Printing a steam locomotive!

Any ideas in particular? I made a steam locomotive shell first only because that's what I needed - anything else (switchers. cars, etc) would be much easier and faster to make by comparison...

Yep you got the idea. As an aside, the soon to be released Z-Corp printers (what Shapeways calls "Sandstone") can actually print finished products in two different materials (one opaque and the other clear) - at least by my understanding. The idea here being that you could integrate the windows into the walls of a structure and print everything in a single pass.

That's probably the biggest knock against Shapeways - they don't let you specify the orientation in which they will print your model. All of the cars that I have received have been printed on their sides not upright for example. This actually isn't as much of a problem as it might sound like though - flat surfaces printed facing straight down actually come out 99% as clean as flat surfaces facing straight up. It's curves that seem to be more problematic (tanks, boilers, etc.).

As for improving the resolution - at least from pictures that I have seen, with each passing month (FUD has only been around since the end of last year) Shapeways has actually been getting better at reducing the "fuzz." I gather that producing really smooth products from these machines requires a bit of an "artists touch" so to speak - and they have been getting better.

 

Matthew,

I would assume the switcher wants would be:
Alco S series (1,2,3, 4 and maybe an S12)
FM H-10-44 and H-12-44

I would imagine that an SW1500 shell would also sell pretty well considering how often this hole in the N scale loco offering is mentioned.

Scott

 

Hmm okay that makes sense - thanks for spelling those out - part of the reason that I'm asking you guys these open ended questions is that I am truly ignorant as to what people have been grumbling about recently in n-scale (I am just coming back from a five year hiatus in On3).

That said, any/all of those look like cake to design compared to steam! As it stands I'm looking for an "easy" (not steam) project for the next month anyway - are there any more people seriously interested in any of those? My only hang-up is that I have no mechanism to work from (not in front of me at least).

 

Thats what I was thinking too, perhaps an Alco high hood switcher as well to fill a few gaping holes in the ATSF roster. While not of interest to me personally Baldwin road switchers would certainly be welcomed by some.

 

One thing all you diesel guys are missing is that while the handrails are pretty good...they aren't great. It looks like the minimum cross-section is about .020? That's significantly fatter than current injection-molded practice.

I'm not seeing anybody out there that's done a typical North-American style supported handrail set at the 30-36" height range. Please correct me if I'm wrong.... These aren't printing in Delrin...not yet anyway. This steam loco demo is about the best handrails I've seen out there yet though - but with this stuff I think low is better. Now for me, I just do them in brass wire anyway for myself, but we're not a miracles for the handrails just yet...

 

I, for one, am definitely interested in Baldwin road switchers or transfer units.

 

I'm not sure, I haven't tried to scale it down yet. I'm currently trying my best to adhere to the prototype dimensions. Its does sound like I need to increase the size of a few things, the rivets on the tender doors are something like 1/2"! What are the dimensions of your handrails? I was planning on adding wire grabs later on, but I'm impressed with how your printed railings came out!

 

This has never been done in N scale before. Would really love one! The Baldwin AS616

 

Matthew-

Started drawing the boiler for my WM 2-10-0 today, and I have a whole new respect for what you've accomplished! I cannot for the life of me figure out how to draw my domes, or how to draw rivets on the curved surface of the smoke box! You used google sketch up correct? Any pointers?

 

I'll admit that I struggled with both of those for a while too... The "intersect curves" function will become your best friend for that sort of thing (but it also creates a few problems). That said, I'll send you a pm if you want to go into things in more detail.

You have a great eye! I just measured them at .019. It's fatter yes, but not offensively so (in my opinion at least).

As for seeing an example - check back in three weeks or so? I have my first diesel half done now and I think I'm going to attempt to print the handrails in place. The handrails I've printed on the 2-6-6-0 are actually surprisingly resilient, and some run the full width and or height of the tender with no intermediate support. They also stand up reasonably well to impacts, FUD is considerably more ductile than styrene (although it does seem to "bounce back" less readily).

 

Hello, maybe you want to take a look at this two threads, the first one it's an UK designer doing New Haven electrics for someone..and in the second one you will find their first release on shapeways.

http://www.rmweb.co.uk/community/in...ral-electric-e33-e44-e40-and-gf6c-in-n-scale/

http://www.shapeways.com/model/495162/ne3301-n-scale-e33-loco-new-haven.html

 

The one question I have is whether Shapeways has solved the problem with rendering curves without the stepping problem? A number of items already finished still show the stepping and while for something like an ELC/E33C it likely will work rather well since they lack a lot of curved body parts rendering something like the NH EF3 he is showing may suffer from this very problem.

 

In theory at least there are two sources for 'stepping'.... I'm speaking here as the CAD support guy not necessarily a shapeways expert, but I'm catching on.

1) Even the most sophisticated CAD 3-d tools go through a surfacing routine to get a a model completed, and that model generates a series of interlocking close-line plates. The trick is to get that resolution way up there so that the plates are smaller than your printing resolution, otherwise you print little flat surfaces on a curve. That makes a BIG model file. It's the same problem in working with topographic maps in civil engineering, the TIN (triangulation) files are a function of contour interval connecting the lines. Imagine the file size if you were trying to topo the Grand Canyon in 1' contours from aerial high-resolution mapping. Computers eaten while you wait, been there, done that. The trick is to make your contours at least equal to printing resolution once you figure that out here. The other thing I don't know until I try it myself is whether or not the scaling process messes this up or makes it better.

2) The printing resolution itself. Here's where I'm seeing some real progress, big change, right in front of us. The smoothing on an interior curve is way better than what it was (like the top half of a boiler). The exterior curve (think unsupported, like under the running board) still has some issues from what's described here, as it relies on a second material to prop it up during the printing, and that curve process still shows some stepping. What I'm also hearing is that if you could always control the 'top' from the 'bottom' it would be a lot better, but for now, you can't, so one may work and the next may not depending on how the orientation of the model is printed on the machine each time. But this high-resolution FUD, combined with the printing resolution, combined with that 'stuff' to hold the unsupported edges that comes out later, wow. This is a completely new process from what I thought could be done before, particularly after looking at the makemymodel stuff.

I'm anxiously awaiting the Barnhart loader as a demo. With that curved roof it should show this concept nicely, for what it can and can't do. That's just an exquisite test design for the material capabilities.

I'm likewise completely baffled at the moment at the learning process of getting things drawn like the transition 'cone' between boiler courses, seating the dome on top, riviting on curved surfaces....yeah. FWIW I think this entire thread is rapidly morphing into its own special area of 3D design use of these tools for N scale. It's here and now.

 

Beautiful work, just stunning possibilities, but the handrail problem is apparent. When you see the beautiful .3mm handrails turn into .6 mm required by this technology and compare the visuals as illustrated in the link, the challenge is obvious. Would it be possible to print the uprights integral to the body but plan for wire handrails?
Still, this technology ( and the talent of the pioneers) blow me away.
regards, Otto K

 

The tech will improve, so eventually scale diameter handrails are feasible. I don't see why you can't just trim off the "thick" handrails and do your own..... no need to omit them from the original model, and the ones included can help you get your bends and such just-right before installing your finescale grabirons and handrails. Just my two cents...

 

I think for now the separate, and 'thick' handrails are the way to go... I know if I was to get one I'd redo it in wire, and it would also be a lot handier to redraw just the handrails as soon as the technology allowed. But the folks that can't do handrails any other way would at least have something.

I love photoetched brass for this kind of application, the CAD has always hung me up, but I'm thinking now that maybe the Sketchup PRO may produce a viable 2D .dwg file without having to learn another program.

 

All, it's my first post here, but I see so many familiar names!

As a 28 year CAD designer at Ford Motor Company, I can surely tell you that sophisticated CAD software creates 3D model accuracy to seven metric decimal places. It is the sterolithography (hence the .stl file extension) process that defines the granularity of the "printed" model, not the CAD model. The process can only create curved and angular (to the printing plane of the machine) surfaces accurate to the thickness of the printed layer. Even if the machine could have 0.001" thick layers (currently incapable), the result of a 0.002" diameter in CAD would be a "plus" sign cross section 0.002" wide x 0.002" high, if that makes sense. Even if there are no angles or curves the process still leaves striations across the part in the plane of printing similar to layers of dried paint of consistent thickness when you cut thru them. There really is no way to have this tool create a true curve unless the material were allowed to flow into the low point of the steps. Try zooming in on a nice curve in MS Paint and you will see the same stair stepping becaose of the square pixel shapes the tool uses to create the curve. Simply put, this is why an Etch-A-Sketch cant draw true curves.

The accuracy of the .stl translation of the native CAD file can also contribute to surface inaccuracy. There are varying levels of .stl file quality that various CAD software can translate to.

I was trained many years ago on an SLA500 machine, back when the materials were hazardous and lazers were used to harden the viscous fluid in the vat and a wiper bar would wipe off the excess fluid from the model below the surface leaving a film layer that would be hardened by the lazer as it traced the outline and hardened inside each cross section through the part. Then the bed would lower and the process would start all over. A large part coluld take days to produce. Had to wear full lab protection!

Anyway, this is not a slam on the process, or the wonderful designs I have been seeing lately. The time is really spent in the creation of the CAD model, but unfortunately the model cannot improve the process. This and the stepping are some of the reasons I have not pursued this myself. If I were, I would refrain from modeling fine detail that IMHO looks better with etched brass stanchions and wire and separately applied appliances, but if the designer is happy with his model who am I to criticize!

I have often wondered if one were to smear filler putty into the stepping, and sanded the model, it would serve better as a model casting master.

Most injection molders skip the stereolithography process and machine the mold cavity directly from the CAD model (after adding material shrink percentage) then polish the mold surface- this is how smooth injection moded castings are made in many cases.

Sorry for the rambling and I hope this helps explain the process so it's not such a mystery to those thinking of using it- it really is a very cool and amazing process!