Switch to Metric? Yes or No

[Doug Garson]

It seems like I am often scaling between cm and mm. Sure, the conversion is easy, but it is also easy to forget and end up with a size that is 10X larger or smaller than expected. This error rarely occurs with imperial measurements. Construction is always in feet and everything else is always in inches.

If you end up with something that is 10x too big or small it would indicate that you don't have a basic feel for the size of the piece you are making. I'm old enough to have used a slide rule early in my career. If you misplaced the decimal point it meant you didn't have a good feel for what the answer should be. Last time I checked, stud spacing in construction was in inches not fractions of feet.
The only reason most people prefer the imperial system is that they grew up with it. Canada went metric a long time ago but I grew up with imperial so I am still more comfortable with it, I have nephews who grew up with metric and guess what? Even for me, driving distances are much easier to picture in metric despite my preference for imperial for woodworking. Why you ask? I can picture the length of a football field which is, approximately 100 metres long so a kilometer is about 10 football fields, Much easier to picture than 17.6 football fields.
The real source of errors is when converting between the two systems, to see a great example of this check out the Gimli glider, the pilot would give Sully a run for his money when it comes to extreme landings.
https://en.wikipedia.org/wiki/Gimli_Glider

[Mel Fulks]

Well, many times when employees "don't have a basic feel for the size of the piece they are making" , they might not even know
what they are making. Sometimes you don't get those details. I have refused to proceed with work where those details were not clear. I don't accept 'smart people don't need all the info'. And some things are made in different sizes. When the next Titanic film is made it will be important to know which model is 15 FEET and which is 1200 FEET.

[Bill Space]

My biggest issue with conversion is the sheer bulk of imperial rulers in my shop. The rules on my tablesaw fence, hand wheels on the metal lathe, more than a dozen tape measures, squares, calipers etc. The complete list would go on for several pages. It would be awkward to be partially switched to metric, so all of them would need to be switched.

I think Steve has hit the nail on the head. This was the conclusion I reached after reading everyone’s posts, before reading Steve’s comment. I have too many imperial tools to convert totally. Couple metal lathes and other machine tools as well as woodworking tools, measuring tools, and so on.

I guess for me converting would be mostly pain with little (if any) gain.

Thanks for the insight guys!

Bill

[Brian Holcombe]

I use both along with occasional use of Shaku.

[Mike Trent]

Several folks have commented about difficulties in conversion calculations, which can introduce errors. Pondering this, I thought to myself “Didn’t a jet run out of fuel in Canada, due in to an Imperial/metric conversion error? I seem to remember that.”

Google provided the answer. A perfect storm, including a conversion error, occurred, and an equally improbable number of serendipities allowed everyone to walk away.

https://en.m.wikipedia.org/wiki/Gimli_Glider

[Frederick Skelly]

All I'm gonna say is that the last time we had the english vs metric debate, I wrote down the following quote:

"The mile is based on a thousand paces, which is very handy if one wants to know how far he has walked. I will keep the metre in mind the next time I walk from the equator to the north pole."
- Warren Mickley

[Doug Garson]

Several folks have commented about difficulties in conversion calculations, which can introduce errors. Pondering this, I thought to myself “Didn’t a jet run out of fuel in Canada, due in to an Imperial/metric conversion error? I seem to remember that.”

Google provided the answer. A perfect storm, including a conversion error, occurred, and an equally improbable number of serendipities allowed everyone to walk away.

https://en.m.wikipedia.org/wiki/Gimli_Glider

mmmmm, where did I hear that before, oh wait, post #61 Yes it was an incredible story

[Mike Kees]

As a Canadian I learned Metric in school. As a carpenter I use imperial all day long. Funny because when I travel to the states it seems to take so long to drive a mile,much longer than a kilometer. I do not know anyone who tells you their height and weight in metric it is always 6'2'', 220. I can't imagine buying gas in gallons here in Canada. Temperature really screws me up in Farenheit, I have no idea what 30 degrees Farenheit is. So at the end of the day we are supposed to be officially metric but in reality because the U.S. is our largest trading partner we are truly caught between two systems. As a carpenter I have worked on large jobs (goverment) where plans are Metric. We used the "bastard tapes" talked about earlier in this thread with both systems on them. You simply used the Metric to cut plates to length and layed out with 16''' centers. All our plywood and OSB is 4'x8' because we export so much to the U.S.I do not think that will ever change. When I was 18 I started buying mechanical tools,I remember asking my Dad if I should buy Standard or Metric. Ended up with both,still use both however Metric is slowly gaining ground .I do work mostly with Imperial measure in my shop.

[Chris Parks]

If you’re doing it for a hobby have at it. If you are in the trades forget it, it’ll cost you money every day. Few trades people talk or use metric , so if you think you’re going to change the world , good luck to ya!

The rest of the world and large parts of US industry have already changed. Witness the importation of metric sized products into the US. It will be a gradual erosion of the imperial system and take many years but it will happen for better or worse.

[Ted Derryberry]

Yeah, like the Russian plywood I mentioned that's 1220 x 2440. Do the math.

[roger wiegand]

I’m a scientist, so I think in metric and centigrade , but I avoid conversions at all costs. Too error prone. As is doing math in fractions. As is dividing units into eight or 12 parts rather than 10. Just the way my brain works. As a cook I appreciate being able to weigh out 300 g of water when the recipe calls for 300 ml (yes, I also do all my cooking by weight/mass rather than volumes, similarly for mixing epoxy, making up shellac, or dyes. Again, less chance for error and relatively easy precision. If you were learning from scratch I can’t imagine why you would choose to use the oddball English measures.

[Gary Radice]

I have the same background as Roger and I mostly agree with him. I can use either system but for me the issue is tooling. My shop has all imperial tooling (drills, measuring tapes, scales, blades, bolts, etc. The only SI stuff is machine bearings! So although I would prefer metric in the shop, the only time I need to use metric is when I buy plywood.

[Ted Derryberry]

Every lumber yard I've ever been to still sells "three quarter inch" plywood, even though it's 18 mmish. Why would you need to use metric? In fact, type in "3/4 plywood" on Home Depot's website and you'll get 55 results.

Today I was in the shop and caught myself using "fractions of a fraction". My tape only goes to 1/16" of an inch, but I work to tighter tolerances. I needed to cut a part that "should" have been 26-3/4", but when I checked it was actually a little over. In my mind I thought 26 inches and 12 and one half 16ths. Never been a problem for me.

The 12/16ths comes from being around commercial drywall and ceiling crews. They usually have one guy measuring and installing and another cutting. With ceiling tiles they work to the 16th and just call out the inches and 16ths, even if its an even number. For example "15 and 8" means 15-1/2". Everybody knows the system so there's no confusion and it cuts down on the number of numbers you have to say or hear on an often noisy construction site. Ironically most of the guys come from countries that use the metric system.

[Patrick Curry]

Strange as it sounds, I think the hardest part of switching from imperial to metric is visualizing the measurements. Imperial is native- it’s like thinking in English.

[Keith Weber]

It's like saying The Swedish Krona is worth more than the Mexican Peso. Nope. It just takes more Pesos to buy a Volvo, but that Volvo has the same value no matter what.

If you think a Swedish Krona is not worth more than a Mexican Peso, then I'm afraid you don't understand the concept of currency exchange. A Krona IS worth more than a Peso (approximately 2.32 times more). That's why it takes less Kronor to buy your Volvo.