Home Forums Hunting & Shooting Ask The Gunwriters Question about metric conversion

Rict300,
Your objection of the metric system is based on the fact you grew up with the imperial system, that's what you were taught, what you used for many years, what you relate to in your everyday life, and what you think in when dealing with units of measure of everything. It's understandable that you find something contrary to a system you've used your whole life to be cumbersome. It's human nature to reject that which runs counter to our experiences, is new...change in general. All these folks who you say agree with you on the superiority of the imperial system probably have similar experiences as you, and were never placed in an environment where they had to work in metric units exclusively for sufficient time that it became second nature to them. I deal with customers across all of North America, and I assure you, your experience isn't anywhere close to universal. Everyone who I interact with who have worked in manufacturing facilities that both use imperial and metric exclusively (not switching back and forth between the two systems) end up preferring metric. They may have been old school and arrived at that point kicking and screaming, but arrive at that point they did. If you don't believe me, I'm cool with that. If you have a different opinion than me, I'm cool with that too. You're entitled to your opinions, but many of your assertions are just factually incorrect. I live and work in Texas just as you do, but working for a CNC machine tool manufacturer, I'm pretty sure I interact with a broader customer base who manufacture a broader range of products than you do. Our customers cover all industries all across North America, and we routinely help them develop their processes used on our machines. I was also a cutting tool, gage and fixture designer for many years, and I've made custom cutting tools for many of these companies.

If you're spending the vast amount of your programming time standing at the machine control, then you obviously aren't using one of the better CAM software packages (MasterCam, Esprit, GibbsCam, EdgeCam, etc) or your parts lack sufficient complexity to make programming with CAM software viable. If you're starting out your programming with 3d CAD models of your parts, importing them into CAM software, and you have a good, proven post for your machine, then it doesn't make a damn what units you're working in with respect to programming time. That you insist otherwise indicates that you're behind the times on technology. I've done lots of programming in both units of measure. Programming in metric doesn't necessarily take any more time or consume more lines of code than programming in inch, and feeds and speeds are no more difficult to calculate in mm or meters/minute vs in or ft/min or mm/rev vs in/rev. It's all a matter of what you get used to using and what you're comfortable with.

I don't know what point you're continually trying to make with regards to the inch being expressed in increments of 10. Yeah, in the machining world you often work in tenths and thousandths of an inch. So what? That's not the point.

No that is the point. 1.000 is an inch, it can be broken down by .1, .010, .001 or .0001 easily. The millimeter





The imperial system is made up of a hodgepodge of units that have random, inconsistent relations to each other. 12 inches in a foot...

What inconsistency? Is there some reason not to have the yard broken into three places on a steel tape?



3 feet in a yard

And your point? Don't you think it would be nice to be able to break the meter into three very useful Parts? Or four?



...5280 feet in a mile...

I find the mile a more useful distance than a Kilometer. Looks much better on a speed limit sign.


231 cu/in in a gallon, 8 pints to a gallon,

Kind of funny you are, 128 ounces in a gallon, 4 quarts, 8 pints, 2 1/2 gallon where is the problem?



etc. Numbers all over the place. In the metric system, EVERY unit is expressed in increments of 10 to all other measures across the whole system...10 mm to a cm, 100 cm to a meter, 1000 M to a KM, etc.

Funny again, useful distances and measures do not wholly depend of their ease of being multiplied by ten. The foot divided into inches divided into fractions is more useful than the meter divided int mm and cm in the real world. And much faster to use. That said have you ever used a metric steel tape?

A mm is just under .04, pretty small and counting the gaps between the lines means you better have good eyes! And ten Centimeters is just under 4 inches, meaning the meter is divided into 10 sets of 100 centimeters. a centimeter measures not much more than 3/8ths of an inch. I have to say that using a metric steel tape is a pain compared to using an Imperial steel tape with it's visually easy markings.




Even if one is completely entrenched in the imperial system, how anyone can't see the inherent superiority and simplicity of a system that relates all measures to each other in increments of 10 is mind-boggling.

Where is this superiority revealed? On a calculator? Even then the fewer figure needed to do calculations gives the Imperial system the edge.


Yes, Bell Helicopter, Lockheed Martin, and Boeing still use imperial units, but not across the board, and that's beginning to change as they pursue international contracts and work with international partners and the military. The US military went completely to metric units a long time ago. Bell Helicopter now uses primarily metric units in the V22 Osprey program. Following a disastrous, expensive loss of the Mars Orbiter due to a calculation error where NASA was working in metric and Lockheed was working in imperial units, Lockheed began converting over to metric in their space-related projects. They also work in metric on projects where they partner with contractors and governments overseas. And I don't even want to get started on the mind-numbing stupidity, inefficiency, and waste at some of those defense-related companies due to the difficulty in making process changes and conflicts with the unions which cause them to still use a lot of 1970's and 80's technology tooling and equipment. Many US manufacturers have stuck with the imperial system simply due to the expense of converting to metric and the vast amount of legacy programs, drawings, and part design families they would need to convert. This doesn't mean the imperial system is superior, only that making radical process and culture changes is costly and painful, especially when your workforce grew up using imperial units.

Do not forget we gain nothing in precision going to the metric system, nothing. I disagree with that there is a lot of 70's and 80's machinery out there simply because most of it has been replaced with CNC machines by 1990, though there are some engine lathes and mills in most shops used to build fixtures or rough parts. Interestingly I have made a lot of V22 parts though mostly 8-10 years ago and the inch still ruled then. So you are blaming the imperial measuring system for NASA and Lockheed not telling each other what they were doing?



As for your comment that "the fasteners that hold the Sandvic inserts in are still loosened and tightened with inch fractional allen wrenches," Sandvik hasn't used any imperial fasteners in their tooling for at least a couple decades. Likely what you're seeing is a 5/64 is the same basic size as 2mm, a 5/32 is only a thou off of 4mm, 5/16" is only 2 thou off of 8mm, etc. so some imperial allen wrenches will work in metric cap screws. Besides, with regards to Sandvik, I was talking about end mills, drill diameters, rotating tool shank sizes, indexable milling cutters, milling arbors and power chucks, collet sizes, modular tooling connections, boring bar diameters, grooving insert widths, and on and on. There are multiple times more offerings in metric than in inch dimensions these days across all cutting tool manufacturer brands' products. It's not even close in fact. And if you're going to make a point about "Sandvic," and least learn to spell "Sandvik" correctly.