Etching question regarding curved formers and wrappers, plus other techniques and drift

Big Train James

Western Thunderer
In applications such as boiler wrappers, or curved car sides or roofs, is there a commonly accepted rule of thumb/percentage factor for the length of the wrapper versus the length of the curved edge of the former?

The specific implementation I'm considering at the moment is the following US outline "cylindrical" covered hopper (it's not really truly cylindrical), but there are any number of similar cars where the answer would apply.
TILX 329931_07272019_Northwood_OH.jpg

The length of the former edge should be simple enough to get right, presuming that the proper adjustment is made to overall dimensions to account for the etching process.

What I'm really curious about is the size of the wrapper, and in particular if there is to be a fold line and hard corner at the end of the curved surface. I realize this is splitting hairs when dealing with something like .40 mm sheet, but technically the inside face of the wrapper will be shorter than the outside face, once rolled. It wouldn't be so much of an issue if the curved surface stood on its own, and could be made to fit with some filing. What I'm really concerned about is getting the fold lines positioned properly,

Is this something that can be accounted for in advance? Or is trial and error going to be the ultimate solution? I'd prefer to keep the T&E to a minimum obviously, but especially if I use PPD for the etching, as overseas shipping costs would get out of hand quickly after one or two tries.

In a related situation, what rule(s) apply for sizing a sheet for a tightly rolled edge, like the corner of the hood on the following loco. The prototype is a 4" radius, so .080" ish in O scale.

092.JPG

Lastly, I have a question about using rollers to form curved sheets. I would like to represent the weld seams between panels on the hopper car side. I am considering a half-etched groove at each joint, to be filled with a length of something like .015" phosphor bronze wire. It seems to me that fitting the wires to the side sheet would be simpler when still flat. So the question is, can the side sheet still be rolled effectively once the "weld beads" are soldered into place? Or will they need to be attached after the side sheet is formed?

Or does anybody have a suggestion for a different way to create the welds? I have considered using Archer weld bead resin surface decals. But they are relatively expensive, and there will be something like 24-30 linear inches needed per car.

Thanks,
Jim
 

michael080

Western Thunderer
Jim,
this is only theoretical knowledge, because I have no practical experience with etching, but in flat sheet metal CAD design there is a simple rule:
The length of the part is calculated using the "neutral axis" of the part. This axis is (in most situations) equal to the centerline of the sheet.
As an example: If you want to wrap a 1mm sheet around a 10mm cylinder, the length of the sheet would be calculated using the radius 5mm + 0.5mm (half of the sheet) A complete cylinder would be l = 2 * pi * r * = 2 * pi 5.5mm = 34,557 mm.

edited the very embarassingly wrong formula.

The experts may disagree :)

Michael
 
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simond

Western Thunderer
I agree with Michael, except, if you’re getting to radii where the thickness is an appreciable percentage (say 10% or 20% as in his example) of the radius, this causes an effective shift of the Neutral Axis. It is around 45 years since I studied this, and have had no need to revisit it in the intervening period, so forgive my vagueness, please!

I just found this - http://courses.washington.edu/me354a/Curved Beams.pdf. which reawakens some recollections... the neutral axis shifts towards the inside of the bend.

In practical terms, it probably makes no measurable difference to the etch design, however.

Atb
Simon
 

mickoo

Western Thunderer
Couple of things, well more than two actually. No need for 0.4 sheet for the hopper side, 0.375 in brass or 0.2 in nickel silver will be robust enough unless you wish to play on the floor around the Xmas tree :p The curve in the side will add all the extra strength you need.

The calculations above are plenty close enough and you can roll the whole lot in one go but it's a real fight, rolling the sides isn't hard, nor the roof but the cant rail tighter radius once you've done the roof and sides will be a real handful. You run a greater risk getting that tighter cant rail bend wrong than the overall size of the sheet being wrong, even with the most accurate of calculations.

You can aid the tighter radius by adding very thin, closely spaced, half etch slots on the inside, you will end up with small ripples on the outside but they are easy to smooth out and make a uniform surface, especially something that large.

Personally (and it's what I'll do when ever I resurrect....find decent drawings....my 2 bay hopper project....I do have some close ups if you think you need them) I would break the shell down to three parts, two sides and a roof. The sides and ends with say three or formers inside will form a good solid core, the roof can then be formed on it's own and stuck on top, the joint would be hidden by the cant rail strengthening strip. Any losses from calculations would then easily be covered by the cant rail and sole bar strengthening strips.

For the strip joints; there seems to be two types, half round bead or flat lap joints, for the lap joint I'd just half etch some thin strips on your etch and solder into place. You can roll those sides with them attached but add a sheet of cardboard to the side where the strips are, just acts as a bit of a cushion and prevents the main skin from deforming. Frankly I'd add them afterward from thin tape, much like I did for the H38 coach roof recently.

For the half round you can etch a slot and fill with round wire or simply buy some half round or D shaped wire. I use half round and just file the top to create D shaped and have a stock of 1.0 x 0.5 mm or 0.8 x 0.4 mm for engine and tender beading but other sizes are available if I recall. Go for Nugold Brass Wire with a soft rating, it's soft enough for tight bends but if pulled straight will hold a decent line for fixing long stretches; Metalclays4You.co.uk is my source, either direct or via their bay of E account. There are other sources.

IMG_9901.jpg

For the engine hood then it's hard to say, I work out as above and then add a bit more, you can always trim back, bloody hard adding if it's too short! If in doubt I'd do two pieces on the same sheet, one to your exact calculations and one with a bit more looser tolerances.

It's one of those things you just get to know and as Simon notes, rarely of measurable difference. We live in a digital age and can measure to silly small numbers, but often you don't need to, I'm as guilty as many, more so, of over thinking something or over engineering something.

I also tend to send small sheets to PPD when developing, using their smallest available size, I might send three of four of those of the course of the testing and once happy, combine them all into one big master sheet.
 
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Big Train James

Western Thunderer
Thanks for the replies. My intuitive reaction would have been to start with the neutral axis, at one half of the thickness of the material, with an idea that the outside will stretch while the inside is compressed. But then I got it in my head that maybe the inside would remain at its original length, with increasing deformation to the outside face.

I took a look at the link that Simon included, and now my head hurts a little bit. I get it all conceptually, but I also haven't had to think about math like that for a long time.

I've been looking around lately at bending and stamping info, K factors and the like, because I'm also interested in the idea of creating some forming dies for effectively stamping model parts like boxcar roofs or side ribs.

wt-roof panel 1.jpg wt-roof panel 2.jpg wt-side rib 1.jpg

Here's a link to a post regarding bending and stamping, in pretty plain terms. I'll dig into things a bit more and make an educated guess on size. And then expect to have to dial it in at least once.

I probably should just let some of this stuff go, but it's hard for me to do that. Besides, it's fun to think about how things work, and how you might achieve certain results. Keeps the neurons firing, and all that.

Cheers,
Jim
 

Big Train James

Western Thunderer
Thanks for the post Mick, I think we were typing at the same time.

Personally (and it's what I'll do when ever I resurrect....find decent drawings....my 2 bay hopper project....I do have some close ups if you think you need them) I would break the shell down to three parts, two sides and a roof. The sides and ends with say three or formers inside will form a good solid core, the roof can then be formed on it's own and stuck on top, the joint would be hidden by the cant rail strengthening strip. Any losses from calculations would then easily be covered by the cant rail and sole bar strengthening strips.

This is exactly what I've been planning in my head, most of the day long and as I fall asleep at night. Essentially create a frame or carcass, with sides and roof formed individually, with the roof capping and trimming the top of the car sides. The sole bar or bottom stiffener would definitely be a separate piece, with the top stiffener as yet undetermined. Slope sheets and hoppers could possibly be one part, folded up.

Regarding the weld seams, I thought you had a question as to whether the tape would adhere sufficiently to the metal substrate, although that may have been an issue specific to aluminum? And you may have solved it anyway, I'd have to go back and look at the thread.

I didn't realize that you could get half round wire, that would be preferable to full round, for this purpose. Instead of filing it to a "D" profile to flatten the top, I was going to experiment with annealing the wiring to soften it, with the hopes of potentially "smushing" it a bit to flatten it and introduce some typical weld bead pattern. I've seen it done by military modelers, and tried a bit myself, with styrene rod softened with liquid cement, then pressed with the back side of an x-acto knife.

I am always happy to gain access to additional detail photos, so if you have them I will take them. While I'm currently working about the Trinity 3281 2-bay hopper, I'll take anything you offer on any modern-ish freight car. There are often details like handbrakes, or hopper outlet gates in this case, that are sub-assemblies supplied by an outside vendor, specified by the purchaser, and therefor are not manufacturer specific.

I'll send you copies of the drawing information I have on hand. I've got some level of drawing with at least major dimensions for both the Trinity 3281 cu. ft. car and the Gunderson 3250 cu. ft. car, and I can also extract vector .dwg files of varying quality from the pdf's as well.

By the way, the original idea was to cut and shut an Atlas Trinity 5161 hopper, which is still a possibility. But then you start to realize that the hoppers aren't the right shape and size for cement or sand, and the outlet gates and roof hatches aren't the right type, and the roof walk needs to be done anyway, and so on, and start thinking about just starting from scratch instead.
 
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mickoo

Western Thunderer
James, for the H38 coach roof I ended up using Scotch tape, the clear stuff, cut into thin strips, the tape is a plastic and as such does not stretch, the adhesive is strong enough to hold it in place until painted which then kind of encases it all in place.

The problem was the aluminium roof, if I had a brass or nickel silver material for the base then thin strips of brass would be soldered on without hesitation. Looking at my photos the covered hopper sides do not seem to be butt welded so the weld is uniform and neat, aka not a weld as such. It looks like the ends of the material have a lip folded up, probably large enough to clamp together on the outside, then the joint is welded on the inside and the resultant flange on the outside ground down, as such you tend to get a square bead.

IMG_7169.jpg

The D shaped wire is already quite soft and could be marked or flattened once soldered to the side skin I would think, for me it's a detail too far :))

Brakes I can do, a 2 bay hopper as it happens :thumbs:

IMG_4023.jpg

I'll sort all my rolling stock walkarounds out and dropbox you a link this week, if not and I forget, prod me at the weekend.......

As well as 2 bay hoppers I've a fancy for smaller tank cars, typically in the 12,000 gal region and end beam flats, the real big heavy duty ones in the 60' - 70' region, they are perfect candidates for etching, especially the end bulkheads. Not sure why I want one, just think it would be nice to trick one out all battered and bent with split wood floor and the such like.

The cut and shut has advantages, but as you say, the more you look, the more you find to change, I think Lionel did a fairly decent 2 bay but it was a while ago when I did any serious US research or modelling.

Stamping would be a nice arrow to the quiver, I'd be more inclined to head toward SD9/24 stamped louvres myself ;) If it were box car roofs then i'd probably opt to 3D print them and secure to a steel inner roof underneath, you could make them as panels that all fit together....like the real thing.

The stamped ribs welded on the sides are a different beast, you need to see thinness of material at the ends and a gap twixt rib and body side, at lease for a few mm anyway.

The thing is, the level of detail we're talking here is close to the limit in O gauge to my mind, but certainly worth it in 1:32.
 
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Big Train James

Western Thunderer
for me it's a detail too far :))
Honestly, I'm currently in the throes of indecision regarding where I want my modeling to go, and how far I need to take things to be satisfied. Unfortunately, I love the detail and accuracy, and I keep coming back to it over and over again. The problem is that I get somewhat paralyzed by the pursuit, the result of which is I never get anything done. There are of course other considerations, but this compulsion is a major factor.

The weld detailing thing was based on the premise that I would be using a full round wire set in a half-etch groove, and I'd need to flatten it out some. Granted, the examples of the technique were probably all 1:35 or larger armor models, so more in line with your last sentence above. Even better, upon further review of some of my photos of the Trinity cars, I agree that any sort of bead is almost indiscernible. In fact, it may actually be a narrow groove instead. So I'll probably half etch a groove instead, or half etch marks and score with a scrawker.

wt-weld seam 2.jpg
wt-weld seam 3.jpg

I've gathered up some data sheets and cad files for you on three modern 2-bay hoppers, and I also have the same for the Gunderson bulkhead flat. If instead of the bulkhead flat, you mean the centerbeams, than I have a lot of cad and info to send on those. Because those are way up on my list of cars I'd like to get done. I don't have much information on the tank cars, if only because I don't have as much interest in them as other car types. However, if you are talking modern era, than +/- 14k capacity sulfuric acid cars are about as small as they go these days I think. I need to check some of the Procor cars as I regularly see them through town. I just don't know what size they are, but they are tiny compared to any of the corn syrup or petroleum cars. If you are talking about earlier versions, there are lots of +/- 10k tanks to choose from. Anyway, I'll send you a link to the dropbox once I get things uploaded.

We previously discussed the stamped louvers, they are more applicable to your preferred era for motive power. Certainly they would apply to all of the early EMD products. Louvers are pretty rare on 2nd generation EMD locos, except for the switchers. Granted, I would like to pursue the switchers as well. I'm interested in them to replicate real world stampings, not because I'm that kind of purist. Rather because I think it might be one of the better ways to render the prototype, while trying to avoid injection molding costs. I'm a bit paranoid about warping with resin castings and 3d prints in certain instances, maybe preventing that is all down to technique or something. But etched metal blanks and forming dies would be a relatively fast, accurate, and reliable way to produce parts.

Again, as with the hopper kit design, you've read my mind on the boxcar roofs. The idea is to have individual stamped panels, with locating tabs as appropriate, which will drop into an etched frame. The beauty of this is that any number of combinations of style and order can be achieved with a small number of parts.

Part of the allure of creating dies and stamping parts, is simply to see if it can be done effectively. Plus it's a different way of producing parts from what is normally found in the hobby, at least from my experience. I'm also wanting to try this because I've spent some time lately learning some machining in general, and CNC and gcode programming in particular. Enough so that a job in the field will hopefully be my big news for 2021 (second biggest news if I were to also actually finish a model!! :rolleyes::cool:) Paired with the 3d cad skill set I already possess, plus some additional learning regarding stamping and some trial and error, I feel comfortable giving this a shot. Certainly the vision I have in my head turns out pretty cool!:p
 

Brian McKenzie

Western Thunderer
We previously discussed the stamped louvers . . . . . . . Certainly they would apply to all of the early EMD products.
I'm interested in them to replicate real world stampings . . . . . because I think it might be one of the better ways to render the prototype, while trying to avoid injection molding costs.


Hi James,

Looks like some interesting times ahead for you on the job front! Here's my attempt at making EMD louvers for a G12 loco in 1:24 scale.
I've also made them in smaller scales for Drewry locos - so those were louvres. :)

0960b 1-24 DC Louvres.jpg
The punch was a length of HSS lathe tool, and after some reshaping, it produced the four louvres (as at the bottom) with rounded ends.
The female die plate is from gauge plate, (of similar composition to [UK] 'silver steel' - or your [USA] drill rod), with milled 'saw-tooth' shaped grooves, and then hardened and tempered. Both pieces are mounted in a frame making use of 6mm diameter threaded rod to index the die plate progressively along below the punch for each louvre.

-Brian McK.
 

mickoo

Western Thunderer
I really didn't want to pamper the US Railroad interest bubble just yet :)) but!

Advanced excuse for photo bombing your technical thread....

A slight diversion, I have many interest bubbles, over time I've found the most important ones that I should really pay attention to are those that most easily distract you, US Railroads and German railways are my canine 'ball'....'squirrel'...attention triggers. USN Warships are also a strong pull that I've successfully managed to closet for some time but wavered at Xmas (more later when it gets delivered in it's own thread).

So, your vexing and hand wringing is normal and you've already worked out, or very close to, that demanding the ultimate detail results in near zero production. I found that I spent more time solving the problems, to then realise that they were impractical, either due to my skill set, work practices, or just plain bloody awkward and overly complicated.

To break the deer in the headlight funk, the path is simple, it's in my signature.....JFDI....anything, just do something. If it comes back wrong then don't get disheartened, look at what you did achieve, chances are it'll be significantly greater that that which you did not achieve. I know prototyping can be expensive, especially cross pond postage but you should know that I am more than willing to run test etches to reduce costs for you on the back of my stuff, the offer is/has always been there.

My current Achilles heel on the GEVO is details like the below, it's multi layered on several levels, some require insets in the base material or an opening (not preferred as it reduces strength in other areas).

IMG_6927.jpg

In my mind I can replicate this, in practice it's near impossible, I can get close in O gauge but not close enough to satisfy that detail freak in me, and I've seen some of your CAD work, you too ;)

This presents a mental dilemma, In my preferred scale I cannot achieve the level of detail I wish for, there will always be a compromise, the exit strategy is really simple to everyone stood outside my bubble, go to a scale where you can achieve the detail. The result is a simple equation, O gauge with simplified detail, 1:32 with much greater detail and that decision has stopped GEVO development for some time....see I can hand wring and vex like the best :p

Back to the real world and wagons, the panel lines are certainly raised. Not sure you can see it on the reduced images on WT but they are certainly raised.

Img_3791.jpg

Img_3793.jpg

Given that information then I'd probably make the whole side in 0.375 mm nickel silver and half etch away the panels to leave the weld lines as raised edges, the reduction in thickness will make it easier to form the curve. Back the side with the raised ribs with cardboard when rolling, helps remove distortion.

Couple of 2 bay reference images.

IMG_3945.jpg
IMG_2043.jpg
This is the one I did a mini walkaround on at Oro Grande.

IMG_4022.jpg

This is an odd one I bagged at Hesperia, it looks 2 bay sized yet is clearly 3 bay with a combined discharge system. I took a few more detail shots as there were quite a few in the manifest.

I suspect it's probably cement from Oro Grande or Victorville just back up the line a little, or more probably off the Thorn, Cushberry branch. I need to explore that branch and the Victorville quarry branch on my next visit.

IMG_3909.jpg

It also had a nice SD39-2 in the head end :thumbs:

BNSF 1893b.jpg

Tank cars, boy did I underestimate their capacities :eek: Most of these are in the 20K region.

Couple of nasties...

IMG_2050.jpg

IMG_2263.jpg

Not sure what's in this one, probably less volatile as the above but probably not nice either.

IMG_3918.jpg

Standard tank car, again at Hesperia and a few more detail shots as well. No markings as to cargo specifics but different from the above in that it's a dropped centre car, all be it slightly.

IMG_3938.jpg

Bulkhead flats, centre beams are also fun, but their sheer size kind of prohibits me getting overly enthused, nice wagon, just need a bigger garden to justify them :D

A few bulkhead flats, solid steel ends.

IMG_2262.jpg

Wooden ends.

IMG_4043.jpg

IMG_5150.jpg

Warping and distortion is a concern in resin and 3D prints, especially large areas or volumes, with care it can be minimised and usually eliminated, the GP9B cab cover was an exercise in that aspect, as was the SD35 cab front. Mind I've read there are now newer resins that help in that region, not only during the print, but post curing which is where much of the distortion can occur.

If you secure the box car roof panels to a metal skin underneath then it shouldn't be much of an issue, the trick is....you guessed, try it....:thumbs:

Just for giggles, I wonder if it is possible to 3D print the all steel ends of a bulkhead flat car, not as satisfying as soldering all those beams up. let alone removing all the cusp...:eek: but overall probably a lot quicker, more repetitive but with a slight loss of fidelity, which brings us full circle :cool:
 

Big Train James

Western Thunderer
The punch was a length of HSS lathe tool, and after some reshaping, it produced the four louvres (as at the bottom) with rounded ends.
The female die plate is from gauge plate, (of similar composition to [UK] 'silver steel' - or your [USA] drill rod), with milled 'saw-tooth' shaped grooves, and then hardened and tempered. Both pieces are mounted in a frame making use of 6mm diameter threaded rod to index the die plate progressively along below the punch for each louvre.

-Brian McK.
Those look quite nice. :thumbs: I'm going to have some questions. :D

For starters, how thick is that material? I had envisaged something nickel silver, in the .005" to .010" range, for the parts I'm considering.

Is the punch also cutting as well as forming, as I believe it would for full scale louvers?

Does the blank size match the intended finished size, or is it adjusted to account for deformation? I am of the impression that something like a rectangular blank won't end up rectangular after the stamping process is complete. I need to learn how the blank will behave as it's formed into something else, because I may not have the means initially to create tooling from anything harder than cold rolled steel. So aggressive punching and shearing may not be a possibility. It's probably more a matter of forming rather than full-on stamping. I'm currently at the stage where I have a lot of "impressions", but not much real knowledge, so I may not be thinking of, or describing, things correctly at the moment.

A fellow modeler and I are considering acquisition of a Taig CNC mill. It's marketed as being more capable than typical mini or hobbyist benchtop mills. The goal would be to 3d model the tooling, cut it in cold rolled steel, and then form etched metal blanks using an arbor press or something similar. This would be from the perspective of individual modeling purposes. If I successfully created a kit for rolling stock, and needed production numbers, I'd pursue something more durable.
 

Brian McKenzie

Western Thunderer
> For starters, how thick is that material? I had envisaged something nickel silver, in the .005" to .010" range, for the parts I'm considering.

The brass sample shown was 0.020" thick, but 0.008" to 0.010" in nickel silver would be ideal, and neat in 1:48 scale.
Louvred panels made for smaller scales used 0.007" stainless steel shim stock - only because it was lying around.


> Is the punch also cutting as well as forming, as I believe it would for full scale louvers?

Yes, and for that reason choice of tooling material is important. Cold rolled steel would soon loose its shearing edge, and may not even provide sufficient consistency for a single model.

A.I.S.I. 01 Oil Hardening flat stock material is readily available from suppliers near to you such as:

Oil Hardening Flat Stock | 418924 | Travers Tool Co., Inc. or O1 Precision Ground Flat Stock, Oil Hardening Tool Steel Presco PM Buy a 18" length of say 1/4" x 3" which will set you up for tooling for a long time.


> Does the blank size match the intended finished size, or is it adjusted to account for deformation?

There is no noticeable deformation. The blank is oversize (and is clamped to the indexable dieplate) but only because it is easier to trim to shape relative to the louvres, rather than having to position a smaller 'to size' piece accurately under the punch.



> I am of the impression that something like a rectangular blank won't end up rectangular after the stamping process is complete.


Distortion hasn't occurred when punching any louvred panels (but change of shape is pretty spectacular when pressing out complex shapes like cowcatchers).


> A fellow modeler and I are considering acquisition of a Taig CNC mill . . . . The goal would be to 3d model the tooling, cut it in cold rolled steel, and then form etched metal blanks using an arbor press or something similar.

Better that you get a manual mill first and gain much operating experience, especially with speeds and feeds appropriate for small diameter cutters, backlash and a thousand other things that are part of machining processes. A manual mill will allow you to get some modelling underway, whereas fiddling with a CNC machine, without prior experience, may remain only just that !! ;)

All the best for 2021.

-Brian McK.
 

Brian McKenzie

Western Thunderer
Part of the allure of creating dies and stamping parts, is simply to see if it can be done effectively. Plus it's a different way of producing parts from what is normally found in the hobby, at least from my experience. I'm also wanting to try this because I've spent some time lately learning some machining in general, and CNC and gcode programming in particular.

Hi James,
I've been making tooling for stamping a new size of louvres (for Hunslet diesel-mechanical shunter) these last few days -
in between watching live coverage of America's Cup yacht racing of the preliminary Prada Cup series.

The American entry has just crashed spectacularly in the last few minutes as I write this, from a leading position . . . had been doing 48 knots earlier - now taking on water. Look out for it on your sports news. The biggest surprise so far has been the turnaround (after a big refit) of the UK entrant from being a 'dog' to now having the most points on the board. :thumbs:

IMG_2647a.jpg

Your earlier comments got me thinking about using the CNC to cut the female die. This was used to provide a constant even feed to the single point flycutter so that it might hopefully complete the job (in oil-hardening steel) without wear or damage.

The louvred piece is inset to a thicker piece, after hardening and tempering both, and finish grinding to size (while removing distortions from the hardening). Next job is the male punch.
 

Big Train James

Western Thunderer
I've been remiss in not responding to several posts here in a more timely manner, which I apologize for. Starting with Mick's post last post, fully agree on the JFDI perspective, it's just that I'm not very good at putting it into action. But as it's a new year and all that, I'll give it a go again. I've made good progress on cad for the Trinity hopper, both the sheet metal parts as well as the appliances. I need some info on the center sill and bolsters, plus some of the end cage parts, I have a friend that will try to acquire the field information for me later this week. Once I have those bits worked out in 3d, I will need to unwrap the carbody into 2d artwork, while giving some thought to the assembly process.

trn-ch3281-001.JPG

trn-ch3281-002.JPG

trn-ch3281-003.JPG

nyab-res-001.JPG

nyab-cyl-8p50x12-001.JPG

miner 13x42 gate-002.JPG

morton-offset ramp board.JPG

Also, while I'm sure that PPD's experience dealing with modelers would be useful, I have a lead on a potential domestic etching company that has also done some model rail work in the past. "Local" etch production would save a lot of time and money while prototyping.

Moving on to some tank car commentary, you say that they don't necessarily say what's inside the tank. However, with any tank carrying a hazmat lading, the required hazmat placarding will identify the contents. In your two examples above, RPBX 23222 is placarded as UN 1830, which is sulfuric acid. TCBX 305092 is placarded as UN 1987, and is a bog standard ethanol car. Of course, non-placarded cars usually do not identify the contents, say for something like corn syrup or inedible animal fats. In that case hopefully something about the reporting marks or brand labeling on the car side will give a sense of what is carried within.

By the way, of the smaller modern tank cars, the sulfuric acid cars appear to be one of the common types. Another are the molten sulfur cars, which also hold something in the neighborhood of 14k gallons. These cars carry a placard or marking of UN 2448.

gatx 22152.jpg

A couple of other notes, the BNSF sd39-2 locos are ex sd40-2's, that have either been rebuilt, or simply de-rated to (I think) 2300 horsepower. EMD never produced a dash 2 version of the sd39 that I am aware of.

Lastly, BNBX 95500 is the same general size as the other typical 2 bay hoppers, in the range of 3200 to 3300 cubic foot capacity, but it is a pressure differential car where the lading is fluidized for handling. That accounts for the piping at the outlet gates. I'm not sure why there are 3 bays instead of 2. Current versions of these cars are made by Trinity, and they have a 5 bay variant in the neighborhood of 5000 cubic foot capacity, for things like flour and other milled product. The 3 bay versions are used in sand and cement service. I really like these cars, and I want them. Add them to the list! :oops::rolleyes::cool:
 
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Big Train James

Western Thunderer
Brian, the newest louvres look fantastic, and I like that you were able to produce those results with .008" nickel silver. :thumbs: I really would like to try this technique with hood doors louvers, but also I definitely want to have a go at the stamped boxcar roof panels.

Could they be made to have the rounded ends, as the set of four did in your original posting up above? Those would match the typical EMD louvre style.

Am I correct in assuming that all 25 or so openings are formed in one stamping operation? Or are multiple ops required, with the part indexed along for spacing?

What did you use to close the dies? Do you think a bench top arbor press would suffice?

The mind races at the thought of what could be produced this way, especially for 3d items that might otherwise require lamination of multiple layers, or a move to a casting instead. One such item I'd like to try this with would be snow plows, where the prototype is formed on a press break. I'm curious if the breaks could be replicated. Also, most castings of plows are okay but it's obvious they are castings by their thickness. I think stamping could result in a much more successful rendering.
 

adrian

Flying Squad
The mind races at the thought of what could be produced this way, especially for 3d items that might otherwise require lamination of multiple layers, or a move to a casting instead.
I've posted this before but I really do admire the work of Gerald Wingrove and his incredible coachwork. As usual I think we can always learn from different modelling fields.

For the car's he's built he made a louvre jig to press curved louvres
Wingrove latest

more photos here of his jig
P3 Alfa Romeo & Louvre Press
 

Brian McKenzie

Western Thunderer
Brian, the newest louvres look fantastic, and I like that you were able to produce those results with .008" nickel silver. :thumbs:

> Could they be made to have the rounded ends

While it was pleasing that the new louvres punched cleanly, rounded ends will come next (when courage is summoned to tweak the punch - one false move and its start all over).

The Hunslet prototype has a flat portion across the top of each louvre which I would like to try to reproduce. Rather than modify what now exists, some extra bits of tooling have been made to tinker with.

Assorted Louvres_2739.jpg

> I definitely want to have a go at the stamped boxcar roof panels.

Roof panels could be tricky if ribs are at right angles to each other. I imagine (with no experience) that the material blanks would have to be held down very firmly along all sides - so that the metal gets stretched to form the indentations. If the ribs all ran in the one direction, then there would be less buckling effect.

> Am I correct in assuming that all 25 or so openings are formed in one stamping operation?

> Or are multiple ops required, with the part indexed along for spacing?

The punch cuts one louvre at a time. The workpiece is clamped to the female die plate which gets indexed along under a guide supporting the punch. A length of 6mm threaded rod controls this, making use of its 1mm pitch to work out the spacing increments.

> Do you think a bench top arbor press would suffice?

A tap with a hammer is all it takes for louvres! However, I do use a flypress for some larger parts, and you may need either that or an arbor press for what you are considering.

> One item I'd like to try would be snow plows

Here's a similar item that didn't go so well. For the couple of pieces needed, the tooling was made soft, being from oddments of mild steel. A thin plastic film was placed over the brass, to help protect it from marking by the punch. But the film got puckered, and bruised the tool leaving an indentation.
Cowcatcher blanks incorporating footboards_0587a.jpg

Another time the flypress was used was for joggling the frame plates for an outside framed British built 4-4-4t narrow gauge loco destined for India - to accommodate the swing of the front bogie wheels.
Outside frames joggled for bogie wheel swing_76615a.jpg
 

Brian McKenzie

Western Thunderer
Update on the louvres - some nerve-wracking time tweaking the tiny protrusion of the punch with a diamond file allowed a narrow width of flat area (0.010") to be retained between each louvre.

Louvered Panels_2863a.jpg

Sufficient door panels have been made (plus a few spares) for the Hunslet prototype, similar to BR's 05 class.

A puff of vinyl etch primer was squirted at one panel (known as PA10 in my part of the world). Painting is not my thing, and have no idea as to the suitability of this paint for models - but it is very durable and protective of large steel weldments. :D
The aerosol advises, "can also be applied to non ferrous metals".
 
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