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3/4 = 18mm

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Blog entry by steliart posted 04-15-2017 04:39 PM 830 reads 0 times favorited 31 comments Add to Favorites Watch

Many times when I’m designing in sketchup, either following a project design, idea or measurements from a video that are in inches, it’s quite confusing for us who did not learn into the imperial system but in metric to get the measurements accurate and loosing a mm there and there that ads up to a significant number.
Watching many videos either tutorial or projects etc. when they give dimensions some say i.e. 1/2 inch and transform this to 13mm… well we all know that an inch is 25.4mm so that number is not very correct.
In my mind since 3/4 is never anymore 19mm but mostly 18mm (at least where I come from) the 1/2 inch in my mind is always 12mm, which actually is less accurate than the 13mm… but since the wood sheets are labeled in imperial with metric measurements I had to think this way
Of course one way is to use an imperial measuring tape when you want to use fractions etc. but neither this is very helpful to me since I’m slow in thinking imperial and second the actual wood measurements in Europe are metric, and even so if I design something in imperial all my machine tape measures are in metric and having metric numbers with three digit decimals is impossible to get accurate unless you sneak into the measurement.
Love to here your thoughts, comments or how you go about it if in this situation?

Stelios

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions



31 comments so far

View jbay's profile

jbay

1301 posts in 529 days


#1 posted 04-15-2017 05:38 PM

I guess it depends on the accuracy your after.
I use the Imperial and usually have to convert to metric.
Whether I’m converting to metric or Imperial I divide or multiply by the 25.4 and then use the decimal equivalent.
I’ve done it enough to recognize whether the decimal equivalent is 1/64 over or under and then bump my fence accordingly.
When material runs undersized, I measure with my digital mic and do all the math using decimals, then convert to Imperial when doing the layout or cutting.

-- If anyone would like to see my Portfolio, PM me and I would be glad to send you the link.

View steliart's profile

steliart

2297 posts in 2318 days


#2 posted 04-15-2017 05:52 PM

When designing you need to be dead on accurate Jbay.
And yes I see what you mean but as I was saying this is frustrating for my as my mind is only trained to metric and all these calculations take my time and sometimes I even make mistakes.
Of course I am not talking about simple measurements that a mm would not matter but if you building like a machine project then I prefer to cut always slightly bigger and sneak up

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions

View jbay's profile

jbay

1301 posts in 529 days


#3 posted 04-15-2017 06:17 PM

”When designing you need to be dead on accurate Jbay”.

Which is why I convert everything into decimals when doing the math for layouts.
Wish there was a magical way to do it but I’ve never learned it.
I’ll follow along to see if a better way comes up.

-- If anyone would like to see my Portfolio, PM me and I would be glad to send you the link.

View kiefer's profile

kiefer

5227 posts in 2297 days


#4 posted 04-15-2017 06:19 PM

Can you not design in imperial measurements in sketch up and then let it convert to metric ?
Here in Canada we still use both metric and imperial talk about confusion and we are officially metric we still buy 2×4 lumber and 4”x 8’ sheet goods and commercial blue prints come in mm not meters, centimeters and millimeters .

-- Kiefer https://www.youtube.com/user/woodkiefer1/videos

View Bricofleur's profile

Bricofleur

1400 posts in 2823 days


#5 posted 04-15-2017 07:19 PM

If one wants to follow a plan to build something, he better get or buy a plan dedicated for the desired Metric or Imperial measurements. Projects found on worldwide forums such as this one, measurements should be taken into consideration only to get an approximate idea. One should sit down and do his homework and review and convert all measurements and make his own plan or sketch. I believe such forums exist only to share projects and inspire viewers, and possibly design, modify and build their own project.

Best,
Serge

-- Learn from yesterday, work today and enjoy success tomorrow. -- http://atelierdubricoleur.wordpress.com

View steliart's profile

steliart

2297 posts in 2318 days


#6 posted 04-15-2017 07:22 PM

Of course you can Kiefer but then you end up with lots of decimals which is not something you can really use practically. The other way is to print in what ever and then use your template prints to cut around but also this has its limitations.

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions

View steliart's profile

steliart

2297 posts in 2318 days


#7 posted 04-15-2017 07:25 PM

Of course you can Kiefer but then you end up with lots of decimals which is not something you can really use practically. The other way is to print in what ever and then use your template prints to cut around but also this has its limitations.

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions

View steliart's profile

steliart

2297 posts in 2318 days


#8 posted 04-15-2017 07:26 PM

Thats exectly what I am doing Serge I draw everything in metric before doing it …. but I was just saying that this is a hassle :) hahaha

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions

View Bricofleur's profile

Bricofleur

1400 posts in 2823 days


#9 posted 04-15-2017 07:36 PM

Hassle, this is what woodworking is all about !
A synonym would be ‘Challenge’.

Best,
Serge

-- Learn from yesterday, work today and enjoy success tomorrow. -- http://atelierdubricoleur.wordpress.com

View jimintx's profile

jimintx

369 posts in 1215 days


#10 posted 04-15-2017 07:38 PM

My approach would be to simplify this stuff.
Pick one and work in it for both design and for cutting and production.
I guess I’m not exactly seeing why that isn’t possible, but I bet you metric guys can tell me what’s wrong with that.

As I have said before in similar discussions, I design a little and then just cut the rest to fit. I am not into using pre-made plans, it would slow me down, I think.

-- Jim, Houston, TX

View doubleDD's profile

doubleDD

5994 posts in 1673 days


#11 posted 04-15-2017 08:23 PM

I use both depending on the job. I know the imperial system but sometimes you have to adapt. That’s how the world is and is good to know both.

-- Dave, Downers Grove, Il. -------- When you run out of ideas, start building your dreams.

View steliart's profile

steliart

2297 posts in 2318 days


#12 posted 04-16-2017 12:29 AM



Hassle, this is what woodworking is all about !
A synonym would be Challenge .

Best,
Serge

- Bricofleur

Very well said Serge … Challenge… I stand corrected (thumbs up) !!!

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions

View steliart's profile

steliart

2297 posts in 2318 days


#13 posted 04-16-2017 12:36 AM



My approach would be to simplify this stuff.
Pick one and work in it for both design and for cutting and production.
I guess I m not exactly seeing why that isn t possible, but I bet you metric guys can tell me what s wrong with that.

As I have said before in similar discussions, I design a little and then just cut the rest to fit. I am not into using pre-made plans, it would slow me down, I think.

- jimintx


Nothings wrong with what you say Jim your right and I did not mean to say that is impossible because thats what I do … I was only referring when you need to follow specific dimensions :)

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions

View steliart's profile

steliart

2297 posts in 2318 days


#14 posted 04-16-2017 12:42 AM

Dave, me I’m not good in imperial never learn to use it … I guess is back to school for me :) hahaha
Well I guess it’s easier if you know imperial to do metric than the other way around :) !!!!

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions

View MrRon's profile

MrRon

4073 posts in 2874 days


#15 posted 04-16-2017 08:28 PM

Unlike most woodworkers, I am fortunate to have AutocadĀ© software. With that, I design all my own projects. Everything is designed to .001” precision. If I’m designing a project for outdoors such as a deck, I will design using architectural format with 1/16” precision. I use actual dimensions of the material used. If I’m using 3/4” plywood, my design takes into account the plywood is actually 23/32” thick, but I check the actual thickness first as the dimensions vary from source to source. I am very comfortable with mathematics, so design is easy for me whether it be Imperial or metric. I know this is a concern for many who don’t embrace math. I can only suggest you convert everything to the system you are most comfortable with and work exclusively with that for the entire project. A small hand held calculator should be a part of anyone’s tool box.

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