Experimental Plug Track: 3D-printed, CNC-milled, laser-cut

Martin Wynne

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@ralphrobertson

Hi Ralph,

Nothing is ever simple. :(

If you change the plug clearance you must then rebuild the templates with the new data. Click this button before exporting the file:

smaller_plug2.png


Which works, but reveals holes in the base of the chair:

smaller_plug1.png


Fortunately the online repair service will fix it (but might not if you submit a file with dozens of chairs):

smaller_plug3.png


I should have checked all this before my previous p.s.

I will get this stuff fixed in the next program update.

cheers,

Martin.
 
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Thanks Martin, I will try this out tomorrow. I have only been building one set of chairs anyway, it is easy enough to replicate them in the slicer software and that makes the repair quick and easy to do.

I will keep you updated with the result.

Ralph
 
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Martin Wynne

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It's clear that the timber-end sprue design is only practical for plain track and simple turnouts.

Within even the simplest pointwork formations such as an ordinary crossover, it won't work where timbers are interlaced or close together end-to-end:

index.php


It also increases the size of the timbering brick.

I wanted the full-depth sprues so that the filament printer can use the "combing" method to avoid stringing across open space. But that makes sense only for sprues on the the timber ends where they are easy to remove after construction and/or after tracklaying.

But if the timber side flanges are acceptable to be hidden in the ballast, then the same applies to more conventional timber webs, if they are not too thick:

sprue_webs.png


Such webs are fiendishly difficult to remove after construction without causing damage (unless you make yourself a tiny nibbler-type cutting tool, I haven't been able to find one small enough), and impossible to remove after tracklaying without damage (the knife blade forces the timbers apart).

But if they can be left under the ballast there is no problem. In any event the connector clips between the timbers will be even more difficult to remove and would have to remain under the ballast.

But there is then the question of providing some sprues or webbing across the 6ft way for double track, to create a timbering brick. It's very easy to add some links manually on the trackpad, but that would get tedious for a large track plan. Ideally we need an automated function to add such cross-template links, but it's not easy to devise.

And that still means finding some slicer settings to avoid stringing across the sockets. I couldn't find any. It could be easily avoided by writing the gcode manually. But I don't want to get involved in writing a slicer function into Templot on top of everything else, life is just too short. :(

A lot to think about, on what on the face of it should be the easiest part of the design.

cheers,

Martin.
 
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Hi Martin,
Personally I prefer the hidden web over the sprue and as you say once you have a flange that must be hidden then a web connecting this "to be hidden" layer makes no difference and it's less work to the builder.

Fair play to your perseverance!

Phil
 
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Hi Martin

Been trying various things out today and printed some chairs with the -0.5 setting and using the card sleepers I cut with a 3mm x 1.5mm socket here is the result so far.
20210802_163326.jpg

The chairs have just come out of the printer so they aren't very strong and they are not glued down only placed in position. The gauge is wrong by 1.5mm which I will change on the cutting of the timbers. The resin is Elegoo water washable which has not really worked with the card sleepers when they are still wet from the ultrasonic cleaner and one of the chairs has a jaw broken away. I am quite pleased with the outcome and will continue to do some trials to see if this is going to work for me.

I have exhausted the Elegoo water washable resin and have some other Anycubic stuff around which I can try but I am thinking I need something stronger - any ideas please?

Is this the right place to post this or would you prefer me to post it on a thread somewhere else?

Ralph
 
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Martin Wynne

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@ralphrobertson

Hi Ralph,

Many thanks for posting -- looking good! :)

Is this the right place to post this or would you prefer me to post it on a topic somewhere else?

Yes please, keep posting here.

I'm glad the size reduction on the plugs worked out. Ideally they should be a press fit in the timber sockets and don't need gluing. Did you increase the plug depth to the full timber thickness? I think I have given up on the blind sockets.

I have exhausted the Elegoo water washable resin and have some other Anycubic stuff around which I can try but I am thinking I need something stronger - any ideas please?

I'm using this "ABS-like" resin which is tougher than the standard resins:

https://www.amazon.co.uk/gp/product/B07P84PQCF/

but it's not water washable and needs IPA for washing:

https://www.amazon.co.uk/gp/product/B082XQ4W4R/

It has worked very well for the chairs:

index.php


I'm doubtful that water washable resin would be long-term strong enough for such tiny functional components? How well do they fit the rail?

Many thanks again for the report. (y)

cheers,

Martin.
 
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Martin Wynne

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This is Monday's idea for the timber webs:

new_timber_webs.png


They need to be wide enough for sufficient strength (they are very thin), and also to ensure they engage with the adjacent timber where the timber lengths differ (as on the right). Even so they won't have much vertical strength -- but don't need it if the timber base is to be stuck down flat. Their primary function is to hold each timber in the correct position relative to the next one.

Notice the complete lack of check rail chairs and crossing chairs! I'm itching to get back to the chair designs, but I just can't until the timbering bricks and webbing is finished, or at least usable.

What's the verdict? Is it going to be acceptable to bury this lot in the ballast? It would be fairly easy to do if the track is built in-situ and ballasted before plugging in the rails. More fiddly with the rails in place. But all ballasting is fiddly.

Now to do battle with the Cura slicer and see if the base can be printed without any stringing. It may help to add some sacrificial "islands" to the design, but as to where to put them -- lots of trial and error needed.

cheers,

Martin.
 
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Martin Wynne

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I tried printing that. After a lot of trial and error I found some settings in the Simplify3D slicer which produced reasonable results without the combing option, with no stringing across the sockets.

While it was still held flat on the (removable) build plate I scrubbed it with a stiff brush which removed most of the remaining stringing, and gave the timber tops a rub over with a Garryflex block to smooth them (Simplify3D doesn't have the surface "ironing" function available in Cura). Followed by a wash to remove the sandings.

This is EM:

timber_webs_raw.jpg


As you can see, the bottom flanges/webbing layers are very scruffy, but fortunately they would be buried in the ballast. The visible timber tops are much better, but would benefit from a wipe over with some filler in places. I don't want to increase the printer fill density because it just causes more risk of stringing.

The chairs were a good press fit in the sockets -- I gave it a scoosh of grey primer to see the chair detail:

timber_webs_grey.jpg


All in all it looks promising and quite good at normal viewing distance -- these are cruel enlargements for EM. Certainly better than the last time I tried without combing, which was an unusable mess of stringing. Which is why I went initially for the full-depth end sprues. I shall leave that option available for where it can be used, such as on plain track.

But for pointwork I think these buried timber webs will work. Once removed from the build plate it feels quite flimsy, but it has a good smooth base for sticking down flat to the trackbed for construction.

Getting there slowly. :)

Martin.
 
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Wonderful. Here's a question from left field... would it be possible or even make sense to be able to print the cant or camber (or whatever the proper term is) of curved track rather than having to insert shims under it?
 
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Martin Wynne

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Wonderful. Here's a question from left field... would it be possible or even make sense to be able to print the cant or camber (or whatever the proper term is) of curved track rather than having to insert shims under it?
@murphaph

That's an interesting thought. The printing is feasible, but at present Templot track design is 2-D only at the rail-top. There would be a lot of work to introduce a 3-D element into the track design for canted track. That will have to go on the NOD list (nice one day). :)

Or maybe a project for the T3 folks?

cheers,

Martin.
 
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Martin Wynne

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Handy Hint:

If resin-printing the chairs, it's handy to snip them from the support slab at the base of the support pyramid, not the top. You then have something to hold while threading the chair onto the rail, making it quite a bit easier to do. The pyramid can be snipped from the chair after it is on the rail. (It will fly to the far corner of the workshop and never be seen again.)

In fact it might be worth increasing the height of the pyramid to make it easier to hold, at the expense of a fraction more wasted resin. The setting for the pyramid height is on the chair/socket fit... button. The current setting is 2.5mm.

The Elegoo printers come with a genuine pair of Xuron flush cutters which are ideal.

cheers,

Martin.
 
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Martin Wynne

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The DXF dialog is getting out of hand. I have had to increase the size again to fit in some new controls:

more_dxf.png


When the development is finished I will reduce the size by using option tabs. In the meantime if you are using a small screen and it doesn't fit, you can shrink it by clicking the up-arrow at top-left.

cheers,

Martin.
 
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I bought some new resin and printed some S1 chairs. Very happy with the result of printing chairs despite using default settings, quality can be improved if I want by increasing the number of layers printed. Changed the plug size to reflect cutting a socket in some shellac soaked card sleepers using 1.5mm good quality (Daler-Rowney) mounting board. Then I glued the chairs into the timbers using 5 minute epoxy but I am not really happy with the result. I will do some more trials to see if I can get a better fit between the plug and socket before trying out the 3D printing of timbers. I do have a PLA printer but I far prefer the quality that comes off the resin printer and rarely use the PLA one nowadays. Also tried cutting some timbers in birch ply but my Emblaser just finds it too hard a material to cut easily. No problem if you have a much higher powered laser cutter but I avoid birch ply and always use poplar ply on the Emblaser if I need to use plywood. Sadly I haven't found a source of poplar ply in anything under 3mm thick.

Results of latest trials:
20210804_170921.jpg
20210805_091723.jpg
 
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Martin Wynne

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@ralphrobertson

Hi Ralph,

Thanks for the photos. Looking promising. I was hoping to try mounting board in the Silhouette cutter, but the thickness was beyond it. As for plywood, no chance.

Are you using the 2-D DXF for the laser cutter?
dxf_2d_timbers.png

You can then adjust the socket size to match your plug settings. You can also change the sprue dimensions. Use the generator settings to remove the timber extensions, do a rebuild after making all settings. You could add further webbing using rectangles in the background shapes.

The filament printer is great for jobs such as the filing jigs:

index.php


But detailed models in 4mm are beyond it, especially in the toughened PLA. Even in 7mm I struggled to produce reasonable chairs:

2_252113_110000000.jpg


The chairs were added in ordinary PLA using a smaller 0.2mm nozzle, but took ages to print. They were difficult to thread the rail through, and being ordinary PLA easily broken. For chairs the resin printer is the only sensible option.

The main or only advantage of the filament printer is the much greater work size, which is why I'm trying to use it for the timbering bricks. But finding the best settings to produce clean accurate sockets 2mm wide with no stringing across them is a challenge. Surface strings can be trimmed out (tedious), but stringing across the sockets at lower layers is a pain to deal with. There are so many options and settings in the slicer software that it could take months of trial and error to find the optimum set-up. But I'm confident I can get there in the end. I haven't tried the plug track yet in 7mm scale -- I'm sure it will work well, but require dozens of bricks for a pointwork formation of any size.

cheers,

Martin.
 
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Are you using the 2-D DXF for the laser cutter?

No, all my drawing use Coreldraw, something I have been using for all my drawings for over 10 years. The cheaper version I currently use doesn't support DXF although I do have an old version which does (stashed away on an old laptop somewhere which I can use if I have to). Here is the drawing I am using at the moment, socket size can easily be adjusted to what I need.

I will try some more tests to see if I can get the fit right.
No, all my drawing use Coreldraw, something I have been using for all my drawings for over 10 years. The cheaper version I currently use doesn't support DXF although I do have an old version which does (stashed away on an old laptop somewhere which I can use if I have to). Here is the drawing I am using at the moment, socket size can easily be adjusted to what I need.

I will try some more tests to see if I can get the fit right.
1628166029179.png
 
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Marsh Lane

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Location
UK
Martin,
Following along with what your doing here, and its all fascinating. Well done for persevering for everyone's benefit. As you know I dont have a 3D printer personally, but have access to a service that does and I am tempted to have a go for my narrow gauge option, with 3D printed sleepers and chairs.

Please keep going and posting your progress, I dont have the knowledge to contribute, but its fascinating reading.

Richie
 
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Martin Wynne

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The cheaper version I currently use doesn't support DXF

Hi Ralph,

Does it support EMF metafiles? For 2-D you could export those from Templot instead of DXF. I will check how much of the chair/socket detail is included in them.

cheers,

Martin.
 
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