Chama Ash Pit

These two photographs [As always, if you click on the photograph you can get a high resolution version] show the prototype Chama ash pit, with and without a locomotive for scale.  The pit is fairly simple, and I did also print an air tank to go uphill of the ashpit for clean out.  The facility is very straightforward to model, and though I think I will add some entrance transitions for rails with ties, it printed perfectly the first time.  Note that I have no idea what the ladder-like contraption was used for that is seen in the bottom photo of pg 86 of the Quick Pic Book Steam Service Facilities D&RGW at Chama, NM Book 1 and whether it was used with the pit, or when it was installed].

Chama Sandhouse

I did get a final version printed of the sandhouse, but now I'm getting the bug for more realism for the log supports. I can vary the log diameters, and perhaps create things that look like branch stubs.  So rather than assemble it, I am waiting to for time to work on that and see if it helps.  I should be able to creating fissures with an hobby knife.

Chama Coal Tower - Coaling Bin

The second prototype came out really well.  I was thrilled with the quality of coal gratings that didn't pass Shapeways guidelines, but they still allowed me to print anyway.  Everything came out great.  However, due to bending of the long timber that supports the coal bin door pulleys, I am going to redo this and add a few detail items.  That will require me to print out in FUD, which is more expensive, but that is better than the assembly issues you can see if you look closely at the photos.  The coal bin doors came out great (ignore the bad paint job) with the exception of the individual wood slats.  I have been using various techniques to show gaps between boards, and in most cases they work out great, but it depends on the print angle.  In this case I will have to redo the gap simulator (currently 0.004" square cut-out, I think it needs to be 0.006").  I have been trying to decide how to color the acrylic so that it looks like concrete.  I like the white flexible which has a nice sandy finish just like concrete, but with the details it will go to FUD which can sometimes be smooth as glass.  I have some "aged concrete" Floquil that I painted a sample and let dry, I will look at it tomorrow.

Chama Coal Tower and Base House

Finally, I have a prototype of the Coal Tower and Base House - this took many dozens of hours to generate.  Before anyone nit-picks, there are at least two dozen things that I have to change and fix. 

In general, they printed out well.  Some interesting printing issues:  If you look at the house, the clapboard siding is not as pronounced as I would like (and this was done very early so it will take a lot of time to fix...) and oddly enough, even though it prints out fine around the window blanks (the house windows are a dead even fit for Grandt Line windows, so that is what will go there) but when I did door detail, or the stovepipe detail, the clapboard lines above those doors are wavy and you can clearly see something disrupted the normal 3D printing pattern.  I have no idea why it did that.

The tower itself has a lot sanding that needs to be done, most in hard to reach places (the ladders are notably messy - which is odd because when printed out separately they came out great, but I can't easily insert them after the fact... the tower overall is not nearly as clean as most of my prints.  That may be due to the complexity.  For example, the print completely lost the board detail for the coal storage bin, which is the same as I used in the sandhouse bin sides, so that is very odd.  But on the good side the coal cars came out great (another case of the accessory print going very well).  There were some tower details that didn't print well - I need to find some gears (could use brake wheels) for the chute mechanism.  I actually printed a gear separately and it came out great, but the one that I printed in place was a total loss so I shaved it off.  I also have to beef up the roof over the chute - it printed out too wavy to be of much use.  Also odd, I printed the sheaves at the base and in the tower top, the ones up top printed perfectly, except for the drive shaft, so they were loose and fell out!  The bottom ones printed out fine, but I need to rethink how to assemble them - I can't accurately place them after the fact.  I have a few options, need to think that one through.


That's all for now.  It will take a while to adjust these and print final versions.  As always, comments and questions are welcome.

Progress On Chama Engine Facilities

Chama Sandhouse

In parallel to the engine building, I have been working on an N scale version of the Chama Sandhouse for the last 9 months.   One of the reasons the project dragged out was that I decided to change CAD programs and had to learn Autodesk123D (freeware).  It has no manual (that I can find), but there are multiple videos on the net that cover the basics.  In the long run, there are also companion CAD programs that promise to do some pretty amazing things like create 3D drawings from photographs, etc.  In any event, I like the new program but it takes a lot of time to figure out how to do some tasks that were simple in ProE, but more difficult in 123D.  On the other hand, the majority of tasks that I perform in structure building are much simpler for me in 123D, so I’m pretty happy with the change.

A prototype of the Chama sandhouse is shown in Figures 1 and 2.  It is close to the final product, which is printing now. I’m adding simulated door handles, trying to make the doors more visible, and making the ties in the sand bin more visible.  The prototype was also put together in pieces, but the final version will be printed from the ground up, thought it will interlock into a baseplate that has the sand bin printed on it.  The tower is a separate structure because it’s hard to finish the roof correctly otherwise.  The air cylinder is also separate because the legs are soldered wire – I tried to print legs but they had to be too big if they were going to survive. I had to make some concessions to N scale it, but it is a very close representation dimensionally.  The prototype includes a prototype version of the sand delivery pipe, gate valve and counterweight that is on the tower.

Photo 3 shows the prototype next to a completed Banta Models kit of the Ridgway sandhouse.  They have similar dimensions, with the Chama house being slightly smaller, and the Chama sand bin being longer.

List of things I know could be upgrade: making the log supports look more like logs;  upgrade the sand delivery gate valve (the valve and delivery pipe were simulated using 0.010” wire and #32 gray electrical wire. The counterweight is just a solder ball). I welcome other comments and observations, particularly with respect to the paint scheme (I will be simulating 1940-1950).  For this prototype, I used D&RGW Freight Car Red for the house, D&RGW Building Brown for the tower, Silver for the dry sand cylinder, Roof Brown for the bin, and Mud on the visible log ends.  Most of those look OK, and my guess is that whenever it needed paint, it got whatever they had leftover from other projects.

 Chama Coaling Tower

Photo 3 shows the first draft of the Chama Coal Tower – just a teaser - the concrete coal bin.  I built two components, a baseplate for the house and the coal bin (so that their heights would be correctly modeled).  The coal bin was done in white acrylic, nothing fancy and I really like the sandy finish – I think it feels just like concrete.   I already found a couple of dimensional errors, and a new coal bin, along with the house and the complete tower itself are at the printers!  That has been a massive project to design.  We’ll see how it comes out, since several things may not turn out so well in N scale (particularly the guides for the coal buckets, the sheaves, the coal bin gratings, and the mechanism for the door and gate in the front.)  I have some backup plans for some of those, but others may need some inspiration…

Comments Welcome!

Well, I’ve had numerous setbacks on my locomotive building enterprise (which between that and work have left me too busy to post) including two today, one of which I have recovered from but the other I have not.

Has anyone used Blacken-It on a brass chassis?  I had paint peeling issues, with the paint flaking and getting into the gears, so I figured I would blacken a new chassis, it’s an external frame anyway, so unlikely to been seen as long as it is not bright brass.  It turned out great, and still looked and worked great the next day.  But a week later, disaster – the steel axles are all rusted and bound up in the brass axle holes (bearings).  I figure it’s one of two problems, moisture from the last 915 alcohol bath (and I hadn’t yet oiled the axles) or galvanic action that is catalyzed by the blackening agent.  I don’t think it is moisture since I routinely use the ultrasonic bath. Has anyone seen this phenomenon before?

On the good side I do have two chassis running, one of them seems to be doing well.  Lots of lessons learned – I’ll have to go back and update the blog soon – probably none of which would have been made by more experienced modelers. 

But, on to another project that seems be making progress and is more fun!

Chama Sandhouse Tower

At last year’s Amherst Railway Society Show in Springfield, MA, I was thrilled to see that Banta Modelworks came out with a Ridgway sandhouse kit in N scale.  It’s an excellent little kit, laser cut plywood, nicely done from what I have seen so far. The only disappointing part of the model is that it is of Ridgway’s version, which doesn’t have a cool sand tower (I doubt that was lost on the workers who shoveled it by hand into the engines…)

So I pulled out my Chama sandhouse plans and put together a 3D CAD model of the tower, and sent the prototype version to Shapeways to see how their new high resolution FUD would print it.  Fortunately it was printed, even with large stretches of just 2x6” scale boards and the detail was very nice. A photo of an unpainted prototype is above, and one of both two prototypes is shown below (one painted, just the tower, and one unpainted with support structure}along with a partially built Ridgway sandhouse.  I have about 7 changes to make, but based on the prototype I am very confident that this is practical with high 3D print yield, and it’s not too fragile (it’s actually quite flexible.) The 3D resolution is not perfect, but there is noticeably less was on the casting and I’m thrilled with Ultra detail. I still need to figure out how to model the down spout (probably just a wire) and valve mechanism.

Thanks to the Quick Pic Books, I noticed something not in typical photos or drawings that I’ve always been puzzled about – there is an air cylinder on the side of the sandhouse to move the sand to the top of the tower – filled by the engines that stop for sand.  Neat, I can make a 3D model of that as well.

A reasonable Chama facsimile could be made from the Banta kit, but I may 3D print the sandhouse as well to see if I can do building walls effectively (may be more expensive that laser cut plywood).

Chassis Construction - Counterweights

The next step was to mount the counterweights on the axles.  The key here was to get the counterweights flat and parallel to the plane of the chassis.  After filing each counterweight to remove burrs, I reamed the holes to fit the 1.2mm axles from Aspen.  I then carefully mounted each counterweight and bonded it with CA on the top face and on the bottom around the seal to the axle.  Some holes were not exactly perpendicular to the counterweight face... but for this part you only need to get the counter weight roughly correct - worst case you can file the front - because you really only see the front the counterweight (however the filing causes an aw shucks moment in a few minutes...).  So I mounted the counterweights on one side, and then set the chassis on its side with the counterweights up, I file them flat to each other and parallel to the chassis.  This eliminated some extra CA and generated a lot of brass dust.  The results of the mounting are shown in Photo 6. (Yes the two middle counterweights stick out about 0.010", there is some play in the axles and I didn't make them equal on the backside before taking the photo, which you can see because the wheels are out from the frame as well.).  I think I got the surface parallel to 0.005" without much difficulty.

Mounting note #1:  The K28 has only one large counterweight, it is on the third axle from the front, which you can see in photos or in a larger model.  The K36 has all large counterweights.  Note #2:  When the large portion of the counterweight is pointing up on the fireman's side of the cab, to correctly quarter the drivers, the large portion of the counterweight should point forward on the engineer's side (90degrees different from the fireman's side). Difficult to see that in a photo of only one side, that's where a larger model comes in handy.  The Aw Shucks moment:  it turns out that alcohol doesn't take off paint very easily, but combined with a 3 minute ultrasound soak to remove all the little brass filings, it took off some of the paint on some of the chassis.  This was a surprise to me because I have not had a problem with alcohol before, see Photo 7. 

While painting the counterweights, I touched up the chassis by hand.  I used Floquil engine black for the counterweights since they will be seen more and should match the engine body.  The finished chassis are in Photo 8.

 Chassis Construction - Frames

The Aspen kit comes with flat chassis frames that you need to bend 90 degrees to form the outside frame on the left and right.  I used a bending tool to do the job, but found it very difficult to get the bend exactly the same on both sides.  Getting it 90 degrees isn't hard (keeping it 90 degrees is another story) but if you don't do it exactly on the dividing line then you form a parallelogram and the frame has a little tilt to it...  In reality, the model interface is the flat unbent surface.  So as long as you are pretty close, you won't notice the difference when the model is assembled.  The outside frames could be a little higher on one side and won't see that even in a head on look.   The bent frames then need to have the pilot attached and the cylinder casting attached.  Assembly Note:  The bent frames are easy to unbend, but then are easily bent back.  If you do that more than once, it's easy to tear the brass sheet.  Because there isn't any interference issue, I ran a bead of solder on the inside edge of the bend.  That fillet makes the bends much stronger and after soldering you can visually bend the frames square (check in all directions), the fillet can be seen in Photo 9.

Before assembling, I modified the pilot to be able to take a real coupler.  I cut two of the support rods, bent them to match the existing bent rods (and they can be soldered to a support rod underneath if you really want, and filed down the pocket so that it will accept a Micro Trains coupler, see Photo 10.  I soldered the pilot onto the frame.  This was a little tricky because you need to make sure the pilot is flat and square to the frame.    It was within my soldering skill set (not novice, but not great).  I used a resistance soldering tool, held the pilot in vice with an alligator clip and held the frame using pliers.  It was very fiddly to get the parts to be flat, and square, and centered on the frame, during the heat application, and I had to unsolder/re-solder once or twice, but it worked.  If anyone has a better solution, I would really like to hear it!  Assembly Note:  you need to file the pilot frame to accept the cylinder casting in the next step.  It's not clear you need to do that (and the pilot doesn't extend that far back in the real engine, so you are filing away something that doesn't exist...), but a rectangular chunk of the two rear corners need to be filed - you can see that in the photo of the finished frame assembly below (look at the back corners of the pilot on the chassis that is holding up the chassis being photographed (lower left).  These I didn't make exact, they are hard to see in the model.

The cylinder assembly is pretty easy.  First I filed the back edge of the pilot (resting on the frame) roughly square to the frame, and then mounted with CA.  If the casting doesn't lay flat, you probably didn't file enough of the corner away!  Assembly note:  make sure the cylinder front faces front, don't ask me how I know...  I then added the castings that go in the holes in the rear of the cylinder casting, also with CA.  Make sure that the slit in the top casting is vertical, and make sure that the bottom casting has its two holes lined up vertically, with the smaller whole above, and either right above, or slightly to the inside.  [These parts only approximate the real valve gear linkages and pistons, I think that rotating the hole slightly inside will make valve gear assembly and operation easier, but I tried to assemble them perfectly one over the other.  We'll see later...]  The final chassis parts and frame parts are shown painted in Photo 11.