Large Scale Central

D&RGW C-18 Build from Bachmann C-19

Today I officially crossed the point of no return with this build. I modified the levers that move the valve rods in and out and connect to the valve gear.

the existing part looks like an after though as it is a solid piece with a reduced diameter on the end and a flat to engage the other lever.

it was fastened to the frame by a u shaped piece with one screw to hold it all in place. given the mods I am about to make to the frame,

accommodating these pieces as is didn’t work. so I found some brass rod of .114 dia. and flied the flat on one end to accommodate the mating flat on the lever.

I then chucked up the round end of these pieces and drilled out .116 dia. for the new shaft.

then using the Dremel cut off wheel cut as close to the lever as possible and cleaned up with a file.

I then silver soldered to the brass shaft, making sure I had the correct alignment. when all was done I assembled several pieces of the Bachmann engine onto my proof of principal frames.

these greenish blue pieces shown in the photo, are the replacement frame sections that will eventually be either 3d printed in metal or CNC milled.

jury is still out on this while I awaite the next batch of parts from Shapeways. those results will be reported in the technical modeling thread on 3d printing metal

this week I plan to start milling out the frame to accept these pieces. also of note is the new positions for driver brakes and the tumbler shaft.

while the photo dosn’t look like much it proved out the new locations for parts being reused. end mills just to keep parts somewhat in position.

Al P.

This is going to be a cool conversion/build. About three levels above my pay grade, but fun to watch!

Looks awesome!


Todays update:

in preparation for machining the existing frame, I built a model of the portion I am going to be modifying, so that I can create a drawing to work from.

measuring the Bachmann frame can be tricky so this was another good exercise.

I will work from the rear of the plate forward, as the end of the plate represents the center of axle #3, which I can measure off of in the mill.

you can see that besides cleaning off most of the top deck flat I have various holes to drill to accept the new frame pieces, and slots to clear the repositioned brake rigging (red)

there is only one place that is a little sketchy, and that is the cutout for driver #2 spring tower, cuts into a no longer used taped hole.

I also designed up an adaptor for the crosshead support in the process.


Been a few days of ups and downs, but I have got a few things to report here.

first up, the model I chose to do this build was the undecorated version, with the red cab windows (more on them later)

the reason this was chosen was because it was the only model offered that had both a round Steam dome and Sand dome, which was essential to the build.

at the time I bought this model I had not even thought of a 3d printer, as I was unhappy with the results from the first FDM machine I had tried.

fast forward to today, I have an SLA printer on my desktop. although I do not need one myself I decide to model and print one up.

original on the left, new one assembled on the right. if there is any interest send me a PM. it will cost more to ship than the cost of the print.


on Tuesday I made a trip to my laser cutter for another project that I am involved with, which also is my machine shop access.

of course I left the primary part I wanted to work on sitting on my Kitchen stove. I did have a couple of other pieces to work on.


I worked on the firebox some and it is still a work in progress. the existing firebox was much longer than needed, and was a visual spotting feature that I became aware of.

in the above picture is the first draft of a piece to fill the offending hole, 3d printed of course. I am still working on what I will do to the sides of the firebox, but they will have

rivets and staybolts like the end of the firebox. I also added some washout plugs. (note the existing sides of the firebox basically only represent rivets)

Yesterday I went back to the machine shop and cleared out the frame, and yes it is fragile.


Note that I removed most of the boiler support here as well. I left the post because it is integral in the locomotive reassembly process.


it is not completely parallel in the machined area, in part due to the fact that this is a die casting, and is only off .03 from front to back. side to side is consistent.

very shim able if needed.


Last up today I have approximately positioned the 3d print of the fireman’s side frame in the approximate position.

I can now proceed to finalize the 3d models and send of for metal printing.

this step was necessary to determine the final heights of the replacement frame members.

I expect additional “metal” parts from shapeways this coming week so the next report will be in the metal thread.


Al, Just which C-18 are you basing your build on? and what year?


I am leaning towards 315 at this point, and 1940 time frame as the 315 visited the Rio Grande Southern then. when I got started on this several years ago I was able to do some parts swapping to get the right running boards on the engineers side. the stock model I chose as a starting point had the rounded domes, but the engineers side running board was the straight one that would be more correct for 318. I had to cut the running board into two pieces as it is one big injected molded piece, and glue back together. picture of this coming soon. one could also do 319 in a similar manner to 315. I feel that 315 overall is the closest match.

Al P.

Very cool!


Al, When we restored 315 back to operational the target date was 1940, Just before the Rio Grande changed from the Toilet Seat hearld to the “Flying Grande”. So all the on line photos you see from the past 15 years of excursions are correct for that time period. From 1917, when she was purchased from the defunk F&CC she was lettered as the 425, And classified as a “Class 72” Locomotive, She had a different headlight, only one compressor, and no main air tank on the engineers side, Until 1923 When she was shopped into what she is now, and re-numbered 315.

She spent several occasions on lease to the RGS. In 1928 she was running the scheduled passenger service from Durango to Rico.


I have the Bible (the big book on 315) so I know the history. I also have a new friend who is at ground zero (Chama) and checking a couple of things for me this week.

one thing my research has show is that this and others of this class only have one blow down valve at the mud ring on the firemans side. Engines I have worked in the past usually had one on each side.


I was going to suggest the “Big Book”. All the graphics, and all the photos I edited, sized and corrected… George and I spent a ton of time figuring it all out.

Yup just one blowdown, It’s located about 1/2 way back of the mud ring. The pull ring comes straight up thru the floor right next to the boiler.

Who’s the new Chama connection?

Dave, see my P.M.

Al P.

Today starts a new direction on the frame pieces. I had looked at 3d printing in metal, but shrinkage of long parts is unpredictable.

I considered CNC milling from solid, but my friend who’s mill I use suggested another way. have the pieces cut out with a laser. I initially

uploaded a file with the intent of having cut out of a solid piece of 3/8 aluminum plate. soon I had a message from the vendor, that features were to thin to

cut out of this thickness of plate, vendor indicated no problem on thinner materials so I investigated using 1/8 brass and silver soldering three pieces together.

this would have been about $75.00 for six pieces. as I looked at my design I realized I could simplify even more. the result below.


the two white pieces are 1/16 brass plate , along with two 1/8 thick pieces that will get silver soldered together

These pieces will run around $50.00 delivered. I then looked at the machining that would be needed after the pieces were silver soldered.


the red brake shoe mounts and the green pivot will get added to the stack after some preliminary machining.

these pieces will form the left and right frames depending on how they are soldered up. and eliminate a lot of machining.


the vendor link below:

Al P.

Very nice. Should someone not want to solder, there are very good structural adhesives available that will create a strong bond of metal to metal parts. They work best if the parts to be bonded are roughed up a bit with sandpaper. I have several I use at work.

Quick update today. my frame pieces arrived! this process started on Tuesday Jan 19th, and was delivered by FedEx on Friday afternoon, Jan 22nd. talk about fast service.


I am working with a friend to formulate how we will jig this up for machining in some part on all four sides.

this may take a couple of weeks to get the final result, so stay tuned.

Al P.