Big Train James's US Outline Workbench - sw1500 Kitbash

[Pugsley]

I think that's the translation step from full field to weak field, though I think by the time EMD got to the SD40 and 645 engine block it was near absent. It's certainly very present on the previous generation 567 engines like GP9 and SD9 as well as all the Euro derivatives in Denmark, Belgium and Luxembourg. It is that single characteristic of the engine unloading at translation that l love the most about EMD engines as well as that lovely whine the SNCB class 55 and 62 have from their fans. I think I've just decided what my next therapy project is

It happens on the 645's as well, SD40's and SD50's it's particularly when they're working hard in Run 8. This video shows it quite well (and is well worth a watch just for the sound) :

My theory is that the running and overspeed functions are handled separately in the governer, and that if the engine speed is set incorrectly, the two fight each other. The fact that the guy does something around the 5:16 mark which appears to solve the problem, and drop the running speed slightly, seems to bear that out. However, I don't know exactly what he's fiddling with in there.

Now I can't find anything to support this yet and if the loco in the video is actually on a load test, I suppose it could be some kind of interaction between the governor and the load regulator. I'll dig through the manuals and see if I can find something that details the operation of the governor.

Of course, the silly thing is that it doesn't really matter and I'm sure there are better things that I should be doing. The problem is, though, I like to know if I'm right, or not

 

[mickoo]

That's not translation and I think your right its an over speed viz throttle issue and you cab clearly see it pulsing in the stack gasses.

I've never seen or heard an EMD do that before, maybe it only does it when running in run 8 with no load,cant see a load bank attached at all so suspect the engine is under minimal generator loading.

MD

 

[Pugsley]

It's definitely a Run 8 thing, it's the only time I've ever noticed it, which is what made me think it was some kind of governor conflict. It probably is running under minimal load, although most US locos have the facility to self load during testing, using the dynamic brake grids. I can't tell from the video if the dynamic brake fans on that loco are running, or not, so can't be sure.

You're a trained engineer, you also think it's overspeed vs throttle, so that's good enough for me

 

[mickoo]

I doubt the dynamic grid will load to 100% and that's some serious wattage that generator kicks out but it'd be enough to prove the engine and switch gear loads correctly. The above does look and sound like a fuel rack over run, sometimes you get a weak governor spring which allows the linkage to hunt but that'll do it at all speeds and it could also be the speed controller stability setting. If you set it too aggressive = quicker loading and acceleration response then it can struggle to hold the required setting and oscillate, if you set it too weak = slower loading but more stable then you run the risk of bogging down the engine during quick load variations.

Either way it shouldn't do that and as shown above just needs a setting tweak might be able to find out what's behind that door from the links above doubt it'd change much between a dash 2 and 3 most of those changes are probably in the control cubicle which I think is directly behind the cab.

MD

 

[Big Train James]

I've gotten distracted for quite some time lately (probably way too much time) creating a 3d model of the bogie sideframes and details that I need for my project. As usual, once I got into it, I kept finding more things that I might as well add, since I bothered with all those other things already. Herewith are some screen shots of the results.



The last two shots show the Atlas gear case and new P48 brass covers that I worked on with Jay from Right-0-way. Obviously, nearly all of the bolster and the center part of the frame will get cut away in the final version. I usually try to draw everything in whole, so that I can take what I need from it for different applications (like different gear case arrangements or attachment points, or output methods like casting versus printing). I really wanted to include the ends of the bolster as the detail there sticks up above the top of the side frame so to my thinking is relevant.

That being said, I didn't bother to draw the traction motors or mounts (yet). They won't be needed for this version, since I'll be using the stock Atlas gear case. Then it's also funny to see how many things you've overlooked despite having poured a good deal of time into getting everything just so. I still need the retainer that spans from the bottom of the journal pedestals to the clasp brake connecting strap. And I forgot to remove frame material at the journal springs to create the cup that receives the springs.

The journal springs are a great example of trying to decide how far to take the modeling, or whether to model as the prototype or as a production piece. My trucks will not be sprung, so I don't need that recess in the frame at the journals. And it would be simpler to cast the frame without that recess. But it doesn't look quite right if you view from the right angle. Perhaps worse, I know it's not quite right.

Does anybody here have experience with casting brass parts? Or even white metal if the detail and quality is equivalent to brass. In the US, brass parts seem common. In the UK kits that I see here, white metal seems more common. I need to figure out how feasible it will be to cast parts, whether to do direct burnout or plan for a mold, shrink rates, and sourcing viable prints for masters and a foundry service for casting.

I need to get back to the rest of the actual model. Or I've been thinking lately that maybe I should just consider this my model railroading. I'm better with these tools and materials (at least at the moment) than styrene or brass. It's probably cheaper. But then I've also lately been thinking that maybe I should move up to G1, the better and more feasible to take the details to the Nth degree. Especially as I seem to be trending toward being a model builder as opposed to a model railroad builder.

 

[mickoo]

James,

Looks good, can't answer your questions on shrinkage but have you considered resin castings, there's little if no shrinkage on those and you've seen the detail you can get from aircraft and military resin castings.

Know where your going with the building path, I kind of worked that out a couple of years ago, it's the building I enjoy the most, not the finished product, even if it doesn't get finished. Eventually something will get finished but I don't get hung up if it isn't

Mick D

 

[Jordan]

Probably not applicable to these trucks (pardon my ignorance ) but one thing I've never seen modelled is rotating bearing caps on a locomotive.

 

[Big Train James]

Visible bearing caps are a recent development on EMD locos. For a very long time, up to the current generation, axle ends terminated inside the journal box and couldn't be seen. I think GE's have been visible for most if not all of their existence.

I have considered resin castings for the sideframes. However, there seems to be a prevailing attitude among many O scale modelers (maybe this a US thing) that sideframes, loco or otherwise, need to be metal. If not they are considered "cheap". My concern is durability. The frames will not be load bearing, as the axles don't actually bear on the journals. I was thinking of just 3d printing everything and using that, but my recent experience with the radiator fan parts suggests a degree of brittleness to that type of plastic. So I'm thinking I will use the prints as masters for either resin or metal casting. I had then considered direct burnout metal castings to avoid constraints associated with 2-part molds. I'll have to consider the costs of each method. Printing will probably run me about $50 per frame so it wouldn't be cheap for the masters. But I wouldn't have the cost for a vulcanized mold either. But if there's no commercial demand for the frames, than do I need the capability to produce multiples beyond the set or two that I will probably need. This is why I'm trying to get an understanding of the casting processes, so that I can get a viable part with as much of the detail I've developed manifested in the physical output. I've got some things I need to figure out.

 

[Yorkshire Dave]

However, there seems to be a prevailing attitude among many O scale modelers (maybe this a US thing) that sideframes, loco or otherwise, need to be metal. If not they are considered "cheap". My concern is durability. The frames will not be load bearing, as the axles don't actually bear on the journals.

If not using commercial drive trucks then one solution it to have a load bearing etched or cast resin sub-frame (more common in the UK) to hold the wheels and bearings onto which the moulded truck sides (resin?) can be attached to.

 

[Overseer]

I have some experience casting in polyurethane resin and have had commercial casters work do for me in whitemetal and lost wax brass/bronze/white bronze/nickel silver. Resin is relatively easy to get a high quality casting showing all surface detail and usually uses silicone rubber so the patterns don't need to withstand high temperatures. Polyurethane resin is tough but not as strong as white metal or brass if it gets dropped or hit.

Whitemetal would be my preference for the flexicoil frames as it reproduces detail well, especially flat surfaces, and provides weight low down where it works best. Commercial casters will probably use vulcanised rubber which does need patterns which can withstand higher temperatures (over 100 degrees c) but can then cast hundreds. The shrinkage tends to be consistent with whitemetal in vulcanised rubber so can be planned for when making the patterns.

Lost wax casting is the most variable for shrinkage and quality of surface finish. Most commercial lost wax casters are set up for jewellery casting which doesn't have the same dimensional requirements we do and rarely has large flat surfaces, plus they usually work with silver and other precious metals so may not be as familiar with brass etc. They can also be wary of brass because of its lead content. Nickel silver tends not to produce fine details as well as brass. Bronze can be fine but is harder than brass and white bronze (which isn't actually a bronze) is really tough to machine. If you can find a caster who is interested and understands what you are doing then go for it. Just check for consistency of sizes and that there are not creases in larger flat surfaces.

These are just my opinions, others are bound to have other views. If only doing one set I would use resin, if multiples then whitemetal with lost wax brass details. It might also be time to look at other mechanisms that don't take up so much of the internal space in the truck so you can put all the detail you have drawn in.

 

[Peter]

Hi Mickoo,


I hope that the following from Australia helps with the therapy. Sincerest apologies if already seen.

Best regards,

Peter

 

[mickoo]

Peter, you're a wicked man! Some I've seen but the Quad S class is the best I've not seen.

Before Finney7 came along I was researching Australian locos, mainly the A and CLP class along with the DL, AN and 81 classes, I may revisit those projects over the Xmas break . It's a shame some of them are broad gauge only, though some classes are dual gauge and they swap bogies depending on demand in each region.

Apologies to James for the hijack

MD

 

[Jordan]

One thing that attracted me to F-Units many years ago was that they had a single cab, and hence a sense of "direction"; a definite front and rear like a steam loco or a shunter, and utterly unlike mainline British diesels (HSTs don't count!!!). Most US locos, still being single-cabbed, still give this impression.
I still find it weird looking at Aussie Bulldogs which have a cab at each end...

 

[mickoo]

Probably not applicable to these trucks (pardon my ignorance ) but one thing I've never seen modelled is rotating bearing caps on a locomotive.

Journals dear boy journals

 

[Big Train James]

Apologies to James for the hijack

MD

I'm not worried about it. Carry on.

 

[Big Train James]

I'll try to respond to several comments above all in one post.

I'll be using the existing Atlas diecast gearboxes and drives as they are on hand, mounting is already accounted for, and they are known to perform well. I'll use the existing motor and drive shafts/flywheels/couplings/gears. I will be replacing the gearbox cover with a new P48 version designed to move the sideframes and brake rigging to appropriate positions relative to the wheels and their treads. I will of course then also use replacement P48 wheelsets (thanks to Dave for these). In the past I dreamed about individual gear boxes that approximated traction motors in appearance. Maybe some other time. The Atlas box will be fine for now.

I think that Overseer's comments and insights have lent me some clarity on production method for my new frames. I will at this point plan on only a handful of copies at most. So I will pursue either a direct burnout metal casting or a resin casting. Or a hybrid method for frame versus detail gubbins. I like the idea of casting the brake rigging in resin for built in electrical isolation, although I can always insulate the connecting straps using the tissue paper method Dave mentions in his gp9 thread. I can most likely get castings done via connection to the foundry that Jay from Right-o-Way uses, who has familiarity with casting for model rail purposes. Or alternatively try to find somebody locally, perhaps a lead from my local NMRA group, that can manage the casting work. I will also need to find a machinist, so I should start asking around.

I will concern myself with physically modeling the center portion of the frame and bolster if and when I use it for a drive with individual gearboxes. There's no point in worrying about it for this application, and to be honest it isn't nearly as interesting as everything else anyway.

A couple of quick phone shots showing the new cover and resulting sideframe position. The left hand truck in each photo also utilizes the existing Atlas cover, which is designed for a worst case scenario employing 3-rail wheelsets. The gaps are bad enough going only as far as 2-rail wheelsets, but approach silliness when P48 wheelsets are substituted. Then also, these are with the Atlas sideframes, which are quite flat and relatively thin. I hope to further appearances by using my sideframes to improve detail and depth rendition. I'll be after the same improvements Dave achieved on his gp9 trucks.


Cheers,
Jim

 

[Jordan]

Journals dear boy journals

Here at the Back we only have comics...

 

[Yorkshire Dave]

Jim

It's a very neat keeper plate for P48 . Fortunately I didn't have this problem with the GP9.

Are the truck side frames plastic? If push came to shove could the original Atlas side frames be cut about in a similar fashion to my GP9 trucks?

One thing I had to correct on the GP9 truck side frames was the slight banana shape when viewed from the top/bottom. To cure this I gently heated the side frames with a hairdryer to warm them sufficiently to straighten by hand.

 

[Big Train James]

Dave,
The keeper plate came about initially as the original Atlas plastic version has shown a tendency to decay and crumble outright, or to a lesser degree, split at the corners where the countersunk screws attach it to the gearbox. Two versions were drawn up, with the difference being the positioning of the sideframe mounting holes with respect to the centerline of the truck. The idea is to position the brake shoes over the midpoint of the treads. One version is for P48, while the other is for 2-rail 5'-0" gauge. No versions were considered for 3-rail.

The existing Atlas sideframes are diecast. I'm sure that the same surgery could have been performed as you undertook on your gp9, with a bit more vigor. However, a couple of problems remain. The sideframe is relatively thin, so that even when moved in with the new keeper plate, there is a decent gap between the wheel face and the back of the frame. I'd like to close that up. Another is a lack of depth on the front side of the frame. I'm convinced that concessions were made on these frames to allow them to be fit to the same keeper plate as used on the Atlas sw8/9. A reasonable compromise for a mass manufacturer in a small market, but an unacceptable stance if one happens to be blessed with detail based disorder such as I clearly have. The solution is to push the face of the frame in the bolster area outward to clear the keeper plate behind. Probably also as a result of this concession, some of the edges, holes, and other details are incorrectly proportioned or out of place. And lastly, plenty of detail is just outright missing.

It perplexes me to no end that HO models roughly half the size of O (like the Athearn sw1500) have detail that absolutely blows away many models in the larger scale . It's inexplicable, to me anyway. One of those do it right if at all things. At some point, I figured I might as well just start from scratch. Then I stumbled on that cache of EMD info and any hesitancy or sense of practicality went out the window. I don't feel too guilty about it. I've already worked up the radiator fan sections and now the sideframes. I will tackle the hood-top radiator core and the cab interior before I finish, and to a lesser degree the fuel tank. All three things on the Athearn version are superior to the Atlas O version.

 

[Big Train James]

Btw, for Dave and Jordan or anybody else, we are about 3 months out from the annual Chicago March meet. At this time, I am planning on attending. Last year I gathered quite a few parts for Dave and Jordan for their US outline pursuits and consolidated everything into a single package for each.

The offer is still on the table for anybody interested, so start making lists. I will at some point post a separate thread reiterating this, but now while I'm thinking about it is also a good time to mention it.