The Home Machinist!

One of the distinct features of the GS-4 and GS-5 class Northerns was the Mars warning signal light. This was the light mounted above the head light. Like the Okadee's, I would have loved to be able to buy one off the shelf and saved time on the build. There is one out there currently, but I was looking for more of an exact copy, so it was off to the drawing and research board. I found patent drawings of the type used on the GS, but no mechanical drawings. I had a general arangement drawing of the smoke box door, but very few dimensions. For those not familar with the Mars light, It is a mechanical light mechanism that creates a lazy figure eight pattern. This is achevied thru a gearbox with a 2 to 1 ratio creating up and down twice for each side to side movement. I found an incredible amount of information at the website posted below. The Mars light gets its name from the Mars candy company. Mr Frank Mars provided funding and the use of machine shop equipment in the development of the various lights designed by Jerry Kennelly. There were also pictures of the 4449 Mars light being converted back to a single large bulb and reflector on the freinds of the 4449 website. That is the version I chose to model rather than the twin sealed beam unit she has had for most of her life. The following picture and drawings was were I started. With that said, on with the build, and if I can figure out how to post video I will.

Vic


http://www.trainweb.org/gyra/

The first part I made was the main body of the light that everything would be mounted to. I was not trying to make an exact replica of the mechanism, but more wanted the light, reflector and outside appearance to be accurate and the movement of the light to be correct. The components were made one at a time and this caused some problems as I went along, but not to many parts had to be made twice. What worked on paper did not always translate to metal. I made drawings and then made running changes as I went. All the parts were made on the lathe and mill and are either brass or stainless. The main body was turned then drilled on the mill for the mounting holes and slotted for the hinge fingers that were fabricated. it was then silver soldered in a jig.

Main body cleaned and lathe work done on the inside. This is were the outer stationary reflector will slide in. The hinge fingers were then filed to shape to represent the stregthening web as seen in the last photo of the prototype. There are 17 seperate pieces in this assembly.

The lens door contains nine seperate pieces. I did not take any individual photos of this piece under construction. the ring was turned and shaped on the lathe. It was then drilled on the mill and the fastening holes were countersunk with an end mill to the first step in the ring. Turnings were then made on the lathe and silver soldered to the ring while being held to the ring with 1/72 bolts. The hinge fingers were made individualy and silver soldered to the o.d. this was done on the same jig used previously for the main body. Slots were milled into the jig to provide the spacing and keep everything square.

The gimbal was made next . Both axis were ball bearing mounted . This was probably not really necessary, but I thats what I wanted. I got some very small bearings from Ed Yungling that he had in his shop. The up/down axis is supported on .187 x.046 flanged bearings and the side to side movement is .250 x .125 flanged bearings. The linkage seen is 2/56 sized model airplane ball links made by DuBro. Again all parts were silver soldered. The parts are probably over built, but I wanted the mechanism to last and be reliable. I did not need a scale model of the mechanism, although I still had to fit it in a relativaly small space. Will post more soon.

Vic

Damned impressive work, Vic.

Wonderful treatise on prototype modeling.

Thanks,
Brian

makinsmoke wrote:Damned impressive work, Vic.

Wonderful treatise on prototype modeling.

Thanks,
Brian

Yeah, what he said. LOL

Chris

Vic, I have the video that you sent with the article and I'll post for you somehow this afternoon.

I can say I've seen the light in person and it is awesome. When Vic gave me the plans and article to publish I had to see it for myself. Glad you're posting it here too, Vic.

By the way, if you think the pictures of his work are doing the parts justice, then you are mistaken. I saw the hinges this past weekend and the use of the wire for letters he used just blew me away.

The outer reflector was made from aluminum the first time and polished. After talking with Ed Yungling he suggested use stainless. He had a piece and since I "always" listen to his advice, I remade the part. I then asked if he had a big ball bearing I could use to hammer the light reflector around to form it. I was then told it should really be a parabala to properly focus the light beam down the road, and this would make for better lighting. So it was off to the internet again to see how to design a parabolic curve for reflecting light. I drew it in CAD and Ed turned it on his CNC lathe. It was made out of 316 S/S. The inside was machined to almost a mirror finish. We roughed the outside and I took it home and finished it on my trusty 9x20 Enco.

The next parts made were the hinge pins for the door and the closing thumbscrews for the door. The thumbscrews are brass and threaded 1/72. They were fabricated on the lathe and mill.They were turned, threaded and shaped in the lathe, then held in a collet and slit to recieve the wing, then silver soldered. I final shaped with a file. The hinge pins were done in the same manner except they were made from stainless and are not threaded.

This group of pictures shows how I held the pieces while silver soldering and shaping. I drilled a hole in the fire brick to hold the shafts while heating. This also prevented any overheating and possible melting of the threads.

Here we have the pieces made so far assembled, but no gear train yet or light bulb The tube slips into the smoke box door with a light press fit and is secured with an allen cap screw inside and out of sight.

Vic