As a machinist I was stunned that we would have to get prints for parts in metric sometimes. Some of the math required to program a CNC machine is pretty complicated. Metric generally takes more numbers and simply because you have to type them in setup takes longer. Not to mention the added complication of having to use a calculator to add, subtract, calculate an angle. Add to that having to put mm at the end! Stupid. Especially after you do that you have to convert it to inch anyway! The vast amount of precision measuring tools are in inch almost everywhere so I know there are people out there in Europe converting inch to metric, good screwm! The only people that think the metric system is even ok never used the inch to any degree.
All just complete nonsense. The reason you think the imperial system is easier is simply because that's what you're accustomed to and how you relate to measures. I'm a machinist. I work for one of the top 3 CNC machine tool manufacturers. I've worked in both metric and imperial shops in the past and can very easily converse in either units, and in fact am required to because we have both imperial and metric customers. Metric is much easier because everything is in increments of 10. I know a ton of people in industry and I'm not exaggerating when I say that every single person I know who has worked for years in shops using both units prefers the metric system. The only reason you're finding conversions cumbersome is because you're doing conversions between the two systems in the first place. If you were to work in a shop that is entirely metric for just a short time, working from part prints that were designed in metric units, the math is no more "difficult" because you're not doing conversions. When the default units are specified in mm on a part print, then no, you don't need "to put mm at the end" of anything. That's what drawing title blocks are for. You also don't "put mm at the end" in any CNC program just as you don't put "inch" at the end of imperial numbers. You define that in the units parameter on the machine control once. Metric doesn't "generally take(s) more numbers" necessarily, depending on the precision you're working with. Sure, metric requires another number or two on the left side of the decimal, but fewer numbers on the right of the decimal compared to inches. If you're talking about part prints and CNC programming, you're dealing with only one unit designator - millimeters. If parts are designed in metric to begin with, then the designer typically used dimensions in whole numbers, numbers with only 1 decimal place, and seldom to more than 2 decimal places, because the units used were always in metric to begin with, not converted over from inch. The exception is if the part in question was designed in mm but intended to mate to another part designed in imperial units.
As for programming, if you're manually fat-fingering in programs at the machine control or typing up a text file and uploading to the control, then you're either doing some really simple programming, you're only doing minor program editing, or your shop is behind the times and too cheap to invest in some good CAM software. If you have a good CAM software package, it doesn't make a damn whether you're working in metric or imperial units and neither have any influence on programming time.
If you truly believe "the vast amount of precision measuring tools are in inch almost everywhere," then you've been hiding under a rock for a long time, and you certainly haven't been to IMTS lately. The exact opposite is true. The "vast amount" of everything in the manufacturing world, be it precision measuring tools, cutting tools, fasteners, etc are in metric because that is what the majority of the world works in. Open up a Sandvik catalog (you know, the world's largest cutting tools manufacturer) and compare the amount of offerings in metric vs imperial sizes. Ironically, every fastener on the CNC machine you're using every day to type in imperial units, and every part dimension on said machine is in metric dimensions. Now I totally believe the "vast amount" of stuff at your local Groves Industrial, MSC, Fastenal, etc are in imperial units. That's only because the shops local to you are predominantly working in inches, especially in oil and gas country, where shops are still clinging to imperial units with white knuckles. So, your local industrial supply stores are stocking what they will sell. In areas of the country where automotive and aerospace manufacturing dominates, metric is most common by far because all of the finished product is either predominantly or entirely in metric. In most manufacturing segments, metric rules...even in the United States.
