EMD F7 in SCALE

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dash9
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Re: EMD F7 in SCALE

Post by dash9 »

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Steggy
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Re: EMD F7 in SCALE

Post by Steggy »

rkcarguy wrote: Thu Dec 03, 2020 12:03 pm The pattern I saw on an F7 with mars light on Youtube, appeared to be an oval pattern about as tall as the train and maybe 2-3x the width.
I'm thinking you just make a ball bearing follower connected to an oval shape "cam" with a spring on it, and then use a slotted arm on a motor to turn it about 30rpm?

https://www.youtube.com/watch?v=mB0_yt-mIE4
That is a Pyle-National Gyralight on that locomotive. The Chicago & Northwestern (the road I'm modeling) used Mars lights, which produced the Lissajous pattern. The Gyralight would be easy to model, since it's a circular motion.
Regarding an electronic version, there is already some offerings in O-gauge that could probably have larger LED's or reflectors fitted to use it for 1.5" scale if you wanted to go that route. I'm not sure how real that would look though.
No LEDs! They have no resemblance to an F-unit's headlighting, other than producing light.
Last thought, you could just shade part of the bulb and have it simply rotate, but would have to give up that oval pattern.
More importantly, the beam would have no projection, since it is the reflector, not the lamp, that gives the Mars light it's piercing beam.
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Steggy
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Re: EMD F7 in SCALE

Post by Steggy »

No LEDs allowed!
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
rkcarguy
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Re: EMD F7 in SCALE

Post by rkcarguy »

Ah I see, so the motion like the 888 style mars lights? (most of what I am seeing is from fire trucks though).
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Steggy
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Re: EMD F7 in SCALE

Post by Steggy »

rkcarguy wrote: Thu Dec 03, 2020 1:24 pm Ah I see, so the motion like the 888 style mars lights? (most of what I am seeing is from fire trucks though).
Correct. The motion paints a Lissajous pattern. The Mars light (not to be confused with a Gyralight, which was a Pyle-National product) found widespread use on locomotives, starting in the 1930s. The oscillating beam could be seen for miles.
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
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Steggy
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EMD F7 in SCALE

Post by Steggy »

EMD F7 in SCALE
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BODY CONSTRUCTION: An Illuminating Task Part II

Mounted immediately above the number boards on an F7 are the classification lights. The exterior lens in the original is a Fresnel type, which causes a relatively narrow beam to be projected from the incandescent lamp within. It is possible to change the color by rotating a disk with colored lenses that is placed between the lamp and outer lens. Despite some statements found here and there on the 'Net, there is no legal requirement that class lights be illuminated while a train is on the mainline. Class lights exist primarily for the railroad's benefit, indicating the type of train:
  1. Not illuminated - scheduled train or first section of a multi-section scheduled train.
  2. Green - second, third, etc., section of a multi-section scheduled train.
  3. White - "extra" train, that is, one that is not scheduled.
  4. Red - shown when the locomotive is trailing the train, such as in push-pull commuter service.
The challenge in modeling the classification lights was in finding something that would make a reasonably-accurate outer lens and would project light in a reasonable manner. It so happens that a certain kind of panel-mount LED holder is very close to what is needed. In fact, I discovered that it is sufficiently close to being the correct diameter that I could make it readily fit the class light openings in the F-unit's nose with some simple surgery.

Below is a photo of the parts involved.

class_lights_parts.jpg

The holder consists of the lens, which is in the lower middle of the photo, and the socket. The lens screws into the socket to hold the assembly together. There is a flange on the lens to seat it against the mounting surface.

This assembly is designed to accept a 10 millimeter "jumbo" LED, which is visible in the socket on the right. As I mentioned in an earlier post, I don't like the appearance of LED headlights. However, I decided using LEDs in the class lights would work out, since in a fit of evil perversion, I decided to have green class lights—green is green, regardless of the light source.

Having gotten the parts, I fitted each socket with a pigtail, in which a ballast resistor is connected in series with the positive lead. The resistor is required to limit the LED current to a safe level. The pigtail is fitted with a polarized plug, since LEDs are polarity-sensitive—hook one up backwards and either it won't light up, or will "light up" for a millisecond or two. :D

The below photo is the two assemblies being tested on my electronics bench.

class_lights_test.jpg

With assemblies made and tested, it was time to get them mounted into the nose. I started by measuring the lens outside diameter, which was 14mm. The hole in the nose was smaller than that, so some drilling would be required. However, a recess would also be required on the interior side to provide clearance for the socket, as the thickness of the nose was too great to allow the socket to simply seat against the interior surface. After doing some more measuring, and a little thinking—always a dangerous activity when it comes to me, I decided I would counter-bore the interior side of the light opening to accommodate the socket.

The first step was to enlarge the mounting holes to accept the lenses. The closest "standard" size to 14mm is 9/16" (the difference between the two is 0.011"). It so happens I have a 9/16" straight shank counterbore that uses interchangeable pilots. That would work for enlarging the mounting hole. However, I also had to counterbore the interior for socket clearance, that counterbore being 7/8". Once again, serendipity came to the rescue. The 9/16" counterbore had a 5/16" pilot and as luck would have it, I also had a 5/16" pilot that would fit the 7/8" counterbore.

So I drilled the mounting holes to 5/16" and then counterbored the interior to 7/8" to accommodate the socket, using a slow-running pneumatic drill motor to turn the counterbore. With that done, I finished the hole to size with the 9/16" counterbore. Voilà! The lens fit like it was made for it. Below is what the surgery to the nose looks like.

class_light_opening.jpg

Here's the F-unit in the shop shortly after I installed the class lights.

es02.jpg

...and here's a lighting test in the shop.

head_class_lights.jpg

Hmmm...a second-section train. Where's the first section? :D
Last edited by Steggy on Wed Sep 29, 2021 12:46 am, edited 1 time in total.
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
rkcarguy
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Re: EMD F7 in SCALE

Post by rkcarguy »

That looks great BDD!
FYI, they make multi color LED's that size :)
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SPSteam2491
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Re: EMD F7 in SCALE

Post by SPSteam2491 »

"That is a Pyle-National Gyralight on that locomotive. The Chicago & Northwestern (the road I'm modeling) used Mars lights, which produced the Lissajous pattern. The Gyralight would be easy to model, since it's a circular motion."

An interesting note about the Gyralite (and the Mars light too) is that the pattern is not circular. There is more left/right movement than up and down for both instances. The Gyralite has 20° left/right movement and 10° up/down movement. There are a lot of interesting motions in those mechanism and really fun to experiment with motion studies in 3D modeling systems.

I have been working with another supplier in the hobby to reproduce 1/8" scale versions that match the full size motions of both a Mars and Gyralite mechanism to fit within the housings of F or E units. I won't spoil the release of it as I will let that supplier make the official announcement but wanted to get that out there. There have been some prototype units built and they look specular.
Thanks
John LaFavor
Pacific Design Shops
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Steggy
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Re: EMD F7 in SCALE

Post by Steggy »

rkcarguy wrote: Fri Dec 04, 2020 1:50 pmFYI, they make multi color LED's that size :)
Yeah, but then I'd feel compelled to add wiring and a rotary switch to select the desired color. :D
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
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makinsmoke
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Re: EMD F7 in SCALE

Post by makinsmoke »

Truman Hefner’s, now Danny Click’s lead F unit has an oscillating light in one opening.

To tell the truth I do not know which prototype it represents, or who built the model light.

But the effect is awesome.

The engines were built by Jim Murray years ago.
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makinsmoke
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Re: EMD F7 in SCALE

Post by makinsmoke »

Just amazing work you are doing, by the way.

There are LED’s that give off different effects than the regular bluish tint. They are common in HO and smaller scales.

Jim Hinds in Houston is one supplier. I’ll try and dig up his info.

I did find a 4 cell maglight at an estate sale today for 4 bucks!
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Steggy
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Re: EMD F7 in SCALE

Post by Steggy »

makinsmoke wrote: Fri Dec 04, 2020 6:43 pmJust amazing work you are doing, by the way.
Thanks!
I did find a 4 cell maglight at an estate sale today for 4 bucks!
An incandescent one, I hope. They are starting to become scarce.

If all else fails, you can use it to defend yourself. :D
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
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