Some things are not going metric

[Tom Bender]

Router collets, table saw and shaper arbors, pipe sizes, ceiling tiles. Of course it is possible to specify them in metric units or in both but router bits specified as 127 mm shank might not sell well. Not sure what's happening with ceiling tiles.

[Tony Joyce]

router bits specified as 127 mm shank might not sell well.

Yea, not sure I've ever seen a 5" shank router bit. :p

[Jim Becker]

Metric router collets are indeed available, albeit are not easy to come by, especially in North America. 20mm and 30mm saw arbors and 30mm shaper spindles are not uncommon globally, but certainly not the norm for North American designed equipment. (many track saws have 20mm arbors...) In the end, it doesn't really matter, honestly. I design in metric and cut with tooling that's otherwise. We buy what's available or required for what we have and some of that has to do with backward compatibility.

[Jacques Gagnon]

Router collets, table saw and shaper arbors, pipe sizes, ceiling tiles. Of course it is possible to specify them in metric units or in both but router bits specified as 127 mm shank might not sell well. Not sure what's happening with ceiling tiles.

I guess it depends on your vantage point. If you turn the table around, our fellow woodworkers who live in countries that use metric units may find it strange to specify a spindle with a diameter of 31.75mm or a piece of lumber that measures 50,8mm by 101.6mm. How about going to the gas station and filling their 22,73 liter tank for the lawn mower?

At the end of the day, regardless of the units you use, your kitchen table apron will be the right length, provided you measured carefully and processed it with due care. And a 30mm bore shaper cutter will fit perfectly on a 30mm spindle, but less so on any other size, regardless of units.

[Curt Harms]

8 mm router bits/collets are not uncommon for dovetail jigs.

[Bill Dufour]

AFAIK: The worldwide standard for socket drive square shanks are 1/4", 3/8" and 1/2". Above that I do not know. No need to make a different size since they are sold for only one thing and no other system is needed.
Light bulbs have always been metric. In the Americas it is E26. for Edison base 26 mm.
What I think is funny is I see metric ball bearing(pretty much all ball bearings are metric since WW1). I see them labeleed i nEnglish unit sfor some reason. As in 1.259843 in" instead of 32 mm.
Bill D

[Vijay Kumar]

Tire rim sizes are in inches, though the tire diameter may be metric, as well as the width.

[Thomas McCurnin]

Believe it or not, I found a metric crescent wrench at a garage sale. I paid big bucks for it, but they are so rare to find these days.

[Osvaldo Cristo]

Router collets, table saw and shaper arbors, pipe sizes, ceiling tiles. Of course it is possible to specify them in metric units or in both but router bits specified as 127 mm shank might not sell well. Not sure what's happening with ceiling tiles.

In metric countries router shank will be 12 mm (and it not frequent to find 12.7mm). Most of my router bits are 8 mm shank, some 6 mm.

I also have 1"/2, 1"/4 and 1"/8 bits I purchased virtually all in the US as it is less and less frequent to find locally stuff in imperial units.

When we talk in different unit systems it is not a mere conversion from one unit to other but it will imply in a change in the round figures used in the practice.

[Malcolm McLeod]

Believe it or not, I found a metric crescent wrench at a garage sale. I paid big bucks for it, but they are so rare to find these days.

My hammers are only metric tools I have.

My adjustable is in cubits - - one-of-a-kind rare. For sale if the offer is right..?

[Jerome Stanek]

Believe it or not, I found a metric crescent wrench at a garage sale. I paid big bucks for it, but they are so rare to find these days.

I have a couple that are metric on one side and sae on the other

[Curt Harms]

In metric countries router shank will be 12 mm (and it not frequent to find 12.7mm). Most of my router bits are 8 mm shank, some 6 mm.

I also have 1"/2, 1"/4 and 1"/8 bits I purchased virtually all in the US as it is less and less frequent to find locally stuff in imperial units.

When we talk in different unit systems it is not a mere conversion from one unit to other but it will imply in a change in the round figures used in the practice.

I assume router manufacturers make collets in those common sizes? The only metric collet for Porter Cable that I've seen is 8 mm.

[Jim Becker]

I assume router manufacturers make collets in those common sizes? The only metric collet for Porter Cable that I've seen is 8 mm.
They do, Curt.

[Wes Grass]

I have a couple that are metric on one side and sae on the other


Hopefully they're a left and right pair. Otherwise, you can only tighten SAE and loosen Metric with one. Or vice versa.

[Jim Dwight]

We are pretty much stuck in the U. S. with using both systems of measurement. Cars are in metric and unlikely to ever go back to fractional inches. Lumber is sold in feet and inches but most plywood is really metric in thickness. We need metric and SAE wrenches and socket sets. Track saws started in Europe and most have 20mm arbors. Dominos are all in metric. Scale on the tool, size of the cutters, size of the loose tenons etc.. Plumbing materials are also sold in inches. Some things might gradually change but also may not. Ceiling tiles are 2x2 or 2x4 feet. Standard kitchen counter height is 36 inches, 18 inches up to the upper cabinet. Base 24 wide, upper 12 wide.

My only two issues with metric is first and largest I have no mental concept of the size of things when quoted in metric. I know that 25.4mm=1 inch (approximately). So I can convert and then I know what size it is. But when I hear 840mm, I have to convert it to understand. I do not want to use it enough so that I would understand. The other issue I have it is feels like the rest of the world really cares that the U. S. is not converted fully and probably never will be. It seems like they are determined to force our conversion sometimes. I don't like it when it seems somebody is trying to force their way of doing things on me.

[Wes Grass]

I know that 25.4mm=1 inch (approximately).

'approximately' ???

I guess it is 'approximate', since that's backwards ;-) The definition of an 'inch' is now precisely 25.4mm. We changed, they didn't. Although the difference is so tiny it's hardly measurable outside a laboratory.

Length is easy, it's the force and pressure stuff that drives me nuts. French engineer: 'it'll be fine, the force on it is only 5 Newtons'. Me: 'what's a Newton'? French engineer: 'It's 1/10th of a kilogram'.

Hmmm ... why 1/10th? Where does that come from? It's not ... It's 1/9.8 Kg ... the 9.8 being the acceleration of gravity in Meters/sec^2, vs 32.2 feet. So they've got a Newton for force, and a kilogram for mass. And we've got the pound for ... weight? ... umm, no ... well, yeah, it's the force applied by the acceleration of gravity acting on a mass of a ... 'slug'. Which is ??? 32.2 lbs? Or 1/32.2 lbs? Huh?

I submit this for a future society rebuilding after the apocalypse: Make your length standard based off the average acceleration of gravity*. That should make all this stuff the same, I think.

* Sure, it varies around the globe, but only physicists would need to worry about that. Any engineering of buildings and bridges should be close enough to ignore.

[Mel Fulks]

I submit this for a future society rebuilding after the apocalypse: Make your length standard based off the average acceleration of gravity*. That should make all this stuff the same, I think.
OK I wrote it all down .....but I’m really bad about remembering to check my pockets before they go in the washer.
New standards would mean the end of standards.

[Curt Harms]

New standards would mean the end of standards.

Not if everybody agreed to use the New Standard.

[Curt Harms]

My only two issues with metric is first and largest I have no mental concept of the size of things when quoted in metric. I know that 25.4mm=1 inch (approximately). So I can convert and then I know what size it is. But when I hear 840mm, I have to convert it to understand. I do not want to use it enough so that I would understand. The other issue I have it is feels like the rest of the world really cares that the U. S. is not converted fully and probably never will be. It seems like they are determined to force our conversion sometimes. I don't like it when it seems somebody is trying to force their way of doing things on me.

The inability to visualize metric units like we do "traditional" units is probably the largest impediment to U.S metric use. We can all look at a 2 X 4 or a 5/16" bolt and recognize it for what it is. And Newtons? Yeah, I'm lost there. Pressure units too. Some are fairly easy, a liter is a little over a quart, a meter is a little over a yard (39 inches), a kilometer is a little over a half mile (5/8 of a mile). Newtons and hectpascals? If there's a simple approximate conversion I don't know it.

[Jim Dwight]

It's a bit like what language we speak, read, and write. All languages work. The serve their purpose. But we want to use what we are most comfortable with (or the only one I know in my case). Metric works. So does feet, inches, pounds, etc.. Arguing one is better than the other is pointless. There are some advantages of the metric system but if it was truly better the conversion would happen. When two languages or two systems of measurement both work fine, which you use becomes a personal preference. The only real problem arises from multiple systems. That can cause mistakes, frustration, etc..

[Brian Holcombe]

The metric system exists because there were something like forty different systems of measure at the time, in France. The same situation is not present here, thankfully, and the standard system is great in my opinion. I can visualize feet and inches. That said, nothing stops you from enjoying some 12.7mm collets and shanks if you want to be fully metric :D

[Rod Sheridan]

Jim, you're absolutely correct in that you have to use a system for some time to become familiar with it.

I'm 63 years old, so too young to have had any real education in the Imperial system as science was metric for me through high school and post secondary.

I design my own furniture, and use metric measurements because I find it easier to add millimeters than 64ths of an inch.

I find that in most aspects of my life I really don't use measurements, when I order luncheon meat at the deli, I let them know how many grams I want ( normally 300) however if you put 250 or 350 grams in my hand I wouldn't be able to tell you that they're 250 or 350 grams. I think a lot of our experiences in life are like that.

Obviously at work or in the shop or garage I use measurements, and have measuring tools in both systems as I own British and German motorcycles. The British bikes are the most fun, 3 different thread and fastener systems on the same machine.......LOL

In Canada we're stuck with the plywood/softwood lumber system in Imperial units as well.

In response to your not wanting someone to tell you which system to use, well they already did, and you're using it without having chosen it yourself. That's what happens in most of our lives...........Regards, Rod.

[Rod Sheridan]

'approximately' ???

I guess it is 'approximate', since that's backwards ;-) The definition of an 'inch' is now precisely 25.4mm. We changed, they didn't. Although the difference is so tiny it's hardly measurable outside a laboratory.

Length is easy, it's the force and pressure stuff that drives me nuts. French engineer: 'it'll be fine, the force on it is only 5 Newtons'. Me: 'what's a Newton'? French engineer: 'It's 1/10th of a kilogram'.

Hmmm ... why 1/10th? Where does that come from? It's not ... It's 1/9.8 Kg ... the 9.8 being the acceleration of gravity in Meters/sec^2, vs 32.2 feet. So they've got a Newton for force, and a kilogram for mass. And we've got the pound for ... weight? ... umm, no ... well, yeah, it's the force applied by the acceleration of gravity acting on a mass of a ... 'slug'. Which is ??? 32.2 lbs? Or 1/32.2 lbs? Huh?

I submit this for a future society rebuilding after the apocalypse: Make your length standard based off the average acceleration of gravity*. That should make all this stuff the same, I think.

* Sure, it varies around the globe, but only physicists would need to worry about that. Any engineering of buildings and bridges should be close enough to ignore.

Ah yes, the slug.

In Canada I find it funny when people state their weight in Kilograms, when of course that's their mass, as you said we need to multiply by the acceleration due to gravity to obtain Newtons.....Rod

[Rod Sheridan]

The inability to visualize metric units like we do "traditional" units is probably the largest impediment to U.S metric use. We can all look at a 2 X 4 or a 5/16" bolt and recognize it for what it is. And Newtons? Yeah, I'm lost there. Pressure units too. Some are fairly easy, a liter is a little over a quart, a meter is a little over a yard (39 inches), a kilometer is a little over a half mile (5/8 of a mile). Newtons and hectpascals? If there's a simple approximate conversion I don't know it.

Hi Curt, the issue is not to convert, no need to.

I have to admit that when driving in the US I put my GPS in Imperial units so that I have a display that matches the road signs (all my modern vehicles are metric). That way I don't have to remember that 50 MPH = 80 KPH, no conversion, I just use the display in Imperial units.

The easiest is temperatures, at 0C you have ice, at +30C it's hot outside, at -30C it's cold..........Beautifully symmetrical :D...................Regards, Rod.