1/25 to 1:1 conversion question

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I've always had the understanding that 1mm in 1/25 scale equals 1 inch in real life. Lately I have been building some chairs for a 1/25 build and they look more like kids chairs next to my Woody. I took measurements from chairs in my house and converted them from inches to mm. Anybody know why they appear too small?

Thanks

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Posted · Report post

i'm no math genius but going by my socket set, a 12mm socket roughly equals a 1/2" socket.... and a half inch in 1/25 equals a foot, more or less. so, 1mm actually matches a half-inch more so than a full inch in 1/25th.

my advice? cut your losses and frustration and buy one of the scale conversion rulers. an architect's or engineer's scale for drafting is what i've been using for decades.

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Posted (edited) · Report post

i'm no math genius but going by my socket set, a 12mm socket roughly equals a 1/2" socket.... and a half inch in 1/25 equals a foot, more or less. so, 1mm actually matches a half-inch more so than a full inch in 1/25th.

my advice? cut your losses and frustration and buy one of the scale conversion rulers. an architect's or engineer's scale for drafting is what i've been using for decades.

Actually, your method calculates 1mm equals 1 inch.

If 12mm equals 1/2 inch and 1/2 inch equals one foot, than 12mm equals 1 foot. Therefore, 1/12mm would equal 1 inch.

Edited by Erik Smith

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Posted · Report post

There are 25.4 mm per inch, so 1 mm would equal 1/25 of an inch. Or 1 mm = 1 inch in 1/25 scale.

So to put it simply, yes, 1 mm = a 1/25 scale inch.

Why do your chairs look small? Maybe you measured wrong somewhere. But the 1mm = 1 inch in 1/25 scale is correct.

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Posted · Report post

That are scale cards you can buy that helps keep your scratch-building straight.

I think I got mine from EZ Scale Card or some such place.

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Posted (edited) · Report post

I've always had the understanding that 1mm in 1/25 scale equals 1 inch in real life. Lately I have been building some chairs for a 1/25 build and they look more like kids chairs next to my Woody. I took measurements from chairs in my house and converted them from inches to mm. Anybody know why they appear too small?

Thanks

Probably because your Woody in 1:1 is large, and your house chairs are relatively small in comparison :o;)

Edited by jeffs396

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Posted · Report post

If you have a calculator all you need to do is take your 1:1 measurement and then divide by 25 to get the 1/25 equivalent. Same thing works for any scale - for 1/32, take the 1:1 and divide by 32, etc. No millimeters or scale rulers needed.

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Posted · Report post

If you have a calculator all you need to do is take your 1:1 measurement and then divide by 25 to get the 1/25 equivalent. Same thing works for any scale - for 1/32, take the 1:1 and divide by 32, etc. No millimeters or scale rulers needed.

You need the ruler to measure the part in the first place!

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Posted · Report post

You need the ruler to measure the part in the first place!

You do need a ruler but not a scale ruler. Just the regular kind that everybody already has. Measure the real thing with a regular ruler and let's say it measures 25" (makes it easy!). Divide by 25 and that gives you 1". Then you know to measure 1" on your model with a regular ruler to equal what you measured on the 1:1. No scale rulers needed.

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Posted · Report post

You do need a ruler but not a scale ruler. Just the regular kind that everybody already has. Measure the real thing with a regular ruler and let's say it measures 25" (makes it easy!). Divide by 25 and that gives you 1". Then you know to measure 1" on your model with a regular ruler to equal what you measured on the 1:1. No scale rulers needed.

Oh, I see what you mean. Right, no "scale ruler" needed. 1 mm = 1 inch in 1/25 scale.

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Posted · Report post

I've always had the understanding that 1mm in 1/25 scale equals 1 inch in real life. Lately I have been building some chairs for a 1/25 build and they look more like kids chairs next to my Woody. I took measurements from chairs in my house and converted them from inches to mm. Anybody know why they appear too small?

Thanks

OK, some conversions: 25.4mm equals one inch. Drop the .4mm, as 1/25 of 4mm is beyond the possibilities of most all of us, unless we are attempting a micro-precision machined part for say, an operating scale model engine. So, 1mm can be said to equal on inch in 1/25 scale. The same is even more true in English measurements (which is what we traditionally use in the USA: 1" in 1/25 scale equals EXACTLY .040" (40 thousandths of an inch!--Evergreen Scale Models has all manner of strip styrene at .040"). So check your measurements more carefully--this is HS Math 101, frankly!

Art

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Posted · Report post

Probably because your Woody in 1:1 is large, and your house chairs are relatively small in comparison :o;)

And having a large Woodie is a problem why?

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Posted (edited) · Report post

Good one Nitro Neil.

Thanks for your comments guys. Here is a pic. Even though the chair looks a bit bigger in this photo, don't ya think it still looks a tad small? It is the chair I actually model in.

IMG_1079.jpg

Edited by noname

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Posted · Report post

So, show us the chair you model in next to your own car. Looks good to me.

As for the conversion question, just bookmark a conversion site like the one listed above.

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Posted · Report post

I thought of doing that. The chair really does look smaller in real life. Any other opinions?

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Posted · Report post

It's hard to say from the picture, but I find it works fine . . .

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Posted · Report post

Maybe these will help.

convchart.jpg

Scale.jpg

Scale20Size20in20MM.jpg

Scale20Size20in20inches.jpg

Scalechart.jpg

Hope this helps out.

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Posted (edited) · Report post

I've always had the understanding that 1mm in 1/25 scale equals 1 inch in real life.

Close enough for small work - say, less than 6 inches or so. After that, you're no longer building in 1/25, you're building in 1/25.4 scale. There's nothing wrong with doing it; you just need to know that the quite small difference in measuring out a scale 2" becomes noticeable at 20", and glaring at 200".

A 20" piece in 1/25 is .8" long; in 1mm=1" it is .7874". That's a difference of .0126" - in 1/25, that's around 1/3". Is that a problem? Probably not for chair legs, but if you're building a roll cage, or something intricate or repetitive, it could be a big one.

A 100" wheelbase would be short by an inch and a half if you use 100mm to measure it instead of the proper 4".

Cutting/marking errors do play a big part too; I usually cut items long and file them to fit/measurement. I'm the type to measure with a micrometer, mark with a crayon, and cut with an ax.

Edited by SSNJim

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Posted · Report post

To convert MM to inches multiply by .03937.

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Posted · Report post

I have the same kit, so I took a measurement of the body height, which is about 2.5". In the picture, the chair appears to come up to just below the door handle (taking in to account the angle), which is approximately 1.375" high. Converting to 1:1, the body is about 62.5" high, or just over 5 feet. The chair is then approximately 35" tall, or just under 3 feet. That seems a little short to me. What are the dimensions of the actual chair?

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Posted (edited) · Report post

Thanks for all your opinions and charts guys. Math was never my strong point.

The chair has legs 16 inches long. My little guy has legs 14mm long. The back of the chair is 32 inches high from the floor. My scale chair is 31mm. The width of the front of the chair is 15.5 inches wide, and mine is 15mm. So I am off a tad, probably from sanding. I wouldn't think that little bit would make that much differnce. I did a rocking chair before this chair and that appeared small as well. Although it looks a little bit better than this chair.

I actually took the 1:1 chair out and sat it beside my car. It actually looks small beside my car as well. So maybe I'm not that far off. It does come up higher to my door handle, but I'm not driving a Woody either.

I am in the process of making a chair slightly bigger in mm than inches of the 1:1. It could be that this one "appears" more in scale.

In starting this thread I was mostly interested in weather 1mm=1 inch is a good rule of thumb. It would appear that most of us is comfortable with this. I will have to look more at all the supplied charts. ;)

Edited by noname

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Posted · Report post

well; i SAID i wasn't a math genius...... you proved it! i always use the architect's scale i've been using since Drafting class....

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Posted · Report post

The chair has legs 16 inches long. My little guy has legs 14mm long. The back of the chair is 32 inches high from the floor. My scale chair is 31mm. The width of the front of the chair is 15.5 inches wide, and mine is 15mm.

<snip>

So maybe I'm not that far off.

I took the liberty of figuring out what the size of your chair would be in 1/25 versus your model. First I divided 1 by 25, and came up with .04. I multiplied that times the length of your 1:1 chairs leg (16"), and multiplied that times 25.4 to get the size in mm:

16" = 16.25mm

32" = 32.5mm

15.5" = 15.75mm

Looks like it is fairly close, but I would be interested in seeing the results of the second chair just for comparison's sake.

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