynamics and structural engineering at university. It made life so much easier for me. But like Neil, I have struggled with the cross slide on the metric lathe, so I have a little scribble written down on the headstock - 1 div = 0.04, 10 div = 0.4mm - and now life is easy! I don’t know why this particular thing has been a mental block.

On a related note, I watched a Lawrence Krauss video the other day, which demonstrates how convenient it is to work with metric units and exponents to get good approximations - https://youtu.be/h9FurAf4C4g

https://youtu.be/h9FurAf4C4g Sorry, trying to embed a YouTube video on an iPad seems to be an impossible feat for some reason.

Edited By Steve Pavey on 05/02/2018 09:35:47

Now there is an interesting point,(arising from Brian’s post).

Roughly how many out there measure their car engine size in cubic inches (excuding our US members on this one)?

SI is here to stay, until a system arrives that explains the theory of the Universe more precisely. So get used to it, I say. I have lived though ergs, dynes, british thermal units, centimetre seconds, kilogram metres, acres and hectares. I know which are simpler - the metric ones. Working to one base is far easier than converting pence to shillings or ounces to pounds, etc.

I simply accept that my lathe or mill is imperial and live with it. The only problem with any lathe might be cutting threads of the ‘other system’. Not a big deal for almost all of us - just a pain changing gears.

One of the biggest drawbacks is one of scale. How many (in the UK) make scale models of 1 to 10? For faithful scale models of trains built in feet and inches it is easier (for most) to scale model plans at 1/3 or 1/12 scale, i suppose, as the original drawings were in that system.

Sometime, in the future, the boffins might make some better sense of time, but maybe never - as we will still orbit the Sun in a year, rotate on our axis once every day (yes, defined as such!), etc. I think that fixing (standardising) the speed of light wad a good move, but that may have repercussions in the future....

What about the car engines quoted in cc,or litres, while the bore and stroke are measured in inches, and tolerances in thou.

Ian S C

Edited By Ian S C on 05/02/2018 10:58:42

Hear Hear!

Ian P

Um, I think nature did that!

Well it certainly confines us to moving into the future or at best staying in the present.

:0)

Martin

Personally though I think MPa's are quite a handy unit and certainly easily 'visualisable' at near on 10 atmospheres and are the riht sort of size for high pressure systems.

regards Martin

I printed it all out on a sheet of A4, metric and imperial!

If I could find the document I'd upload it...

Was it A4 or American Foolscap? Just thought I'd throw in another measurement...

Did anyone else buy , or recall buying , potatoes in gallons? (10 lbs = 1 gallon) Always so in my (very distant) youth!!

rgds

Bill

Thank goodness that has stopped.

I could get New Potatoes in my Escort, but King Edwards are a real pain. So messy.

Gazza

Finished the piston rod oilers for a tank engine on a steam railway (the bit with a just-visible ring in the top pic):

Simple parts, but not so easy. The main thread is a total batsrad - M22,46 (prob 22,5) x 2,5 as near as I can measure. It would've been nice to've had one o' them 3-wire spiral gauges to measure the originals and work to that, but nothing like that was to hand, so I just started from the OD and cut the thread to just under the 1,53 nominal depth for 2,5 pitch.

The only gauge I had was the loco sitting in the shed, and my lathe is in my garage.

So I've ended up with a bit more of a rattling good fit than I'd like, possibly due to the crest flat I had to put on my screwcutting tool to stop the tip breaking off. I'm hoping that good old PTFE tape will resolve any problems.

I'm sure they'll let me know...

Edited By Mick B1 on 05/02/2018 13:29:12

Wonderful naming of that size of US paper.

I have worked on aeroplanes & in general engineering & find that I can drop from one unit system into the other, but find a certain amount of difficulty relating between the two. For me, it's metric in millimetres to use at home. But I will refer to inches (by which I mean 25mm), feet (300mm), yards (900mm), pounds (500g) and pints (500cc) in my own form of metricated imperial when making rough adjustments for people stuck in the past who use superseded units.

Regards,

Richard.

Used to buy shrimps by the pint, back when shrimp and melon was cool as a starter. My friend who was a miller, as opposed to a milling machine operator, used to get orders from older farmers for feed in bushels, which he had to convert to metric to comply with trading standards.

On metric lathe cross-slides, I've always understood that the dial is calibrated in diameter as standard, so if you feed in an indicated 1mm it actually moved 0.5mm - which is logical to me. 4 metric lathes I've used have followed that convention. I usually work in diameter mode now I do CNC turning too, though in Mach 3 it is slightly odd that you program the wizards with cut depth and it takes twice that off the diameter in the g-code.