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

Martin Wynne

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Yes, Coreldraw seems to support everything apart from DXF and DWG unless you pay for the full version at just under a grand.

Thanks Ralph.

Sorry, no chair/socket detail in the exported EMF at present. I have added it to the to-do list.

It might be better to add EMF to the DXF exports in addition to STL. Always something to think about. :)

cheers,

Martin.
 
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Builder of Finescale Signals in 2mm scale to 7mm scale, Trackwork, Turnouts and Layouts.
I have Coreldraw 12 which purports to import DXF DWG but I haven't managed it to date. I presume that because there are so many versions of DXF it's a bit picky.
 
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Martin Wynne

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I have Coreldraw 12 which purports to import DXF DWG but I haven't managed it to date. I presume that because there are so many versions of DXF it's a bit picky.
@Stephen Freeman

Hi Stephen,

After you select DXF in the file-type drop-down, you should then see a button or tab or link to Options or Settings or Setup or similar.

You can then set the required DXF version, which for Templot exports should be the oldest available.

There should be a setting for DXF imports somewhere in the software, because at the very least Coreldraw needs to know what units to use for the import -- mm or inches or whatever (DXF files contain no units information). For Templot exports the default file name contains "mm" or "in".

cheers,

Martin.
 
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I think the safest DXF exports are back in Versions 11 to 14 of the file which appeared during the 90s. I've just checked my version of NanoCAD and it has several versions going back to version 11 and the last time I used AutoCAD LT 2007, it offered a range of DXF export options going back to V12. I think the problems started in the 2000s when AutoCAD altered the structure of the DXF file to accommodate new features in their drawing software. I do remember discussions on newsgroups and email lists about DXF import problems from newer versions of the software and the advice at the time was use DXF V12.

Jim.
 
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Location
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Builder of Finescale Signals in 2mm scale to 7mm scale, Trackwork, Turnouts and Layouts.
@Stephen Freeman

Hi Stephen,

After you select DXF in the file-type drop-down, you should then see a button or tab or link to Options or Settings or Setup or similar.

You can then set the required DXF version, which for Templot exports should be the oldest available.

There should be a setting for DXF imports somewhere in the software, because at the very least Coreldraw needs to know what units to use for the import -- mm or inches or whatever (DXF files contain no units information). For Templot exports the default file name contains "mm" or "in".

cheers,

Martin.
Hi,
Works with Templot DXFs, previously I tried with a more modern version (I think) generated by Turbocad 2015 which didn't. I think the version of CorelDraw I have is quite old and any DXF file after 2003 is likely to be problematic for me.
 
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I have no connection to the company other than being a satisfied customer (of other items, I have no laser cutter) but somebody mentioned not being able to find plywood <3mm thick. I think. Anyway this company supplies 1.5mm thick "laser cutter suitable" ply:
 
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Martin Wynne

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If the quality of filament-printed timbers is not felt to be acceptable, there are other possibilities. :)

For example if the timbers were individually resin-printed, or laser-cut from plywood, it would be possible to filament-print a timbering fret, or "3D template" to locate them:
timbering_fret.png

For Plug Track the track gauge and rail alignments are set by the sockets, so the timbers need to be more precisely aligned than would be possible simply by sticking them on a paper template manually. But a 3D template such as this would provide the required precision. Depending on the thickness, it could be left buried in the ballast, or be removed from the underside of the finished pointwork in the same way as a paper template.

This option provides the quality and precision of resin printing for the timbers, with the much larger work area of the filament printer for construction.

And a very much larger work area would be possible if the Silhouette cutter could be persuaded to cut thick enough card to create such a 3D template.

If the timbers are being resin-printed, there is also the option to print them complete with chairs instead of sockets. This requires the rails to be threaded into the chairs from the end, rather than plugged in from above, but is feasible for simple formations.

I'm hoping that the DXF dialog will provide for all these options if wanted.

cheers,

Martin.
 
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Martin Wynne

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The DXF dialog settings allow several other options. For example:

half_chairs.png


In this case only the inner jaws are printed on the chairs, to provide the gauging and rail alignment. The prepared rails are placed in position and then fixed by gluing on separately printed outer jaws.

The half-chairs can be integral with resin-printed timbers, or plugged into filament-printed or laser-cut plywood timbers.

The outer jaws are going to be very fiddly to hold and apply in the smaller scales of course. But it would be possible to print holder/applicator tools for them in a rubber-type resin:


https://wanhao.store/products/3d-printing-resin-rubber-resin-1000ml-bottle

With several such holders to hand, the holders could perhaps be pinned or blu-tacked in place while the glue sets. A rubber holder could have small claws which engage in the space below the key to hold the jaw:
half_chairs1.png

Or several outer jaws might be printed attached to a positioning sprue, which could be trimmed or snapped off after the glue has set.

Always some things to think about. :)

The first one being, any suggestions for suitable glue?

cheers,

Martin.
 
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Martin Wynne

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It's almost certainly crazy to be thinking of separate jaws in the smaller scales. :)

half_chairs2.png

But it might work in 7mm and above.

The difficulty is not necessarily the small size of the jaw, but in holding it. But with a 3D printer we can make intricate holders and applicators, which might make it easier than it looks. For example a tool would also be needed to press the chair plug into the socket without having the rail in place to hold it.

I have added a peg and slot to provide a positive engagement, but with the screw-head in the way and needing to get the key under the rail head, it might now be impossible to assemble! But just maybe the jaw+key could be pushed down vertically, and the rail would tip over enough for the key to clip under the head -- without breaking the inner jaw?

In 4mm scale that peg is 1mm x 0.5mm, so it's tiny, but not invisible.

Just another option in the settings. I'm trying to keep in mind how things might work in the larger scales.

cheers,

Martin.
 
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I have spent the last few days refining the technique of making the latest Templot enhancements work for me. I realise that not everyone will have the sort of equipment that I have to hand but I wanted to see if the ability to 3D print chairs would work. The photo below shows that I have cracked making straight track, which for me is all I want, I am happy with ply and rivet turnouts and cosmetic chairs (I am modelling 18.83mm P4 track) but I don't want flexitrack for plain track and doing ply and rivet with cosmetic chairs can be a pain. I know this is a bit like making my own flexitrack but here I can control the gauging which in flexitrack you can't and past experience has shown me that the way flexitrack adjusts itself can sometimes cause major issues.

20210807_160603.jpg


The photo shows the first length of track I have made using this method. I have painted it but I will probably do some more work with the colouring to get a better representation of the prototype.

The method I used is a combination of 3D printing the chairs with a plug and laser cutting the sleepers with a socket. A lot of work was done making the plug and socket size correct but I think I have got that right now. The sleepers are cut from 1.5mm mounting board and shellacked to beef it up. The sleepers are then placed into the spacing jig and the chairs mounted into the sleepers. They are then removed from the jig and the next step is to glue the chairs to the sleepers from underneath using 5 minute epoxy (I will get some 20 minute epoxy to make this easier for me but I don't have any to hand right now). The glued sleepers are put onto a piece of celluloid to dry after which they can be peeled off and any excess glue trimmed off.

Once the glue has hardened the sleepers are put back into the spacing jig and the rail is threaded through the chairs. You might notice on the photos there is a small mark by one of the sockets on the white side of the card, this is a marker to ensure that all sleepers are put in the same way into the jig. Once the rails are threaded the completed track piece can be removed and the ends of the rails can be made to the right length and squared off.
20210807_110551.jpg

Shellacked timbers being inserted into the spacing jig


20210807_110916.jpg

Chairs being taken from the 3D print and pushed into the sockets on the sleepers. (A few stray pieces of resin to be cleaned away yet).
20210807_113050.jpg

A pile of sleepers with the chairs put in waiting gluing.
20210807_121810(0).jpg

The sleepers having the sockets glued placed on a sheet of celluloid until hard - the celluloid in this case is a clear binding cover sheet.
20210807_131316.jpg

The sleepers flicked off the celluloid sheet leaving dry glue behind and a pile of completed sleepers.
20210807_133554.jpg

The rails threaded through the chairs. One chair broke and one wasn't seated properly but otherwise I was pleased with the result.
20210807_160632.jpg

A closeup of the painted track.

Hope this inspires others to have a go, this is a fantastic enhancement to Templot Martin and thank you for adding it in, it will save me hours filing rivets and cutting chairs in half to glue on ply and rivet track.

Ralph
 
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Martin Wynne

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Its just out of curiosity but My knowledge of what to send is zero, as you know I have bought items from Shapeways, but they seem to be very expensive against other retail items I have bought, this from the UK seems it might be an answer and I guess it would be a good place to keep an eye on

Do they use the some material as you for the filing jigs please and is this something that can be downloaded now
@Hayfield

Hi John,

My knowledge or use of Shapeways is nil, so others will have to answer for them.

The filing jigs are FDM printed, not resin. The proposed new service on RMweb will seemingly include FDM (filament) printing:

https://www.rmweb.co.uk/community/index.php?/topic/166241-uk-3d-printing-marketplaces/

The polymer material I use is ESUN PLA-PLUS which is readily available, so I assume you will be able to ask for it. It's a toughened version of ordinary PLA. Many other polymers and equivalents are available and I would be surprised if some other ones don't work equally well.

At present you can create the file for a 1:5 code75 jig only. Full details of how to do it are at:

https://85a.uk/templot/club/index.php?threads/rail-filing-jigs-3d-printed.226/post-2022

At this stage that is purely a proof-of-concept. The intention is that you will be able to click on any template in Templot and create a filing jig for the exact crossing angle and scale of rail, in either bullhead or flat-bottom. Likewise switch filing jigs and rail bending jigs.

I wish I had a pound for every time I have written "the intention is...", at present we are barely at the start of this entire project, there is still 100 miles to go, and I have just turned 73. :(

But if you want a 1:5 jig for code75 bullhead there is no need to do any of the above because here it is. The STL file from Templot for both halves, mesh repaired and ready for printing. Just send it to the 3D printing service of your choice. You will also need a couple of M6 roofing bolts.

filing_jig_code75_bh_1in5.png



index.php


STL file attached below. You will also need a nice sharp 2nd-cut file, but that's a different kind of file -- this could get confusing. :)

p.s. tell the 3D printing service that the STL units are in mm. I don't know if that is the assumed default for STL files, software from the USA has a habit of defaulting to inches. The finished jig should be 145mm long.

cheers,

Martin.
 

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I am getting quite excited by these developments. They certainly get the old grey cells thinking.

Would it be possible to produce a laser cutting file (I assume that would be .DXF) for a trackbed layer complete with sockets?
This could be laser cut in cork or 2mm greyboard.
Then lasercut the sleepers in 1.5mm ply or 1.6mm basswood, complete with sockets.
Produce resin 3D printed chairs with longer plugs, or some temporary alignment plugs(ABS say).
Stick down your trackbed.
Stick the sleepers onto trackbed using the temporary alignment pegs (or the the chairs with longer pegs)
Remove temporary plugs
Thread rail onto chairs, then plug the chairs into the sockets.
Steve
 
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Location
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Builder of Finescale Signals in 2mm scale to 7mm scale, Trackwork, Turnouts and Layouts.
Possibly easier to put the chairs on the rail first, you might not think it but once you have more than a few chairs to thread it gets more difficult due to resistance.
 
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Martin Wynne

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Would it be possible to produce a laser cutting file (I assume that would be .DXF) for a trackbed layer complete with sockets?
This could be laser cut in cork or 2mm greyboard.
Then lasercut the sleepers in 1.5mm ply or 1.6mm basswood, complete with sockets.
Produce resin 3D printed chairs with longer plugs, or some temporary alignment plugs(ABS say).
Stick down your trackbed.
Stick the sleepers onto trackbed using the temporary alignment pegs (or the the chairs with longer pegs)
Remove temporary plugs
Thread rail onto chairs, then plug the chairs into the sockets.
@Steve_Cornford

Hi Steve,

Thanks for your ideas. (y)

Most of that is already possible in the current version 228a -- but so far for plain track only. (I haven't yet done the special chairs for pointwork, and the socket sizes will vary.)

At present you can't have the sockets without the timber outlines for the trackbed, but I will fix that. For the DXF file most of the features are in their own layer, so if importing into a CAD program it's easy to switch layers on and off to get whatever you want for the laser cutter.

The plug depth on the chairs is already an option setting, and you can switch off the chair jaws to print some socket locators, like this:

socket_locators.png

Ideally they need to be a fraction smaller than the press-fit chair plugs, which is also doable now, but I will add some specific options to make it simple.

To make it easier to locate timbers on the trackbed it would be better to have the plugs only, without any tops, and with an upper taper, so that the timbers can be dropped over them. So I will add that option too.

I want to add whatever options anyone wants to create a flexible system for whatever equipment they have access to. But it means a formidable array of tickboxes on the export dialog. :)

cheers,

Martin.
 
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Hi Martin,
Thanks for the amazingly quick response and for the info supplied.
I have used the 2D export, timbers only to get a .DXF file.
I am hoping to get a 3rd party laser cutting service to produce some trial pieces in 1.5mm ply and 1.6mm basswood.
As I don't have a CAD package, I have opened the .DXF file in Inkscape, and can see that it is compsed of many layers.
First tried "importing" to Inkscape, but only got one layer, then tried just "opening" it with Inkscape and got all the layers:-

1628769552591.png


I can see that in this case the two relevant (populated) layers are TIMBOUTL and TIMBER3D.
If I hide TIMBER3D I get:-

1628769670011.png


Both the timbers and the sockets are made up of 4 discrete lines rather than a rectangle, but this might just be the way Inkscape has interpreted the .DXF.
I am assuming that for laser cutting will not need the "sprues" (layer TIMBER3D)

Anyway I will make an enquiry at a CO2 laser cutting service & see what they say.

Steve
 
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Martin Wynne

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@Steve_Cornford

Hi Steve,

To remove the extended outlines, untick this option and then rebuild the templates. Then export the DXF again:

no_outline_extensions.png


p.s. there will be more options in 228b. :)

cheers,

Martin.
 
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Martin Wynne

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@Steve_Cornford

p.s. Steve,

You wanted the trackbed edges in the DXF?

trackbed_edges_dxf.png


modify group to match to update the background templates.

cheers,

Martin.
 
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