seeker589 Posted December 21, 2009 Share Posted December 21, 2009 (edited) I haven't purchased a scale ruler yet. I'm looking for advice regarding how to scale out measurement for a 1/25 scale model. Is 1/25 of a foot to .48 inch a proper conversion? For example - A 1:1 1969 Camaro's wheelbase is 108 inches - is a 1/25 1969 Camaro's wheelbase 4.32 inches? Edited December 21, 2009 by seeker589 Quote Link to comment Share on other sites More sharing options...
Harry P. Posted December 21, 2009 Share Posted December 21, 2009 1/25 scale is just that... 1/25 the size of the original. You don't need a "scale ruler"... if the wheelbase of the 1:1 car is 108", then in 1/25 scale it would be 4.32" (108" divided by 25). Any scale works the same way... the scale is just another way of saying what size the model is compared to the original. 1/8 scale is 8 times smaller, 1/16 scale is 16 times smaller, 1/12 is 12 times smaller, etc. Quote Link to comment Share on other sites More sharing options...
seeker589 Posted December 21, 2009 Author Share Posted December 21, 2009 Thanks Harry. Then my instincts were correct. Quote Link to comment Share on other sites More sharing options...
diymirage Posted December 21, 2009 Share Posted December 21, 2009 do you have a metric ruler ? in real life in inch is 25 mm (roughly) so in 1/25 scale what is an inch in real life is 1 mm in the project so if your wheel base is 108 inches it is 108 mm or 10.8 cm Quote Link to comment Share on other sites More sharing options...
bobss396 Posted December 21, 2009 Share Posted December 21, 2009 I use the metric conversion as well. For 1/25th scale, 1 inch = 1mm which is close enough to .040". So if 1" = .040, 2" = .080 and so on. I find this to be the easiest way to go and use it all the time. Bob Quote Link to comment Share on other sites More sharing options...
Pete J. Posted December 21, 2009 Share Posted December 21, 2009 I think the problem that most people have is that we express the scale as a fraction when it is in reality a ratio. The proper mathematical annotation would not be 1/25 but actually 1:25 or a ratio of 1 to 25. To me, the the question is much easier if you understand that bit. Also, because it is a ration and not a dimention, it can be measured in anything. It doesn't matter. What ever dimension you plug in, either inches, feet, meters, cm it all comes out correct. "Just a walk in the park Kazanschy" Quote Link to comment Share on other sites More sharing options...
seeker589 Posted December 21, 2009 Author Share Posted December 21, 2009 (edited) do you have a metric ruler ? in real life in inch is 25 mm (roughly) so in 1/25 scale what is an inch in real life is 1 mm in the project so if your wheel base is 108 inches it is 108 mm or 10.8 cm I just used my metric ruler. While 25mm is close to one inch - it is just that CLOSE. I measured out 108mm and then flipped the ruler around and the measurement was 4 and 1/16 inches. With the equation in my first post - the measurement is 4.32 inches which comes out to just a hair over 4 and 5/16. The resulting findings are a loss of about one quarter inch. With a small measurement - that's not much of a big deal. But when calculating wheelbases, or car width or body length the loss (or inaccuracy) can be just enough to throw the proportions off just enough to make it look not-right. But I would like to thank you for your input - I will use the 25mm equals about one inch in the future. The metric system is SO much easier to work with. I SO like to deal with whole numbers and not complex fractions. Can anyone but a machinist picture the length of 21/64 and is it longer or shorter then 9/32. Where as 23mm is shorter then 32mm. I'm working on a scale fractions table and should have it posted this week. Edited December 21, 2009 by seeker589 Quote Link to comment Share on other sites More sharing options...
seeker589 Posted December 21, 2009 Author Share Posted December 21, 2009 I think the problem that most people have is that we express the scale as a fraction when it is in reality a ratio. The proper mathematical annotation would not be 1/25 but actually 1:25 or a ratio of 1 to 25. To me, the the question is much easier if you understand that bit. Also, because it is a ration and not a dimention, it can be measured in anything. It doesn't matter. What ever dimension you plug in, either inches, feet, meters, cm it all comes out correct. "Just a walk in the park Kazanschy" Very nice explanation of adjustment of perception! Kudos for thinking just outside the mainstream. I have seen Japanese kits with a ratio and not a fraction to explain scale. Quote Link to comment Share on other sites More sharing options...
Harry P. Posted December 21, 2009 Share Posted December 21, 2009 I think the problem that most people have is that we express the scale as a fraction when it is in reality a ratio. Actually the scale of a model is a fraction. A 1/25 scale model is one twenty-fifth the size of the original. That's a fraction, plain and simple. It can also be seen as ratio, but whether you want to see it as a fraction or a ratio doesn't make any difference. Whether 1/25th of the original, or 1/24th, or 1/8th, or any other scale, they are all fractions, and all tell you what fraction of full size the model is as compared to the original. Quote Link to comment Share on other sites More sharing options...
randx0 Posted December 21, 2009 Share Posted December 21, 2009 something else to take into consideration is that there is a lot of discrepency between the models we build and the actual real life counter parts so sometimes exact scale measurements will make some items look wrong . for example a stop sign is way bigger than you think if you put one that was scaled out exactly it probably would not look in scale .in short measurements will get you close but you still need it to look right. Quote Link to comment Share on other sites More sharing options...
didgeytrucker Posted December 21, 2009 Share Posted December 21, 2009 You can go to an office supply store or art store and ask for an engineer's scale (as opposed to an architects scale). It divides inches into decimals instead of fractions. The 1:50 side of the scale divides an inch into 50 parts or 1/25 scale half inches! Yes, the 1:100 side will give you 1/25 scale quarter inches. Tracy Quote Link to comment Share on other sites More sharing options...
charlie8575 Posted December 21, 2009 Share Posted December 21, 2009 You can go to an office supply store or art store and ask for an engineer's scale (as opposed to an architects scale). It divides inches into decimals instead of fractions. The 1:50 side of the scale divides an inch into 50 parts or 1/25 scale half inches! Yes, the 1:100 side will give you 1/25 scale quarter inches. Tracy I hadn't even thought of that! Thanks for the tip! Charlie Larkin Quote Link to comment Share on other sites More sharing options...
Modelmartin Posted December 21, 2009 Share Posted December 21, 2009 I just used my metric ruler. While 25mm is close to one inch - it is just that CLOSE. I measured out 108mm and then flipped the ruler around and the measurement was 4 and 1/16 inches. With the equation in my first post - the measurement is 4.32 inches which comes out to just a hair over 4 and 5/16. An inch is 25.4 MM. When you measure something longer like a wheelbase that is a lot of .4 mm to add up. 108 x .4 is 43.2 mm short in full size which is 1.7 inches. That would be approximately 1.7 mm which is .067 inches which is a bit more than a 1/16 of an inch. Not a lot but it can make a difference. I don't know how you ended up a quarter of an inch short. By the way, I am a machinist and do this stuff every day including trig!! Quote Link to comment Share on other sites More sharing options...
diymirage Posted December 21, 2009 Share Posted December 21, 2009 By the way, I am a machinist and do this stuff every day including trig!! i remember skipping al sorts of trig and geo classes under the banner "ill never use this nonsense in real life" then i got out of college and got a job as a metalworker CNCing sheetmetal trim for buildings all of a sudden my days were filled with trying to figured out the lenght of a piece of trim and the circumference of an angle and wether it i an inside angle or an outside angle and how many of them i can get out of one sheet of metal and where i can trim it just a MM or two so i could get one extra piece out of a sheet great fun Quote Link to comment Share on other sites More sharing options...
seeker589 Posted December 21, 2009 Author Share Posted December 21, 2009 An inch is 25.4 MM. When you measure something longer like a wheelbase that is a lot of .4 mm to add up. 108 x .4 is 43.2 mm short in full size which is 1.7 inches. That would be approximately 1.7 mm which is .067 inches which is a bit more than a 1/16 of an inch. Not a lot but it can make a difference. I don't know how you ended up a quarter of an inch short. By the way, I am a machinist and do this stuff every day including trig!! OOPS!!!! I just measured it out again - I'm still looking for my "lost" quarter in also. 25mm is much closer to one inch than I had initially thought. I'm sorry if I insulted anyone. It was truly an honest mistake. I'm off to find my lost quarter inch. Quote Link to comment Share on other sites More sharing options...
Modelmartin Posted December 21, 2009 Share Posted December 21, 2009 OOPS!!!! I just measured it out again - I'm still looking for my "lost" quarter in also. 25mm is much closer to one inch than I had initially thought. I'm sorry if I insulted anyone. It was truly an honest mistake. I'm off to find my lost quarter inch. No worries! Math doesn't come easily to everyone. I am just lucky that it is easy for me. Practice helps. Quote Link to comment Share on other sites More sharing options...
Harry P. Posted December 21, 2009 Share Posted December 21, 2009 By the way, I am a machinist and do this stuff every day including trig!! The only Trig I'm familiar with is Sarah Palin's kid!!! Quote Link to comment Share on other sites More sharing options...
seeker589 Posted December 21, 2009 Author Share Posted December 21, 2009 No worries! Math doesn't come easily to everyone. I am just lucky that it is easy for me. Practice helps. My problem had nothing to do with math. I physically measured out the 108mm then measured out the same marked distance with inches! That is why I'm so perplexed! No calculators were harmed in the measuring of this distance. Quote Link to comment Share on other sites More sharing options...
george 53 Posted December 21, 2009 Share Posted December 21, 2009 Harry, I graduated with a guy named Trygve. We just called him Trig.(he was Scandanavian) Quote Link to comment Share on other sites More sharing options...
Pete J. Posted December 22, 2009 Share Posted December 22, 2009 Actually the scale of a model is a fraction. A 1/25 scale model is one twenty-fifth the size of the original. That's a fraction, plain and simple. It can also be seen as ratio, but whether you want to see it as a fraction or a ratio doesn't make any difference. Whether 1/25th of the original, or 1/24th, or 1/8th, or any other scale, they are all fractions, and all tell you what fraction of full size the model is as compared to the original. Harry - This part came from my drafting training back in the dark ages before CAD, when we actually used ammonia to make blue prints. All of our drawings had to have the scale shown in the caption and it showed it as 1" = 25" or what ever. That was a ratio. The fraction you mention is true but it is thinking in reverse to the scale drawings I was trained for. In the world of drafting, the drawing is usually a small drawing of a full sized object. In modeling we are using the scale in reverse as we are making a scaled down version of the original. Now days with micro-everything we have to draw larger drawing of what we make that is small. A bit of a turnaround from the days of my schooling. The reason that there are Engineers scales in .10" and architects scales in fractions, is that machine tools are calibrated in .001" and buildings (architects) are built in feet and inches. Thinking in ratios made a lot more since to me and it was a formal notation for us. Never used it professionally but it has come in handy over the years. Quote Link to comment Share on other sites More sharing options...
Guest Gramps-xrds Posted December 22, 2009 Share Posted December 22, 2009 Simple way to get any 1/25 scale dimension is to remember just 2 things. .040=1in and .480=1ft. With these 2 measurements you can make anything in 1/25th scale you want. It's very basic math. All you have to do is either multiply or divide. Quote Link to comment Share on other sites More sharing options...
Modelmartin Posted December 22, 2009 Share Posted December 22, 2009 (edited) Simple way to get any 1/25 scale dimension is to remember just 2 things. .040=1in and .480=1ft. With these 2 measurements you can make anything in 1/25th scale you want. It's very basic math. All you have to do is either multiply or divide. That jives with everything else here. Your dimensions are right on. Divide 1 by 25 and you get .040. One millimeter is .03937(rounded) Thats only 6 thou per scale foot difference or about .050" actual for a typical scale wheelbase. Nobody will ever notice. Edited December 22, 2009 by Modelmartin Quote Link to comment Share on other sites More sharing options...
E St. Kruiser50 Posted December 22, 2009 Share Posted December 22, 2009 (edited) For me, it's a lot easier to use digital calipers than a scale. You can measure inside and outside dimentions much more accurately, and for $12 to $20, you can get a descent pair of 6 inchers at a Harbor Freight store, and for hobby guys like us, they work great, and you can use them to directly transfer a measurement to a part by using the pointy end to scribe a location. As far as scale goes, I'm like everyone else here, either divide or multiply by the scale you're working in, depending on if you're getting bigger or smaller. Edited December 22, 2009 by Treehugger Dave Quote Link to comment Share on other sites More sharing options...
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