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REPRODUCING A RARITY: THE DORFAN 419 SIGNAL BRIDGE

By Bill Scandariato, TCA 87-26317

An original Dorfan No. 419 Signal Bridge

I am quite fond of standard gauge trains and accessories, especially signals. That is why I was overjoyed to see a Dorfan #419 (circa 1930) for sale on Ebay during November 2006. I just had to have that signal bridge. Unfortunately maybe partly due to fate, timing and some very big pockets on the winning bidder, my bid did not win, nor did several other contenders.

Immediately after the crushing blow of knowing that signal bridge would not be mine, I decided I would still have one, even if I had to build one myself. When your back is to the wall, the only way to go is up. Without an original available, reverse engineering was not an option. I am not a machinist nor do I know how to do any foundry work or how to use a lathe, but I have a good eye for details and clues as to the construction of things and I am fairly good in math which plays a vital role in a reproduction of this undertaking.

Planning stage sketch

The major problem with this project is that there are simply no replacement parts available, and very little opportunity for obtaining a sample to reproduce them. Well, that is only partially true. There is one part of this signal bridge that has been reproduced not as a replacement part, but as a vital part in a reproduction item. I am speaking of the legs used on the excellent remake of the Dorfan crane made by T-Reproductions in 2002.

Dorfan crane reproduction - note legs

Crane leg castings

Dorfan No. 421 - need that post!

It became readily apparent upon looking at the photos of the signal bridge, that the two horizontal girders on its upper portion are the same as the legs on the crane. It was a very common practice by a given manufacturer of the era to use parts that were shared by different trains and accessories. The four red upright supports with the raised girder details, are another example parts found on other Dorfan accessories, namely the posts used on crossing signals, signs, bells and telegraph poles.

Four cast repros of post

What follows then is that this accessory is 14 inches wide (the same as the length of the crane legs). Very fortunate for myself was the fact that the seller of the signal bridge took very many large and high resolution pictures. Using the photos to establish and very carefully measure scale lengths and widths and comparing these values proportionately to the actual known length of the 14 inch girder, yielded fairly accurate actual measurements of the major parts.

Planning stage sketch with dimensions

The next step that followed was locating suppliers of brass plate, brass rods, machine shops willing to do a small run of turnings (for the brass handrail stanchions) and to make the two bases. I would also need mold making supplies to copy the signal heads, a small foundry to do castings of the posts and girders from sample parts, a laser cutter to make the ladders from hand drawn or CAD artwork, and a toy train parts supplier for bulbs, sockets, screws, nuts etc. In addition, I had to quickly learn 2 part mold making and casting myself to move forward with the project.

The parts that were the most difficult to reproduce were the two green bases and the signal heads. The bases were probably unique to this accessory only. I decided to build a base that was similar, but much more structurally sound for support.

The #419 used position light signal heads that were also used on the Dorfan #417 block signal, an accessory that is almost as hard to locate as the signal bridge itself.

The 2 part signal head (consisting of the faceplate with visors and bulb openings, and the back/interior containing the bulb sockets), is the most complex part of the signal bridge. The visors would have been very difficult to fabricate from ‘scratch’, and the diameter of the bulb openings, though not critical, was obscured by the bulbs themselves in the photos. Fortunately, a #417 was located and I used it to mold and cast reproduction signal faceplates in a thick plastic compound which retained even subtle characteristics of the original metal cast surface.

Successful molds

Signal faceplate reproduced

The backplate was fabricated to be functional, not an exact copy, using the faceplate’s interior as a ‘mold’. This compromise had to be made for the back / interior of the signal heads because of damage that would occur to the original from removing rivets and the extremely high cost of machine work that would have been incurred to fabricate it in metal . An exact plastic copy was not an option because the resulting threaded bulb sockets would not provide ground.

Bulb sockets with ground wiring

Bulb sockets installed in molded backplate

Rear view of signal head backplate

Signal head backplate (internal view), and painted trimmed faceplate

Complete signal heads with signal head posts attached

It was fun to see the curiosity, amazement and enthusiasm of the machinists who helped on this project with the brass turnings, signal head support columns and the two bases.

completed brass turned stanchions for railings (threaded in bottom)

Laser cut brass ladders

Initially when I brought in the photos to show them the brass stanchions I needed made, the foreman of the machine shop noticed the signal heads in the photos and came up with suggestions of how to make a mock up to cast, or to fabricate an actual machined part of them even before I was thinking about that next task.

Sample of some painted major parts

If the owner and foreman thought they were impressed by the quality parts and construction of the signal bridge (and Dorfan history I gave them), they were about to be blown away by the complexity and craftsmanship of the Dorfan crane that I presented to them.

 

completed platform with railings, stanchions, girders and signal heads

Well, it was a long project (just under 2 years), with many mistakes requiring going back to ‘square one’, as well as many unanticipated delays but it was well worth it. It’s not perfect but it’s close and I can live with that. I would love to reproduce the accessory for sale, but it is simply too cost prohibitive, and too time consuming to do so.

The finished product

Hopefully MTH will make one of these magnificent signal bridges to compliment their small, but hopefully growing line of Dorfan trains that they have made thus far. If not and your back is against the wall, you can always consider doing it yourself.

Clear track ahead!

SPECIAL THANKS :
Pace Tool & Machine – brass stanchion turnings, machined bases, threaded signal head support columns as well as advice & suggestions – thanks Bruce

Restoration Train Parts – quality castings of girders and four upright posts – thanks Chris

A & J Sheet Metal - fabrication of the 2 gussets in aluminum – thanks James

McMaster-Carr –brass rods for stanchions, railings

On Line Metals – custom cut brass plate for deck, 1/2" brass rod for signal head supports

‘decobill’ –Ebay seller for permission to use picture of his original #419 which was the inspiration for this project – thanks Bill

Smooth-On –mold making & casting supplies

Lasertech –laser cut ladders – thanks Roman

OTTP –Olsen’s Toy Train Parts supplied bulbs, sockets, bulb contacts, screws, nuts – thanks Sal

Chuck Brasher –thanks for verifying length and width of bases

Misc. – Radio Shack – wire, knife switches, solder ; Home Depot– drill bits, spade bit, formica scrap & screws to build mold box; Michael’s – modeling clay for mold box prep. ; NAPA – paint; Ace Hardware - primer; Arianne – thanks to my lovely daughter for putting up with me during times when
nothing was going right !

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