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A lockdown project: Building a laser-cut folding DCC test track which doubles as aThomas layout for my children


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My wife has prompted to start this thread, as she has encouraged me to share my efforts.  She isn't normally interested in trains, but she likes this project and she thinks others may find it interesting too. But first a little background.  Please feel free to skip to the next post if you just want the modelling.

 

Background

 

Since mid 2018, modelling has taken a distinct back seat in my life. My home layout went into storage in the UK.

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It's in there somewhere.

 

Then we moved to Australia, including the 3-month old.

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We must have been mad - the jetlagged children certainly nearly drove us insane.

 

And after we arrived there was a lot of flatpack furniture to build, and not much railway.

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I have lost track of how many free allen-keys I have. And how many days of my life were spent using them that I will never get back.

 

Although I tried to do some modelling, by building a lever frame, it ground to a halt (you can see my very limited progress on my thread "Garelochside" here on RMWeb. It's really not so much of a thread as a loose end. One day I'll finish it).

 

As I think many enthusiasts my age find, between a full time job and a full time family, there isn't much time for modelling. When I do get some free time I try to keep vaguely healthy by doing a bit of running and cycling (although never enough). I can't really complain - Australia is an amazing country, and we're very lucky to be here.

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And so life went on. This is the type of modelling I've been doing most of

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Any resemblance to a modified Minories is purely intentional  - I like to sneak classic designs into the kids games when they aren't looking! :-)

 

But then, of course, COVID happened, and our return to the UK, which had been planned to take place in the middle this year, got delayed. Amongst all the other, far more serious implications of everything going on, I got homesick, and I missed my railway, so I started to think about a project that I'd had in the back of my mind ever since getting here.

 

To be continued...

 

 

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The Plan

 

Although I had left all my models behind in storage in the UK, I hadn't been able to resist buying a few new releases like a Hornby J35 and another Bachmann Class 37 (the Mickelover MRG limited edition 37026). I'd sneaked a Sprog DDC to USB connector into my bag on the plane, and I had JMRI on my laptop, so I wanted a test track for me to be able to test run my new purchases. It had to be a simple layout, and only 1 (or max 2) engines as the current output of the Sprog is only 1 amp so it wouldn't have enough power for anything complicated. I also wanted continuous run, so that I could get things up to speed and play with the CV values for acceleration and braking. Set-track has the advantage of being easily available, quick to lay, and of constant, predictable geometry, and protypical accuracy was not a concern, so that's what I went for.

 

So, my first idea was just a simple circle of R3 track, on an unbraced piece of plywood that I'd just lean against the wall when not in use. Not a layout, only a slight upgrade from laying track temporarily on the carpet.

 

Then I thought that it could double as a Thomas layout for the kids. By adding a loop and some very basic scenery, they would get some play value out of it. So the second iteration was a slightly ovoid track plan, with a passing loop. That then made me think about adding some bracing, and I also wanted to try out laser cutting of boards, but I didn't want to build legs, and it had to pack away compactly for storage and eventual move back to the UK.  Because a braced board would be too big and cumbersome to be in one piece I tried to make it into 4 identically sized and shaped square boards - that way I would only have to draw up one CAD file for cutting, and get 4 copies made. I drew it in Anyrail below. The 2 sides of the track plan are slightly different as I was trying to find a neat combination of set-track pieces:

 

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Several more iterations brought this track plan, giving up on the 4 square boards idea and going for 2 rectangles instead, which made the track planning easier, and with an extra siding to allow 3 vehicles on each train for me, and more play value for the kids.

 

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 So then I played around and thought - what if instead if having bracing under the boards, I built the railway into a box and had it going through the bracing which was also the sides of the box?

 

So I sketched this:

 

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It's pretty crude, but I hope you get the idea. The roadway would add stiffness, and also provide additional play value for the kids.

 

Obviously a pretty key thing to get right would be the loading gauge: too small a hole and I'd get a lot of damage to expensive models, too big and I'd lose stiffness in the box structure. So I did some measurements and drew myself a diagram.

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So now I had a plan, I then decided I needed to prototype (in the engineering sense rather than the modelling sense) my ideas, which will follow in the next post.

 

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The engineering prototype

 

I decided to do a 400mm square box as a test of my ideas. It would enable me to test my structure gauge, how my corners went together, and also just the general ease of drawing up files in my chosen design programme (QCAD - usual disclaimer, no links just a happy customer), getting quotes and how long they took to deliver.

 

This is the way I laid out the drawing first off... showing all my workings and cheat lines. Red are cut lines and blue are etch lines.

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I then removed everything extraneous leaving just the cut and etch lines, and juggled everything around to fit onto a single sheet of ply for cutting.

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I emailed it off to 3 different local (or local-ish: Australia is a big place!) online laser cutting companies, 2 of whom replied with quotes, and I accepted one of those quotes, paid my money, and waited. A surprisingly small number of days later my flat-pack parcel arrived. Unfortunately I didn't get a picture of the parcel before construction, but I was very pleased with how well it was protected for transit, and with their cutting which looked clean and accurate.

 

I couldnt' resist getting the pieces out on the kitchen table and trying a dry assembly. It went together very well, and with almost no mistakes which pleased me no end! :-)

 

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I took some photos of it just dry-fit together and still with the protective tape over the wood.

 

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The roadway worked very well to stiffen the structure, which was pretty rigid for 6mm ply. Assembly highlighted the fact that I need to think very carefully during the design phase about the order in which the pieces would go together, as there was a distinct possibility I could accidentaly end up with something that was impossible to assemble.

 

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The structure gauge seems about right as well. No sideswipes or taking the roof off.

 

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FInally I had done a little test piece to check the kerf on their laser so I could tighten up my tolerances on the final build.

 

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Overall, I was very pleased with the prototype. It wasn't particularly cheap, but it absolutely acheived the aim of proving the design and build process, it was fun to do, and it gave me something satisfyingly concrete to experiment with. At some point it would probably make a good diorama to improve my scenic skills, but that is a different project for a different rainy day.

 

Next stage would be the full size design, which I will write about next time. As encouraging as my wife is of my hobby, I think she wants me to stop messing about on the computer now as it's late. Goodnight all.

 

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Design evolution

 

Having proved my prototype, I started working on the final full size design which would be 2 halves of approximately 600 x 1100mm (2 foot x 3 foot 7 inches).

 

I hate to think how many hours I spent on producing CADs - It's not a skill I use regularly, so it was slow and involved quite a lot of re-work getting the detail design correct. I think we watched quite a few series on Netflix with my wife knitting and me with my laptop on my knees moving lines around on the CAD. It helped the evenings go past when COVID killed our social life. This is one of the earliest versions I have saved, and shows the basic plan pretty much unchanged from my sketch in the post 2 above.

 

One of the changes I made pretty early was to change the thickness of the long side pieces from 6mm to 12mm to give additional stiffness as I was worried about bending along that long axis. The roadway in the middle provided a nice stiffner to prevent twisting and lateral bending, but only on one side, so this version I have saved shows an extension of one of the side-walls of the centre-right ramp to give a stiffner to the right-hand half. I also put a short flat "landing" on the ramp to make the joints at the board edge easier. The text in the middle is just a note to self - I like using pythagorean triples for the triangles in my designs, such as the ramp here, because it means all the edges are whole-number dimensions which makes verification of the design and cutting much easier.

 

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At this point, unfortunately, I realised I made a massive mistake: I'd forgotten to check that the laser cutting firms I'd found could cut the size of boards I needed for the main baseboard pieces. Neither of the ones who I was talking to could do it. Mild panic ensued... and some nautical language.  In the end I decided I would have to go back to my original idea of 4 quarters, albeit now they wouldn't be squares, and they wouldn't be identical. It did mean a lot of work to split the drawing and add the extra sides, plus a whole load of extra detail that resulted from the change. On the plus side, the finished boxes would be smaller and lighter for handling and storage, so it wasn't all negative. In retrospect I'm very glad it changed because I think particularly the right-hand board in it's original form would have been seriously under-braced and therefore not very robust.

 

This drawing shows the new arrangement, plus some extra details I added when I realised I would have spare material on the sheets after they were laid out for cutting, so I added a laser-cut platform for the station.

 

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This final image shows an example of all the parts laid out for cutting. It is an earlier version than the one above, and it shows how although I tried to get the parts onto fewer sheets, I just couldn't do it. In the end I filled some of the extra space with the station and extended road ramp shown above, and the remaining space with other projects.

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Because I wanted 2 different thicknesses of plywood, in the end I used 2 different companies to do the cutting - both provided a very good service with clear communication and help when I was laying everything out on their particular templates for their systems to read.

 

At this point I should mention cost. As a custom-cut, one-off design, this was NOT a cheap way to build a baseboard!!! One of the reasons I have done it is because the process of producing a computer aided design gives me a lot of satisfaction, and I enjoy the doing the detailed design work to get something that I am confident will work when it moves from electrons on the screen to solid material. I also wanted to try a new (for me) method of construction, that I thought could produce a high-quality, dimmensionally accurate and lightweight result. Even so, if I had got my full set of woodworking tools and power tools with me from home, I don't think I would have bothered: I would have gone with "traditional" sawn timber glued-and-screwed together with butt joints. But because the majority of my heavy tools were 16,000km away, I thought laser cutting would be cheaper than buying a duplicate set. Probably not, as it tuned out, but you live and learn, and by the time I realised the full cost I had invested too much time in the project to turn back, and we'd just received the refund from our cancelled family holiday so there was money in the bank account.

 

So I placed my order(s) and waited.

 

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Home Delivery

 

So while waiting for my laser cut flat-pack baseboard kits I gave the computer a break for a while and did a lot of this...

 

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And a little of this...

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But not as much as I'd have liked. :-)

 

The first package to arrive was the 12mm ply.

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Followed a few days later by the 6mm sheets. The courier was very interested to know what they were!

 

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The kids were excited to help me unwrap it, and I'm always happy to have them involved and to feed their enthusiasm.

 

 

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To start with they were more interested in one of the side projects, which was extra bridge supports/abutments for their wooden railway, so I set the eldest 2 up to glue some together.

 

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I couldn't resist getting all the peices together for one of the quarters and dry-assembling it just to see if all my joints worked, especially as until that point I wasn't 100% sure what the effect of different tolerances from 2 different lasers would be. Fortunately, it worked!

 

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That's all for tonight, but I'm telling this tale several months in arrears (I'm not his quick in real life) so there's more to come next time I can get some time on the computer. I hope it is of interest to some people. Good night all.

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