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BM70KA update


Chuck Heuer
 

74 drill points for 28 grabs later...I,m happy that I'm only doing 1 car, not a fleet!

Following the general order of the instructions and other narratives I have read about building these kits, while taking breaks from the drill, I worked on fitting the ends to the roof. This took a not insignificant amount of filing, increasingly toward the outside of the top curve on the ends as the curvature of the clerestory roof was noticeably tighter than that on the ends. This wasn't too bad as the curve is a simple radius, nothing complex. But what the instructions don't tell you is that after doing this you end up with an end piece that is markedly too short for the sides, .06" in my case. So out came the instrumentation for some careful measurements. The height of the sides checks out as prototypically correct, and reducing their height would not really be practical even if they were wrong. The kit instructions would have one attach the ends to the roof after shaping without further consideration. This is a plastic/plastic bond and the roof + ends assembly is the primary structure of the body assembly. The result of building this kit per the instructions is evident (now that I see the issues) in Steve Hoxie's rendition, pictures of which he kindly shared with us at the very beginning of this project. 

To address this situation I pre-formed (using a scrap length of 4"  gas dryer vent pipe as a form + heat gun) some .06 x .20 styrene strip to laminate to the top of each end. I will need to tweak the resulting curvature for fit as well as sculpt the form to blend properly to the roof. I am thinking that I will probably assemble the ends to the roof before painting as this alignment is critical and I would rather not be stressing about the paint while focusing on how to best control accurate, square joints. This will allow me to finish shaping the roof-end joints as an assemby and also allow me to be able to measure the resulting distance between the ends and accurately trim the brass side length as necessary to fit the assembly before painting and decaling the sides. I am estimating that I am going to be removing about 1/32" from each end of each side. The length of the spliced roof in the kit is the controlling dimension here. All interesting challenges to solve!

As far as the interior goes, while I do intend to provide some interior detail I am not making any decisions on this until the car body shell is complete and I can evaluate what will actually be visible thru the windows and I also decide whether I am going the provide lighting in the RPO apartment (probably, and I'm using Walthers trucks which certainly facilitate this). But I decided to stop even thinking about it until further along.




Chuck Heuer
 

I have made some progress on the sides of my BM70KA. It took some time to work out the stirrup steps to my satisfaction. There are only 2 pictures I am aware of showing this class car with single outside body bearings trucks - and since I'm planning to use the Walthers "RPO" trucks that have this configuration I have been paying very close attention to these pictures. (I actually suspect both photos may be of the same car based on their proximity in both time and place (1951-53 in New Jersey) although neither picture reveals nor has noted a car #.) The 2 pictures do give me both sides of the car, but both show only the mail end.

Because of the offset location of the mail doors relative to the step the PRR applied to the truck below them on this class with this style truck, this original configuration was modified to have a single wide step under the mail door running the full width of the door. I found an cast brass step that could be modified to meet the requirement (PSC # 33303 ), however that created a real visual discrepancy with the delicate and very flat etched steps integral to the brass sides of the kit in the other 8 locations. I also had a concern that the etched steps at the ends were both not really done in a prototypical way and were going to further be an issue when they lost one point of attachment when the sides get trimmed in length to fit the roof (as described in my prior post); as well as a concern about the ability of those unsupported, paper thin etched steps to survive any kind of actual operations.. After some more research I found that I could fabricate suitable cast steps from PSC # 33145 steps, with some careful work with a jeweler's saw and files. As cast, these are the correct width and have about the correct spacing to the middle step although the appearance of that middle step was wrong. All these steps were thinned to .04" thickness which I aligned with styrene of the same thickness to create the inset for all the doors. This is double what the kit instructions suggest for door recess but still slightly less than the Walthers B60B and BM70M/N models. All the brass steps so far were soldered to the sides. The end steps, along with  the doors and grabs, will be added after the sides are trimmed to length. I'm not sure yet if I will try to solder the end steps before painting the sides or wait until after paint and body assembly, in which case glue will be required for attachment.

Next up is finishing detailing the ends and roof, gluing these up and then doing some body work at the roof end seams - leading then to trimming the length of the sides to fit. After fit is finalized, the sides will be painted before attachment to the separately painted roof/ends assembly.

Chuck