Can a metric baby do imperial?

[JasonBModerator @jasonb]

Ah but they would want top make the Ultrafabwonderwidget first which will take even longer 😉

Depends a bit what your hobby is and how much free time you have. If still working and with family commitments and the workshop is just a tool to support your other main hobby then you may want to get things done quicker than a retired person who has all day to potter and contemplate then maybe get round to making the tool to make the part.

[Howard LewisParticipant @howardlewis46836]

As a hobby, time is what we invest in a project, and material m(If we don’t think it good enough, we bin it and make another, where possible)

In industry, if the object is to make and set 5,000 injection pumps, and 20,000 injectors, that work satisfactorily,  every day. The machines are specialised, automated, and integrated into a transfer line

But the cost is HUGE and amortised across the millions produced each year.

On a hobby workshop, if the time were charged at industrial rates, where the machines are general purpose, (Not industrial quality and not driven to their limits all day and every day) we would be horrified at the cost of one component.

Most of us cut metal for pleasure, not profit!

Howard

[CirclipParticipant @circlip]

As a retired person, I strongly resent being classified as a Potterer! Sad that a so called “Moderator” holds this opinion. In discussion with a mate, he said that he ‘Pottered’ when straightening nails for reuse. Have always maintained that the journey in making toy trains to toy planes and all points in between A to B may be detoured and making things to make things is part of the equation.

Fortunately my interest was fired more than seventy years ago, long before the “Spare cash” and “Where do I buy it” brigade.

Ian.

And not even a regards with this reply.

[Graham MeekParticipant @grahammeek88282]

As someone who worked for several years in a “Jobbing Toolroom” and someone who might be considered a “Professional”. I find the comment concerning “Economics” and “Professionals” to be offensive. I can assure him that time is money in such an environment. Or maybe I have interpreted this all wrong, again?

I am with Circlip, as regards some of the comments made by this particular “Moderator”. At 72 years of age I try to work as efficiently and quickly as I can in my workshop. Even here time is money. I have to pay to heat the place and the electric I use to produce the items which I cannot buy. The longer it takes the more it costs.

As an example. I have recently purchased a chuck for my Emco C5. They no longer make this direct fitting chuck, nor are there spares available, so the repair of the damaged one is the only option. I have the skill and the facilities to do this, so I shall. If I take longer than my target time I shall be very annoyed, with myself.

Just remember, Stone was replaced by Bronze and then Iron. We move on, or we die out, like the Stone age ancestors.

Regards

Gray,

 

[Howard Lewis]

On Howard Lewis Said:

[…] It will not change the part whether we measure it as 1/4″ or 6.354 mm

[ ahem ]

… I make that a four micron discrepancy, Howard

Maybe time for a new calculator 🙂

MichaelG.

.

Edit: __ my apologies for the superfluous comment … I now see that Duncan had already addressed this.

It’s been a rough week.

[SillyOldDufferModerator @sillyoldduffer]

Appears that Graham and Circlip don’t understand what moderators do. They apply the forum’s Terms and Conditions and Code of Conduct.  There’s no requirement to pander to individuals!

Gray said:  ‘As someone who worked for several years in a “Jobbing Toolroom” and someone who might be considered a “Professional”. I find the comment concerning “Economics” and “Professionals” to be offensive. I can assure him that time is money in such an environment. Or maybe I have interpreted this all wrong, again? ‘ 

Yes, Gray you have got it wrong again, taking offence, when none is intended.  That time is money is exactly the point I’m making, and it’s directed at members who may not know that yet.  You’re offended because I’m telling you something you already know and agree with, and I have no idea what that is.  That Gray knows stuff and works to a high standard doesn’t mean that everyone else on the forum is too.   My posts aren’t about Gray, so he shouldn’t take the hump!

Model Engineering is a hobby enjoyed by professionals and amateurs.   Covers a wide range of skills, equipment, talent, and time spent.  Everything from the chap with a few hand tools under the stairs up to a large fully equipped workshop.  Pottering is fine, so is working at Victorian piece rates, if that’s what’s wanted.  It’s a hobby, with no particular rules.  BUT, the hobby is influenced by the outside world in interesting ways, sometimes controversial.  Let’s not pretend otherwise.

I say engineering issues are worth discussing on the forum.   The forum would be empty without them.  Examples include:

• Fitting versus the American System of Manufacture
• Understanding that words like quality, power, work and energy have particular technical means.
• Metrology – beginners buying unnecessarily expensive micrometres and Gauge sets etc.  Or more experienced chaps expecting uncalibrated second-hand equipment to be “good enough”, without specifying what that is.
• Believing brand-names protect second-hand equipment from historic damage.  Nope, condition is all!
• Traditional methods vs modern alternatives, such as HSS vs Carbide inserts
• Modern methods and new technology: CAD/CAM, outsourcing production, microcontrollers, computers, and much else
• The apparent decline of ‘Model Engineering’ and the rise of ‘Makers’
• Relying on experience without checking it’s still valid.
• Imperial vs Metric
• Health and Safety
• Electrical, mechanical and electronics
• How economics matter, understanding they apply differently at home and at work.
• What influences industry – such as what happens to a steel works when the local coal has all be burnt. Change!
• Risk Management
• Energy futures
• Understanding EMC
• Industrial history and learning from past mistakes.
• Continual improvement methods
• Theory vs Hands-on

I’m on the forum to help, learn and educate.   I’m not here to please individuals or pretend everything is simple.   There’s no obligation to read any of my posts.   All I ask is that if they are, it’s done without jumping to emotional conclusions. Follow my logic and evidence, don’t expect it to fit the consensus, and remember I might be right.   I’m widely read…

Happy to correct mistakes and explain misunderstandings.   Don’t expect me to kowtow though!    Gray and Circlip and others can take offence as they like, but I’m not going to change unless they show good reason.  I suggest an emotional reaction to ideas they dislike is their problem.  Before shooting from the hip, please consider the value of the idea.  You might learn something!  Or be able to explain where I went wrong.  Studying ideas and thinking out of the box is good, not bad.

Dave

[Graham MeekParticipant @grahammeek88282]

“Professional machinists should take a crash course in economics!”

[CirclipParticipant @circlip]

Gray, perhaps you and I should stand our lathes on the headstock end and get some lumps of clay?

Regards  Ian.

[Graham MeekParticipant @grahammeek88282]

Hi Ian,

I am not really into ceramics, but I get the pun.

I fear the personal comments made have done more damage than the person in question can realise.

Regards

Gray,

 

 

 

[DalboyParticipant @dalboy]

I found this definition of Pottering

 

“Pottering about” is a British idiom that means to spend time doing small jobs or other things in a relaxed way.

[Dalboy]

On Dalboy Said:

I found this definition of Pottering

 

“Pottering about” is a British idiom that means to spend time doing small jobs or other things in a relaxed way.

Splendid ^^^

”in a relaxed way” covers it very nicely

MichaelG.

 

[Howard LewisParticipant @howardlewis46836]

Michael,

Quite right.

Not calculator failure, just a persistent memory.

“354” figured greatly in my life for many years, with “6.” before it!

Howard

[Michael GilliganParticipant @michaelgilligan61133]

I really shouldn’t have mentioned it, Howard

… it’s just that as an amateur microscopist, four microns is big enough to define a ‘region of interest’

MichaelG.

[derek hall 1Participant @derekhall1]

I have a myford ” imperial” lathe and an Emco FB2 metric mill. I did my apprenticeship using a mixture of both units. In the shipyard where I did my apprenticeship, fitters worked to the nearest “thou”, welders to the nearest inch and platers to the nearest ship!

However I restore clocks and other old mechanical equipment and also make or modify tools to suit my requirements. I don’t have any issue working to either units because I have to. I am not getting rid of a perfectly useable lathe just because it’s not metric. I don’t have the dosh to go the DRO route.

I like having the flexibility of being able to repair old stuff that can be easily fixed using imperial taps, dies or whatever. If I was asked to make a new stud for example, for an old engine that was originally in imperial measurement and thread, then I would copy that – not make a metric equivalent.

Sometimes understanding what the component is for and its suitability to be made in metric or otherwise is the key decision for me.

I don’t work in a production tool room, i am now retired, I take as long long as I like, so what if it’s taken me several years building my Quorn grinder. I built it for the challenge, to learn new (for me) machining techniques and to end up with a copy of Professor Chaddocks masterpiece. Economics for me is meaningless in the workshop. For example if the Quorn was sold for £500 my hourly rate would work out to be 0.00001p per hr. But I don’t care, it’s my time, my “hobby” and I can do or make what I like and take as long as I like and use whatever measurement system I like.

Slightly off topic I made a copy of a design from Tom Walshaw it was a soldering and brazing clamp assembly, he said it would only take a couple of hours. Took me best part of 6 hours!

Please let’s keep this thread civilised… and in regard to the OP, yes of course “a metric baby can do imperial!”

Regards to all

Derek

 

[noel shelleyParticipant @noelshelley55608]

99, 108, 154, 203, 236, 354, all numbers Howard will know, but what about 903 ? There not metric ! Noel.

[BazyleParticipant @bazyle]

In a way it makes sense to force yourself to actually do some projects in the ‘other’ system in order to flex your brain cells and expand your knowledge. Bit like going on holiday and learning at least how to say good morning in the local lingo.

[BazyleParticipant @bazyle]

Measurement systems are a bit arbitrary; even when linked back to some atomic level thing it is just a human invention. I have a lathe with a 12tpi cross slide thread and it is logical in some ways if you have divided your foot into 12 to go on in similar vein. So I might make a dial for it divided into 12 major divisions and perhaps then 4 subdivisions. Very few things actually have to be done in exact thous; more likely to be ‘made to fit’.

[Bazyle]

On Bazyle Said:
[…] I have a lathe with a 12tpi cross slide thread and it is logical in some ways if you have divided your foot into 12 to go on in similar vein. So I might make a dial for it divided into 12 major divisions and perhaps then 4 subdivisions. […]

Very handy, given the plethora [a nice ‘agnostic’ unit] of 1/12 and 1/24 scale models that must exist.

MichaelG.

[BazyleParticipant @bazyle]

Oh bother! 1/32 scale is common for G1 (when not using 10mm). The 8 and 16 tpi some lathes use would work better. My metric lathe has a 1mm thread with 10 major and 4 minor divisions and I do just use them as thou. No wonder nothing fits.

[JasonBModerator @jasonb]

Needs one of Graham’s geared handwheels. Then you could have one turn =0.1″ or 2mm whichever you like to work in, double if you like diameter rather than radius

[Nigel Graham 2Participant @nigelgraham2]

One thing I don’t see mentioned much is why so many model-engineers still use inches. Most work to long-established designs dimensioned in Imperial because the original machines were, but further because the standard model scales are to binary fractions of feet and inches.

Sort of…. scaling locomotives by gauge gives…

3.5″ g = 1 / 16 very closely. Fine!

5″ g. = 1 / 11.3. Who?

7.25″ g. = 1 / 7.79. Nearly eigth-ish.

And so already introducing compromises. I do not know the “garden-scale” inch:mm arcanities.

Other models, such as traction-engines and aeroplane engines, are scaled easily to true binary fractions.

Either way the drawings are not only dimensioned in inches, but to “things-over-bits” of inches and frequently no datum corners. So even with decimally-calibrated machine-tool dials we still have to convert the stated sizes to 10s-based. Might just as well go metric and be done with it IF your machines are metric.

On the other hand I would expect clocks, scientific-instruments and other non-model projects being all-metric.

 

I am used to both Imperial and Metric (yes I know it’s sniffily called “SI” but the main units are Metric), so I consider purpose.

An accessory for an old, British-made machine-tool? Inches and BS fasteners for compatibility including the fewer spanners the better. I wish the new Myford-branded accessories followed suit!

Extending my commercially-made clamping-sets? Compatible threads.

My model steam-wagon? Ah… well. This project has dragged on for so long it has become cross-bred, so I will bring most of its fasteners to BS (historically comformable though not vital) and BA standards. The components are all in inches and machined to decimal-inch dimensions. The exceptions are a few bought parts like clevises.

Anything else? As appropriate / convenient, frequently metric.

.

It is possible to become too hung up on this: use whatever you find the easier for your knowledge and workshop, but bear in mind the sun is setting on the Imperial.

 

+++++++

A little wander into the sidings…. as a relief from debating turning mm on 8tpi screw lathes with 1/128ths dials

Fulmen says the Pascal works fine. Does it? In Physics perhaps.

The Pressure given by a Force of 1Newton acting over 1 Square-metre.

I find the Newton awkward anyway, but even without that, think with the Pascal the SI scheme matches pure physics more than physical use. It is absurdly small. So mm, fine. Litres, fine. kg, fine. Pa, err…

100 000 Pascals for ordinary air-pressure, so 600 000Pa (0.6MPa) for most miniature locomotives.

Right, what can we use the Pa for, sensibly?

 

Sound pressure-levels? Those are tiddly, even at dangerous levels.

 

Ah, the Pascal is much too big for that. Oh dear… divide it by a million and count micro-Pascals, (µPa).

Now we have very wide ranges of awkward powers of ten, so use multiples of logarithms-of-ratios and call them deciBels. Only, that needs a reference-level equating to 0dB. Not equal to 0µPa as that creates a division by 0. So the measured sound pressure level is quoted as ” x dB re [the reference-level in linear units]” .

And for sound pressure level in air, because it is us lot for whom sound-levels really matter, it is logical to set the reference as the softest a fully-healthy human ear can detect.

 

It is staggeringly tiny, a mere 20µPa…. one-five-thousand-millionth of standard atmospheric pressure.

That flexes the ear-drum by about the diameter of a hydrogen atom.

 

Marine acoustics including biology is quieter still: just 1µPa for its 0dB:  -26dB re 20µPa.

 

 

[John HaineParticipant @johnhaine32865]

1kg bag of sugar weighs about 10 Newton.  If you buy a 1kg bag containing 10 smallish apples each one weighs about a Newton.

For pressure 1 mbar is 1 hPa

[John Haine]

On John Haine Said:

[…] If you buy a 1kg bag containing 10 smallish apples each one weighs about a Newton. […]

Amazing foresight on young Isaac’s part ^^^

MichaelG.

[Bazyle]

On Bazyle Said:

Oh bother! 1/32 scale is common for G1 (when not using 10mm). The 8 and 16 tpi some lathes use would work better. My metric lathe has a 1mm thread with 10 major and 4 minor divisions and I do just use them as thou. No wonder nothing fits.

Hi Baz,

When I first started out in Home shop Machining. My first lathe was a Unimat SL. This lathe has 1 mm pitch leadscrews and 40 divisions per rev on the dial. Only possessing a 0-1″ micrometer I took each division to equal 0.001″ (1mm =0.03937), so close to 40 thou’ not to even worry about it on incremental readings. Longer dimensions needed the use of the Slide Rule as Calculators were costing more than the lathe at the time. Or Log tables if the slide-rule was at work.

After I completed my apprenticeship and in the real commercial world of engineering. Drawings were in an assortment of Imperial and Metric. Machines were all Imperial with the exception of the Jig-borers and Jig Grinder which had “Valve” style digital readouts in both units.

The 40 Thou rule was always handy when taking off material, on an imperial machine. After a while you soon remember some of the common numbers, 3mm-0.118″, 4mm-0.157″, 5mm-0.196″ etc. (please note these are not the exact conversions, just what remains in the grey cells).

I hope this helps

Regards

Gray,

 

[Nigel Graham 2]

On Nigel Graham 2 Said:

One thing I don’t see mentioned much is why so many model-engineers still use inches. …

Only British and US Model Engineers!

…

 

A little wander into the sidings…. as a relief from debating turning mm on 8tpi screw lathes with 1/128ths dials

Fulmen says the Pascal works fine. Does it? In Physics perhaps.

…

 

Nigel is spot on when he says SI/Metric doesn’t do a good job with pressure.  It’s true, the Pascal is downright awkward  because it’s so small – 0.00015 PSI! Scientists can live with Pascals, but in engineering it’s easier to comprehend units that match human experience like Bars or PSI.   Even kilo and mega pascals leave us unsatisfied.  Fair cop guv’ it’s bad.

The CGS iteration of metric had many similar scale problems.   Units derived from centimetres, grams, and seconds often end up outside human scale, which was a source of error.   So CGS was ruthlessly abandoned in favour of MKS.  Units derived from Metres, Kilograms and Seconds almost all scale nicely into human range.   MKS is more practical than CGS.  Not perfect though – there cannot be a perfect system, only worse ones!  Our job is to weed out the rubbish.

Identifying one example of human mismatch in MKS doesn’t make Imperial a good alternative because Imperial commits the same sin and is further riddled with internal inconsistencies.  Imperial may do well with pressure, but the rest of the Foot-Pound-Second system is badly flawed.

Promoting and perpetuating Imperial measure in Industry and Science for cultural or “can’t bear change” reasons is contentious.  I see no good reason to lump youngsters with it today.  There are a few exceptions: hobby needs, restoring/replacing classic equipment, and meeting US compatibility requirements.   Sorry if it offends, but I can’t take defence of FPS (Imperial) measure seriously unless the protagonist explains how the Velo, Celo, Poundal, Foot-Pound, Foot-Poundal. BTU, Horse Power, and Slug help anyone do the maths.  In the absence of good reasons for keeping it, like CGS, off with it’s head…

🙂

Dave

 

 

[Author]

Posts