Pennsy Centipedes

[GimpLizard]

Marc,
Not trying to be a braggard here, but quite a while back I made a complete set of Baldwin "babyfaces" for Train Simulator. Including the New York Central 1500 HP "pocket" passenger units (DR-6-4-15) and their freighters (DR-4-4-15)...

They are 3D models, but I'm not sure what can be done with them. I know about Shapeways and 3D printing, but I don't think the technology is fine enough. If I could use these in a CNC milling machine I would rather make aluminum molds and cast a few.

There's a bunch of other stuff I made...Mostly first generation cab units and cars and trucks from the 40's. There's few PRR buildings too.

Frank

Frank, may I ask what file format you have those 3D models in?

[kelticsylk]

Frank, may I ask what file format you have those 3D models in?

The models were made in Train Sim Modeler but I have a way to convert them to 3ds.

Frank

[kelticsylk]

So, how bad do you want your "Baby Faces"???

Bob,
What I would like to do is create enough of the things to "share the wealth" with other Pennsy modelers and make us less dependent on manufacturers who keep releasing turbines and Big Boys and God knows what other engines they THINK we want". I miss guys like Irv Athearn and Gordon Varney who took care of us little guys.

Spending $140 to outshop the models annoys me (and my budget). I keep looking for ways to do it myself (a pipe dream, I know). I found ways to build my own CNC mills (www.instructables.com) but I'm not sure they could get the job done. I am looking into the info at www.silpak.com as a way to get things done.

If I had my druthers (and enough money) I'd make my own mechanisms too.

Frank

[GimpLizard]

The models were made in Train Sim Modeler but I have a way to convert them to 3ds.

Frank

I don't think 3ds is a true CAD format. Meaning the model is made up of a mesh. As opposed to faces & features, like you'd see from CAD, such as Solidworks. In fact I don't even find 3ds listed in my Solidworks import menu. Nor does it show up in Keycreator's import list.

It might be readable in a 3D printer, however. They generally use STL files. Which are also "mesh" models.

[peteski]

GimpLizard,
judging by your post, you know more than I do about 3D solid modeling.  But I have messed around with Google Sketchup and read through the Shapeways tutorials.  Those seem to show that Shapeways needs objects with surfaces which make a watertight object (not mesh).  It might be just semantics and I just don't understand a difference between "mesh" and "surface".  I think of a "mesh" as a "wireframe" - it only depicts the edges.

[Iain]

3D model of a BLW DRS6-4-1500.  While I only have it displayed as wireframe, that doesn't mean it's a mesh.  Meshes are only models of the surface, whilst this  is a solid as far as the software is concerned.  Using dedicated drafting software such as AutoCAD also allows you to precisely and accurately scale the model, something you can't do in software designed for cinematic viewing only.

[wcfn100]

something you can't do in software designed for cinematic viewing only.

Not really true. 

However, those programs aren't native solids modelers and do have many disadvantages for this type of work.  On the other hand, there are many types of more organic type models that would much easier in a program like 3DS Max, Rhino, Maya, Softimage, Lightwave etc...

Jason

[LV LOU]

I'm working on a CNJ Babyface,but I kinda planned to do a Centipede out of the same shell.I started with a Life Like E8,removed all the detail,filled in everything,and made a generic shell.My plan is to mill aluminum sides,graft them into the plastic shell,and them make masters of them.This is a pic of a Life Like F7 I started messing with before I got the E8..The E8 nose looks better..
 
 

[robert3985]

Bob,
What I would like to do is create enough of the things to "share the wealth" with other Pennsy modelers and make us less dependent on manufacturers who keep releasing turbines and Big Boys and God knows what other engines they THINK we want". I miss guys like Irv Athearn and Gordon Varney who took care of us little guys.

Spending $140 to outshop the models annoys me (and my budget). I keep looking for ways to do it myself (a pipe dream, I know). I found ways to build my own CNC mills (www.instructables.com) but I'm not sure they could get the job done. I am looking into the info at www.silpak.com as a way to get things done.

If I had my druthers (and enough money) I'd make my own mechanisms too.

Frank

Frank,

Even though I am not a Pennsy modeler (I am a consumer of all the UP transition era steam and diesel power I can justify...and I can justify a lot!), there are some common engines that ran regularly on the U.P. between Ogden and Green River that will probably never be produced by any major manufacturer.  So, although more is probably available for me than Pennsy N-scale modelers (SPF's), I also hope to be able to "share the wealth" with other modelers who would be willing to pay me for my design, engineering and production efforts.

However, I am realistic and I fully realize that to fashion a well-detailed model either as a kit or a finished, limited run is not an inexpensive proposition.  By the flip side of the coin, it is not overly expensive nowadays as far as producing the models, as the main expense is in the time spent on the computer doing the 3D modeling.

By the way, that $140 (app.) price was for four caboose bodies, not for one.  The print envelope might enable two, three or four Babyface bodies...depends on the machine being used.  That would be only $35 per body if you could get four done in one printing, which I cannot believe anyone would balk at.

I've done mold making for injection molding and it is both complex and unforgiving...and very expensive.  Injection molding also has serious limitations that the RP process simply does not have such as draft angles, no undercuts, etc., etc.  Babyface contours, such as on the nose, will involve an extremely complex and precise mold.  This, of course is why injection molding is so damned expensive to tool up for...before a single product is ever shot.

Another way of looking at the whole project would be to use 3D printing to pop out a master to be used for other production processes, such as for making RTV molds for casting the bodies and appropriate parts in resin...which would be much cheaper than printing them, but more time consuming to the manufacturer. 

The Perfactory process will also produce hard, heat resistant masters that can be used for making vulcanized rubber molds for injecting wax into, to use as lost-wax masters for investment casting of brass parts.  It will also produce the wax masters, completely bypassing making and injecting rubber molds, so there are no parting lines.

I am assuming that these hard, heat-resistant parts could also be used as masters for vulcanized rubber molds to make zinc alloy parts for such things as locomotive chassis.

Doubtless, it will be a complex process but highly rewarding when the first pilot model runs on your track. 

It might also be a good idea to get some kind of feel for how much other modelers would be willing to pay for either a partial kit, a full kit, or finished model.  Sharing the wealth also means sharing the cost, and there's nothing wrong with making a profit for your efforts.

Nevertheless, it should be apparent to potential buyers, that they're going to have to pay more for such a limited run model than if a major manufacturer produced it.  That's just the way it's gonna be, especially for a comprehensive kit or finished model.

[kornellred]

Keep in mind that the PRR Baldwin Centipedes were tapered at both ends.  They had the so-called "babyface" design, but the dimensions of the cab area from the behind the cab access doors to the tip of the nose gradually narrowed several inches, and that makes it entirely different from the CNJ, NYC, MoPac, Seaboard and (1 unit) CNW "babyface" cab and noses.  No such thing as having your cake and eating it, too, when it comes to Baldwin diesels.

The Hallmark N Scale Centipede model is nowhere near accurate as far as dimensional accuracy is concerned.  It is, however, an adequate representation.  Using it as the basis for a resin shell is possible, but the effort would probably not be worth it.

[GimpLizard]

Peteski,

By "mesh" I don't mean like a screen. But the "model" is made up of a thousand (more or less) tiny triangles meshed together to form the shape. What would be flat surfaces are usually made up of larger triangle. While shapes - curves & radius' - are made up of many more, and much smaller, triangles. Thus those curves & radius' aren't truly smooth. But rather faceted.

This is fine for 3D printing. As those triangles are (or can be made to be) finer that the resolution of the printer. However, it's not okay from a CAD perspective. Because the model does not have features, such as a radiused edge, that can be edited.

I could post a couple of images - one the native CAD image, another of the same model in a "meshed" STL image - to show what I mean. IF I could figure out how to post pictures here. (It's probably easier than schmidt, but I'm rather stoopid. And it takes me a while to figure things out. I'll bet it has something to do with that "Insert Image" button up above.)

[nstars]

I think rapid prototyping is coming very close to feasible. We already made one (british) steam locomotive whereby the shell was made using Shapeways. In a couple of weeks I'll talk to somebody who says that he has access to a 3D printer with better resolution than Shapeways. Now we only have to work on the model itself. I already have a Hallmark Centipede set, so at the moment I would be more interested in getting the NYC or CNJ babyfaces. We model the PRR, but we have a weakness for those none standard diesels. The NYC would be the easiest to motorize as the ER sharks are perfect for it (and I already have some units lying around).

Marc

[peteski]

Peteski,

By "mesh" I don't mean like a screen. But the "model" is made up of a thousand (more or less) tiny triangles meshed together to form the shape. What would be flat surfaces are usually made up of larger triangle. While shapes - curves & radius' - are made up of many more, and much smaller, triangles. Thus those curves & radius' aren't truly smooth. But rather faceted.

This is fine for 3D printing. As those triangles are (or can be made to be) finer that the resolution of the printer. However, it's not okay from a CAD perspective. Because the model does not have features, such as a radiused edge, that can be edited.

I could post a couple of images - one the native CAD image, another of the same model in a "meshed" STL image - to show what I mean. IF I could figure out how to post pictures here. (It's probably easier than schmidt, but I'm rather stoopid. And it takes me a while to figure things out. I'll bet it has something to do with that "Insert Image" button up above.)

Thanks for the explanation - I understand the difference now (without pictures). Now that you mentioned it, I have seen those triangles making up the surfaces of objects for 3D printing.  Looks like for "real" and precise CAD/CAM work the objects need to be represented more accurately (both for easier editing and exact manufacturing).

As far as posting images goes, you aren't stoopid. It is not easy or intuitive. You can't upload images here. You need to upload them to one of the zillions of free photo hosting websites out there, then include a direct link to that image in your posts.

[kelticsylk]

Bob,
Wow...Lot of ideas here. I did realize that the $140 was for 4 units but did not think what that meant per unit. You are right, $35 a hit isn't bad. The Bowser N5 cabeese I buy normally retail for around $25 (I buy 'em cheaper when I can). I'm glad you explained the injection molding. I always wondered why a plastic model should cost so much. If I understand some of the other things you brought up, would I be able to take the Perfactory product and cast the shell in metal? Seeing how traction weight is a big drawback in N scale locomotives metal would be preferable to resin. I understand that some low melt alloys expand into the mold and capture a lot of detail.

By the way, I found a few companies that use Perfactory printers.
http://lightbeam3d.com
http://www.metropolitanworks.org

Lou,
I really like the Babyface. I think you caught the look perfectly.

GimpLizard,
The TSM models use faces rather than mesh. They appear as triangles. A rectangle, for instance, would be made up of four triangles. You can actually manipulate the points where the faces meet. Here is screen shot of the poly mode with all the "normals" showing...

The trouble is that the TSM format is proprietary and needs to be converted into something else to port it to other software. One of the Train-Sim fellows wrote a utility for 3D Canvas that converts the TSM fle into 3ds. I'd have to look to see what 3D Canvas can save it as. I should go the Best Cast site and see if they have a list of compatible formats.

P.S.
After I posted this I found a program called 3D Exploration that  converts .3ds files to .stl. Here's the .stl file of a Baldwin DR-4-4-15...

I looked at it closer. Although the shape was good enough for Train Simulator, it needs some work before it can make a decent model. Aside from the bad curves, the nose needs to be rounded and the big droppy eyes aren't big enough  ...

Frank

[robert3985]

Bob,
Wow...Lot of ideas here. I did realize that the $140 was for 4 units but did not think what that meant per unit. You are right, $35 a hit isn't bad. The Bowser N5 cabeese I buy normally retail for around $25 (I buy 'em cheaper when I can). I'm glad you explained the injection molding. I always wondered why a plastic model should cost so much. If I understand some of the other things you brought up, would I be able to take the Perfactory product and cast the shell in metal? Seeing how traction weight is a big drawback in N scale locomotives metal would be preferable to resin. I understand that some low melt alloys expand into the mold and capture a lot of detail.

Frank

Frank,

Yes, Perfactory machines will use a material that makes "hard, heat-resistant" masters specifically formulated for using as masters to make vulcanized rubber molds from.  Vulcanized rubber molds use heat a pressure to get the unvulcanized rubber to flow into all the nooks and crannies of the master, then the heat of the press makes the rubber go from slightly gummy to stablized but flexible.

These molds, if used for injecting molten wax into for the lost-wax casting process (investment casting) will last virtually forever if taken care of when not in use because molten wax is not very hot.

A body shell made of zinc alloy could also be made since the vulcanizing of the rubber molds for molten lead/zinc/zamac castings is essentially the same as what I described above, but the mold is circular and much larger than a mold made for injecting wax into.

I can foresee potential problems with the Perfactory hard masters however.  Much depends on how rigid they are, and I have no experience with them to develop an opinion one way or the other. Larger masters are always harder to work with than teeny small masters for detail parts.

I also do not know what the resolution of the hard-heat-resistant material is.  My assumption is because it is specifically formulated to create masters, that its resolution is excellent.

If you were planning on casting the body shell yourself using low-melt-temperature Bismuth alloys, you would not need to specify the hard-heat-resistant material, since you would not be creating a vulcanized rubber mold, but you'd be creating a well-supported RTV mold, so material resolution would not be a problem.

However, I would approach the Perfactory process not as an end-all to your model production, but one of three steps if you're going to create a fully functional kit or finished model. 

The other processes you will most likely need will be to etch either brass or stainless parts for fine and sturdy details such as grabs, vents, fans , then truck gear and wheel bearing surfaces and electrical pickups from a bronze alloy.   You'll need to cast the truck side frames and gear towers out of non-conductive resin, and perhaps other details such as windows, headlight lenses, numberboard interiors from water clear resin.  For the chassis and motor mount, you'll probably need to do that using a zinc alloy and contract it out using a spin-casting process.

Some parts you're just going to have to purchase, such as u-joints, gears, motors, bushings, wheels and axles and couplers.  You might also want to purchase such things as air hoses, horn, MU connections which are already being offered through several detail parts manufacturers.

I almost forgot.  If no decals are available, you should also offer a complete decal set for your model.

WHEW!!  That's a lot to think about, much less plan!

Good luck!!