So now the DT6-6-2000 is all drawn and the test print has been order it was time to think about the dummy version of the locomotive and how I was going to do it.  In this post I will share with you what I have decided to do.

Below is a rendering of the finished shell sat on the Atlas chassis along with the replacement truck side frames.

The dummy version of this locomotive needs to look exactly the same as the powered version as I intend to run them together, recreating Mark McDowell’s image in the link below.

http://www.rrpicturearchives.net/showPicture.aspx?id=219383

The first part to do was the trucks.  Having already created the side frames with all their details and parts for the powered DT6-6-2000, I was able to use the same details for the outer face of the dummy trucks. The inside face of the frames are relatively smooth as they don’t require details, just axle pockets for the wheel sets.  I added the side frames to a similar arrangement I had already used with my UP Water Tenders.  Being a typical draughtsman I don’t draw anything twice if I can hep it.  The trucks for the tenders have evenly spaced wheels so I offset the bolster pin, I did this so the center wheel didn’t need to be removed to install in the pin.  For the DT6-6-2000 I wanted to do the same thing but as the wheels are already unevenly spaced in the trucks this meant the pin could be moved closed to the center of the truck as shown Below.

The truck has been designed to take 3 Fox Vally 36″ metal wheel sets (FVM3611), there are no couplings because they will be body mounted on the shell.

The truck for the other end is exactly the same, just rotated by 180 degrees.  As with my other trucks these are only printable in the Frosted Ultra Detail material from Shapeways.  This is because of the level of detail and the thin sections that are only achievable in this material, the bolster pins are also printed in the FUD to complete the set.

For the chassis I decided to make it out of the White Strong & Flexible material as I did with my DDA40X dummy chassis.  Because the DT6-6-2000 has those large side plates that hang down over the fuel tanks and air cylinders there is very little, if any, of the chassis that will be seen once the dummy locomotive is assembled.  WS&F is ideal because it is lot cheaper than FUD, it can be printed in black and it doesn’t need to be soaked in a solution to remove the waxy residue left on the FUD parts.

Although it is not really visible I still like to add what detail I can to parts so I included the fuel tanks and air cylinders to the underside of the chassis.  As you can see from the image below the fuel tank is hollow which allows extra weight to be added.  This will be important as the majority of the locomotive will be 3D printed and it will be very light.  With out the extra weight the locomotive will have a tendency to ride up over the rails and come off the tracks, especially if between the powered locomotive and a heavy train whilst going around a tight curve.

The chassis looks a lot chunkier than the dummy chassis I produced for my DD35 dummy.  This is because the design requirement for WS&F are thicker than FUD, and it also shorter.  I added the lip around the top of the chassis as a structural element, as with the tie across the top of the up stands.  The bumps on the up stands match the dimples in the shell, but rather than move them down for the dummy I left them in the same location, that way the same shell will fit on either the Atlas chassis or my dummy chassis.  Pictured below are the finished trucks and chassis, they will fit inside the shell using the same fixings and lugs as the Atlas chassis uses.

And together the dummy and powered DT6-6-2000s should look something like this.

The dummy is in the front, without the fuel and air tank detail on the dummy chassis there would be a big void under the locomotive from this angle.

The test print for the shell is due to arrive this week so in next post I should have an actual model of the DT6-6-2000 to share with you.

Over the last few weeks I have been working on the 3D model for the Baldwin DT6-6-2000 center cab locomotive and it is now ready for a test print.  In this post I wanted to share with you some of the details I have included in this new model.

If you missed the first part of this model design you can find it here.  I finished the first part with the image below which showed an overall view of the shell at the then current stage.

Since then I have finished all the little details and fixed several of the issues that were not working.  The biggest issue was the size, or to be more precise, the length.  Although the 3D model has been accurately drawn, this shell has been designed to fit onto a powered chassis taken from an Atlas C-628 with the trucks rotated, as I illustrated in the first post.  The issue arose when the trucks were rotated they were not located in the same position as the DT6-6-2000’s trucks and they clashed with the bulkheads at either end.  To resolve this I have added 100mm at each end, which doesn’t sound a lot and in fact, in N scale, it works out to be an extra 1.25mm overall, but having tried to keep it as accurate as possible, suddenly adding 100mm made it look odd.  To hide this I dispersed the 100mm throughout the model by moving door sets up by 10mm etc and I don’t think you’ll be able to tell.  I also had to add about 60mm to the height because of the chassis being slightly taller but once again I don’t think it will be noticeable in N scale.

To make sure this would fit the power chassis snugly I also modeled it in along with all of its lumps, bumps and fixing points so these could be replicated in my 3D printed shell.  Below is an image showing the chassis fitted into the 3D model with half the shell removed.

I also modeled in the power chassis trucks without their side frames.  This is because I need to provide new side frames as the C-628 frames are not right for this model.  A fellow modeler has also produced side frames for this locomotive in cast resin and when this kit goes up for sale I will include a link to his website for anybody who would prefer to use those.

My truck side frames for this kit, pictured below, are designed to fit directly onto the power chassis trucks using the same fixing lugs.  The side frames also clamp the power pickup strips to the wheel tips so getting the size of the side frames right is very important; if they are loose the locomotive will have bad power pickup or even worse, will simply fall apart. If they are too tight the wheels may not turn easily and this will overstress the motor.

Another issue I ran into was that the C-628 trucks are not only taller but also have a lot more going on.  Consequently, when I put my frames over the power chassis trucks you can see way too much.  To resolve this I had to increase the height of the frames by 60mm and blank off some of the clear spaces. However, as pictured below, I don’t think they look too overworked, and on the plus side it adds strength to the print.

The other major detail I have added is the cab interior and engineer.  Just about all of the ready to run locomotives I have ever purchased don’t have engineers or crew in the cabs and given the capabilities of 3D printing it seems silly to leave them out.  The real DT6-6-2000 has a cab which stretches across the whole locomotive, and as there is an engine in each nose section, you can see through to the other side.  However with this model when you look into the cab from the side all you will be able to see is the C-628 metal chassis, so I have designed a cab section with a blanking wall that is a separate part.  As well as hiding the metal chassis this allows you to paint the inside of the cab and the engineer before fixing it into the shell.  I have provided a cab section with an engineer for both sides allowing either one of the engineers to be removed as required.

The cab and controls look a little basic but remember this is for an N scale locomotive and they will only be visible through the windows, a bit like the image below.

And if the cab was illuminated with a nice yellow light from above this would look great!

The windows have a recess on the inside of the cab to make it easy to fit a small rectangle of clear plastic as glazing; I will provide a template in the instructions for cutting these to the right size. I have also included details such as the air horns, body lifting brackets and steps on the shell as shown below.

Behind the headlights I have included a cutaway so after drilling through the headlight an LED can easily be pushed in from behind.

The handrails are all separate parts and I have added holes in the shell which match up to lugs in the handrails, which makes them easier to install.  If you want to make your own handrails out of a thinner material, such as brass wire, the holes are designed to be in the right places so they can be used as guides.

And here is the finished 3D model

The test print has now been ordered and in a later post I will show you how it came out.

A few months ago I was asked by a fellow modeller, through one of the model railroad forums, if I could draw and design a 3D printed shell for a Baldwin DT6-6-2000 Center Cab. So in this post I will show you what this locomotive is and how the design is coming along.

In 1946 the Baldwin Locomotive Works, who were already manufacturing small switching diesel locomotives, set about designing a locomotive with more power to be used as a transfer locomotive.  Its primary function would be to transfer rolling stock from one freight yard to another locally so it needed the power of a road locomotive but not the speed. It also needed to maintain the visibility and benefits of the smaller switching locomotives.  Baldwin’s answer was the DT6-6-2000 Center Cab.

Baldwin’s naming convention, DT6-6-2000, refers to several things: DT stands for “Diesel Transfer”, the first 6 refers to the number of axles, the second 6 refers to the number of axles powered by traction motors and the 2000 refers to the locomotives horsepower rating.

The locomotive, as the name suggests, has a centrally located cab allowing the engineer to see both ends which makes it easy to couple to rolling stock at either end. Road locomotives normally had a cab at one end with windows only facing forwards, they would either need to be turned at the end of the line or run in pairs with another road locomotive facing the other way.

Here is a link to a picture of Torna Railway No.51 out side the shops at Trona, California, November 7, 1970 courtesy of www.railpictures.net.

The DT-6-6-2000 is powered by two diesel engines, one for each three axle truck. The design was effectively two switching locomotives back to back sharing one cab.  The original prototype had a pair of 8 cylinder normally aspirated diesel engines (Type 608NA) but all the other production locomotives had a pair of 6 cylinder turbocharged diesel engines (Type 606SC).

Several railroads tried the locomotives and a total of 46 were made between 1946 and 1950, each with slight differences as the design improved. There is only one left now and it is preserved at the Illinois Railway Museum in Union, Illinois. The Elgin, Joliet and Eastern Railway purchased the most ordering 27 in total but for me I like the 6 ordered by the Atchison, Topeka and Santa Fe Railway mainly because of the fantastic black and white striped paint job, so for this model I am going to base it on AT&SF No.2601.

Here is a link to a great photo of 2601 at San Bernardino on the 18th April 1952

And another on the same day.

And again at San Bernardino on the 24th July, 1952

(The three links above are from http://www.snowcrest.net/photobob/ where you can buy prints of the photos)

As this is a locomotive that has never been mass produced in N scale before, not even in brass, there was no easy place to start.  The shell will be completely 3D printed so that is not a problem, but as to what power chassis to use we had to do some digging around.  The biggest problem with the power chassis is the trucks, unlike most other diesel locomotives the axles in the trucks are not evenly spaced.  The DT6-6-2000’s first axle is spaced further apart than the other two as you can see in the photo links above.  The answer came in the form of an Atlas model of an Alco C-628 as pictured below. ( The C-630 will also work as they have the same chassis).

The Atlas C-628 is a very good running model but the reason why this locomotive is perfect is because of the trucks as shown below.

On the C-628 they are the same as the DT-6-6-2000 in that they are not evenly spaced however they are facing the wrong way and the truck side frames are completely wrong for the DT-6-6-2000.  This is not an issue because the side frames are only cosmetic and pop off as shown below.

Also because of the way the trucks have been designed they can also be removed and re-installed backwards as shown below.

The chassis is now ready to be used for a DT-6-6-2000.  As the chassis is a bit shorter than the DT6-6-2000 I have designed the shell to fit onto it without any modifications, except for turning the trucks around.  The Atlas shell also has several areas designed to receive the lugs on the chassis so that it simply clips on and the DT6-6-2000 shell will be the same.  The couplings will be body mounted Micro-Trains.

The 3D model for the shell is almost finished and below is a screen shot showing the progress.

The interior of the cab and trucks still require modelling and there are some small details to be added around the shell.  The hand rails look very chunky because they are modelled at the smallest diameter that can currently be 3D printed however they will be printed as a separate part so wire rails can be hand made if required.

Hopefully I will get the model finished over the next few weeks and get a test print ordered.  In a later post we will look at fitting the shell to the chassis and finishing up the model.