EMD F7 in SCALE

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makinsmoke
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Re: EMD F7 in SCALE

Post by makinsmoke » Sun Aug 28, 2016 10:05 am

Sorry, Dave!

fly5150
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Re: EMD F7 in SCALE

Post by fly5150 » Sun Aug 28, 2016 10:20 pm

makinsmoke wrote:Sorry, Dave!
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BigDumbDinosaur
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EMD F7 in SCALE

Post by BigDumbDinosaur » Mon Sep 05, 2016 9:19 pm

I will soon be resuming on writing the narratives on this build. Meanwhile, here are some more pictures.
es_front_view_reduced.gif
Above is a front view from the engineer's side. Since I posted the last set of pictures I've done a little more detailing, and have test-fitted the engine room ventilation grilles (made by Dave Newell, fly5150). Also, the body skirt (also made by Dave Newell) is visible, along with the fuel tank falsework. The skirt is mounted on the chassis, not the body, so it doesn't move when the body is opened.
body_lock_reduced.gif
Above is a picture of one of the two locks that keep the body closed and centered on the chassis. What you are seeing is a miniature toggle clamp with a rubber tip on the screw end. When closed, the screw bears down on a thick part of the lower part of the nose casting.
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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Sun Sep 11, 2016 5:37 pm

EMD F7 in SCALE
————————————————
A number of posts ago, I had described how the components for the F7's trucks had been made by Bob Snippe but due to a number of engineering issues, were less than satisfactory. There was more to it. I had gotten the unit out to the railroad in 2008 following a period of serious illness (I was a year behind schedule at that point in time) for a series of shakedown runs. Generally speaking, it ran well and things mostly worked as designed.
1st_run02_reduced.gif
First-Ever Run of the F7
However and almost immediately after putting the unit on the track, I encountered some new problems with the trucks.

Rather than press-fitting the wheels to the axles, as is customary practice, Mr. Snippe had made them a slip fit and secured them with setscrews. It didn't take long for the wheels to start working loose and going out of gauge. I discovered the problem when I was passing through a turnout and the rearmost wheelset picked the frog and derailed. One of the wheels had loosened and drifted outward enough to catch the point of the frog. My remedy at the time was to jack up the locomotive, get the wheel back into position and tighten the setscrew as much as possible. Later on, I returned the unit to my shop and replaced all of the original wheel setscrews with new ones with knurled cup points (made by SPS Technologies). These tend to lock into the surface against which they bear—the axle key in this case—reducing the likelihood of loosening. It was a temporary fix at best.

Over time and despite the better setscrews, loose wheels continue to be an issue and as I put more operating time on the unit, the wheels started to wear in odd ways, suggesting a faulty profile, metallurgy issues, or both.
old_wheel_profile_reduced.gif
Old Wheel Profile
I noted that the tread-to-flange fillet was turning into a sharp corner, which would tend to increase the possibility of the flange climbing the edge of the railhead. I had already concluded that the constant loosening of the wheels was an artifact of the material with which they and the axles had been made, which was too soft, possibly some sort of free-machining steel. It was clear that these wheelsets were not going to work out and would have to be replaced with something better, with the wheels pressed onto the axles to keep them tight and in gauge. As it turned out, construction of a control (riding) car to go with my F-unit gave me the direction I needed to make proper wheelsets for the locomotive.
control_car_rsfqv01_reduced.gif
F7 Control Car
The control car's trucks were built up from some old Tom Bee Blomberg style side frames I had, with the wheelsets being made from 1.6 inch scale Diesel wheels also made by Tom—these wheels incorporate the same machining characteristics that Tom has long used in his freight car wheels.
new_wheel_profile_reduced.gif
Tom Bee Diesel Wheel Profile
Note in the above photo of the Tom Bee wheel profile that the tread-to-flange fillet is more pronounced than on the Snippe-machined wheel. This enlarged fillet causes better tracking and a reduced tendency to pick turnout points and frogs.

Axles were machined from C1144 TGP, with the wheel mounting surfaces sized to produce a four to six ton press fit. Running under the control car during the 2011 and 2013 seasons (I again fell ill in late 2011 and didn't resume railroad activities until some eight months later), the wheels showed no tread or flange wear, and were staying in gauge.

Seeing how well the wheelsets were performing under the control car, I made up drawings for new locomotive wheelsets, and got the pieces made and assembled.
new_wheelsets_reduced.gif
New Wheelsets for One Truck
As with the control car's wheelsets, the wheels are a press fit to the axles, with a little bit of anti-seize compound being used to prevent galling as the wheels were pressed into place. The sprockets and disc brake rotor are a precision fit on the axle and are secured with knurled cup point socket screws that bear down on both the axle proper and on the key. Keys are made from C1144. The axles run on full sealed ball bearings.

Since the above photo was take, the wheelsets were assembled into the trucks and will soon (I hope) be rolling down the rails. However, I'm not yet done with improving the trucks. :D I'll save that for another time.
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6491
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Re: EMD F7 in SCALE

Post by 6491 » Sun Sep 11, 2016 7:11 pm

Thank you for your concise descriptions of what you do. I have had no engineering experience in the first 65 years of my life, but in the last 5 I have found that I am enjoying the learning process (I was 14 when the last teacher tried to educate me). Sometimes I have to Google to catch the meanings but with the text and good photo's I do appreciate it.
Thank you again from the Southern Hemisphere.......
Have a good one....John.

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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Sun Sep 11, 2016 7:56 pm

6491 wrote:Thank you for your concise descriptions of what you do.
You're welcome.
Thank you again from the Southern Hemisphere.......
I see you're on the east coast of Australia. Australia is one of the few places in the world that I have not visited but would love to see. Unfortunately, chronic health problems are keeping me home. :(
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Glenn Brooks
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Re: EMD F7 in SCALE

Post by Glenn Brooks » Sat Oct 01, 2016 1:51 pm

Indeed a superb rendition of the real thing!
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Thu Oct 06, 2016 12:41 am

Glenn Brooks wrote:Indeed a superb rendition of the real thing!
Thanks! It's my first-ever locomotive build and I'm trying to produce something reasonably presentable.
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BigDumbDinosaur
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EMD F7 in SCALE

Post by BigDumbDinosaur » Sat Oct 08, 2016 9:58 pm

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

Constructing the body has been the most time-consuming part of this project to date, and the one aspect of it where I constantly encountered delays. Blunting speaking, a major part of the delay was caused by me getting involved with Bob Snippe and foolishly giving him front money to make the body. In retrospect, I should have vetted him before proceeding. I didn't and hence suffered the consequences.

After quite a few years of endless delays and excuses, Mr. Snippe had not accomplished anything (and has yet to return funds and MDM detail parts he was given to get it done—let that be a caution to you if you are thinking about purchasing anything from him). His dereliction almost caused me to abandon the project, as a chronic health issue that had arisen in 2007 was making it increasingly difficult for me to do the kind of "long burn" in the shop that was previously not a problem for me. Succinctly stated, with no body at hand and me becoming increasingly weakened by rounds of chemotherapy, I didn't think I would be able to finish the locomotive. By late 2011, when I had become very ill and spent much time in the hospital, I had decided to end the project and dispose of everything. I was so sick for a time I hardly did anything railroad-related for nearly a year.

Toward the latter end of 2012, I started to get better and as I had not disposed of my "naked" F-unit I decided to see if I could come up with a plan B for the body and finish the locomotive. Plan B unexpectedly materialized when I ran across a series of pictures posted at the Yahoo Live Diesel forum by Dave Newell (fly5150his website is here) of his completed and nicely-detailed SOO Line F7. I carefully studied the pictures, decided that what Dave had done was workable for me, and contacted him, explaining my situation. What I did was offer to purchase machine-readable copies of all the drawings Dave had produced so I could have a local shop cut and form pieces for me. Dave, instead, suggested that he do the manufacturing and sell me parts, from which I could do my build. We "shook hands" on a price—in an encouraging note, Dave did not want front money—and in a matter of several months he delivered everything, essentially accomplishing in a little more than eight weeks what Bob Snippe had been unable to accomplish in nearly nine years. There were a lot of pieces, all fabricated from 16 or 18 gauge steel (easy to weld with a good quality MIG machine), and all nicely made.

Near the end of 2013, following a period of design activity to work out how best to attach the body to my chassis, I was ready to start jigging and welding. This post will describe some of that process.

The body assembly consists of six major subassemblies:
  • Skeleton

    The skeleton, as the name suggests, is (to belabor a metaphor) the "backbone" of the body, joining all the major components. I described the fabrication of the skeleton starting with this post. This item was completed prior to any other body work, as everything else was dependent on it.
  • Nose casting

    As previously described, the nose is produced from Alumilite, a high strength casting resin that was originally developed for non-structural aircraft applications (e.g., production of wing root fairings). A silicone rubber mold is used to produce the casting and if the process is properly carried out, a high degree of detail can be achieved.
    nose_reduced.jpg
    Alumilite Nose Casting
    Above is what the nose casting looked like when originally received. It subsequently underwent two modifications, one of which was to be able to mount a headlight assembly into the front door (described in an earlier post), and the other to make it possible to fit a certain kind of light emitting diode (LED) lens assembly into the classification light pods immediately above the number board pods. The lens closely resembles the original's in both appearance and relative size, and can be fitted with a "jumbo" (10 millimeter) medium or high output LED of various colors. Incidentally, the same lens assembly in red fitted with a white jumbo LED can be used to model the marker lights on cabooses that had them built into the carbody (as opposed to the older markers that were separate lanterns).

    If you are interested in building an E8, E9, F7 or F9 and plan to fabricate the body from scratch, you can obtain a nose casting like the above from Dave Newell.
  • Number two end bulkhead casting

    This item is also made from Alumilite and also available from Dave Newell. Almost any reasonable material could have been used, but Alumilite is convenient for casting in the anti-vibration ribs that the original's bulkhead had. Pedantic note: the end opposite the cab of a carbody style locomotive is conventionally referred to as the number two end, not the B end. Such a convention is also common with subway cars, especially those in which there is a cab only at one end (the number one end).
    num2_end_reduced.jpg
    Number Two End Assembly
    In the above picture, the diaphragm faceplate assembly, which is made from aluminum pieces, is attached. I subsequently scrapped that assembly and replaced it with one fabricated from steel, the parts for it also coming from Dave Newell. The steel version looked better and was several orders of magnitude stronger.
  • Side sheet subassemblies

    Each of the two side sheet subassemblies consists of a relatively large piece of sheet steel into which numerous holes have been pierced for attaching the battens, upper grilles, etc. Large holes were also cut for the engine room porthole glazing and the sand bunker hatches. As delivered by Dave, the battens were attached using solid steel rivets, giving the sides a decidedly realistic appearance. The only work I had to do on the sheets after receiving them was to finish drill and tap the grille mounting holes, and some other holes used to attach grab irons at certain locations, followed by priming.
    body_mockup_reduced.jpg
    Test-Fitting Body Side Sheet
    In above picture, I was test-fitting the engineer's side sheet assembly to find points of interference with the machinery. You can see the riveted batten detail if you expand the picture. Although one might think otherwise, the battens add relatively little to overall sheet rigidity, which is why I developed the skeleton to hold the structure together.
  • Roof subassembly

    Other than the nose and cab area, the F7's roof is the most complicated part of the body to model. The roof subassembly consists of a main sheet, roof-line battens and three removable hatches ("removable" meaning they are removable on the prototype—more on this aspect of the body later on). The main sheet has three large cutouts where the hatches are mounted, and a lot of rivet holes for attaching the roof-line battens (visible in the below picture). There were no holes present for attaching the hatches—these were added after the body had been built up and it was possible to place the hatches into position. Although having to drill and tap all those holes might seem to be an onerous task, the reality is rolling sheet steel is not an exact science and if the holes had been pierced with the roof sheet in the flat it was likely they would have not aligned with the matching holes in the hatches.

    After laser cutting, the sheet had to be rolled to form the main crown and the curves that blend it into the side sheet assemblies. This rolling process has to be quite accurate if good fit-up is to be achieved.

    As received, the number two end of the roof sheet was cut in a way that brought it to a sharp point at the center. Abrupt discontinuities in sheet metal can precipitate cracking in the presence of vibration (in the past, some commercial airliners were brought down by fatigue cracking in the fuselage at sharp corners), and the pointed end wasn't cosmetically pleasing. So I decided a modification was in order.
    bare_roof_reduced.jpg
    Bare Roof Sheet
    In the above picture, I have monkey-rigged a setup to use my belt sander to grind the aforementioned point to a straight edge that looks like the roof overhang of the older F3. After roughing to shape on the belt sander, I dressed the end with my hand-held angle grinder to get the final shape. A final dusting with some 3M Roloc abrasives broke the edges so they wouldn't draw blood, and the finished product almost looked factory. :D
    roof_trim_reduced.jpg
    Trimmed No. 2 End of Roof Sheet
    Above is how the number two end of the roof sheet looked after grinding. This modification is one of several "convenience" deviations from the prototype that I made. As I noted in the intro article to this series, I'm not a rivet counter, so I don't feel compelled to model the real F7 right down to how the traction motor cables were routed and the way in which the engine leaked oil. :lol:
As noted above, the roof subassembly includes three hatches, which from the front of the unit are the dynamic brake hatch, main hatch and steam generator hatch. As my F7 is a freight unit and the prototype (C&NW 401) was operated over mostly prairie terrain, it does not have dynamic brakes or a steam generator. Hence those two hatches are just plain-appearing pieces of rolled sheet metal fitted with scale sized lifting eyes obtained from Precision Steel Car. On the other hand, the main hatch mounts the four radiator cooling fans and prime mover exhaust stacks, and thus has quite a bit of detail. I'll cover fabricating the main hatch in the next post.
Last edited by BigDumbDinosaur on Fri Dec 02, 2016 3:29 pm, edited 3 times in total.
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Andrew Pugh
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Re: EMD F7 in SCALE

Post by Andrew Pugh » Sun Oct 09, 2016 11:32 am

Great to see you back and posting BDD!

I'll be checking back often for your excellent, detailed posts.

AP

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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Thu Oct 20, 2016 3:59 pm

Don't know what is going on, but the above post somehow got scrambled and the images are not where they were before. Also, GIFs can't be uploaded. I suspect the upgraded software has one or two bugs in it.
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BigDumbDinosaur
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Re: EMD F7 in SCALE

Post by BigDumbDinosaur » Fri Dec 02, 2016 3:18 pm

BigDumbDinosaur wrote:Don't know what is going on, but the above post somehow got scrambled and the images are not where they were before. Also, GIFs can't be uploaded. I suspect the upgraded software has one or two bugs in it.
I was able to fix up the photos.
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