D&RGW RPO #66
Lets start this with pictures of others work. Give us all an idea of where I'm heading. First is a few pictures of Accucraft's version.
A friend has an On3 model which I took a couple pictures of the underbody.
Still doing some research about the underbody. The On3 car is far more detailed than the Accucraft model. If I can verify this bracing, it will be on the kit.
I found a vender that sells a tape sort of decal with different hole patterns for rivet detail. The tape is applied and white glue like the Tit-Bond II wood glue is applied over the holes. Wait a few minutes and carefully remove the tape leaving behind a perfect rivet pattern of glue drops. Let it dry and you have 3 dimensional rivets. I watched a video (which I can no longer find) of the process and really like it. A company called Wow Planes sells it but their website had stated "due to a family illness, the site would be closed to sales". Today it appears gone. Hope it comes back or someone takes over the product line. I know there are some O scale raised decal rivets and have seen them applied to a large scale tender. In my opinion, they're a bit to small for the steel plates on the bottom sides of the car. Here's picture of the tape method.
This tape is made by Cal-Grafx. Can't find a source for it either.
After studying pictures and information about the lower plate along the bottom sides of the car, it was added to give lower weight as the car was top heavy. Help to keep the car from tipping over. It was held to the car body with round head slotted screws. From any distance, they appear to be rivets. I'm now thinking that O scale or even HO scale decal rivets from Archer might fit the requirements. The screws are spaced 4" apart. It's going to be a tradeoff between smaller rivets spaced to close or larger rivets with spacing closer to what is desired. If anyone has used them and can provide measurements, I'll share that info with everyone.
I've been working on the parts requiring 3D drawings to be cast in brass at Shapeways. Also the rood end and car ends which will be printed in versatile plastic. That's the same plastic I had the short passenger car roof ends printed in. From there, I make silicon molds and cast them in polyester resin. So, here's a few pictures of my work so far.
The roof end. Like the short passenger cars, this will be attached to the main roof once built.
The car end. Kind of hard to see the scribing and rail in the left picture. Right picture shows it off a little better.
6 different angles of how the end will go together. These are just individual 3D images I pieced together to get an overall rendering. The end beam will be wood. The lock pawl, brake wheel and "L" brackets at the base of the rail will be white metal. Only the roof end and end wall will be resin.
Next set of pictures is the needle beams with primary queen post and auxiliary queen post. I drew up the sills and needle beams along with truss rods to get an idea of how it's going to look.
So, this should give you an idea of truss rods and queen post. All the queen post will be white metal with the 1/16" aluminum rood for truss rods. Way easier to bend than brass or stainless.
And what would the side of the car be without the mail slot?
The actual mail slot on the car has raised lettering "LETTER BOX". There are several limitations for lost wax casting with Shapeways. Minimum width and height as well as spacing between letters. All I could get in the space was LETTER. This will be white metal measuring 1/2" tall and .7" wide. Both sides. You can see it in these pictures.
Right below the M in MAIL
Below the T in UNITED
Again below the T
Below the M in MAIL
So that's where the kit development is for today. Hope my work is satisfactory. 4-24-2020
I just received 3 of the masters needed for silicon molds. The car end, the roof end and the corner rounds that fit either side of the baggage and postal doors. First up is the car end. It pure white and taking pictures of white is difficult at best. Nothing for the auto focus to lock onto. Plus the detail is a tad washed out.
As I said, a little hard to see the rail clearly. The smooth bottom edge is where the wood end beams will glue.
I'm hoping I didn't make the rail web to thin. The resin is water thin when first mixed and should flow into the rail web and rail head. Guess I'll find out!
Here's the roof end. Side to side is 5".
Side profile.
Roof end and car end together.
Looks weird right? This is 4 parts stemmed together to cut down printing cost. Either side of the baggage door and postal door is quarter round with steel plate for protection to the wood. Beings it's a custom size, I felt doing them in resin would be easier/cheaper than trying to find a custom size wood quarter round. You can see that the lower third has the added thickness simulating the plate.
End view of piece. I need to cut the stems and sand smooth to create 4 identical parts. The kit will use 8 of these. 2 per door opening.
That's it for this update. All the brass parts for making white metal spin casting molds are in limbo land. More to come. 5-12-2020
6-9-2020 Update
The steps below the baggage and postal doors are rather unique in that they curve out from beneath the sills they are mounted to. This is because the outer queen post are mounted on the needle beam right above the outer sills verses set inside a little. The truss rods block the step legs from dropping vertically from the sill. Here's a picture that captures how the steps curve out.
I have no way to cut brass bar to this shape but I do have access to metal laser cutters that can. So I drew up 2D CAD and uploaded it for cutting.
And, 10 days later received this.
2 lengths. One for the baggage door and one for the postal. Then bent a couple up to test.
I added 4 of them to my short RPO from the previous limited run.
My coffee cup sure finds it's way into many of my pictures!!
That's it for now. The frame jig should be here in the next week so I can start on a prototype of the kit. Stay tooned. Phil