New to the trade and in a metric shop: Are metric measuring tools by best bet?

[mc3608]

My shop and all tools are inch. Our main customer's prints will have both metric and inch, so no converting needed.

 

[projectnut]

Like many here I grew up with the imperial measuring system and still defer to it today whenever practical. Most of my measuring tools date to the 1980's when metrics were just starting to appear in this country. Metric micrometers, calipers, scales, and parallels were all but unheard of, and when they were available the prices were astronomical.

I know I'm getting old and possibly a bit more lazy, but I prefer to measure in the system the prints are created in. I hate going through the conversion exercise. If I do need to do it I run the numbers at least 3 times to be sure they're correct. Many years ago I had a problem when the calculator I was using would intermittently accept information from the #3 key. I would only run a set of numbers once trusting the answer to be correct. One time I was interrupted and didn't finish a calculation. I started over and got an answer that was so far out I couldn't believe it. I ran the numbers 5 more times and got 4 different answers. That's when I discovered the problem with the #3 key. It took me 20 minutes to discover that even though I attempted to make a proper conversion the machine I was using wasn't doing the job. From that time on I decided it was in my best interest to work in the system the prints were made in rather than attempt conversions.

To that end I purchased the most common sizes of micrometers, calipers, and rules with metric readings. My current mill came from the factory (1972) with both metric and imperial dials. Some years later I added a DRO that measures in either system. My lathes are still a bit of a challenge. Neither has a DRO and both have imperial dials. I use metric measuring tools when working in metrics, but still have to do some conversions to hit the tolerances.

In the last couple years I've started seeing more metric lathe work come through the door. It's about time to add a DRO capable of either system to make the jobs easier and less time consuming. So to answer the OP's question I would buy tools that work in the metric system since that's the measuring system used in the shop you're currently working in. It may not be your preference, but digital tools are here to stay. All those I have measure in either system making life easier no matter what comes through the door. As an FYI my preferred brand for digitals is Mitutoyo.

 

[HuFlungDung]

My biggest beef with going metric, is that the important unit .01mm is too coarse and .001mm is too fine. This is akin to a lathe mounted DRO that doesn't have the correct range of resolution for the work at hand, and where tenths of a thou matter. So the mental switching back and forth takes practice, and if you have to throw in reading machine scales graduated in the 'other' system, well, you're going to make 3.14 times as many errors as somebody who doesn't have to do that.

 

[dandrummerman21]

Could get mechanical "combimike" from mitutoyo with metric on the digit counter and inch on the thimble.

Mitutoyo 159-211 Combimike Digital Outside Micrometer 0-1" .001 Graduation 603908059424 | eBay

They also have em with metric on the thimble and inch on the digit counter.


Mitutoyo 159-101 Combimike Digital Counter Micrometer, 0-1"/0-25mm Range, .001" 4946368024073 | eBay

 

[EmanuelGoldstein]

My biggest beef with going metric, is that the important unit .01mm is too coarse and .001mm is too fine. This is akin to a lathe mounted DRO that doesn't have the correct range of resolution for the work at hand, and where tenths of a thou matter. So the mental switching back and forth takes practice, and if you have to throw in reading machine scales graduated in the 'other' system, well, you're going to make 3.14 times as many errors as somebody who doesn't have to do that.

This, and the related facts that metric threads are an abortion - there is a reason to have coarse and fine thread series ! And metric gearing sucks balls, it is like Fanuc, upside-down and backwards.

Inches developed organically to fill a need. They work extremely well in the physical world. The metric system developed in a french brain, based on the cockamamie idea that everything should be measured based in the cirrcumference of the planet. Like, this is supposed to be better ? It's crazy.

Sure, people can adapt to anything. We could measure stuff based on the length of a standard banana if we wanted. But why ? To please a frog ?

It's dumb. And in practice, a step backwards.

 

[modelmakerblue]

My biggest beef with going metric, is that the important unit .01mm is too coarse and .001mm is too fine. This is akin to a lathe mounted DRO that doesn't have the correct range of resolution for the work at hand, and where tenths of a thou matter. So the mental switching back and forth takes practice, and if you have to throw in reading machine scales graduated in the 'other' system, well, you're going to make 3.14 times as many errors as somebody who doesn't have to do that.

First of all I am retired so I don't give a s**t, I was taught Imperial at school but learnt metric in the early 70's, I must be a genius because I can use both if required.Just to let you know .01mm is .0004", too coarse what a load of typical BS!!!!
Tony

 

[Mark Rand]

This, and the related facts that metric threads are an abortion - there is a reason to have coarse and fine thread series ! And metric gearing sucks balls, it is like Fanuc, upside-down and backwards.

There are metric coarse and fine thread series. Just like BSW and BSF in the civilised world and whetever weird system the colonials use in their little bit of the world

 

[michiganbuck]

Big work or small? grinder, mill, lathe, all?

Don't try to convert but buy what you need in metric measuring tools.
Low-priced brand name calipers are just as good as best for a shorter life at +- .025MM or so if you are stressed for cash.

Doing closer than .001 or .025MM then good to have your own set of metric JoBlocks. Doing small work then good to Have your own homemade gage plate, it being a 12"x 8" (about) steel or cast iron plate on a push truck that can take to the next job/machine. Yes, the push truck for your This-job-tools. A small surface plate is Ok but you don't have a few threaded holes so to hold a gauge or surface gauge down.

I had to run a Greman mill back before calculators, That was a bugger.

 

[triumph406]

This, and the related facts that metric threads are an abortion - there is a reason to have coarse and fine thread series ! And metric gearing sucks balls, it is like Fanuc, upside-down and backwards.

Inches developed organically to fill a need. They work extremely well in the physical world. The metric system developed in a french brain, based on the cockamamie idea that everything should be measured based in the cirrcumference of the planet. Like, this is supposed to be better ? It's crazy.

Sure, people can adapt to anything. We could measure stuff based on the length of a standard banana if we wanted. But why ? To please a frog ?

It's dumb. And in practice, a step backwards.

I'm making parts for some electronics guys, one of them has got it into his head that everything should be as metric as possible. Metric threads I'm ok with as the assemblies are going to Mexico.

But making parts (for instance) that are 75mm wide and 10mm thick are a pita. He's getting parts from 3.0 x 3/8 barstock, whether he likes it or not. As I'm doing the assembly he's not going to know. There's a vast number of parts that could have been made from imperial plate or barstock, I've changed sizes where I can.

 

[michiganbuck]

QT [ I've changed sizes where I can.]

You can mark prints to run everything in inches, Or learn to use metrics.
Better to learn to be comfortable with metrics... or likey you will mess up.
Having standard parts it is good to make your own gauges, and also good to have high and low limits built in the gauge.

Agree there is a trade-off when using inch dial machines and running metric parts. Likely that is why we get a lot of China parts that are off a tad, perhaps they are running inch parts on metric machines..

 

[EmanuelGoldstein]

There are metric coarse and fine thread series. Just like BSW and BSF in the civilised world and whetever weird system the colonials use in their little bit of the world

Yeah, and they get used about as much as BSF and BSW ... Whitworth, grows on hardware store shelves, mmm-hmm

Even then, metric fine and coarse are physically not as good as imperial.

I know, no point to fight it, if you're going to get raped in an alley struggling just makes them enjoy it more and it's only a dick after all but still. Sad

 

[michiganbuck]

QT:[Even then, metric fine and coarse are physically not as good as imperial.]

But you gotta do what you gotta do.

Re: I hate metrics, I hate metrics, I hate metrics, I hate...
Your fired, punch out your card and take it to that office.

 

[Conrad Hoffman]

A bit OT, but a designer isn't a designer unless he/she knows what size stock comes in and how much you have to take off to clean it up. Whatever system he/she works in, the cost of having to go up a stock size, in raw materials and in process time, should be understood before insisting on stupid dimensions. Here in the USA there's an extra hidden cost involved in going full metric.

 

[chineshop_guy]

it doesn't take much to get any given topic off the rails on this forum. it's kind of amusing
it's just numbers which ever way you go to me.
i'd go with digital if you can.
if not over time you'll have all the numbers/conversions memorized no biggy

 

[HuFlungDung]

First of all I am retired so I don't give a s**t, I was taught Imperial at school but learnt metric in the early 70's, I must be a genius because I can use both if required.Just to let you know .01mm is .0004", too coarse what a load of typical BS!!!!
Tony

Yeah, you're a friggin genius alright! I'm not retired and have to deal with the limitations of measuring tools in the real world.

Even with a good quality digital mic like a Mitutoyo, there is an average uncertainty of +/-.0001" in repetitive measurements. It can do far better than .01mm but its not so good as to do .001mm. Whether its the mic or the man, that's how it is.

 

[Hodge]

I'm making parts for some electronics guys, one of them has got it into his head that everything should be as metric as possible. Metric threads I'm ok with as the assemblies are going to Mexico.

But making parts (for instance) that are 75mm wide and 10mm thick are a pita. He's getting parts from 3.0 x 3/8 barstock, whether he likes it or not. As I'm doing the assembly he's not going to know. There's a vast number of parts that could have been made from imperial plate or barstock, I've changed sizes where I can.

Here's to hoping your customer doesn't follow you on pm. I wholeheartedly agree that the design should have been based around available materials not an asinine insistence on one system over another. However you can charge for the extra work.
Hodge

 

[Yan Wo]

... Just to let you know .01mm is .0004", too coarse what a load of typical BS!!!!
Tony

I get 0.000393700787401574803149606299213 -- approximately.

 

[cskolnick]

Wow, a lot if great info, thanks all.

Ironically enough, I think the one tool I have decided on is the Digital 6" Mito calipers, as it seems like a no-brainer. If I want to see a dial spin I have the imperial caliper I have been using.
One thing I did not realize is that there do not seem to be many options for higher-end analog mics in metric. With that said, I think I will pick up an import 0-75mm analog mic set just to see how working fully in metric goes. My imperial calipers are imports as well, but from what I gather and have been told, the tolerances I am working with are "wide open" ie .008-.020" so even a decent mid-range mic set should be just fine for now.

The dials on our machines are imperial but yes, I do have a DRO and use it to toggle back and forth between units. I have actually been doing my roughing, squaring and set up in imperial because I am used to it and can imagine a visual image of the numbers used. When it comes time to locate features and drill or tap I switch the DRO to mm and crank away...

Interesting mention with regards to the "too course, too fine" comment. I had a previous co-worker when I first dipped my toes in a machine shop about 5 years ago who talked a bit about aspect with me.
My inexperienced, intuitive-thinking self sorta sees the use of imperial as almost a finer-tooth comb or as being able to zero in on a more useful range of measurement with regards to tolerance; but I may be wrong.

Thanks again everyone, looks like I will be going for the 6" Mito digi-cal, "affordable" metric analog mics, and a set of machinist squares and some 5R and metric scales.

 

[EmanuelGoldstein]

But you gotta do what you gotta do.

Assbolutely ...

Your fired, punch out your card and take it to that office.

You can't fire me, I quit !

A guy's gotta draw the line somewhere, right ?

 

[triumph406]

A bit OT, but a designer isn't a designer unless he/she knows what size stock comes in and how much you have to take off to clean it up. Whatever system he/she works in, the cost of having to go up a stock size, in raw materials and in process time, should be understood before insisting on stupid dimensions. Here in the USA there's an extra hidden cost involved in going full metric.

That is the frustrating part. The guy who designed the parts used to work for me, I'm the one who trained how to machine, at which he quickly excelled.

When he was working for me we did a huge amount of parts for a local machine builder. 90% of the parts were made from stock sizes, cut 1/16-1/8 long on the saw. Machine to length, put some holes in, deburr, off to the anodizer. It was very rare that we had had to machine a width or thickness to a dimension that wasn't stock.

For some reason it didn't dawn on him to make the parts he designed stock sizes, which he could have done. So I had to do it