C&S #30, a C-16 conversion

[Keith Hayes]

What Todd says. I was meaning 0.001 inches, not mm.

[John Greenly]

Ouch, yes, Todd!

 I work a lot with Brits, and in the UK nowadays everybody says "mil" for mm.   When I go there and say "millimeter" they look blank as if they'd never heard the word before.  When they come over here to work in my lab the confusion is horrible.  None of them had ever heard that a "mil" is .001" here, at least for most traditional machinists and old folks like me.

Cheers,
John

... and then, of course, there is HO scale, 3.5mm to the foot,  what a weird mashup of units that is!

 

[ComoDepot]

I grew up being taught in Imperial measurements, I was on the cusp so am familiar with both.

I assumed mil was being used for metric..

[John Greenly]

Keith,

what you say about Sketchup's 3D matching of photos is very true.  You really have to pay close attention working in three dimensions not to go off on the wrong axis by mistake or, even easier to miss, work in the wrong plane without realizing it.    Setting it so that as you draw lines they appear in the color of the axis they are parallel to is a help, but I am always making multiple checks to be sure I'm referencing the plane I want.  You can't just go and measure the distance between two points on a photo and get the right answer.  You have to establish reference planes and work only directly in those,  or you get nonsense.  Hence, for instance, the critical importance of that line I mentioned in the example I showed, the line that establishes the displacement in the orthogonal, third dimension, of the plane of the cab side relative to the parallel plane of the drivers.  

Yes! I like your way of saying it; the folios call out "dimensions that are a concern to the shop forces."  

As far as exactness of dimensions goes, what matters to me is just how things look to me.  With cabs, for instance, the 4" too long and wide cab on my #30 isn't bothering me much, while the too-narrow cab on #13 really bugs me.  For me,  a very distinctive and pleasing feature of the smaller 3' gauge engines is the way the cab looks oversized to the boiler, compared with standard gauge engines.   So I'll fix #13's cab width for sure, but maybe not worry about #30.  

It is unfortunate that this cab stuff is buried in this thread.  How about if I start a new thread called cab stuff,  and just reference these posts in it?

Cheers,
John

[Todd A Ferguson]

Yes, I recall working with the high tech tool rooms in the auto industry 25-35 years ago and they would say 10th, meaning a ten thousandth I believe.  Back then the design was done in mm and the tool and die makers worked in imperial measurements...  When mil was mentioned I was thinking a thousandth but the discussion seemed to lead me to think mm.

Todd

Sent from my iPhone

On Dec 12, 2020, at 9:13 PM, John Greenly [via C&Sng Discussion Forum] <[hidden email]> wrote:

 Keith,

what you say about Sketchup's 3D matching of photos is very true.  You really have to pay close attention working in three dimensions not to go off on the wrong axis by mistake or, even easier to miss, work in the wrong plane without realizing it.    Setting it so that as you draw lines they appear in the color of the axis they are parallel to is a help, but I am always making multiple checks to be sure I'm referencing the plane I want.  You can't just go and measure the distance between two points on a photo and get the right answer.  You have to establish reference planes and work only directly in those,  or you get nonsense.  Hence, for instance, the critical importance of that line I mentioned in the example I showed, the line that establishes the displacement in the orthogonal, third dimension, of the plane of the cab side relative to the parallel plane of the drivers.  

Yes! I like your way of saying it; the folios call out "dimensions that are a concern to the shop forces."  

As far as exactness of dimensions goes, what matters to me is just how things look to me.  With cabs, for instance, the 4" too long and wide cab on my #30 isn't bothering me much, while the too-narrow cab on #13 really bugs me.  For me,  a very distinctive and pleasing feature of the smaller 3' gauge engines is the way the cab looks oversized to the boiler, compared with standard gauge engines.   So I'll fix #13's cab width for sure, but maybe not worry about #30.  

It is unfortunate that this cab stuff is buried in this thread.  How about if I start a new thread called cab stuff,  and just reference these posts in it?

Cheers,
John

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[Paul R.]

John, what about the European O scale which is 7mm/ft, which is where the HalfO scale comes from at 3.5mm/ft. This is what those of us in Aust who work in O scale contend with.Enough of nitpicking, You are all doing an excellent job of giving the rest of us the correct sizes for our locos, a question are the cabs on the overland S locos correct and for what period? thanks for any help. Paul R.