EMD F7 in SCALE

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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Fri Dec 08, 2017 12:51 am

rkcarguy wrote:Very nice BDD!
Thanks!
I like the industrial grey you hit all the internals with, makes it look like a workhorse instead of a trailer queen haha
Coincidentally, the company that did the blasting and painting for me refinishes (full-sized) locomotives. They've got literally hundreds of gallons of machinery grey paint on hand at all times. Plus it's an epoxy enamel, so it should hold up well. When I get to doing the body, the interior of it will also be machinery grey.
That briggs "chug" is hard to get rid of isn't it? Granted, its one of the least lawn-mower sounding gas powered loco's I've heard in a long time.
Well, whaddya gonna do when you only have two cylinders making noise? :D The microphone in the camera is not high fidelity by any measure, so what you are hearing is not quite what it sounds like in reality. When it is idling, most of the sound is mechanical noise, not exhaust.

In the first clip, the prime mover is running at 2400 RPM in notch eight while in low transition, explaining the racket. In high transition, the same road speed would be developed in notch four, at which the prime mover is spinning at 1600 RPM. When operated that way the unit has a decidedly locomotive sound to it.

Incidentally, the exhaust goes out the top, same as with the real F-unit.
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rkcarguy
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Re: EMD F7 in SCALE

Post by rkcarguy » Fri Dec 08, 2017 12:53 pm

I hear you on the engine noise. I've noticed when I've shot footage of my karts, that the camera seemed to pick up more of the ticking noise from the engine than the exhaust notes, and it makes it sound worse than it is.
I'm not sure if you have room inside your body, but the insulation system our shop put in some compressor skids was amazing at quieting things up. It was a layer of acoustic foam, covered with a layer of rock wool, with perforated metal panels riveted over it. These skids went from deafening loud, to more like standing next to an idling vehicle.
I am having real exhaust come out my stack as well, now If it was only black exhaust lol!

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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Sat Dec 09, 2017 12:14 am

rkcarguy wrote:I'm not sure if you have room inside your body, but the insulation system our shop put in some compressor skids was amazing at quieting things up.
Actually, I don't want to make it quieter, and in any case, there's little clearance between the body structure and the machinery. Also, insulation could cause some cooling problems.

The real F7 when idling made quite a bit of racket, much of it mechanical in nature. I've been told by a number of people that mine sounds like a miniature version of the full sized F-unit when idling. Idle RPM is 1000.
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BigDumbDinosaur
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EMD F7 in SCALE

Post by BigDumbDinosaur » Sat Dec 09, 2017 6:01 pm

EMD F7 in SCALE
————————————————
BODY CONSTRUCTION: Part V

One of the most complicated aspects of building the body was fabricating the main (center) roof hatch assembly. A number of pieces are part of the assembly, including the hatch itself, fan deck, exhaust stacks, reinforcing ribs, fan adapters and fan grilles. Excepting the grills, all parts are fabricated from sheet steel.
roof_hatch_center_blank03.jpg
Main Hatch Sheet After Rolling
Above is the main hatch sheet after rolling. The fan deck fits into the rectangular opening, as well be seen in a later picture.
fan_deck01.jpg
Fan Deck w/Rib Jigged
Above is the fan deck with one of the supporting ribs jigged in place. These ribs extend under the main hatch sheet to tie the structure together. The ribs are a bit of overkill in material thickness to help prevent distortion during welding.
fan_deck_stacks02.jpg
Fan Deck w/Ribs & Exhaust Stacks
Above is the fan deck after the supporting ribs and exhaust stacks had been attached. A lot of care was taken to get things as accurately positioned as possible, since the main hatch is a point of detail that is immediately visible to the casual observer upon seeing the locomotive for the first time.

Once I had finished the fan deck it quickly became apparent that a simple fixture would be a big help in getting everything lined up for welding. So I got busy. :D
fixture01.jpg
Main Hatch Welding Fixture
This fixture was fabricated from a piece of extruded aluminum tooling plate drop that I picked up from a local machine shop. It was a bit too long, but I was able to put this piece into my (9" × 13") horizontal band saw and shorten it to the required dimension. I fabricated some clamping bars out of 1/2 inch thick cold rolled I had laying around. The two large holes bored through the plate give clearance for the exhaust stacks when the fan deck assembly is in place. The clamping bars then secure the deck, with bolts threading into four tapped holes in the fixcture.
jigged02.jpg
Main Hatch in Welding Fixture
Above is what the hatch assembly looked like after jigging. The cutout in the center of the hatch naturally pilots on the deck's perimeter, which made achieving alignment fairly easy. A long piece of rectangular tubing acts as a clamping bar to hold the entire mess in alignment, along with the usual army of C-clamps.

As all of the sheet metal pieces are 16 gauge, I used 0.025 inch wire in my MIG welder, along with 75/25 shielding gas, and skip welded the joint between the deck and the hatch sheet, as cosmetics would be important. Somewhat heavier welds were made to attach the ribs to the hatch sheet. These welds produce some localized distortion that would be visible on the exposed side of the hatch, which is not necessarily a bad thing—such distortion can be seen on the hatches of the real F-units.

The next post will have some pictures of the completed weldment.
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BigDumbDinosaur
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EMD F7 in SCALE

Post by BigDumbDinosaur » Sat Dec 09, 2017 6:17 pm

EMD F7 in SCALE
————————————————
BODY CONSTRUCTION: Part V cont'd

Below are some pictures of the completed main hatch assembly.
center_hatch01.jpg
Main Hatch Assembly After Welding
fan_grilles01.jpg
Main Hatch Assembly with Fan Grilles
fan_grilles02.jpg
Closeip of Fan Grilles
main_roof_hatch_fan_deck_reduced.jpg
Main Hatch Assembly Primed
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NP317
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Re: EMD F7 in SCALE

Post by NP317 » Sun Dec 10, 2017 11:45 am

Quality work!
Your careful fixture and setup is commendable. And time-consuming.
~RN

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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Sun Dec 10, 2017 2:01 pm

NP317 wrote:Quality work!
Thanks!
Your careful fixture and setup is commendable. And time-consuming.
You'll get no arguments on the time-consuming part. :D There is other tooling and fixturing I made to build up other body subsassemblies, as well as items such as the frame, trucks, etc. Aside from the desire to achieve reasonably accuracy, somewhere way back in my head I have this idea to also build a fully functional B-unit. Just about all of the tooling that I have made to build this unit will come in handy should the B-unit ever make it from fantasy to reality.

Speaking of fixtures and such, if I can ever find them I will post the pictures in which I used a Black & Decker laser level device as an alignment indicator for building up the frame.
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BigDumbDinosaur
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EMD F7 in SCALE

Post by BigDumbDinosaur » Sun Dec 10, 2017 8:21 pm

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Andrew Pugh
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Re: EMD F7 in SCALE

Post by Andrew Pugh » Tue Dec 12, 2017 1:10 am

It's great to see you updating your build thread BDD.

Your F7 is looking great!

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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Tue Dec 12, 2017 1:41 am

Andrew Pugh wrote:It's great to see you updating your build thread BDD.

Your F7 is looking great!
Thanks!
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WJH
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Re: EMD F7 in SCALE

Post by WJH » Tue Jan 30, 2018 9:46 pm

That is a beautiful F body!

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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Wed Mar 21, 2018 4:09 pm

WJH wrote:
Tue Jan 30, 2018 9:46 pm
That is a beautiful F body!
Sorry for the belated reply, but thanks! Health woes have "grounded" me and an endless parade of doctors, nurses and therapists have replaced trains for now. :roll:
Science makes it known. Engineering makes it work.

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