To paraphrase Vane Jones, "Knowledge is of little value until shared with others."

Sunday, February 1, 2015

Introducing a New CRT "Baldie" Model and Modeling Techniques

To paraphrase a well known TV sci-fi show, "To boldly go where no man has gone before . . ."; Chicagoan Terry Gaskin under the name "Chicago Traction Models" has produce a new kit for a Chicago Rapid Transit (CRT) "Baldie" 4000 to accompany the Q-Car 4000 "Plushie".

Ever since Q-Car produced the Plushie 4000 in the early 1970's, I have wanted a model of a Baldie. The Baldies operated alone or with other Baldies or Plushies. The new kit answers my desire.

What makes things more interesting Terry is making the kit out of 3-D printed parts. For the modeler this kit is a whole new realm of model making. We need to go through some of the behind the scenes of this new realm to understand what makes Terry's work more suited to the modeler.

Someone mentioned at a recent Trolley Evening, "3-D printing may very well be the new form of scratch building!" However, when one considers the number of hours required to make the 3-D drawings for a printer to be able to do the 3-D printing, printing only 1 model is a shame.

First, you do not get the kit from Terry. He spent many hours designing the 3-D drawings which are used to make the parts. The printing of the parts is done by a separate organization - Shapeways. You need to contact Terry at to be given the instructions on how to order the parts and construct the kit.

The instructions are long due to the need for you to be told how to pretreat (clean) some of the parts prior to construction. The actual construction is straight forward and Terry includes plenty of drawings and tips for constructing a great model.

I taught high school chemistry and have been interested in material science for some time. The material used in 3-D printing is not an epoxy therefore I'm calling the material plastic. 

From reading the Material Science Data Sheet (MSDS) obtained from Shapeways, the material used for the Baldie kit is a nylon. There are many different plastics and within the term plastics are different nylon plastics.

From recycling you may be aware not all plastics are the same. The different types of plastics have different physical and chemical properties. The solvent for one plastic will not dissolve another. This the reason styrene glue will not work with other plastics.

For now, if you are not aware of how 3-D printing works, the object (part) is made by building up multiple rows of material upon itself. Think if it as building a wall of bricks. Instead of individual bricks side by side for each layer, each layer in 3-D printing is one long brick. The wall is one long brick layered upon one long brick until the wall is made. No form of grout or cement is used between layers. the layers are fused together.

A difference in the position of the print head as it goes back and forth printing each layer causes a ribbed surface between the layers. It's this ribbing that needs to be sanded smooth by the modeler. The next post will explain more about 3-D printing.

To give the modeler the best model possible Terry chose to have the roof printed using one plastic while the sides and ends are printed from a different plastic. The material chosen for the roof is hard, durable, flexible, sandable, does not hold detail as well and is less expensive. The roof being a curved surface and due to the print process requires more sanding than other printable plastics to produce a smooth surface.

Other individuals have available through Shapeways 1/4" scale streetcar, commuter and interurban bodies available using the same material Terry chose for the roof. Although these bodies are one piece, modelers are finding them hard to finish. It's hard to sand them to a smooth surface for final priming and painting. Friends of mine know modelers who have these bodies and are unable to finish them.

From what I've been told Shapeways is unable to print entire O scale models using a more modeler friendly plastic material due to the size of the print job.

For the sides and ends of the Baldie kit Terry chose a different plastic to print these parts. This plastic is far easier to work with than the plastic used for the roof. The modeler has to do minor sanding to achieve a smooth surface and at the same time not loose the detail. To achieve the best possible printed parts, the balance of the body, excluding roof, was broken into parts.

The process to obtain a smooth surface by sanding is explained in Terry's instructions. The ends are 1 piece. The sides are composed of 5 pieces - the 2 end doors, 1 middle door, and 2 panels of windows between the doors. One benefit of the 5 part side is the individual parts are easier to sand and protect the detail. If you have looked at photos of the CRT/CTA 4000's you will realize part of the gestalt of the 4000's are the multiple rows of rivets. It's these rivets the modeler wants to maintain.

At the same time the multiple piece side and separate ends, allows for all the variations found in the Baldies. The CRT/CTA 4000 may have been the series of cars these 2 companies, CRT and CTA, built and rebuilt the most of all their cars.

A month ago, Bruce Moffat tallied up about 2 dozen varieties of changes to the Baldie bodies before the entire series was retired. By now, his tally may be up to 3 or 4 dozen changes.

It seems like the CRT did just enough modifications to keep the cars current with operating conditions. Under CTA ownership the 4000 underwent the most number of "rebuildings" to make the cars ever more interesting.

The CTA's "L" cars can be broken down into 4 broad groups - the woods, the steel 4000's, the "spam-cans" (6000's), and everything afterward!

Terry initially decided to build the Baldie from the 1940's to match the Q-Car 4000. He now has additional parts to make the original cars plus the cars with as many of the window and end variations as possible. With the 5 part side it will be easy to make a model with square windows in the side, doors with the oval, rubber gasket windows, and ends with Christmas tree route/marker lights - or - you name it! There are so many variations it's impossible to list them all here.

To assist the builder of his kits, Terry will have both exterior and interior parts available.

In the next post more info on the 3-D printing process will be given. The post after the next will be the start of building my Baldie from Terry's kit. The building process will take the Baldie up to the same point of finishing as my Q-Car Plushie from prior post. From there the 2 models will be finished together.

When finished, my 2 models will be operated as a 2-car 1940's CRT "Evanston Express via Subway" which originated from either Kenwood or Jackson Park. I have to check! Interesting? Yes? No?


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