EMD F7 in SCALE

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Jerry_H
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Re: EMD F7 in SCALE

Post by Jerry_H »

Here's hoping that you get back in the cab soon.

Jerry
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Steggy
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Re: EMD F7 in SCALE

Post by Steggy »

Jerry_H wrote: Wed Mar 21, 2018 7:14 pmHere's hoping that you get back in the cab soon.
Thanks!

Although not fully recovered from all the health sturm und drang, I am back in the cab, metaphorically speaking, and will be updating this build log some more.
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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: Part VI

With the body structural work completed, the next step was to start detailing. Some of the details are fairly easy to handle: grab irons, for example. I used several different sizes of Precision Steel Car (PSC) grab irons, which are secured to the body with 4-40 stainless steel, hex head screws. 4-40 is a bit too large for 1.6 inch scale, but using that size screw made things a lot easier for me. I daresay that once the unit is in paint the slightly-too-big screw heads will be quite unobtrusive. :D

Grab Iron Details, Fireman's Side
Grab Iron Details, Fireman's Side

I made the long irons straddling the cab door by cutting short PSC grab irons in half and joining the pieces with a piece of 3/16" x .032" hard-drawn brass tubing. As the ID of the tubing is slightly too small to accommodate the diameter of the grab irons, I ran a number 30 drill into each end of the tube, which made for a close fit. A drop of cyanoacrylate adhesive at each end keeps the parts together.

Another interesting bit of detailing is in the portholes, of which there are four engine room ones, plus one in the number 2 end vestibule door. The vestibule door porthole glazing was relatively straightforward to make, involving some turning of a piece of cast acrylic rod and drilling some mounting holes. The outer face, which is visible in the below photo, was polished with automotive rubbing compound to give it a glassy appearance. The inner face was roughed up with 60 grit abrasive to make it translucent.

No. 2 Vestibule Door Glazing
No. 2 Vestibule Door Glazing

The above piece will be inserted into the door from the inside and secured with four hex head machine screws that go into tapped holes in the Alumilite. When everything is finished, a small incandescent lamp will be mounted near the porthole to give the illusion of engine room lighting.

The engine room portholes proved to be more of a challenge. On the exterior of the prototype there is a bezel, into which the porthole glazing is secured with rubber molding. I kicked around a number of ideas on how to go about doing this, finally coming up with a two-piece design, consisting of a steel bezel and acrylic glazing.

The bezel is a machined ring that fits into the porthole opening in the body. The inside-facing part of the bezel has a shoulder that pilots into the body opening, whereas the outside-facing part has rounded edges that approximate the appearance of the full-sized part. Below is an illustration of how the porthole assembly goes together:

Engine Room Porthole Design
Engine Room Porthole Design

The glazing pilots into the bezel's ID, and will be secured to the body with epoxy.

The below photos are of one of the bezels:

Engine Room Porthole Bezel (inside surface)
Engine Room Porthole Bezel (inside surface)
Engine Room Porthole Bezel (outside surface)
Engine Room Porthole Bezel (outside surface)

Conveniently, the inside and outside diameters of 2-1/2 inch, schedule 80 pipe are almost exactly what is needed—only a small amount of turning was required to achieve the right dimensions. I used ASTM-rated pipe for this part to avoid the scale present on ordinary black pipe—that scale can wreak havoc on lathe cutting tools, as well as result in a rough finish. Visible in the first bezel photo is the shoulder that pilots the piece into the body.

Once the bezel was inserted into the body, I held it in position for welding with a monkey-rigged holding fixture made out of some scraps laying around the shop. Some small and precisely-placed welds secured the bezel's shoulder to the body, and a little cleanup with the angle grinder got everything nice and smooth.

Here's what one of the bezels looked like after installation and priming:

Engine Room Porthole Bezel
Engine Room Porthole Bezel

I've run out of room in this post for more photos, so I will continue in the next post with more photos of the porthole stuff.
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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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NP317
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Re: EMD F7 in SCALE

Post by NP317 »

Gorgeous!
There aught to be a law...
~RN
rkcarguy
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Re: EMD F7 in SCALE

Post by rkcarguy »

As always, beautiful work BDD. Glad to see you are back on the build.
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Steggy
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Re: EMD F7 in SCALE

Post by Steggy »

NP317 wrote: Thu Aug 16, 2018 10:03 amGorgeous!
Thanks!
There aught to be a law...
Don't we already have too many of them? :D
rkcarguy wrote: Thu Aug 16, 2018 11:36 am As always, beautiful work BDD. Glad to see you are back on the build.
Thanks! As I wrote in my first post when I started this build log, this project has taken far longer than I ever expected. Rickety health can really mess up things. :x
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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: Part VI cont'd

Continuing on the detailing of the engine room portholes, here are some more photos.

Porthole Bezel Holding Fixture, Inside View
Porthole Bezel Holding Fixture, Inside View

Above is my monkey-engineered bezel holding fixture I used during welding. :D


Porthole Bezel Holding Fixture, Outside View
Porthole Bezel Holding Fixture, Outside View

Above is what the holding fixture looks like from the outside.


Porthole Bezel After Welding
Porthole Bezel After Welding

Above is what the interior looked like after one of the bezels had been welded and cleaned up.


Porthole Outside View
Porthole Outside View
Porthole Outside View
Porthole Outside View

Above are exterior views of the porthole with the glazing in place.
———————————————————————————————————————————————————————
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 I

A locomotive has to have a headlight, and my F-unit is no different.  For me, a headlight is not a cosmetic feature.  My night vision isn’t good, so I needed a headlight that can actually light up the track to where I could see obstacles laying on the rails, misaligned turnouts, threatening rabbits, etc.  Although I’m not a rivet-counter, I’m not willing to accept gross deviations from the prototype.

LED lighting is very bright and efficient, which is likely why many large-scale locomotives use it in their headlights.  However, the high color temperature of LED lighting looks nothing like the 74-volt, incandescent lamps used in the real F7’s headlight.  Not wanting the LED appearance, I needed to cobble together an incandescent headlight, one that I could run on slight reduced voltage to give it that old-time look, as well as to extend the life of the lamp.

The accidental solution to the problem came about one day as I was using my green “suspect beater” (a large Mag flashlight of the type the police sometimes use) and happened to notice the outside diameter of the business end looked to be about the size of the locomotive’s upper headlight pod.  A quick check confirmed my suspicions: the flashlight’s bezel was a near-precision fit into the pod.  Discovering that led me to making some sketches of how I would adapt the flashlight to headlight duty.  I wasn’t going to use my “suspect beater” as a headlight, so I needed to find another one, preferably black.

The plan was to disassemble the flashlight to the point where I could cut down its body to fit into the available space—most of the body length, of course, is there to house the batteries, which wouldn’t be needed.  A pigtail with a two-pin plug would make the electrical connections and I would somehow bypass the flashlight’s switch, since it too wouldn’t be needed.  A saddle epoxied to the F-unit’s nose would hold the modified flashlight in position, with the saddle designed so the flashlight could be readily removed if necessary.

A little scrounging around found me a black Mag unit that uses four D-cells—it was on sale for nine dollars, hanging right next to the Mag LED flashlights selling for 35 dollars.  :D  I will come back to why I chose the four-cell unit.  I bought two of them.

The next step was to disassemble the unit so I could rework it.  Naturally, removing the batteries and the bezel-and-lens assembly, of which the reflector is a part, was easy.  Getting the switch and socket out of it was less easy—it wasn’t readily apparent just how Mag assembled the mess.  So I fired up an Internet search engine (not Google!) and did a little digging.

While digging, I learned a subculture exists that modifies Mag flashlights to accept five watt laser diodes, for what purpose I don’t want to know (the output from such a laser can be very dangerous).  In order to do that, the flashlight has to be fully disassembled so a heat sink can be installed to support the diode.  In the process of reading, I also learned the switch and socket are a single assembly and that Mag, believe or not, actually sells replacement parts.  Yep!  You can rebuild a C- or D-cell Maglite...although I question the economics of doing so.

Anyhow, it turns out the rubber cap on the on/off push button is removable—you can pry it off with a jeweler’s blade screwdriver, exposing the push button’s switch plunger.  You access a setscrew through a hole that is concentric to the switch plunger.  Recently-made Maglites have a setscrew that requires use of a T8 Torx® driver, which I was able to get at the local Ace Hardware store.  However, the shank of the driver was a tiny bit larger than the diameter of the switch plunger’s access hole.  My battery-powered drill motor and a #40 drill took care of that problem—I was going to scrap the switch anyway.  :wink:

Below is a photo of the Torx driver being used on the flashlight.

maglite_loosening_setscrew.jpg

With the setscrew backed out a turn or so, the switch and socket assembly slipped right out of the body.  Here’s what the flashlight looked like after being eviscerated.

maglite_disassembled.jpg

Before going any farther, I should mention that that same website that instructed me on how to field-strip a Maglite also had a link to another website that sells parts for doing the laser diode conversion.  One of those parts is a lens made from borosilicate glass (same type of glass used to make Pyrex® cookware), which is able to tolerate the intense output of the laser—the stock polycarbonate lens will badly discolor and warp.  Also, the borosilicate lens has scratch-resistance, which was of interest to me.  So I bought some borosilicate lenses, one for my soon-to-be headlight and one for my green “suspect beater” (the “suspect beater” seemed to be a little brighter after I changed out the lens—go figure).

The next step was to shorten the body, which is an extruded, aluminum tube.  I only needed enough body length to support the socket assembly and give me a place to anchor the assembly to the the F-unit’s nose, so the cut was made about 3/4" south of the body’s push button hole.  Here’s a photo of the body after the dicing and slicing, with the bezel assembly next to it—aside from lens replacement, the bezel assembly is unmodified.

maglite02.jpg

The next step was to butcher up the switch-and-socket assembly to eliminate the switch.  Here’s a photo of the assembly following disassembly.

maglite_switch_disassembled.jpg

The switch plunger and its contacts were no longer needed, so they got tossed.  I then made up a pigtail and soldered the wires in place, the positive lead to a cap that presses against the center contact on the lamp, and the negative to that longish metal piece with the nut, which is also what anchors the socket assembly into the body.

With the now-headlight wired up and assembled, it looked like this.

headlight_upper01.jpg

The next step was to mount the headlight into the F-unit.  The goal was to have the center of the beam focused on the track approximately 30 feet in front of the locomotive.  In order to work out the mounting angle that would be required, I did a layout in CAD.  It worked out that the headlight needed to be inclined 1.5 degrees from level to achieve the desired focus.  Due to the rearward slope of the F-unit’s "bulldog" nose, the included angle between the headlight and nose worked out to 102 degrees.  As I intentionally made one of the mounting saddle pieces oversized, it was a matter of doing some grinding to get the right mounting angle, as well as get the saddle to properly fit the internal contour of the nose.

With grinding and fitting completed, I trial-fitted the headlight to the body and energized it to verify its aim.  Having done that, I inverted the body, thoroughly cleaned the saddle mounting surface, mixed up some PC-7 epoxy and placed the saddle where it belonged.  PC-7 is a relatively slow-curing epoxy that responds well to heat, so I put a heat lamp on it.  Here’s a photo of the saddle after the PC-7 had cured and I had cleaned up the area.

headlight_upper_mtg01.jpg

More photos in the next post.
Last edited by Steggy on Tue Dec 12, 2023 5:02 pm, 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
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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 I, cont’d

Here are some photos of the headlight mounted in the F-unit’s nose.  I arranged the mounting so it is possible to remove the socket assemble in situ to replace the lamp.

headlight_upper_mtg03.jpg
headlight_upper_mtg05.jpg

Here’s what the headlight looks like from the outside.

headlights_outside01.jpg

Recall from my previous post that the flashlight I used to make the headlight was a four-cell unit.  Four D-cells wired in series produce about 6 volts and in the big Maglites, produces a powerful, dazzling-white beam.  The real F-unit’s headlight wasn’t dazzling white (although still quite bright), so the plan was to run the headlight on reduced voltage to take some of the “edge” off the beam.  The 6 volt rating of the flashlight’s lamp was convenient, as the lamp could be powered at 5 volts to reduce light output about 25 percent, which was what I was guessing would give me the desired results.  Hence the choice of the four-cell Maglite.

For test purposes, I monkey-rigged a 78S05 voltage regulator (rated 5 volts at 2 amps) to power the headlight so I could test my handiwork.  As I expected the regulator to get nice and toasty while operating, I mounted it on a substantial heat sink.  The assembly was ty-rapped to one of the battery hold-down brackets for testing purposes.

headlight_regulator01.jpg

Here’s a photo of the F-unit idling with the headlight on.

headlight02.jpg
Stay tuned for more writing about lighting.  :D
Last edited by Steggy on Tue Dec 12, 2023 5:09 pm, 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
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makinsmoke
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Re: EMD F7 in SCALE

Post by makinsmoke »

Very, very nice!

I keep circling back to Nelson Reidel’s Shay and heisler loco build pages, and this is another great example.

Nelson used the Maglite flashlight to make Head lamps for his locos. He did as you did, shortening the tube and slightly turning it down to fitting 2” exhaust pipe. The screw on bezel was left as is, as it’s a steam loco headlight. Closed the back with a piece of turned plate, and simple brackets.

It’s no Pyle or Golden Glow headlight, but the diameter and length are very close to prototype
and it sure passes the 3 ft test.

Thanks for taking the time to document and post. We all learn something.

Take care,
Brian
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Dick_Morris
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Re: EMD F7 in SCALE

Post by Dick_Morris »

Looks good!

A tempered glass lens for these flashlights is available from Amazon for $6.99. I bought one just last week. There are also warm white bulbs in the P13.5S style at 3v that have clear domes over the LED element which don't look too far from an incandescent. Going further down the page, I see a couple of warm white bulbs with domes for 3-18v.

I just got some warm white LEDs with a different base style for a locomotive headlight project and the color doesn't look bad. I'm going with LEDs to extend the battery life.
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Steggy
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Re: EMD F7 in SCALE

Post by Steggy »

Dick_Morris wrote: Sat Nov 28, 2020 8:24 pmLooks good!
Thanks!
There are also warm white bulbs in the P13.5S style at 3v that have clear domes over the LED element which don't look too far from an incandescent. Going further down the page, I see a couple of warm white bulbs with domes for 3-18v.
The reason I am using incandescent headlights is because dimming them is a trivial exercise and when they are dimmed they get that yellowish cast like you see on real locomotives. You can't just reduce the voltage to an LED and expect it to dim in the same way. It maintains its relatively high color temperature even at a lower intensity.
just got some warm white LEDs with a different base style for a locomotive headlight project and the color doesn't look bad. I'm going with LEDs to extend the battery life.
My F-unit has an alternator to power the electrical loads, so battery life is not an issue.
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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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