# mm's and or inches



## DaveH (Mar 4, 2011)

Just as a bit of fun I thought it may be nice see what units are used for different 'things' around the world.

Do you mix and match, inches only, mm only? Or do you have your own special units?

I'll start.

Mainly mm general/marking out

Inches on the lathe

mm on the mill except for the Z axis thats inches.

Dave


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## b.lindsey (Mar 4, 2011)

I am confused easily enough as it is without adding to it by mixing systems across machines or within the axes of one machine. Can I convert when needed? Sure, and have to pretty often. Most DRO's and even electronic calipers these days make the job even easier, but when I start a project it ALL in one system, and for me that is inches.

Bill


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## DaveRC (Mar 4, 2011)

I prefer working in mm but my lathe is imperial but the mill is metric and have to swap about between them a bit. Smaller stuff I like to use mm all the time, but if it gets big, like I am doing some woodwork I tend to measure everything in feet and inches. It is an odd mix... 

I also shoot and everything (distance) is all in yards. 

So anything under a foot is in mm and anything over 300mm is in inches, feet, yards..... scratch.gif

Dave


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## Ken I (Mar 4, 2011)

I once came up against a 45mm x 24 TPI thread - go figure ?

I had to tool up for a production run and figured that my tooling supplier - EMUGE - in Germany - would ask all sorts of questions - but no - not a peep - they supplied all the required tangential dies, Go-No go gauges etc without questioning a thing.

Anyone mixing units like that deserves to be shot.

Ken


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## Mainer (Mar 4, 2011)

Inches, almost totally. If inches were good enough for King Henry, they're good enough for me. ;D

More to the point, my lathe and milling machine and micrometers and rulers are all graduated in inches, my taps and dies are inch sizes, my drills are all fractional, etc. I'm not set up for metric.

It really doesn't matter which you use though.


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## GWRdriver (Mar 4, 2011)

Ken I  said:
			
		

> my tooling supplier . . . supplied all the required tangential dies, . . . without questioning a thing.


My #1 pet peeve . . . being asked "Are you sure you want that?" when I have made a clear written or verbal request.

MMs or Inches? That's now not only a function of location but of age, and wot you was taught in school. I'm of an age and location that was Imperial but I have made myself comfortable swopping back an forth at will. I do think it would be a bother to have machine tools in mixed systems.


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## lordedmond (Mar 4, 2011)

All my machines are mm ones mill has dro so can be ambidextrous ,lathe is marked on the dials as a radius machine dial in 1mm stock is reduced by 1 mm



but also in the UK you buy plywood in 8 foot by 4 foot sheets 10mm thick !!!!!!!!!!!!!!


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## mu38&Bg# (Mar 4, 2011)

I work in metric. But some of the work I get ends up in inches. My CNC mill is native metric, but I currently use inch cutters. My lathe dials are inch, and it doesn't cut metric threads. I learned inches here in school in the US of course, but metric must be in my blood as my parents are from eastern Europe. My measuring tools are a mix of inch and metric, but I'm slowly filling the holes with metric tools. I have only one digital mic that of course reads both, but I prefer vernier calipers with both scales for general work. Of course, my own prints are dual dimensioned.

If you're designing or producing something for production that has or may need replacement or interchangeable parts, picking one or the other would be important. For a one off model you're building in the shop use whatever you're comfortable with or can actually produce. However, if your work of art is dug up out of the ground 100 years from now and somebody wants to restore it, they might have trouble.


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## bearcar1 (Mar 4, 2011)

The very wise but ancient (sorry guys) :bow: instructor that guided me during college engineering/shop classes would tell us it was not a good idea to mix and match metric with imperial in the same project, not that it could not be done, and obviously it is, being done, it just adds to the potential for a mistake being made. Personally I have never really had any great need for or used metric dimensions and convert them to imperial if I am building from a set of drawings that are dimensioned as such. All of my tooling is in inches as are my taps and dies. It would be great to have both types of tooling in the shop but for my needs, inches is where its at, for now at least. ;D It is funny though, I recall, as a very young lad, when the metric system was being 'introduced' to the US and how the big bruhaha over it replacing inches was going to happen in the next 20 years, well that time has come and gone and here we are still, using both systems. I wonder what the situation will be after the next 20 years. Of course everything then will most likely be imported from other countries (just as now only more so) so it really won't matter much anymore. Sorry for the digression but I'm OK now. :big:
I do have to say thought that the Red ones are my favorite, right Zee? :-\

BC1
Jim

BC1
Jim


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## bambuko (Mar 4, 2011)

lordedmond  said:
			
		

> ...in the UK you buy plywood in 8 foot by 4 foot sheets 10mm thick !!!!!!!!!!!!!!


yeah, you might be buying it in ft, but if you cared to measure it you would find that your "8 b 4" sheet is actually 2400mmx1200mm  

Chris
ps I am not really bothered - prefer metric but just as happy using imperial ;D for example my lathe is metric but I am using 3C imperial collets in it. No big deal ...


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## tel (Mar 4, 2011)

Like most of the above I'm quite happy in both systems, tho all my machines, other than the X2, are graduated in imperial. My screwing tackle started out typical of the Aus/Brit systems in use at the time - BA (metric-based) ME, Whit, BSB and BSF. Since then I've added metric and a (very) limited range of UNF/UNC. 

One thing I will say to the all-imperial blokes tho - a set of 0.1 mm drills is a very handy thing to have, far better than the number drills.


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## Antman (Mar 4, 2011)

If there is anything that would make one want to go metric it must be imperial micrometers. Having to constanly add thous to fortieths is just overload for my little pip.
    Ant


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## GWRdriver (Mar 4, 2011)

bearcar1  said:
			
		

> Instructors . . . would tell us it was not a good idea to mix and match metric with imperial in the same project


A-bleeding-Men to that. As one who occasionally takes in models and boilers for repair I can attest that all manner of mixtures will appear. I think the first admonition that it's best to stay with one system I read was in a very old ME magazine and one of the reasons given was that subsequent owners (and repairers) would have less trouble sorting it out.


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## Artie (Mar 4, 2011)

Seems I am a bit 'younger' than some of you ole stagers... 8) ... I was half way through primary school when we metrified over 'ere... so Im conversant in either and automatically do the conversions in my head when one of you mentions 27/64th etc.. I prefer metric but happy in both....

The auto industry here is fully metric yet most techs stil think of the engine clearances in thou. When I was an apprentice our domestically built fords had metric bodies and imperial engines/drivelines (bolts etc). That soon changed.

Therefore my shop is a mixture of metric/imperial but I always use metric for the builds as we have a much larger range of metric fasteners available. And Tel's right, 0.1mm graduated drill bits are much nicer... ;D

Dont know what its liek where you are but a new tool kit here almost always is both metric and imperial...


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## kvom (Mar 4, 2011)

I have only imperial machinery and tooling, but don't have a problem converting metric plans to inches where needed.

My Jeep has a mix of metric and imperial fasteners, so I have both systems for wrenches and sockets. For models I use strictly imperial fasteners.


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## bp (Mar 4, 2011)

I did my apprenticeship in the UK in the mid sixties. However from the early '70's I worked as a draftsman working in metric, so I'm pretty much bi-lingual. Whilst I appreciate the history etc of the imperial system, how much easier is _everything_ in metric?
All my gear is in metric except for a small collection of ME and BA taps and dies, and yes Tel, drills graduated in mm are so much easier that numbers/letters etc.
My hobby is aeromodelling. I fly competitively in F1B (Google it, it used to be called "Wakefield") which I think of entirely in metric, right now I'm building a vintage stunt control line model which was conceived, drawn and is being built in inches.
cheers
Bill Pudney


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## milotrain (Mar 4, 2011)

Things aren't imperial or metric, things just are. We define them in one way or the other so that we can communicate between drawing and part, or order and part. The early Greeks who built the Acropolis didn't have a system of measurement with units, they simply used proportions. A building being so many times longer than it was wide, and taller than it was wide. Spacing of columns were proportions of height and widths.

It's like quantum mechanics, a photon is no more a particle or a wave, than a part is x inches or y mm. It's just that's how we can define it.


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## dreeves (Mar 4, 2011)

Well I like Inches. My mill with the DRO will switch to both. I still like Inches. I will let you know if that changes after the Cracker Build which is in MM. So far Its looking like I want to stay with what I know.


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## kuhncw (Mar 4, 2011)

Maybe I'm missing something. I work in inches, but once your dimensions are in decimals, I really can't see much difference between inches or mm. One should be as easy as the other, assuming your measuring tools are calibrated in the units your are working in.

I don't care for fractional dimensions for parts I'm making. 

Regards,

Chuck


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## rake60 (Mar 4, 2011)

I worked with a few people who hated metric prints.

*WHY?* A size is a size.  I'd sing them a song, _(but not this well.) _

[ame]http://www.youtube.com/watch?v=gBAV9ZRKV7I[/ame]

Such confusion, even way back in 1942! 

Rick


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## Tin Falcon (Mar 4, 2011)

I prefer imperial measurement. It is what i grew up with more or less. Mertification was the big push in the late 70s the world was going metric so everyone had to learn it. An metric units are used in physics and science books. 
My shop machines are all calibrated in imperial. 
Tin


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## Ken I (Mar 5, 2011)

> MMs or Inches? That's now not only a function of location but of age, and wot you was taught in school.



I was halfway throuh my trade / engineering training when we were metricated.

So I'm a conflicted engineer.

In dimensions I prefer metric - but somehow I've never broken with PSI for pneumatic/hydraulic and stress calculations and end up doing my caculations in imperial and converting back.

Mentally I intuitively "get" PSI - Pascals just doesn't ring any bells for me.

Ken


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## Maryak (Mar 5, 2011)

My fingers can feel 0.002" variation

MY eyes can/could see 0.002" misalignment

I was brought up in an imperial world.

Since we metricated I have a foot in both camps but normally, I don't feel with my toes


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