F7a Correct Windshield Shape


R

rbrown7713

New Member
I am scratchbuilding an F7a loco. and I had problems locating drawings of the windshield. After days of hunting on the web without results, I located a full scale F7. I then got some cardboard and traced the full scale shape, because I was tired of trying to reproduce the correct shape and failing. I am now in the process of transferring the shape into CAD. After trying to capture the gentle curves, I have come to conclusion that the shape was drawn from french curves. I am transposing the curves into meaningful arcs. So far I have about 20 arc center points, but I think that the shapr will be very accurate, probably within 1/8th inch of full scale. If anyone would like to discuss my endeavors or have info., I am all ears. Thanks Rbrown.
 
What scale are you building this engine in? If it's HO, Walthers new Genesis F units are literally about as close as you can come to perfect for both the windshield and nose. Kalmbach's Railroad Cyclopedia, Volume Two is expensive but it has some of the best blueprints for first generation diesels.
 
Windshield

Thanks for your input. I am scratchbuilding in 1:32. I have some blueprints, but unfortunately, it has no measurements of the windshield. By measuring the full scale, I will be dead on, no guess work. Taking shapes from another model, is at best, their interpretation of the shape, could be correct, could be not. I have seen many models of the F series, and yes they look good, but without measurments, it is difficult to transform the shape into CAD. When I started to extrapolate the arc centers of the full scale windshield, I had no idea how many points were involved.
 
Wow, I can see your problem now. You're right, that windshield is really complex to reproduce. Most model companies haven't gotten it right in the last 50 years. :) Good luck on your project.
 
Hello Jim, My name is Bob. I just finished the drawing of the windshield full scale in CAD, and I will later scale to 1:32. I am slow, so it took me all day to get it right. I ended up with 8 arcs, and 9 end points. I think I have an accurate record of the shape. Thanks, Bob.
 
Bob, you can't be that slow - it would take me about a week just to figure out how to get all the arcs in the right place. :) Do you have all the measurements you need for the nose? That seems to be about as difficult as the windshields to get right for modeling companies. Can you imagine a company producing a locomotive with that many compound angles just because it looked nice? Things were different back in the 40's.
 
Hello Jim, well thanks to Turbo-Cad, there are tools to make arcs tangent. I used that tool quite a bit. I did take a measurement from the end of the light to beginning of the arc just below the windshield. I don't think there is a straight line on that cab design. I might have to redesign the whole cab because I was modeling by eyesight and I can see my scale was off, too much guessing, that's why from now on I will be taking alot of trips down to the Gold Coast RR museum in Parrish to get specs. off of the prototype. Bob.
 
Pictures E-8 a and b

Hey Jim, here are some pictures of my E8s, I have quite a bit of work to do on them, but I am on my way. These are 1:32 scale. Bob.
 
Bob, are those models resin? Great job on the nose of the E-8. In theory, the nose of an E-8 and F-3 to F-9 are exactly the same except for the number boards, and some railroads ordered them or retrofitted them with F unit number boards. As far as I know, the windshields on the F and E units should also be identical but I don't know what your measurements will show. Compared to the rolling machine shop look of locomotives today, you can really see designers had their work cut out for them with EMD cab units.
 
I agree with you Jim. In the past, I would study an F or E unit nose when I was modeling it, and I sensed that when I looked at different locos of the same type, there were subtle differences and I couldn't put my finger on it, but then I read that they were built by various people and that there were no two exactly alike, close but no cigar. My cab was sculpted by hand and the sides were done on a Bridgeport. I now have a CNC, with Anilam controls, so that's why I am getting so exacting with the numbers. Yes, the models are made of epoxy and glass. I have molds for some Pullman corrugated passenger cars, circa 1945, such as the Texas Special, with the red and silver exterior. Here is a picture of an observation car I built, 1:32. I appreciate your interest in my endeavors. For me, this is a lifelong task. Bob.
 
Bob, you must have quite a shop to have CNC equipment. You'll probably be making the most accurate bulldog noses ever in 1/32 scale. My dad started out as a machinist before he went back to college to get his engineering degree and my first job was in a machine shop so I've always had an interest in how things are made.

I think you've put your finger on it when it comes to F and E unit noses. Although I'm sure the major pieces of steel were formed over molds, there was still a lot of hammering and hand fitting to get things to fit together. I doubt you'd ever find two F unit noses with the same dimensions in all planes. Most people really wouldn't notice but, with an eye like yours, you'll pick up the differences. As long as you have the skills and equipment, you can produce a very accurate model of an F or E unit but there will still be small variations between engines. I suspect that's why EMD made sure there were no curves on Geeps.
 
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