Why are good metric micrometers so hard to find?

[projectnut]

The optimum temperature for parts inspection is 68*F +/-2*. The optimum humidity is under 50%. My shop is temp controlled to 68*F and 43% humidity

 

[Aaron_W]

Domestic automotive production has switched to the metric system.
I was working on a neighbor's 2000 Jeep the other day. Some components were imperial and some metric.
I think most of us baby boomers struggle with the metric system.
Strange considering it's so much easier than imperial. imho

I see measuring systems as language. I was in second grade in the mid 70s when the USA began the big push for metric, so just like somebody in a bilingual society I was around both systems from a young age which has helped me a great deal. I still think in inches, pounds, gallons so if I see 3km or 6kg, I have to convert it to about 1-1/2 miles or 15lbs to see it in my head.


I looked into the automotive transition some time back. What I found was the Ford Pinto in 1971 became the first US domestic car built using the metric system. GM was a few years behind with its first all metric car being the Chevette in 1976. I believe the Dodge Omni / Plymouth Horizon was the first for Chrysler in 1978. I have no doubt that the export potential of these small cars played a big part in these cars leading the way.

It took decades for full metric conversion of the US auto industry. New parts were designed in metric, but many older parts, engines, transmissions etc just kept chugging along, so you got a lot of cars with a mix of systems. No reason to make a redesign of a component that worked just so it used metric fittings. A good example being Ford's small block V8. It was introduced in 1961, and wasn't phased out until the late 1990s so it was used in many later cars and trucks that had a mostly metric body and chassis, 3rd gen Mustang, 7th gen F-series etc.

 

[SouthernChap]

You know, I've had a bit of a think about this and maybe I'm a bit slow on the uptake (and where this sort of thing is concerned, it wouldn't be a surprise if I am and everyone else in this discussion has taken this for granted!) but it seems to me, we've been treating 0.01 mm/0.001" as roughly equivalent and 0.001/0.0001" as roughly equivalent. If you're using Imperial, you use thous and tenths and if you're using Metric you use 0.01 mm and 0.001 mm.

One thou (0.001") is more than double the absolute size of 0.01 mm and obviously one tenth (0.0001") is more than double the absolute size of 0.001 mm.

Measuring to 0.001 mm means one is more than doubling the resolution compared with measuring to 0.0001".

The resolution with which we measure to will often have a psychological impact (and even more so for less experienced hobbyists like me) on the level of our work to precision 'anxiety'.

If we're working in Imperial, we can say to ourselves "Right, working to a thou here, so I'll measure to a half a thou or a couple of tenths" (and if we need to work to half a thou, or even a couple of tenths, we can measure to a tenth).

Let's face it, in the hobbyist shop, for the overwhelming majority, working to a couple of tenths is pretty much going to be the top end of our precision.

Switching to metric though, working to 0.01 mm, means we'll be measuring to 0.001 mm.

Well okay, given in the hobbyist shop we're not generally worried about absolutes but things like fit, if we have decent quality metrology equipment with the right resolution (say, a Mitutoyo 0.001 mm mic') we can measure to that resolution just fine.

However, working to 0.01 mm already demands more than double the precision of working to a thou.

Add the effect of measuring to 0.001 mm and that could well affect our level of work to precision 'anxiety', leading to us chasing our tail in the pursuit of precision that's more than double what we actually need.

Now, we could use metric equivalents of the standard hobbyist Imperial levels of work to and measure to, and work to 0.025 mm and measure to 0.0025 mm

But that adds extra mental effort, with the measuring at least (my little 7x has carriage handwheel dials graduated in 0.25 mm and cross-slide and top-slide dials graduated in 0.025 mm). Who in their right mind habitually counts 2.5, 5, 7.5, 10, 12.5 as opposed to 1, 2, 3, 4, 5? Speaking for myself, I don't need any extra mental effort requirements, thank you!

So, @Rex Walters is absolutely spot on in everything he says. However, using Imperial means one is chasing a larger target. A larger target that is more appropriate to the hobbyist workshop.

So, my conclusion is that hobbyists should abandon this new fangled Metric silliness and work in Imperial (but not bloody fractional inches; 3/8" can kiss my arse, give me 0.375" )

Seriously though, it does seem that using Metric can easily ramp up the pressure on the poor hobbyist to chase precision they don't need.

Thoughts? Corrections of flawed logic?

All are welcome.

 

[Rex Walters]

it does seem that using Metric can easily ramp up the pressure

My thought about a 0.01mm mic without a vernier is that it’s more precise than my inch mic without a vernier and less precise than reading to tenths on my inch mics with a vernier.

Using a metric mic with a vernier to 0.001mm is wild to me. But I can understand occasionally aiming for “between” readings (above or below a line on the barrel).

I know 0.0005”/div are my favorite indicators to use. They have just the right level of sensitivity: not too coarse, but not crazy jumpy like a tenths indicator.

It occurs to me that a 0.01 mm/div mic has roughly the same precision, so I’d probably like using one.

 

[SouthernChap]

My thought about a 0.01mm mic without a vernier is that it’s more precise than my inch mic without a vernier and less precise than reading to tenths with a vernier.

Using a metric mic with a vernier to 0.001mm is wild to me. But I can understand occasionally aiming for “between” readings (above or below a line on the barrel).

I know 0.0005”/div are my favorite indicators to use. They have just the right level of sensitivity: not too coarse, but not crazy jumpy like a tenths indicator.

It occurs to me that a 0.01 mm/div mic has roughly the same precision, so I’d probably like using one.

That's another good point right there.

My 0-25 mm/0.001 mm Mitutoyo 'mic has a vernier scale, but when I do use that 'mic, I often only look at the vernier to see whereabouts in the range of n.nn I am.

I must say, I have been using my slightly tatty but reliable CombiMike more often and using the Imperial scale and vernier.

That reminds me, I bought a 'non-working', oldish (293-766-10; if there are any members that know the article codes and their relation to years of production, it would be nice to know) , 0-25 mm/0-1" Mitutoyo digital mic' for not very much recently, and the previous owner clearly overestimated their micrometer repair abilities.

It arrived in its slightly grubby 'creepily-flesh-coloured' fake-wood-grain textured plastic box, in really great nick (measuring surfaces are pristine; buttons are spotless, body and thimble are clean and free of corrosion, even the lettering on the plastic plates is unworn)...apart from the fact that it's in 3 pieces: the control board/display, the thimble/spindle, and the body/sleeve.

To get the modern (and, I might add, distinctly less attractive) equivalent, I'd need to spend about £200. So I had a chat with Phil (that's what he said his name was, I don't know the guy personally or anything ) in the repairs department at Mitutoyo UK and I now have to remember to send it off.

 

[Rex Walters]

It arrived in its slightly grubby 'creepily-flesh-coloured' fake-wood-grain textured plastic box

Literally laughed out loud. That's some great writing right there! I know exactly what kind of box you mean.

I've been spending so much on a machine rebuild lately that I really don't need any more itches, but a digital or metric mic is now on my want list (I've also been on the lookout for a Starrett Unimic for ages).

 

[Oscar Lazo]

You know, I've had a bit of a think about this and maybe I'm a bit slow on the uptake (and where this sort of thing is concerned, it wouldn't be a surprise if I am and everyone else in this discussion has taken this for granted!) but it seems to me, we've been treating 0.01 mm/0.001" as roughly equivalent and 0.001/0.0001" as roughly equivalent. If you're using Imperial, you use thous and tenths and if you're using Metric you use 0.01 mm and 0.001 mm.

One thou (0.001") is more than double the absolute size of 0.01 mm and obviously one tenth (0.0001") is more than double the absolute size of 0.001 mm.

Measuring to 0.001 mm means one is more than doubling the resolution compared with measuring to 0.0001".

The resolution with which we measure to will often have a psychological impact (and even more so for less experienced hobbyists like me) on the level of our work to precision 'anxiety'.

If we're working in Imperial, we can say to ourselves "Right, working to a thou here, so I'll measure to a half a thou or a couple of tenths" (and if we need to work to half a thou, or even a couple of tenths, we can measure to a tenth).

Let's face it, in the hobbyist shop, for the overwhelming majority, working to a couple of tenths is pretty much going to be the top end of our precision.

Switching to metric though, working to 0.01 mm, means we'll be measuring to 0.001 mm.

Well okay, given in the hobbyist shop we're not generally worried about absolutes but things like fit, if we have decent quality metrology equipment with the right resolution (say, a Mitutoyo 0.001 mm mic') we can measure to that resolution just fine.

However, working to 0.01 mm already demands more than double the precision of working to a thou.

Add the effect of measuring to 0.001 mm and that could well affect our level of work to precision 'anxiety', leading to us chasing our tail in the pursuit of precision that's more than double what we actually need.

Now, we could use metric equivalents of the standard hobbyist Imperial levels of work to and measure to, and work to 0.025 mm and measure to 0.0025 mm

But that adds extra mental effort, with the measuring at least (my little 7x has carriage handwheel dials graduated in 0.25 mm and cross-slide and top-slide dials graduated in 0.025 mm). Who in their right mind habitually counts 2.5, 5, 7.5, 10, 12.5 as opposed to 1, 2, 3, 4, 5? Speaking for myself, I don't need any extra mental effort requirements, thank you!

So, @Rex Walters is absolutely spot on in everything he says. However, using Imperial means one is chasing a larger target. A larger target that is more appropriate to the hobbyist workshop.

So, my conclusion is that hobbyists should abandon this new fangled Metric silliness and work in Imperial (but not bloody fractional inches; 3/8" can kiss my arse, give me 0.375" )

Seriously though, it does seem that using Metric can easily ramp up the pressure on the poor hobbyist to chase precision they don't need.

Thoughts? Corrections of flawed logic?

All are welcome.

My thinking was using multiples of 0.02 mm as rough(er) mental equivalents of thousandths of an inch. Though I do see the pitfall you are pointing at regarding precision mental pressure. My take on that would be something like: "Well if you wanted an easy hobby, it would not be this, would it?"

 

[SouthernChap]

My thinking was using multiples of 0.02 mm as rough(er) mental equivalents of thousandths of an inch. Though I do see the pitfall you are pointing at regarding precision mental pressure. My take on that would be something like: "Well if you wanted an easy hobby, it would not be this, would it?"

Honestly, I think adding further avoidable hurdles to what is already a challenging hobby, is probably not the right way to go.

To be fair, for a lot of (probably most) work, a 0.01 mm mic' will be fine, 0.01 mm is just under 4 tenths. If you need to measure to below that resolution (and wanting to be precise for parts like bearings and cylinders, you probably will) and you want Metric, you'll have to get yourself 0.001 mm micrometers, covering the sizes you need.

In the UK, used digital Mitutoyo mic's come up regularly for sale. Sure, some of them do look like they've been used to open beer bottles or as hammers, but oftentimes, they're in good condition and are priced at less than half the cost of a new Mitutoyo digital mic' (and the old micrometer designs are much prettier anyway).

So maybe rather than going out and splashing the cash, perhaps consider buying used.

 

[Janderso]

I see measuring systems as language. I was in second grade in the mid 70s when the USA began the big push for metric, so just like somebody in a bilingual society I was around both systems from a young age which has helped me a great deal. I still think in inches, pounds, gallons so if I see 3km or 6kg, I have to convert it to about 1-1/2 miles or 15lbs to see it in my head.


I looked into the automotive transition some time back. What I found was the Ford Pinto in 1971 became the first US domestic car built using the metric system. GM was a few years behind with its first all metric car being the Chevette in 1976. I believe the Dodge Omni / Plymouth Horizon was the first for Chrysler in 1978. I have no doubt that the export potential of these small cars played a big part in these cars leading the way.

It took decades for full metric conversion of the US auto industry. New parts were designed in metric, but many older parts, engines, transmissions etc just kept chugging along, so you got a lot of cars with a mix of systems. No reason to make a redesign of a component that worked just so it used metric fittings. A good example being Ford's small block V8. It was introduced in 1961, and wasn't phased out until the late 1990s so it was used in many later cars and trucks that had a mostly metric body and chassis, 3rd gen Mustang, 7th gen F-series etc.

I had no idea the metric idea went that far back on the domestic side.

 

[Oscar Lazo]

Honestly, I think adding further avoidable hurdles to what is already a challenging hobby, is probably not the right way to go.

To be fair, for a lot of (probably most) work, a 0.01 mm mic' will be fine, 0.01 mm is just under 4 tenths. If you need to measure to below that resolution (and wanting to be precise for parts like bearings and cylinders, you probably will) and you want Metric, you'll have to get yourself 0.001 mm micrometers, covering the sizes you need.

In the UK, used digital Mitutoyo mic's come up regularly for sale. Sure, some of them do look like they've been used to open beer bottles or as hammers, but oftentimes, they're in good condition and are priced at less than half the cost of a new Mitutoyo digital mic' (and the old micrometer designs are much prettier anyway).

So maybe rather than going out and splashing the cash, perhaps consider buying used.

I'm sorry, I didn't mean to dismiss your comment outright. I was just being a bit flippant. I am going to buy 0.001 mm analog Mitutoyos on the 0-50 range, as you suggest. In fact, I just bought one. And actually at a great price on ebay, as you say. The seller has a good score, and I am willing to risk it