My roundhouse has a machine shop attached to one side and I'm slowly populating it with an overhead belt drive system and machinery. When I built the drop pit for the roundhouse I knew I wanted to have a locomotive driver wheel lathe in the shop to complete the narrative but there aren't any models available on the market. My Anycubic Photon resin printer is the answer but the lathe design is going to be pretty complex.
I spent several days in TinkerCAD working on the face plates. The two work stands and the gear and belt drives will take some time too.
Because my layout is On30, 1:48 scale, the drivers on my two larger locomotives, 2-8-0 Consolidations, are only 48" in diameter. The drawing that I'm working with is of a 66" lathe and that seemed just about right figuring the shop would have felt that would accommodate any new locomotives for quite a while. So the photo at the top of the page here is pretty much what I'm trying to build.
The drawing I'm working from is from the East Broad Top RR book about their shops.The only known dimensions I had to work with are the 48" drivers and the 66" face plates so I drew those with the CAD program and worked out everything from there purely by looks. The first thing I printed out was a face plate, mostly as an experiment, just to see how it came out. When I stood the 5'10" shop foreman next to it I realized I needed the face plates to be larger for visual impact. I Googled the Lathe manufacturer and found a book they had printed in 1917 to show their product line. They had several different sizes of lathes and I chose 88". As I worked out the design in TinkerCAD and started printing parts I again changed the face plate size and ended up with 82". That's my final answer. This was all driven by how it would look overall. I changed the face plate size but not the dimensions of anything else and it worked out pretty well.
These lathes had several interesting features and I tried to include several of those details. Instead of using a crane to lift the wheel set onto the lathe centers they built an I beam that fit into slots on the face plates. A chain with hooks at each end was hung from an eye on the beam. The hooks were attached to the wheels and the face plates were rotated to lift and center them. Pretty slick. They also had a plate on the backside of one of the face plates that had hills and valleys along it's rim. A small wheel and lever rode along the rim creating a rocking motion as the lathe turned. The lever was connected to rockers on an overhead shaft which were, in turn, connected to a lever on each work station. As the lathe turned the rocking motion caused the cutting bit to advance across the surface to be cut. An automatic feed. That too was pretty slick.
With the design completed I printed out my parts in groups. The housings and end frames were printed with the centers and hand wheels but the face plates were printed separately. The two work stations were printed with their rack plates attached. Each gear was printed out individually. About 15 parts altogether. The picture below shows the work stations as they came out of the printer. Very little cleanup was necessary once the base and supports were removed.
I used 3 different sizes of brass rod for the various shafts on the lathe and again this was decided strictly by looks. The gears were printed with the correct size holes for their shaft and the final print was so clean they only needed a slight cleaning out with a drill bit.
Before final assembly I'll complete the painting and most of the weathering. At this point I've airbrushed everything with a coat of water based Acrylic grey. Gear teeth will be painted "steel". Tracks for the workstations will be grimy bronze. Bolts will be black. I used a "metal silver" Sharpie for the face plates, hand wheels and levers. Here's a shot of what I have so far. The streaks on the face plates will hopefully be hidden by oil stain type weathering. More to come.
Update 7/28/2022 -
It took me a while to figure out how to add aging to this model. I had seen the prototype for it at the East Broad Top RR shops in Pennsylvania. The belt driven lathe was built in the 1880’s and used continuously into the 1950’s. It then sat unused for 70 years. The faceplates and exposed metal surfaces have a beautiful patina most likely caused by surface rust and carbonized oil.
My model represents a lathe that’s been in constant use for about 30 or 40 years, in 1927. I wanted a look somewhere between shiny new and decrepit old. I added “grimy black” to the gear teeth and bearings to represent grease and smeared some on the floor to represent splatter from the gear teeth. For the dirt and grime on the floor of the lathe I used black and brown chalk dust mixed with water and applied in puddles, smeared around and left to dry. I used “metal” magic marker, chrome on the faceplates and a combination of brass and gold on the guides and drive cogs. To get a patina on the faceplates I used orange, dark red, tan, brown and black chalk dust, each applied with water. I lightly rubbed the surface with a dry paper towel to blend the colors, added more color where needed and then sealed with satin clear spray paint.
