IHC passenger cars

Just a note to let you guys know i have an ad in our yellow pages forum for some Amtrak IHC and Tyco passenger cars and some odds and ends to trade or sell. Curt

 

Don't need anymore at this time, but I was wondering if you knew of a good method of scratchbuilding diaphrams to join your passenger cars?

 

Scratch building diaphrams would be a great idea considering how expensive they are-unfortunately i've never run across any info on that. Perhaps a fresh question with that in the title would get some ideas. Curt

 

Justin, there were some articles on that years ago that were put out by the So-La-Goma Company. They had a method of using their liquid rubber that you painted onto a master form. It was toxic fumes, so probably not available today. You could probably use polyurethene today (even though that is also toxic) if you get the mix that is very low durometer, (like a toy baloon). Probably about 2 to 5 Du.

You shaped the form with the acordian pleate that best fits the shape needed, apply hard carnuba wax as a mold release, buff polish with cotton, then paint a very thin coating of the rubber mix, and let set to full cure. (You had to thin So-La-Golma) The polyurethane may run down, requiring some careful trimming along the bottom. Your form looked like a tooth brush, that you dipped, or painted, then stood it upright in a hole in a block of wood til set. (You cut around the bottom to get it off, by blowing into the bottom.)

The car was to be mounted so one end is up right, then a thin layer of glue was run along the "open" side of the diaphram and a hard paper "face-place" was to be glued onto that surface. The face-plates were part of the kit. (You could have a steelrule die made at a print shop to cut these with a block of hard maple and a hammer.) When that has set up, you were to apply a thin coat of glue to the car, and carefully lay the back (closed side) of the diaphram in place and allow to set up fully. After set up, you were to trim out the hole inside the face plate, (so the people could get from car to car), and the paper faceplate held the rubber in shape.

Then the practise was repeated on the other end of your car.

The problem was, they worked very well... on straight track, and around some large curves 30" radius or GREATER. The paper faces allowed the "slip" necessary to prevent derailing the cars. They were not intended to work on 18" radius track.

On older heavyweight cars, with the narrow diaphrams, any switch smaller than a number 8 would cause one diaphram to slide far enough to one side to catch on the facing diaphram, and derail the car as it straightened up on straight track. The full size diaphrams for streamlined cars worked a little better, but even they would sometimes catch of the inside of the facing diaphram, especially on "S" curves.

They looked great for shelf models, and unless the two diaphrams actually touched eachother, any gap left was very noticable. We were instructed to place two cars on our smallest radiused curve and measure the distance between the cars on both sides of the diaphram, then allow 1/64" more on each diaphram for overall free length including the faceplate. The acordian really had to work, see? I finally got one pair to work OK on a 28" radius (HO) by waxing the face plate, and leaving a couple of cross members at the top and bottom for the plates to slide against. You were to have NO burs on the sliding faces!

There were some "ready-mades" on the market that came with a paper face plate furnished. They were made like a baloon, dipped, then powdered with talcum powder to prevent self-sticking. You had to carefully trim off the sprue left on the bottom, or they wouldn't work at all. There was an aligning peg at the upper right and lower left of the faceplate, that was to match into a hole in the upper left and lower right of the facing car's diaphram. These were to works more like the real ones. They still had the same problems as the ones you made from scratch. Too much curve, and the acordians could not travel far enough, and the cars derailed. You must NOT paint them.

The rubber of either type had more than enough "spring" to hold them together. Sometimes it was hard to couple the two cars together because of this "springyness".

I haven't seen any of them since about 1948, but then, I haven't looked either.

[ 26 October 2001: Message edited by: watash ]</p>

 

Thanks for the info. I am not going to run these cars a lot now, because I have mostly 18" curves. I thought the diaphrams would be a fun scratchbuild. They don't have to be overly prototypical for me, so I will tinker with them and if something actually works I will let you all know...

 

Justin, I remember seeing one pair of diaphrams a guy at the club was tinkering with for 0 gauge. He folded pleats (I think it was 6 or 8) fairly deep to make the sides, then reverse folded pleats across the top. The paper was black and thin like "Bible" paper and was well creased. It was also glued to the car, but he had hand filed brass foil (about .0015") shim stock to make the face plates.

I suppose it could be done in HO and maybe even in N scale, but you would have to work like a jeweler in order to file the foil edges, then probably tumble the face plates to remove all sharp edges. (A jeweler sandwiches the foil between sheets of .06 aluminum to prevent the foil edges from bending from the file. Now days a mototool would do better than a file I think.)

Keep in mind that if you find it works, yet seems to take a "set" and does not stay "out" or extended, that you can use a couple of horse hairs for "springs".