Welcome back! This is the story about achieving our long time goal of 3D printing realistic cut stone blocks. For the longest time it was out of reach, mainly because of my limited abilities, coupled with the limitations of the tools I’m using to capture the designs. But renewing the search to find new approaches to solve the design problems finally paid off recently!

Before we dive right in there’s some history we need to cover. It may seem like the long way around, but some backstory helps describe the problems looking for solutions, and the journey to find them. This all started long ago when we decided to use the concrete patch casting method for the walls of our Downtown Marketplace buildings.

We were off to a good start, learning from the mistakes of the first casting, and made two more. Painted, weathered, and detailed with 3D printed windows, doors, and display cases, they were impressive. We used mortar to attach them to concrete blocks for added strength against the Barkyard’s marauding German Shepherd population. Then other priorities stole us away.

I wanted to give proper credit where it’s due, but I’m sad to say the original site (rrstoneworks.com) I used as a reference for this technique is no longer online. They sold plastic pattern sheets and actually sliced real stones into what they called “Stone Sticks”. I have two boxes of them, with no way to get anymore of them. Need to check the “Wayback Machine” for anything useful…

It didn’t take long to realize the 3D printed PLA parts weren’t up to the task. The final nail in the coffin was the grand experiment, the Grand Hotel, also 3D printed from PLA. It lasted only days before it warped, got brittle, and fell apart. Another failure. The only thing durable enough to last over the years were castings. We detailed what it took to make that happen in this old post.

A Bit Of History

Fast forward a bit to casting retainer walls for the track to climb the grade it makes along the back fence and around the corners. We’ve already moved a LOT of dirt to create the embankments with the proper slope that sits beneath the tracks to support the retaining walls, pretty much following prototypical practice.

Struggling with designing casting molds for weeks, then months, the final version is still lacking years later. It lacks a definitive means of supporting the walls and connecting them together in a rugged fashion. It lacks a mechanism for adding on new segments to previously placed ones. Most bothersome is the lack of detail in the large, cut stone blocks that make up the wall.

The idea was to pour concrete into forms that would capture the castings and hold them in place while the concrete hardened then remove the forms. The design progressed about this far, printing mockups, and assembling them to help visualize what we’d encounter when doing this for real with mixed concrete ready to pour, detailed in this post. It was overwhelming. The design was tabled.

More Backstory

Fast forward a bit more to casting concrete roadbed bricks. Another learning process. Another shelved approach. The original approach was to form and pour in place, then “screed” the ballast profile into the wet concrete, like those concrete curbing machines do. That proved to be a lost cause, perhaps because the mix wasn’t wet enough, perhaps because I’m a novice and not a Mason.

The next iteration was to create a long mold to cast individual “bricks” from the concrete. Screeding the top flat was much easier than trying to form a profile shape, but setting up the mold with all the pieces in place then cleaning up the mold afterward was tedious and time consuming. The mess of pouring concrete and the strenuous effort of mixing it adds up to more effort than reward.

Another drawback to any sort of casting is the amount of time involved, beyond the preparation and effort. It’s a series of “hurry up and wait” events that have to occur within a fairly strict timeframe. Once mixed, the pour has to occur quickly afterward. Then wait at least a day but not much more than that before removing the green castings from the molds. Time to find another way.

New Solutions To Old Problems

Previously I had designed and printed insulated sections for the SplitJaw™ clamps on the diverging routes of the wye. It quickly became apparent that PLA is no match for the Florida heat! Essentially the plastic slowly deformed until it simply gave out and the joints popped open with all the stress those curved legs of the wye were under. Another found out the hard way item.

Even PETG struggles with the heat. Nick was having similar issues with 3D printed parts for his “under hood” automotive applications, but he found a solution, High Temperature PLA (HT-PLA). He printed a set of coil mounts with it to test how well it stands up to the high temperatures in the engine compartment. The parts need “annealed” first though to give them their heat resistance.

As a test, he annealed one mount but not the other, then installed them on the engine. One melted. One did not. Needless to say annealed HT-PLA passed the test. He swapped out the melted one with another annealed one and they’re still going strong. I bought a roll of black HT-PLA filament a while back to see if this recent innovation will fit the bill for our needs too.

New Opportunities For Old Projects

The bench space issue in the garage has delayed further casting, waiting for the bench to be cleared off, literally for years now. The reason for castings is twofold. First is durability when faced with constant pounding from three German Shepherds. The second is resistance to the brutal Florida heat and environmental challenges in general. Concrete holds up better than wood or PLA.

PLA lasts only days before warping. We found out the hard way with the Grand Hotel “skin”. We need a quick way to test this HT-PLA in the baking hot Florida sun. The quickest way there is to print something we’ve already designed, like one of those brick walls from the Downtown Marketplace stores. But instead of manually editing it to make it thicker, it’s time to try out OpenSCAD.

What better test for something that’s an exhaustively “manual intervention required” task than laying out a brick pattern? In a little over an hour the OpenSCAD model is rendered, exported as STL, and printing! While that’s printing, it’s time to learn even more about OpenSCAD and make the hard coded preliminary model more parametric.

Parameters like how tall and wide is the wall? How many windows? What scale? Brick dimension? Adding those features took a little more than a day to resolve, but now it’s totally configurable and can even create Downtown Marketplace storefronts! Just flip the switches and change the values and render another model, then export the STL and print!

Test Time

Before going any further with the grand experiment of HT-PLA, we need to test whether it will perform as required. I expect it to perform as well as it did for Nick. The first brick walls were printed using red HT-PLA. They were then annealed at 100°C (212°F) for 30 minutes as recommended by PolyMaker, the filament manufacturer, and allowed to cool back down slowly in the oven.

Glad I saved the “Easy Bake” toaster oven from the scrap heap. The only thing wrong with it is the broken handle, quite the nuisance when dealing with that hot glass door. It still works fine though. And it’s old school! Everything’s set using dials, including one of those timers that winds up and slowly ticks away, counting down to DING! It’s done. No modern computer crap to fail.

Once annealed, I set the walls out in the sun all afternoon, standing against the half high concrete blocks, where they can bend at about the halfway point under their own weight if they’re going to. Thinking the oven was plugged in when it wasn’t, the first brick panel didn’t get annealed, creating a side by side comparison test similar to Nick’s. That panel warped slightly into a convex shape.

But the rest of them passed the test with flying colors! WOOT! They’re only ⅛” thick and no deflection whatsoever! No warping. No distortion. No discernable changes at all. Nothing. Absolutely amazing! I tried re-annealing the warped one using a weight to try to flatten it back out, but it just warped into a concave shape this time. Oh well, at least now we know what to expect.

Riding The Wave Of Success

It’s the convergence of multiple successes coupled with a potential solution to the heat resistance problem that prompts pulling the cut stone retaining wall design out of mothballs. A quick search online reveals a post on the Model Railroad Hobbyist forum by Glenn Butcher about his solution to the exact thing I’m looking to accomplish! What are the odds?

At first glance it’s way too overcomplicated as a quick solution, but then I see that Glenn has already created 20 textured stone STL files, and in OpenSCAD no less!. Now that’s the ticket! Without getting way too technical, he generated “height maps” to use as the textures using a technique the makers of Star Wars used to generate realistic, computer generated terrain.

In fact, the approach is captured in an publicly available library, libnoise, that anyone can use in their own programs. That’s exactly what Glenn did then shared his work, noisetool, online. Sounds good, right? The drawback is those height map files for OpenSCAD are tens of thousands of lines long. Each. Now put 20 of them in one program! Good luck scrolling through something that big!

Making It Work

I know, engineers, right? I thought I over-engineered things, but Glenn takes it to a whole new level. That’s a good thing! Each of these textures is meant as a 3″ x 6″ HO scale wall, but our cut stone blocks are ½”x1″, a 6:1 scaling factor. If we want one out of six in two directions, 6 x 6 = 36, and we only want one of them. We could throw out 35 of 36 values and still have plenty of detail.

In an attempt to work around pasting all those huge files into OpenSCAD and simply import a series of 20 files that captured each of those height maps as solid models I used an online tool that converts STL to OpenSCAD files to be able to import those 20 STL files as modules I could include in OpenSCAD and then arrange them programmatically.

I get it all working up until I try to actually render it to export the STL and get a “Thrown Together” error for every stone! Not sure what that means or how to fix it. A quick search says I should try a development version newer than the 2021 release version. I don’t have the time to throw at getting a development version of the program working. This was supposed to be a quick win.

Next!

Well that was a LOT of wasted time for absolutely no reward! Time to get it working in SketchUp. I imported the series of 20 STL files that captured each of those height maps, one at a time, into FreeCAD. Once there, I created a mesh from the STL, optimized the mesh, and then created a solid from the optimized mesh and exported them as .dae design file models SketchUp understands.

Alright, I promised I wouldn’t get too technical, but it’s worth noting how I created the models. Rather than write a program to sift through all that data and throw out what we don’t need, I just pulled the solid models exported from FreeCAD into SketchUp. From there they’re scaled and the stones manually arranged into our familiar 4″ x 7″ retaining wall segments.

Next HT-PLA test, black cut stone retaining walls. If anything doesn’t stand up to baking in the hot Florida sun, it’s black anything. Anyone who has a black car interior knows how scalding hot those surfaces get after baking in the sun all day. Can’t even touch the steering wheel for minutes, even after the A/C is blowing cold on it, and even then you wish you had gloves.

Adding Realism

It takes some time to get all those stone models imported and resized to fit our existing retaining wall dimensions. It’s soon apparent there’s WAY TOO MUCH DETAIL! What used to be snappy response times are now so sluggish I’m wondering if I actually pressed the key or clicked the mouse. In any case, I lay out a pattern of blank, mock stones then replace them with the imported ones.

One by one I substitute the textured stones until I’ve used all 20 of them, the first three courses out of eight. The next three courses I start at the beginning again, but flip them along their green (Y) axis, from left to right, effectively making them a mirror image of the originals. The last two courses use a similar approach, except this time flip along the red (X) axis, mirrored from top to bottom.

That leaves the “half” blocks at the end of the staggered courses. I chose a handful of stones that look the flattest, with the least amount of detail, because sizing them to half their length will stack twice as much detail in the same amount of space. It works out well and the mock half blocks are replaced with the actual stone models in a similar fashion to the full blocks.

There! Now we have a “flat” wall with realistically textured cut stone blocks that we can test with. Well, once the STL is exported, sliced and 3D printed we do. First it goes into the Easy Bake oven to anneal. Then it’s punished by the Florida furnace. Fingers crossed this will hold up to the heat. The flat wall passes with flying colors! It sat out all day, then overnight, and again all the next day.

Testing While Adding More Realism

Meanwhile I’m working on making the flat wall sloped to match prototypical construction. When I say “flat” I mean the blocks are stacked directly on top of the course below, with no lean either way. The prototype calls for an inward lean to account for the increasing forces exerted by more and more dirt the deeper down it goes. The sloped profile is more realistic than the original flat version.

Each new iteration of the evolving design gets printed and added as a new test subject. All the black test subjects have been baking in the sun all week with no discernable changes. Absolutely awesome! That means using the HT-PLA for tie strips is a possibility too! Time to try printing the switch ties for our new curved switch with it.

Another practical use is rebuilding the Downtown marketplace using HT-PLA instead of castings. It may not save much time over castings, each 5″x8″ wall segment takes hours to print, but it’s far less messy! And it certainly doesn’t take as much prep and cleanup time as casting. But we’ll save all that for another post.

Some Caveats

There’s something to be said for getting it right the first time. Something that seldom happens. I have a bin full of useless prototypes that didn’t make the cut. May as well get used to burning through at least a 1kg spool of filament prototyping a design to get to the production version. Or should I say a production version? There’s always that one last tweak to add…

Each part of this design has evolved to suit the requirements of the station siding, and now by extension, the ever evolving station platform. But I’m getting ahead of myself again. The initial design elements are primarily the walls and pillars that join them together, the track deck and capstones, and the underlying frame that ties everything together around the stringers.

Originally the walls were glued to the pillars. More like solvent welded, similar to using plastic model cement. But it quickly becomes obvious after about four wall panels that a wall 10′ long can’t easily be moved all together all at once without breaking apart. Time to rethink the design. So now everything is modular, held together using M2.5 stainless steel socket head cap screw hardware.

Modular Design

That four wall panel section is still sitting on the office book cases. I just can’t bring myself to throw it away yet. Why four panels? Because that’s the magic number of roughly 8″ (~20cm) sections it takes to make a complete 10′ diameter track section. The pillars are designed to angle each wall panel from the last by 7.5°. Four gives a total of 30°, the extent of a 10′ diameter curved track section.

Two M2.5x6mm screws hold the pillar to each wall panel, a set for each panel on either side of the pillar. The transition to tangent track and remaining walls have another pillar design that has no included angle so the wall panels remain straight and parallel to one another. There is one exception for the inside transition from 10′ diameter, mainly to accommodate track deck mounting.

The track used to sit directly on top of the stringers, but now it sits in a “trough” in the track deck, as deep as the ties are tall. The “floor” of the trough the ties sit in is ⅛” (~3mm) thick and now sits directly on top of the stringers. The track is not mounted down to the track deck, but rather left free to “float” in the trough, and the track deck itself mounts to the underlying frame.

Keeping Things Where They Belong

The frame surrounds the stringer, the main reference for track placement, holding things together and where they belong relative to the stringer. The frame is a three piece design. Two tall sections that mount to the back of each opposing wall pillar using two M2.5x8mm screws. The third “Twist Lock” piece pulls the opposing mounts together and locks the assembly around the stringer.

Leaning the twist lock back at an angle allows the set of “hooks” at the bottom to catch and hold just inside those two mounts, then by twisting it up into position, it locks everything together, including the wall pillars. The twist lock section is secured to the mounts using two M2.5x10mm screws from the top, mainly because that’s about the only access left once everything’s assembled.

The track deck itself mounts to the underlying frame using four M2.5x10mm screws, covering and blocking access to those two screws securing the frame pieces together at either end of the deck. The socket heads are recessed into the raised portions of the deck on either side of the track that forms the trough. Eventually they will be concealed by a fence, roof supports, or some other cover.

The capstone strips are secured to the deck from beneath using M2.5x16mm screws. Once the deck is mounted to the frame, they are no longer accessible. The single, larger pillar capstones can be held in place by simply inserting their built in tabs into the slots in the underside of the deck capstones. They can also be secured using button head cap screws, but it generally isn’t necessary.

New Challenges

With enough 10′ diameter sections in place to account for the surrounding grade increasing to meet the track level and the kinks in the transition to tangent track hammered out, it’s time to think about the station platform and how to connect it to what we have so far.  More specifically, how to incorporate the old station platform 4″x8″x16″ half height concrete blocks into the new design.

The whole sad story about how nothing’s left of the original station platform was left out of the earlier history lesson. The abridged version is there used to be raised bed planters along the entire length of the patio. Those blocks sat between them and the track stringers, with a roof of sorts from the planters above acting as a covered station platform.

The planters were removed long ago, leaving just those blocks along the station siding track. Because the track sits roughly 4″ off the ground, any kind of platform would need a good bit of support or dirt fill beneath to hold up to the constant pounding from the pups. We already have all those blocks just sitting there anyway, so why not incorporate them into the design?

Transitioning From Curved To Tangent

Before we can use those half blocks, we have to transition from the curved approach to tangent (straight) that will become the station track alongside the platform. This is the exception for the inside transition described above. The exception it refers to is where the curve track deck meets the tangent track deck.

Originally the thought was to have a transition track deck and transition pillars. Partway into that design it was discovered that not only would it take one transition track deck, it would need two of them and both of them would be different! Basically one to go from 7.5° apart to 3.75° apart, and then from 3.75° to straight and corresponding pillars to match. But that didn’t make sense.

The current design simply reuses the curved and tangent track decks along with a regular 7.5° pillar outside and the new transition pillar inside. The inside transition pillar has a 7.5° angle too, but the stones are offset from the middle of the angle to account for the track deck mounting locations. I feel like I’m waving my hands again, but this gets us from curved to straight using fewer parts.

By shifting the mounting points on the inside transition pillar to accommodate the standard track decks, it eliminates the need for at least three or more additional, specialized parts, only useful in this one situation. Too bad I didn’t think of it before designing a number of those specialized parts first and then having to toss them out after wasting all that effort.

Transitioning To A Platform

So now that we’ve transitioned from curved to straight, before we can use those half blocks, we still have to transition from the current approach track with retaining walls on either side to a platform with a retaining wall on one side and a station track on the other, the station track with its own retaining wall on the other side, continued from that side of the approach track.

Hopefully the “see through” panels give a better view of how all these 3D printed parts come together to give the illusion of a believable scale model. For me, seeing them slowly come together and become what I’ve always dreamed of seeing is more than satisfying. It truly is a dream come true. The black and gray colors aren’t very realistic, but until the design is finished, it’s good enough.

The design must account for the inside wall changing direction, in this case perpendicular to it. In order to widen the footprint and conceal the half blocks with something that looks like a station platform, we need a different inside transition pillar, plus an additional outside transition pillar to redirect the wall back to the original approach wall direction along the side of the platform.

Unfortunately, because of the dimensions of the half block in that direction, we can’t use the standard 4″x7″ wall connected to all the other pillars. Altogether they add up to 8″ total, too short to wrap around the 7⅝” width of the block. We’ll need a 4″x8″ wall to allow just enough clearance for that block width.

Expanding The Design

So now instead of two opposing wall pillars separated by the width of the track deck one of those frame mounts will now connect a “hidden wall” section to the opposing cut stone wall. These hidden wall sections will mimic the cut stone wall dimensions along with their own pillars. They connect to a widely separated cut stone wall pillar on the other side of the block every 16″.

Because the block is actually only 15⅝” long, that leaves just ⅜” to work with. The connecting frames between the hidden walls and far cut stone walls are only ¼” thick, leaving barely enough room to spare. It’s a tight, snug fit, but it anchors everything and supports the platform sections. Each section is still only 8″ wide because of 3D printing build volume and “Easy Bake” oven limitations.

Two platform sections are joined together and fitted 16″ at a time. A “stub” mount for the platform sections is used in place of a connecting frame section where the block length is in the way. This ensures the hidden and far cut stone walls are still rigidly secured together even where a connecting frame member can’t be placed.

Adding The Station Platform

The track deck still mounts to the twist lock frame, but now only one of the capstone strips is needed for the side opposite the platform. The platform design itself takes some thought about how to make a believable scale model that doesn’t have obvious separation “cracks” every 8″.  Why not a brick herringbone pattern framed by what appears to be stone blocks?

OpenSCAD to the rescue again! It takes a bit longer than expected to perfect the design, but it’s a believable herringbone pattern, centered about all four sides. It even has mounting holes to attach a support frame that the framing stone block strips will also attach to. Those stone block strip designs are captured in SketchUp along with an imported version of the brick herringbone piece.

To facilitate the modular design concept for adding new sections, the edge of the new platform section will simply slide in beneath a previously mounted section without need for mounting screws. If anything, loosening the existing mounting screws that hold the previous section may be necessary. Then both the old and new platform sections can be tightened down together.

One last “transition” design item is necessary for the first platform section along that 4″x8″ wall. There is absolutely no room for any mounting hardware to fasten the edge of the platform to the wall beneath. The half block butts up against the back of the wall to fit everything in the limited 16″ space. Instead, a set of tabs on the first platform subframe slides into slots on the transition pillars.

Assemble, Rinse, Repeat

After that first transition section from the approach configuration to the platform configuration, it’s simply a matter of adding on another 16″ platform section to the previous. Expanding from first platform section to the third doesn’t happen happen overnight, but it doesn’t take long since I’m printing most of the parts while redesigning the ones that aren’t working as expected.

The only limiting factor on the platform expansion is how long it takes to 3D print all the parts, anneal, paint, and assemble them into the next 16″ section. It takes a lot of parts! Four each retaining walls and pillars, two each hidden walls and pillars, twist lock frames, hidden frames, platform decks, platform subframes, deck border stone sets, track decks, and track deck capstones.

I’ve tried to capture the estimated print times of all the parts when slicing them. Let’s see how well I did and whether I can add them all up for a rough estimate of print time. Add at least another hour to anneal each print, although the last part printed can be annealed while the next is printing. Then add painting the annealed parts and assembly time. It all adds up. But progress is progress.

Color Considerations

Our color palette in HT-PLA is fairly limited, even more so than PLA. Just the basic colors. While the capstones could have been printed in white, the single ACE cabinet only has four slots it and would mean having to constantly swap between white and one of the other four colors, namely black, brown, gray, and red.

Gray was chosen with the idea that the red is too bright for bricks and would need painted brick red anyway. The track deck and capstones can be painted concrete and light stone colors. The black cut stone walls don’t need any paint, but should probably have some sort of UV protection painting the other parts offers, and perhaps a wash with a lighter color to bring out the details.

After an extensive Google search for matches to the Model Master “Aged Concrete” color from my HO scale days, satin Dover White and satin Ivory are chosen for the concrete and light stone colors. At first, they look like they’re same color, but later spray paint batches aren’t as close. Natural variations in stone colors? Plausible explanation if anyone asks. LOL.

Brick red is brick red. Alright, there are variations to be sure. I even made brick color selectable for OpenSCAD, brick red or creme (beige). I’ve seen many modelers design and print painting masks to expose “random” bricks and paint them slightly different colors to mimic the natural color variations. I know I’m a rivet counter, but I haven’t made it to that level of obsession to detail (yet).

What’s Left?

The station platform is slowly expanding. The original platform was 16′ long. Now it extends beyond the end of the patio, so approaching 20′ maybe? So far we’re about half way done, right at the end of that first 10′ stretch of flex track. We can add another 16″ section every couple of days in production mode, pretty much 3D printing parts 24/7.

I’ll wake up in the middle of the night and kick off another if the previous print’s finished. Sometimes I’m a sound sleeper though. But it only delays the inevitable, kicking off of the next print once I’m able to. So far I’ve only screwed up twice trying to go faster than I should have.

First was forgetting to put the PEI sheet back in the printer and frantically killing the print before it could cause more damage. I’m missing a small chunk of the magnetic material that holds the PEI sheet to the build plate after that little fubar. Kicking off another print while the previous one was still sitting in there on the PEI sheet was another. “Why’s it making that clunking noise? OH SHIT!”

I can laugh about it now, but it certainly wasn’t all that funny at the time! Getting back to what’s next, the end panel of the platform still needs designed. Similar to the transition to platform configuration, now we get to the terminate the platform and need to finish it off with walls and pillars that connect the retaining wall together. We won’t have the luxury of tabs and slots this time!

Future Reference

Observations for future reference – overlaying two stone textures atop one another gives a much more realistic looking stone face, but not sure how to “add them together” in a usable fashion. Maybe someday. This is mainly a note to my future self when revisiting the stone texture design. It’s strange that when I rendered the imported stone modules this time it didn’t error out. WTF?

I’ll update this post periodically with progress toward completing the station platform. For now, I just want to get this posted. I’ve been so busy doing so many things it seems impossible to both do and post. I haven’t looked at editing a video in months. Everything takes time and right now the focus is getting the trains running and restoring the previous “luster and glory” of the Barkyard RR.

I have to say I’m pleased as punch with the outcome of this project! It’s been a long time getting here, but it’s worth the wait for the result! All the projects I put on hold are slowly coming out of mothballs. All the things I’ve put off for so long are finally coming to fruition.

In the past I worried about prioritizing things that needed done first. Anymore, I just do what’s staring me in the face, then ask myself, “What’s next?” and just do it. I kind of have to since I do things like buy a bunch of clearance Aristo-craft stuff that’s not in the best condition, then have to design and 3D print replacements for all the broken and missing parts while juggling 19 other projects.

So far so good, but that’s another story.

 

Disclaimer – Not Sponsored

I should mention that the Barkyard is not sponsored by AnyCubic, PolyMaker, Elegoo, Sunlu, or any of the host of other manufacturers of 3D printers and filament or any other entities, like Harbor Freight. I don’t think they’d care much for my nicknames for them anyway, like Horrible Freight, Hazard Fraught, etc. No freebies or evaluation promotions here. This is all paid for out of pocket.

 

Question? Concerns? Leave A Comment!

If you’re interested in obtaining the STL files to print your own block walls, leave us a comment and we’ll be happy to provide them to you. Also, if you have any other questions or concerns, please feel free to comment on this post. In any case, you’ll need to create a user account to do so. We don’t use any personal information for marketing or to spam you (see our privacy policy). You’ll receive a verification email. Reply to the link provided to verify your email address. It’s all automatic. No waiting on moderator approval! No spamming your inbox with useless advertisements and “Special Offers”. None of that nonsense. We do it this way to prevent bots and spammers from detracting from your experience.

More to come. Stay tuned!

 

This is a short follow up on the original 3D Printed Casting “Mock Ups”. Considering the length of the original post, that’s an understatement. But sometimes it’s necessary to fill in the blanks when progress is low and discouragement is high.

Even though progress has been slow, it’s actually been beneficial in this case. The original design is based on our “fleet” of Bachmann passenger cars, literally dozens and dozens and dozens of them. Some modified with our Passenger Car Lighting systems, some still sporting the original 9V battery twin light bulb version. All of them suffering from flimsy, rubberized plastic handrails.

I wouldn’t mention those handrails except we’re talking about 3D printing. What better replacement for plastic than plastic? Well, metal for one. Brass to be exact, but then we’d need jigs for bending the brass to shape, most likely 3D printed as well.

Design “Flaws”

Just like those original handrails that failed the test,  so did our original casting design. Well, at least the mock up did. The first flaw was discovered when first fitting the 10′ diameter curved track section. A redesign doubled the number of segments to better fit the curve. This was discussed in the first installment and it works quite well.

The next “flaw” is genuinely a “new” one, as in there’s not enough clearance for the new USA Trains Heavyweight passenger cars. And before you ask, no, there are not dozens of them. But there is a decade of them. There was a bulk deal on ten of them around Christmas time, so I pulled the trigger, as well as ordering a pair of F7 A-B units for A-B-B-A running.

They’ve been packed away since then, awaiting completion of all these “infrastructure improvements”. After unboxing one of them to test with, it was readily apparent the design was too narrow for these behemoths. The car is longer than the mock up! The wheels just fit on a single curve section though.

The steps and the equipment boxes both will interfere with the platform or the capstones. Back to the drawing board! It took some doing, and some days to do it, but I managed to add a “crude” approximation of the new passenger car to the mock up design.

Back To The Drawing Board

The test fit also reveals a flaw in the “track trough”. Not sure where I picked up that fault, but for whatever reason, the track is sitting proud of the platform rather than flush with it. To give an idea of how the prototype fits together, most platforms are slightly higher than the track, by about 4″ (10cm). In scale, that’s roughly 1⁄6″.

I figured giving the equipment that little bit of a height boost would hopefully compensate for any errors made while measuring their dimensions. Looks like I worried about the wrong measurement errors. Add that to the list of things that need fixed.

I’m back and forth with whether to try to forcibly disassemble the mock ups or just print all new pieces. I say try because the chemical solvent I use to cement the plastic pieces literally melts the two together into one part. Printing all new pieces is going to take a lot longer.

Each 4″ x 7″ retaining wall segment takes 4½ hours to print. Two of the pillars that join the wall segments take 3½ hours. An 8″ long track trough takes 5 hours. It should have been obvious when the curved track trough only took 3½ hours to print.

Anyway, these flaws are certainly obvious now. Not to worry though, the entire reason for all these mockups is to find the errors and flaws before they’re cast in stone, er… concrete.

Time Is Of The Essence

Alright, being overly dramatic, but time certainly is the essence of the conundrum. As in there is not enough of it to get ahead of everything that needs done. So little to do and so much time… Strike that. Reverse it.

Some say if deadlines are not set, they’ll never be met. Tell that to hurricane Debby. Now instead of spending time moving closer to the goal of running trains, it will now be spent preparing for a hurricane.

Retract the SunSetter™ awning. Stash any loose items that will blow away, like lawn chairs and cushions. You get the idea. Now add to that the garage where those items are usually stored is still the disaster it was right after the A/C decided to leak all over everything.

Progress is slow, but progress is progress. The large empty storage bin that used to sit in front of the table saw because there was no place else to put it is now filled with HO scale items that used to occupy a slot on the bookshelves in the office. It will fit beneath the work cell, taking up the wasted space under it.

Next Steps

Immediate steps are hurricane preparation, like dumping the work cart full of dirt at the end of the driveway where it has washed out around the apron and sidewalk, then retract the awning so as not to create a cart full of mud.

Beyond the immediate, back to the drawing board. The track trough and curved section redesign has already begun, old hold temporarily to prepare for Debby. I don’t like leaving the 3D printer sit idle for any length of time, but short of printing more 4″ x 7″ retaining walls, it will have to wait for the new part designs.

The big ticket item is capturing the step by step process for actually creating the station platform from all the separate cast pieces and how to create forms with them for a concrete pour. So far the mockups have captured segments of the final product, but not the process of creating those final products.

The garage needs a few more items completed before it’s ready for casting concrete patch into those retaining wall panels. There’s a stud space or two where the sill plate is totally rotted that could use a new chunk of 2×4 before setting the table saw in front of there.

The new shelves are already installed but need some thought put in to organizing what should go there and what will fit. All the things that haven’t been used and won’t be any time soon were thrown out to make more space.

It continues to evolve, like the wall cabinet for electrical items expanding to occupy two cabinets. Next is going through that cabinet that has all the “might be useful” items for the model railroad, ripe for harvesting more trash that will never be used.

Long Term

Long term is 3D printing with PETG, a more suitable material for use outdoors. Definitely more heat resistant than PLA. Not sure about its UV resilience, but paint can mitigate any shortcomings there.

The first designs will be concerned with ties and insulated split jaw parts. The originals printed in PLA lasted about ten minutes before they started to melt and deform in the Florida heat. Those stainless steel rails get mighty hot in the sun!

Next will be structural items, like window and door frames, “gingerbread” decorations and supports on buildings, etc. The ultimate goal is to create our own switches and turnouts, custom fit to the needs of the Barkyard Railroad.

Stay tuned. Much more to come.

 

 

 

 

 

 

 

 

 

 

 

 

 

I’ve been busy 3D printing lately. So busy I’ve gone through nearly eight 1Kg spools of filament so far. That’s almost twenty pounds of plastic and I’m not finished yet! Why so much? Well, that’s a bit of a story, but I’ll try to keep it brief.

I’ve been struggling with optimizing the casting process, or rather, processes. Roadbed bricks. Buildings. Infrastructure, like retaining walls and culverts and such. You name it. I’m struggling with it, and how to marry the castings with pouring concrete using the castings as forms for the concrete.

It’s difficult to visualize how all the parts need to come together to make one final piece. How do all the puzzle pieces fit together? How to hold the castings in place? How much concrete and where? A lot of questions with no answers, even with many design drawings to help.

The photo shows the initial mock up for the culverts and retaining wall of the station siding along the patio. That passenger car looks mighty lonely sitting there all by itself. Why so much mockup? I’ll blame learning curve for that. Learning from the mistakes of the initial design, and iterations that followed, to reach the final design… For the mockup.

And that’s just the tangent (straight) part. The curved portions require their own designs, and one for every different curvature! While one design is printing behind me, I’m sitting at the computer working on the next design element, be it a different part or an iteration of an existing one.

The work bench is littered with inadequate parts from failed designs. Stacks of parts yet to be assembled await the remaining pieces necessary to put the next 8″ unit together. Be it tangent or curved, each unit is based on an 8″ length.

Design Constraints

Why 8″ and not some other length? There are two main reasons why that size was chosen. The first was a matter of print volume. The old 3D printer’s bed is roughly 8½” x 8½”, capable of printing to a height of a little over 9″. All my original designs had to fit within those limits.

The new 3D printer has a print volume of 12″ x 12″ x 15″, so my later designs don’t have that constraint, except for the second reason. The sectional curved track requires a certain number of sections to complete a circle. The smaller the diameter, the larger the track section can be, requiring fewer sections to make a circle.

For example, the 10′ diameter sections are roughly 32″ long, and require only 12 to complete a circle. By contrast, the 20′ diameter sections are nearly 48″ long, and require 16 to make up a circle. So here’s some math for you. What’s the lowest common denominator for those two sizes? That’s right, you guessed it, an 8″ length!

The next choice in the design may not seem so obvious, but it’s time to select the angle occupied by each roughly 8″ section. In the case of the above design capture, it takes three 10′ diameter curve sections to create that 90° arc. It takes four of those 8″ units for each curve section, by three sections, for a total of twelve segments. Each sweeps a 7.5° angle.

While the wood stringers and other structures made up of thin, “laminated” strips may be formed into continuous curves, we don’t have that luxury when it comes to concrete. Granted, continuous monolithic slabs can be formed.

But when multiple, separately cast parts are involved, not so much. The design has to be segmented to allow for many individual parts to be cast independent of one another. And at different times. These cast wall parts are made in assembly line fashion, one or two at a time.

Design Decisions

The whole point of 3D printing these mockups is to better visualize the overall casting approach. Let’s take a closer look at what we’re dealing with. Near the center and moving to the right are the casting molds for a cut stone retaining wall and 8′ diameter arch culvert. Note those additional pieces on either end.

These pieces can be fitted as necessary to create 7″, 7½”, and 8″ long castings, roughly ¼” thick, made using concrete patch. This is very similar to the process used to cast the Downtown Marketplace building faces. Those older castings were made using a brick pattern sheet and crude foam blocks. But that’s another story…

Another piece is precision fit to the arch of the culvert section, knowing the difficulty of slicing a piece of foam to fit that opening. The piece on the very right is meant to cast the “pillars” used to disguise the joints between each of the wall or culvert sections.

The top left portion shows how the various parts, including the casting mockups from the bottom half, fit together. This helps to visualize developing a plan around pouring concrete, the external mold parts, and the steps involved.

It doesn’t reveal all the pitfalls that await, like how to form that depression for the track or how to form the pillar in place over the joints, but it will help to reduce the number of avoidable mistakes before they become mistakes.

Discoveries

That’s not to say I’ll find every problem by constructing these mockups, but it sure does help to get “hands on” experience with parts before the first casting is created. It’s too late to find out the track won’t fit in the casting or the passenger car steps will hang up on the pillar capstones once the concrete’s already set.

I’ve already found that the track won’t fit the curved mockup, we’ll call it a “track trough”, so the design needed modification. Even then it’s a tight fit, but hopefully that will help hold the track from going places, especially with the pups pounding on it.

And while the Bachmann passenger car steps clear the capstones with no problem, I have yet to try it with the new USA Trains heavyweight passenger cars that are nearly twice as long. At almost three feet long, it will require two of those 32″ sections to accommodate testing even one car.

I suppose with a little “modification”, those early sections already assembled with the faulty “track troughs” could be reworked to allow the track to fit. The original straight section was divided into two straight segments at half the angle each.

In other words, if that design drawing above had 24 segments instead of 12, and each 8″ unit included two segments rather than one. Looking ahead at the next steps is much easier with mockups in hand.

Next Steps

Speaking of next steps, what are they? Now that mockups can be made in assembly line fashion, it’s time to address how things need to come together to produce the desired outcome, a more or less permanent concrete fixture.

First is to define the process, from start to finish, and the steps involved. This includes what forms and external rigging are needed, along with an estimate of the amount of concrete needed, optimizing for 60# or 80# bags if possible. Of ultimate importance is how to keep it puppy proof while curing.

Once the process is defined, it’s time to test how well it works, making changes as needed. But even then, many questions remain. This will most likely be an iterative process, experimenting with different approaches before deciding on the final definition.

• Will the new, “wetter” mix allow the track relief to be worked in place?
  • If so, will a mold need left in place (to overcome slump)?
  • If not, will it take a roadbed brick equivalent to be laid on top of the fresh pour?
• Will each 8″ unit need to be poured solid or can it be made hollow, like a concrete block?
  • If solid, how to allow for segments and/or expansion joints?
  • If hollow, could a sacrificial 3D printed insert be used and left in place if necessary? How will that affect simple footing?
• Will the retaining wall and culvert castings require a dedicated footing? The designs simply use a block of wood in place of a footing currently.
  • No dedicated footing – Simple formed and allowed to run out the bottom as one monolithic pour.
  • Dedicated footing – Needs to be poured first then built upon.
• Determine how capstones work. Cast as separate piece and placed atop the pour?
• Modify designs for “staircasing”, i.e. gradually build altitude above terrain or lose it as terrain rises.
• Measure and record terrain height map. See if it can be imported into SketchUp.
  • What format for import?

And honestly, some of the next steps have nothing to do with mockups, or even casting at all. It’s been a balancing act between work, home improvement, and making progress toward these Barkyard goals. There’s always something else that needs done first!

Excuses, Excuses!

Work has been absolutely brutal lately, busier than it’s been since I started there more than two years ago. As for home improvement, let’s just say it’s not our goals, it’s our individual goals combined. Ann wanted the raised bed planters along the fence by the driveway removed.

I wanted to get all these 3D printed mockups and jigs complete enough to get the assembly line started, saving all that hard work of removing the planters until Fall when the weather finally cools down from the “feels like 107°” by eleven o’clock in the morning, already here at the start of Summer.

Ann removed one of the planters and even transplanted the ponytail palm herself. She did not ask for, nor want my help. Unfortunately, that left me with bent screws and the aftermath of just ripping everything loose. Not wanting to sound like sour grapes, but not the kind of work I prefer doing in the Barkyard either.

That left behind a large area of dirt in need of turf. I’ve had a 7′ x 13′ roll waiting for placement elsewhere that got “requisitioned” for this task. The hardest part was getting that old chunk of turf out of the way, now full of dirt, and twice as heavy.

Always Something Else That Needs Done First

That revealed the ragged, rotten bottom edge of the 6′ tall fence panels we put up not even five years ago. Add to that one of the 4×4 posts is rotted out right at the ground, allowing the fence to sway with the breeze, and it’s time to replace that fence before it blows over.

And while replacing the fence doesn’t necessarily mean the other raised bed planter has to go, it does mean the dirt has to go somewhere while the fence panel gets replaced. The fence used to be only 4′ tall, but was replaced with 6′ tall fence to keep Brigel from jumping over it and chasing the neighbor’s cats into their yard.

Now that Brigel has crossed the Rainbow Bridge and the neighbor cats are seldom out during the day, we’d like to go back to the 4′ fence.  Well, guess what Lowe’s no longer carries in stock and must be special ordered and delivered, to the tune of an added $75? All for three fence panels!

Plan “B”

Time for plan B. B, as in cut off the rotted Bottoms of the 6′ panels to make them 4′ panels! I got set up with the makeshift bench on saw horses, ready to make the cuts and coat them with wood preservative, while Ann and Nick handled wrangling the panels and posts.

We got ahead of ourselves on the first panel. It went up before I could cut the post down. Try as I may, I couldn’t get a clean cut, even with Nick removing the panel out of the way. It wasn’t certain that the rotted post was rotted off until the last screw holding the panel to it came out and the post toppled over.

Nick was able to fish the rest of the old post out of the ground. What was left of the post was just tall enough to go back in the same hole, once I gave the bottom a coat of preservative that is. Cutting those last two panels went quickly, but Nick was having a time of it, getting those two gate posts separated.

That gave me time to cut the gate down as well. One of the gate posts needed cut to length, and both needed a coat of preservative before they went back in the ground. Things kind of went downhill from there.

All Downhill

The drill bit broke off when it hit a screw in the post while Nick was making a pilot hole for the new hinge location. That meant even more work as the entire hinge needed relocated on the gate to avoid the bit still stuck in the post. Then one of the carriage bolt’s threads were stripped when it hit another screw in the post.

But even with all the trouble at the end, we managed to knock it out in just two and a half hours! The only things that remains is installing a new gate latch. I mentioned I may have one in the garage we could use, but Ann was having none of that. She’ll go pick one out tomorrow.

Tomorrow came and Ann went to Lowe’s, only to be disappointed they didn’t have the latch she wanted. Turns out I had the exact slide bolt latch she wanted sitting right there in the bottom drawer of the desk in the garage the night before. Oh well, all’s well that ends well.

If you thought that was the last of the distractions, the relentless things that needs done first, think again. Ann decided to remove the other planter and transplant the other ponytail palm a bit further away from the fence.

Then came the inevitable new turf to replace the old, now inadequate to cover the area required of it. The new roll is sitting outside the fence, waiting on me to cut up the old piece into strips more easily handled than the entire chunk all at once.

But wait, there’s more!

The split unit A/C in the garage decided it was going to flood the shelves, workbench, and table saw beneath it when the condensate line clogged up. I had just spent the last few weekends getting things squared away enough to start using the casting and trestle workbenches again.

Nope. Not this weekend. Now I get to move everything out of the way, everything I just moved out of the way of the casting bench by putting it away! And now I get to climb up and down a ladder with my bum knee just to get thing apart enough to work on it.

In the end the fix was to vacuum out the clog in the drain line. Sounds easy enough, but when the vacuum is on the other side of everything that had to be moved out of the way, now in the way of getting the vacuum out… Can’t win for losing sometimes.

The good news is everything is put back together and working again, without flooding the garage. Again, not so much sour grapes as comic relief for others. Life is what happens when you’re busy making other plans indeed!

It’s easy to see why it takes me so long to get anything accomplished on the Barkyard.

Other 3D Printing

And the 3D printing hasn’t stopped with casting mockups. I’ve even designed multiple trestle jigs for assembling the massive curved trestle from the deck to the new bridges and beyond.

Beyond that, it’s time to do something with that PET-G I’ve had for over a year now. Everything I’ve printed so far has been PLA. I bought so much PLA, and in so many different colors, that I didn’t notice my favorite maker, 3D Solutech, went out of business!

They are the only filament manufacturer I’d found that had such a wide variety of color selections. All the other have red, green, blue, black, white, gray, and that’s about it. Maybe yellow and orange. None of them have denim blue or steel blue or wheat or even brown for that matter.

Thankfully, white and gray will do for now, and I have plenty of it. At least another 8Kg anyway.