Monday, July 11, 2016

Modeling Monday: Making Locomotive Passenger Car Buffers

Still working on the P1k RS-2 NHRR DERS-2b (click herehere and here for earlier related posts) and have just about finished adding the body details, so I've turned my attention to the pilot.

Building on their positive experience with dual-mode diesels during the war years (the 60 Alco DL-109s/DER-1s), the New Haven returned to Alco in late 1947 for its first roadswitchers - the RS-2 (class DERS-2b) - and made sure they too were equipped for passenger service. In fact, many of the NH-specific details that have to be added to RS-2 models have to do with adding passenger mode equipment.

But these details aren't limited to just adding a steam generator intake & exhaust stacks. One of the first things you notice about the pilot on the New Haven's version of the RS-2, is the presence of a passenger car diaphragm buffer.

Problem is, there's no detail part for this.

Well, there's this one:

Custom Finishing #306
and it's practically a drop-in for the Atlas RS-1 model. But it doesn't come anywhere close to fitting the Proto 1000 RS-2 model and, as a metal casting, isn't easily modified. So I figured I'd try making one out of styrene that would fit on top of a standard Kadee coupler box.

I started with a strip of .060x.118" for the main part of the buffer and HO scale 1x10 (.011x.112) for the sides. I quickly discovered that .060 wouldn't get me out past the end of the coupler box, so I added a strip of .060x.060 like this:

The buffers are .31" wide to allow the sides to clear the sides of the KD coupler box.
As you can see above, it's easier to use a long strip as a handle, gluing to both buffers at the same time (which I did on a piece of glass to make sure everything was flush). Then trim to fit.

Next, I added the sides as above. In addition to the perfectly-flat surface of the glass, I made sure the side was perfectly vertical by pressing it against a machinist's square as I added Tenax with a microbrush.

The above is the result. Repeat four times.

Once you're done, you have only to sand/file the corners of the main buffer itself and snip/cut the corners off the sides at an angle. This is what you'll have when you're done:

Now, unfortunately, I discovered that the buffer interfered with the coupler once I put it in. Ugh! Fortunately, fixing this was a simple matter of adding a .010" shim between the top of the coupler box and the frame/buffer, as below:

And - bonus! - doing so put the coupler at exactly the correct height (it had been ever-so-slightly high before. Um, about .010" high...)

The coupler still rubs on the buffer a little, but that'll be a simple matter of filing a little material away from the end of the buffer itself.

For an evening's work, I'm pretty pleased with how these scratchbuilt buffers came out, though I'm considering redoing the sides to .020 wide so they'll cover the entire side of the coupler box (and look even more like the prototype - a bit more bulky).

Speaking of the pilot, I plan to replace the molded-on coupler lift bars and grabs with wire. The lift bars are no problem (Detail Associates makes the right bar, but the brackets aren't correct - though I think I can live with that), but who makes these crazy grabs?

They're pretty common on the prototype, and very distinctive with those double bends. But I'll be dipped if I can find anybody that makes them. If you know of a source, please let me know. Otherwise, like the buffers, I may have to figure out how to make them myself.


  1. Kato still offers the handrail set for its older RS-2/RSC-2 model. $6 for a set which includes those pilot grabs. However, since they are a plastic part, they are not as fine as wire grabs. Given the other details you are adding, you may be better off just making them yourself, but I figured I'd pass it along.
    Really enjoy the blog. Best,
    Todd Hermann

    1. Thanks very much Todd! I didn't realize Kato was still making these available. Heh - if I'd figured that out sooner I may have been sorely tempted to just use one of those sets from the start! But you're right, at this point I might as well just create a jig and make my own. How hard can it be to just make 4 little grabs #temptingfate :) Thanks for your comment and for stopping by the blog - have a great weekend!