So here we are again, talking about roadbed bricks. Third time’s a charm? Well, not exactly…

While this go round is certainly an improvement over last time, there’s still more fine tuning that needs done. And while I’d love to say we’ve moved into the production phase and show how easily all the stringers for the ground level trackage were replaced, that’s not the case.

The wetter mix is definitely the way to go. And even though the release agent was used this time, the concrete still shrank and pulled away from the forms in the same jagged fashion. I’m thinking I’ll take the “draft” out of the 1×4 sides of the form and see if that helps.

Unfortunately, the new, taller dividers I 3D printed for this go round were too tall. Their height prohibited an end to end screeding sliding the shovel along the top of the form. But that’s easily remedied with a new round of prints for the next go round.

How Not To Screed

All things being equal, this time it took two glue sticks to prepare the form instead of one the first two times. I use hot melt glue to attach the 3D printed ballast profile molds to the bottom of the form as well as attach the dividers. It’s not a big deal that it uses two, but the inability to explain why it took two is bothersome.

The beauty of using hot melt glue is twofold. First, it’s not a permanent attachment and easily removed after a pour. Second, I can use the cordless glue gun to avoid tripping over cords. The battery still has plenty of power left after prepping the entire eight foot long form. Time to pour concrete!

Unfortunately while screeding this time around, I end up knocking one of those tall dividers loose, creating a goofy “wedge” slope between two of the bricks. I did this the first time around as well, trying to work the drier mix into the form. Again, not a big deal, as long as those two bricks are used together as a pair.

Taking A Different Approach

The main difference this time around is keeping the concrete wet. The hope is it will prevent the shrinkage and increase the strength of the bricks. I may have gotten a little overzealous while spraying down the excess concrete spilled on the driveway, by not missing the fresh concrete in the form by as much as I should have. Oh well.

I tried to wet the bricks every few hours, but even that wasn’t enough to keep the bricks from shrinking away from the form in the same jagged pattern as last time. Maybe next time keep the fresh pour out of the sun and a tarp? Regardless, the bricks remained in the form for a several days until I finally took the time to free them.

As much as I’d like to blame an uptick in work escalations, the truth is I got a bit lazy about it too. When I saw that same ragged edged shrinkage as last time, even using a mold release agent, it just didn’t seem as important anymore. Once the bricks were carted to the Barkyard, the 3D printed pieces were left strewn across the driveway, haphazardly stacked, for days.

That’s a mistake not to be repeated. The PLA plastic is not all that heat resistant, so it doesn’t take much to guess what happened to them, in June, in Florida, on a concrete driveway. That’s right, they melted. Well, they didn’t really melt, but they certainly became warped and misshapen from the Florida Summer heat.

In a moment of disgust with myself at leaving them stacked atop one another long enough to warp, I decided to lay them out flat on the drive, individually, to see if baking in the sun would flatten them out again. And it did! Talk about surprised. Once they were flat, I stacked them off to the side, where they would be shaded.

So a few more lessons learned on this batch. Don’t leave the freshly poured concrete or the 3D printed mold pieces out in the sun. Don’t have dividers that are too tall. Don’t wait to wash the concrete off the 3D printed pieces after breaking down the forms to release the bricks.

Prepping For Round Four

Along those lines, for next time I’m considering cutting that eight foot long form into two four foot long forms, hoping to be able to more easily move them after a fresh pour. The addition of a third four foot long form should help to avoid the waste when mixing up an 80# bag of concrete too.

I’ve already 3D printed a new, shorter set of dividers, and test fit them to be sure. I may need to 3D print more of the ballast profile molds as well. Several of them were printed with less UV resistant PLA than the others, and they turned yellow and brittle sitting out in the sun for days on end. Some others need glued back together.

The biggest change will be removing the “draft” angle formed between the 2×6 base and the 1×4 sides of the form. Hopefully this will help reduce the amount of shrinkage and eliminate that ragged gap, or at least minimize it.

Are We There Yet?

Not yet. I already bought a couple more 80# bags of high strength concrete mix. Hopefully the next post will show some real progress in roadbed brick laying. There’s much more to accomplish before that can happen, and even more work to be done to run trains again. Baby steps.

If you read the previous post about the casting mockups, you may remember the setback when the A/C split unit in the garage “flooding” the table saw, shelves, and the casting bench beneath it. It’s setbacks like that to take away any momentum I had to start the concrete patch castings for the station retaining wall and culverts.

I had just spent the last few weekends getting things squared away and put back in their place enough to start using the casting and trestle workbenches again. All that work was wasted when I had to move everything back out of the way to gain access to the A/C indoor unit!

Bet you can’t guess where everything was left sitting afterward. Disgusted and discouraged I turned my attention to better organization, both in the garage and in the office. Along those lines, I picked up a couple of 12″ x 8′ shelves to replace the waterlogged and now hopelessly swollen and warped cheapo depo laminated ones the garage.

For the office, I bought a 16″ x 6′ shelf to replace the functional but stupid looking 2×6 over the window. Is it really stupid if it works? Here it would depend on the definition of stupid. If we’re talking stupid looking, yeah, it still looks stupid. Not for long, but that’s another story…

Making Progress… Slowly

I’ve been moving a chunk of furniture grade plywood around the office, generally every time it’s in my way again. Time to remedy that. It’s roughly 24″ x 45″, so ripping it down the middle yields two 12″ x 45″ shelves. One of them is now “floating” above the monitors for the work cell, thanks to the leftover floating shelf brackets from the previous shelving upgrade post.

The other shelf is now above the doorway to the bedroom, in hopes of relocating all the ½” plywood remnants from my old HO layout at the other house. AS part of this latest organizational effort, I cataloged all the pieces and their sizes in a spreadsheet. I went full OCD and captured models of them in the SketchUp drawing of the office too!

But let’s get the Barkyard back in operation before even thinking about yet another layout to build and maintain! The plan is to relocate those plywood pieces, mainly various radii curve sections, from the top of the shelves they are prone to falling off of to an out of sight and out of mind perch on that new shelf.

Speaking of OCD, I took pictures of the trestle bent inventory when last organizing in the garage, and created an inventory spreadsheet with all their sizes as well. This complements the design drawings for the various trestle templates. There is much more detail in the Trestle From The Deck post.

Next Steps

Most everything that needs done has already been captured, but prepping for round four did not include any activities outside of casting more roadbed bricks. The casting mockups for the curved approach to the station retaining wall sections revealed the original design is too narrow to accommodate the new USA Trains heavyweight passenger cars.

Thankfully there’s space for all these 3D printed mockups with all the new shelving, but there’s still more work to do there before we can expand the concrete casting to include those detail castings as part of the forms. It won’t be long now though.

Stayed tuned. There’s plenty more to come!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

We finally got around to the second pour of the roadbed bricks. The first pour was not the best, and for a number of reasons. First was the quality of the form and the 3D printed mold inserts used to shape the concrete into a roadbed profile. Second, and more importantly, the quality of the actual concrete mix itself.

The form itself held up well, but the sides need to be tighter against the bottom if we’re going to try a wetter mix. Breaking down the form after the first pour reveals enough of the mix managed to get into the gaps between the sides and bottom. Gaps large enough that the concrete needs cleaned off the pieces before the form can be reassembled.

Closing those gaps is easy, just add more screws between the ones already there. The 3D printed profile molds now fit snugly as well, which should help hold the 3D printed dividers in place better than the first time around. The problem the first time around was the dividers moved on us, probably because of using the brick trowel to work the mix into the form and breaking them loose.

Fitting the molds and dividers in place takes the same amount of hot melt glue this time around as it the first time, one stick. That’s a dot on each of the four corners on the molds themselves and two or three dots on each divider. Somehow it seems more sturdy than the first time. Here’s hoping…

The weather is still pleasant enough to sit outside on the deck this time of year while we prepare the form for the pour. As you can see, the railing provides a suitable work surface for assembly. It can also slide back and forth on the railing as needed. The added bonus of easy access for Rocket to bring the Jolly Ball makes it even more enjoyable to sit outside in the Barkyard.

Enjoying it while we can. It won’t be long before the oppressive heat will keep us indoors all but early mornings and late evenings. We’ve already had a few record breaking days recently in the 98°-99° range. Soon it will be every day in the upper nineties, without relent, until Fall.

Time To Mix

Now that the form is ready, it’s time to mix the concrete. The first time around, we used ~5 quarts of water, not quite twice the maximum of three quarts recommended on the bag. This time we’re mixing it wetter, “soupy” is the term, “Thick as a milkshake, but not so thick that you can’t suck it up with a straw.” Now the only problem is how to translate that into quarts of water per 80# bag of concrete.

Starting with 6 quarts, the mix is still too “dry”, as in not wet enough for all the mix to be easily incorporated. Adding another quart still isn’t enough. One more quart makes it a total of 8, and finally wet enough to call “soupy”. Beginning to wonder if they meant three gallons and not three quarts. After all, eight quarts is two gallons.

A few more quarts would make a fairly thin mix, but still workable if pouring. Maybe nine quarts next time? Let’s not count the chickens before they’re hatched. It’s certainly something to consider, but let’s see how this batch turns out before making more changes. It would be nice if this batch wasn’t so crumbly like the first batch for sure.

Time To Pour

Well now we know eight quarts equals soupy. This time all it takes to fill the form is to shovel the mix into it. No working the mix into the form is required. It’s certainly hard not to be sloppy though! Each shovelful fills about two brick “slots”. Screeding the mix toward the next empty slot helps to level off with the top of the form.

It helps to angle the shovel toward the middle of the form to keep from pushing the excess mix over the edge and onto the driveway, but there’s no amount of careful that can prevent even a little spillage. We’ll wash that away with the hose when we’re done. It also helps to turn the mix over a few times before the next shovelful to keep the water from floating up and separating from the mix.

It’s about this point I remember I never sprayed the form with WD-40 as a release agent, even though I reminded myself twice before starting. Oh well. Too late now! Guess we’ll find out how much we really need a mold release agent. Hopefully it won’t cause too much trouble.

Once the pour is complete, it’s time to clean off the driveway, starting with shoveling the excess mix off of it. Next is a good wash down with the hose to push any remaining concrete off the edge of the driveway, carefully avoiding the fresh pour.

Now We Wait

Nothing left to do but wait for the pour to setup enough to remove from the form. Because the first pour was so crumbly, we’re waiting longer than a day. Besides, it’s way too hot the next evening to even think about doing anything with this latest pour. I do saturate the concrete with water to help keep it hydrated, but it will have to wait until tomorrow.

I was curious to see if the lack of a mold release agent will keep the concrete from pulling away from the sides like it did the first time. I was surprised to see that not only did it NOT keep the concrete from pulling away from the sides, it actually caused a jagged separation line, like part of the concrete wanted to stick to the sides while the rest pulled away from it.

It’s disappointing to say the least. I’m wondering if maybe I should have worked the mix into the form better. Maybe the mix didn’t fully fill the form, leaving it weak enough to separate in that jagged fashion. Doesn’t quite explain why it did it along one side and not the other though.

Mixed Results

Noting the telltale cracks above the dividers, it’s time to release this batch of bricks from the mold. Taking most of my lunch hour to remove them, I drag the form through the gate onto the back stoop, where I can sit and work on it. The bricks fall right out of the form one by one, splitting cleanly along the crack at the dividers without fail.

But I find another problem related to the lack of a release agent. While the bricks may be popping right out, the 3D printed molds are sticking to them like glue. For the most part, the dividers pop off without issue. All but two. Those crack along the ear on one or the other, snapping apart at the ear that’s still stuck to the concrete.

It takes quite a bit more force to pry those 8″ molds loose from the concrete though. It acts like a vacuum tight fit, where once the seal is broken, the rest of it peels right off. But even those suffer damage from overstressing the glued joints, often splitting the joint, sometimes for the full length. A number of them are now separate pieces again and will need to be reassembled.

Better Results

While these bricks are crumbling along the jagged separation line, they are NOT crumbling anywhere else. The bricks from the first attempt would have broken with the amount of force it took to remove the molds from this time. These bricks have much more strength. They’re holding up well to the strong arm handling.

In fact, they’re resisting my attempts to trim where the dividers didn’t quite reach the top of the form. That’s one change we’ll be making for the batch. I’ll need to print a couple of replacements for the broken ones anyway.

Another thing that worked quite well was the placement of the dividers and they stayed where I put them. Not working the mix into the form with the brick trowel seems to have saved us from having misshapen bricks. They also peeled right off with the bricks and didn’t require removing the sides of the form like the first batch.

The best part is the 100% yield! All 12 bricks came right out of the form and none of them are cracked or broken. I can even read the writing from the embossed text on the dividers! Round two is a success! We’ll give them the rest of the week to cure and put this idea to the test.

Time To Lay Bricks

Well, almost. First we need to clear a path for the bricks to sit on. The two concrete blocks with the chunk of 2×6 across them is to protect the puppies’ paws from the sharp ends of the track. We’ve been losing ground lately with three puppies pounding things to pieces, having to remove more and more track to keep it from getting damaged and them from getting hurt on what’s left.

In fact, all that’s left are the stringers that survived where the track used to lay. This “experiment” is meant to mitigate that damage and provide a means to protect the track and the pups. Time to pull the stringers out of the way and replace them with the roadbed bricks.

It only takes removing a few screws and the first stringer is free, after releasing it from the join with the next stringer of course. Now we need to lay out the bricks and cut the turf along the edges to make room for them. But first we need to rake all those leaves out of the way!

A leaf blower will just make a huge mess everywhere and a big rake won’t fit, so it’s a good thing we have a “mini” rake that’s about as wide as the bricks are. It makes quick work of moving just the leaves we want out of the way. Pretty handy. Not our first either. IIRC this is our third.

Bumps In The Road(bed)

Anyway, time for the Dremel saw. It does an adequate job of cutting the turf without much effort. If there is a single complaint, it would be the lackluster locking mechanism for the foot. It’s a flip / twist handle that gets cinched down to lock the foot and set the depth of cut, but the damned thing is at its end of travel before it actually tightens, constantly coming loose!

It would do a great job if the depth of cut didn’t need constant attention. You may think you’re cutting, but guess what? That damned foot is once again set to not cut at all! This time it’s taking two, three, even four tries to get a cut, and the cuts are now crooked and ragged. But enough “belly aching”, it’s just another unnecessary annoyance due to poor quality control.

Part of the problem is uneven terrain and cutting along the edge of the bricks, laid out in the circular pattern where they’ll sit. That uneven terrain is also causing an “elevation” problem with the first few bricks after the track leaves the 4×4 roadbed. The problem is twofold. First is having to make up for the height of the 4×4 itself and second is the 4×4 is sitting proud of where it should.

You can see how the track is dangling off the end of the 4×4 in the picture above. Those PVC pipe risers were also in the way and have been removed. Because the first batch of bricks is so crumbly, it begs the idea of crumbling them into “rubble” to restore the elevation needed.

Rocket is helping too, making sure to pace me by “pestering” me to throw the Jolly Ball… Constantly! But that’s okay. He didn’t get much play time this last week because we’ve been so busy with the latest “emergencies” at work. “We must overreact immediately!” comes to mind. Can’t wait to retire and kiss all that constant chaos goodbye!

On the plus side working remotely still has its advantages. After all, I was able to spend my lunch hour to get these bricks out of the form and ready to work with now. We get to stay home with the pups so they don’t have to go to “Doggy Daycare”, and we still get to play with them during the day, even if it’s not as often as they’d like.

Crumbling Infrastructure

What was originally a disappointment is quickly turning into an advantage, an opportunity to use those crumbly bricks in a way they were not originally intended. Where’s my hammer? My favorite place. Somewhere. Oh well, hopefully the “mini” hammer will do the trick. Let’s finish the job of crumbling them into rubble.

The idea is to crumble them the rest of the way and use them as fill to make up the height difference at the end of the 4×4 roadbed. One won’t be enough. Turns out even two isn’t enough. Three? Nope. More. In the end, all but four of them are pulverized to become fill beneath those four that remain. But not all at once.

I start with a first course of crumbled bricks, spreading it even and level until more is needed. Then start the next course, levelling it, and so on. As I sit there pounding those bricks into rubble, I continue to test fit until pleased with the progress.

One thing’s for sure, that 4×4 needs to sit down in the ground at least another ½”, if not more. The track doesn’t like bending over the edge of that 4×4 much. Side to side, sure. But not a sudden drop of ½” or more. A concrete block coerces it into position for now. Maybe the tie strips can be adjusted to leave an opening so the track will sit down over the end of the 4×4.

Lessons Learned

• DO NOT FORGET THE MOLD RELEASE!
• Tamp the mix into the form with the shovel to ensure complete fill, then screed.
• Vibrate the mix to remove trapped air and eliminate gaps.
• Make the dividers extend all the way to the top of the form (redesign).
• Increase the font size for the end marks or just assume one size fits all?

The first two are fairly self explanatory, plus I covered them earlier. What I didn’t cover was the amazing amount of detail the wetter mix captured. I can see the layer lines from 3D printing the molds in the concrete! The only thing that spoils it is air bubbles and “inclusions” where the concrete didn’t quite fill the gaps. Need to try vibrating the form once tamped and screeded next time.

Making the dividers tall enough to meet the tops of the 1×4 sides of the form should avoid having to snap off the jagged excess by hand to make the ends flush. That means a redesign of the divider model then printing more with the new STL. Some of them broke and need replaced anyway.

While we’re at it redesigning the dividers, it’s time to think about a one size fits all approach. Rather than having bricks of varying degrees of curvature and having to stock many different types, including tangent, why not have one that can be used for everything? The difference between the various curves is at most 3.75°, so a small gap one way or the other will barely be noticeable.

Another bonus is tangent track can be accommodated by alternately rotating the bricks 180°, such that the angles point left, then right, alternating to effectively create a straight section. If you look close in the picture with Rocket inspecting things, you’ll see I had to do that in a few places to help adjust accumulated error in the curvature, a straight section as part of a curve.

More to come, so stay tuned.

 

 

 

 

We finally threw in the towel! Using wood stringers as a roadbed is just not working out. It’s been one thing after another using wood. The first setback was rot. We finally found the answer to that, but the next thing was keeping the track fastened to the stringer – with a couple puppies constantly pounding on it. Even adding screws every 8″ didn’t help! We now have track with much larger holes in the ties where the screw heads pulled through them.

Fast forward. We’ve added yet another puppy to the team, Jasper. Alright, three full sized German Shepherds! None of them are little puppies anymore. We were barely keeping ahead of things with two puppies pounding the track into the ground. But now we’re fighting a losing battle with three, we’ve been removing track, not adding it. And that’s moving in the wrong direction!

Concrete roadbed should certainly hold up to the constant pounding, if sidewalks and driveways are any indication that is… Beyond that, the idea is to shape the concrete with a center depression, a “well” of sorts, that will “cradle” the track. The only question left is whether molding roadbed bricks will work better than forming concrete then screeding the profile.

After all the trouble we went to on the forms for the trial version of casting concrete roadbed, only to be thoroughly disappointed with the results, we’re hoping the roadbed brick approach will be more successful. This time around we’re counting on the forms to produce a much more defined profile and a better defined well for the track to sit in.

The Design

The molds are all 3D printed a “standard” 8″ in length, with a ballast profile. A picture is worth a thousand words. At the top of the diagram are the individual parts on the right and how they are assembled into a casting mold, or form, on the left. At the bottom are the “dividers” for the various diameter curved segments.

The molds are designed with the deep well profile, the center part of three. The other two are meant to emulate a standard ballast profile. The three parts are glued together, held in place with three of the “assembly jigs”, seen beneath the assembled 8″ brick mold. This assembled mold consists of a 2×6, with sloped 1×4 sides, and the assembled 3D printed parts set inside the “U” shape formed by the lumber pieces.

The dividers are designed for the three different curved track segments we use, 10′, 14′, and 20′ diameters. Each has a different angle and number of segments for the associated diameters and there are left and right version for each diameter. You can see the text slightly raised above the divider body, and mirrored so as to emboss the brick casting correctly. Can’t wait to see if it works.

The relationship between the three designs for 10′, 14′, and 20′ diameter curves are shown in comparison below. A quick explanation will help to understand the information it contains. Obviously the arrangement of the bricks into the three different curves demonstrates the 8″ segmentation, but not so obvious is the arrangement with respect to the track segments.

The Explanation

Note there are two angled guidelines. One is 22.5° with respect to horizontal and the other 30°. These angles are related to how many track segments required to complete a circle of track. For 14′ and 20′ diameter circles, 16 pieces are required, 22.5° per piece. The 10′ diameter circle requires only 12, 30° per piece.

Let’s look at the 10′ curve to begin with. Counting the number of bricks required to complete the curve to the 30° mark, we count four. Observe that while the nominal size is 10′, it’s really 59.055″ because Aristocraft decided to try to stay compatible with European track makers. Doing the math, one of those track segments is ~30.92″ long, just shy of 32″… That’s roughly four 8″ bricks.

If we round off to ~31″, we need to lose roughly ¼” per brick, making them 7¾” long. Note that these dimensions are along the centerline of the circle. Adding the extra 1¾” to get to the outside edge of the ties is ~31.84″, which rounds nicely to 32″.

Now consider the 14′ diameter curve. This time we’re using the 22.5° guideline to count bricks. Again four are required for a single segment of track. And again, it’s not really 14′, but 82.677″. That yields a length of ~32.467″, again roughly four 8″ bricks, only this time we add about 1⁄8″ to each brick.

The 20′ (118.11″) diameter curve is similar, using the 22.5° guideline except now we count six of those 8″ bricks to match a segment of track, ~46.382″ in length. Again we subtract roughly ¼” per brick, making them 7¾” long. By now it should be abundantly clear why the 8″ length was chosen.

The Decision

If all that math hasn’t turned your brain to mush, the key point is all the bricks are roughly the same length, with roughly the same angle on their ends. The angles range from 3.75° to 7.5°, but they must be halved to obtain how much the end angle diverts from perpendicular with respect to the centerline. It’s 1.75° to 3.75°, which is large enough to be discerned with the naked eye.

So let’s start with the 20′ bricks, the ones with the smallest end angle of 1.75°, and see just how noticeable it is. While the picture shows an independent 8″ mold for each brick, a more practical approach starts with an eight foot or ten foot long 2×6, and matching length 1x4s. The ten foot length is preferred since an 80# bag of concrete mix will just fill it, give or take.

Unfortunately all we have on hand is eight footers, but that just means a bit of wasted material, roughly three bricks worth. The thought is to attach the 1×4 sides in a sloping fashion to provide enough draft that the casting will slide out of the form. The 3D printed ballast profile has a built in draft angle spacer effect, this is it’s slightly wider than the 2×6, which should cause the 1x4s to splay out by just enough.

Sounds good anyway. In practice, putting this together demonstrates how imprecisely everything actually fits. Every single piece of wood is warped. Trying to precisely fit the dividers at the precise angle is an exercise in futility. At this point, those 3D printed parts are held in place with hot melt glue. The main 8″ piece gets a dab in all four corners and the dividers get a bead along both edges. That rechargeable hot melt glue gun sure did the trick though!

The Pour

The directions call for 3 quarts of water for the entire 80# bag. Despite using one of the measuring buckets to dispense three quarts exactly, the mix is too dry. Adding another quart results in a mix that’s still too dry. Not quite another quart and now the mix seems too wet. This time I used the correct (read larger) mixing tub and still manage to spill some of the mix over the edge.

Oh well, I’m more worried about getting it mixed and tamped into the form, which lays across the driveway just outside the gate. About the only place I can put it that’s pretty much level and leave it sit for a few days. Tamping the mix into the form then screeding it off with the same square shovel floats quite a bit of moisture from the mix.

I should mention I liberally sprayed WD-40 over the entire form as a mold release agent before mixing the concrete. Continuing to shovel the mixture into the form until it’s full, the extra goes in the spot along the drive where the old well used to be.

There’s quite the story about having the trees removed from the Barkyard and the crane’s front wheel “falling” into it up to the axle. We filled it in with chunks of the trees and old scrap concrete and whatever was available at the time, but over time it’s slowly settled, leaving a void beneath the edge of the drive.

The Cure

I think my phone is messing with me. I’m pretty sure I took pictures of the pour right after and the next day. Guess what? No pictures! GRRR!!! Looks like I need to get in the habit of checking afterward. Seems like this isn’t the first time it’s happened either. Guess I’ll have to describe what I saw…

Just hours after the pour, the edges had shrunken back from the sides of the form already! That seems odd. It’s definitely unexpected. The next morning, I noticed thin cracks had formed above the divider locations. At first I was worried they didn’t stand quite as tall as the 1×4 sides, but figured the stress on the small amount of concrete would make it easy to split the bricks apart anyway.

Removing one of the sides of the form later in the day, I noticed the concrete itself was still quite crumbly, more unexpected oddness. I did expect where the concrete seeped through the cracks would be weak, but not the entire brick. When the brick on the end started to crack and split into pieces trying to remove it from the form, it was decided to use a different approach.

Perhaps just rolling the entire form over with the other 1×4 side still attached would give them more support and aid in removing the entire form all at once. Considering how some of the dividers stayed with the wood and tried to pull the bricks alongside with them, that was probably a mistake too.

All in all, nine of the twelve bricks survived the rough handling. Two of them pretty much crumbled when exposed to any sort of stress. Another split along the entire length at the edge of the well. The “crumbles” got thrown in the spot along the drive where the old well used to be on top of the extra concrete.

The Result

While 100% perfection was not the expectation the first time through, a 75% yield of lesser quality, low strength bricks is less than pleasing. Worries that too much water was used soon turned into questioning whether not enough water was added, leaving the mix dry and crumbly.

If you’ve ever seen one of those videos where they compare the strength of “dry cast” concrete, tamped in the forms dry, then wet afterward, to casting already mixed wet concrete, the bricks had the strength of the dry cast method. Hopefully it’s as simple as that, mix it “soupy” next time and compare the results.

Perhaps a slump test would prove more useful, but it’s easier to just measure out the same amount of water per 80# batch and go with that. Once the magical amount is known that is. Nick says mix it soupy, so soupy it is for the next round.

The dividers sticking is another issue to be dealt with. A redesign may be in order both to help better align them without the need for tools and to eliminate the need to hot glue them in place at all. Aligning the divider angle within the accuracy of even a few degrees is difficult without some sort of alignment tool.

Hot melt glue is the quick and dirty method of “loosely” assembling the mold parts into the forms. There were a few that had too much hot melt and refused to let go. Clean up is a pain too. Normally the blobs of hot melt will pop right off with a bit of persuasion. Too much persuasion for wet fingernails!

The Comparison

As far as the amount of work involved, the most work is mixing up the concrete by hand with a shovel, but that much is required using either method. Let’s compare the two methods, which takes more work, and the pitfalls of each, starting with the trial version first.

By far the method involving the most work is setting the forms in the ground and screeding the profile into the wet concrete. It takes days just to get everything formed proper and level for pouring. If the mix is too dry, we know using a screed tool won’t work, it needs to be a trowel. And that trowel’s a guess since it hasn’t been tried. If the mix is too wet, the profile will slump regardless of what method is used to create it.

Using the casting molds approach is much simpler to prepare for pouring, using a dab of hot melt glue on each of the four corners to hold the mold to the 2×6 form base. A couple more dabs of hot melt to hold the dividers in place and we’re off to the races. The best part is the only screeding required is to level the top of concrete with the sides of the form.

As far as pitfalls, the formed in the ground method is almost as much of a pain to disassemble and it was to assemble. The form slats are held to the stakes by one small brass screw, removed one at a time, the same way they went in. Granted, disassembly can be accomplished in hours compared to days to assemble. At three days for every ten feet of right of way, it will take forever to finish.

For the brick molds, it takes a few hours to clean them up too, washing away the remaining concrete residue and removing all those hot melt globs. Those raised letters are nearly impossible to read. Vibrating the form may have helped alleviate some of the small voids and filled in around the letters more, but just working the mix into the form with the shovel did a pretty good job otherwise.

Next Steps

The advantage goes to the brick mold. Those parts can be turned around and assembled into a form ready to reuse in about an hour. The first thing to try is a wetter mix, perhaps even vibrating the form too. If that fixes the voids and the strength issues, then maybe a few tweaks on the dividers. It would be nice if they were thicker and snapped in place instead of needing hot glued.

 

 

 

 

 

 

 

We finally threw in the towel! Using wood stringers as a roadbed is just not working out. It’s been one thing after another using wood. The first setback was rot. We finally found the answer to that, but the next thing was keeping the track fastened to the stringer – with a couple puppies constantly pounding on it. Even adding screws every 8″ didn’t help! We now have track with much larger holes in the ties where the screw heads pulled through them.

Fast forward. We’ve added yet another puppy to the team, Jasper. Alright, three full sized German Shepherds! None of them are little puppies anymore. We were barely keeping ahead of things with two puppies pounding the track into the ground. But now we’re fighting a losing battle with three, we’ve been removing track, not adding it. And that’s moving in the wrong direction!

Concrete roadbed should certainly hold up to the constant pounding, if sidewalks and driveways are any indication that is… Beyond that, the idea is to shape the concrete with a center depression, a “well” of sorts, that will “cradle” the track. The question now is how deep of a well and how to screed and shape the concrete. A picture is worth a thousand words.

Choices

There are two choices that must be made. The first is whether to make the well as deep as the track and the ties are tall or only as deep as the ties. The second is whether to form the roadbed then screed the well into the freshly poured concrete or cast “bricks” that can be placed independently once cured. At the bottom center of the above diagram is the deep well profile “screed tool”, with the “only ties deep” version to the right of it. Above them are the “bricks”, along with some dimensions. That particular set is designed for 20′ diameter curves.

Let’s start with a continuous formed pour with a full depth well. Had we known how much work… Well, the work to “trench” out where either the forms or the bricks will sit is a wash, but the forms themselves take days to “perfect”. Essentially we want the track to be about flush with the terrain. That requires a thickness of at least 1½”, with roughly a ¾” deep well down the middle. It may not be readily apparent, but the profile we’re shooting for has a taper at the top, away from the well, to simulate a prototypical ballast profile.

Getting Started

But before all that, we need to cut out a stripe in the artificial turf roughly 6″ wide that follows the path of the existing wood stringer first. The Dremel saw with a plastic “blade” makes fairly quick work of that task. The before and after shots show the recent relocation of the lower loop track, sitting atop the turf, and the new path awaiting installation of the forms.

 

 

 

 

 

 

 

You can see a start of staking out the forms using the 2×6 roadbed pieces we used to “elevate” the new middle loop track up off the deck. These are a perfect fit for spacing apart the ¼” thick x 1½” tall slats we’re using, attached to 8″ stakes “strategically” driven into the ground. This is just a test fit of sorts. The track is roughly at the desired height, but the forms need to be installed lower such that the top of the rails is even with the tops of the forms, a difference of ¾”.

After filling a yard cart with the dirt removed along the 10′ stretch we’re pouring concrete into, the real work of installing the forms begins. It’s taken a day’s work to get this far. It takes another day just to get all the stakes driven in the ground and the slats bent into shape. And yet another day to attach the slats to the stakes! It’s all adding up… Three days for every ten feet of roadbed means it’s going to take forever to replace the exiting wooden roadbed.

Regardless of the time spent getting here, we’re finally ready to pour concrete, starting with mixing. The directions call for 3 quarts of water for the entire 80# bag. Despite using one of the measuring buckets to dispense three quarts exactly, the mix is too dry. Adding another quart results in a mix that’s still too dry. Not quite another quart and now the mix seems too wet. At this point, I’m winded from all the mixing by hand using the shovel. It doesn’t help that I’m using the small mixing tub, which is obviously meant for 60# and not 80#.

After shoveling about three feet or so into the forms, I try to screed the profile using the 3D printed tools, but they’re just not working. It seems the tools would have been better designed like trowels to better float the profile into the pour. The tools are crudely scraping the profile more than smoothly forming it. Even working the tool back and forth like a simple screed board doesn’t seem to do much better.

So far this seems like a losing battle. By the time the entire ten foot length is poured, the only thing that worked as planned was the amount of concrete needed. I’m more than a bit discouraged by the outcome, but way to exhausted to do anything more than cover the fresh concrete to keep the pups out of it. We’ll see how it turns out tomorrow when we can remove the forms.

The picture tells the story. It’s obvious that the profile we were looking for did not materialize. It’s a crude approximation at best. Thankfully the track does fit in the well, but not very well. The sides that are supposed to protect the track and hold it in position are crumbling at the slightest touch. Removing the forms breaks large chunks of the sides loose. Not a good first impression to say the least. By now the meaning of trial version is apparent…

Stay tuned for more updates. A change in plans is definitely called for though.