TEMPLOT 3D PLUG TRACK - To get up to speed with this experimental project click here.

  • The Plug Track functions are experimental and still being developed. Some of the earlier pages of this topic are now out-of-date.

    For an updated overview of this project see this post.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics include contributions from members who are creating and posting their own CAD designs for 3D printing and laser-cutting. Do not confuse them with Templot's own exported CAD files. All files derived from Templot are © Martin Wynne.
  • The Plug Track functions are experimental and still being developed.

    For an updated overview of this project see this post.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics include contributions from members who are creating and posting their own CAD designs for 3D printing and laser-cutting. Do not confuse them with Templot's own exported CAD files. All files derived from Templot are © Martin Wynne.

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

Quick reply >
@James Walters

Hi James,

Looking at that again it is fine for single turnouts, but is going to be a minefield for complex formations. Even ordinary double track is going to fall to bits:

View attachment 5164


I think we possibly need a range of options for this function (more tick-boxes!):

View attachment 5165

The question is -- which one should be the default setting for cutting a kerf line? Or something else? Do we need an option to change the setting individually for each end of each timber?

Also, if it is undesirable for loose bits to remain on the laser bed, presumably something similar will be needed for the sockets? Without affecting the bash fit.

Is it reasonable to assume that everyone with a laser-cutter will have some CAD software and an ability to use it, to edit the Templot DXFs? It's my firm intention that it should be possible to make plug track using the files from Templot without needing any CAD software or skills. I'm confident I can achieve that for FDM printing, and hopefully also for CNC milling.

But I'm beginning to wonder for laser-cutting. The output at present can put a kerf-adjusted line around every timber and socket. But if it is laser-cut as-is, it's going to fall apart on the cutter bed and how will you know which timber goes where? Is there any backing sheet which the plywood can be attached to, which is unaffected by the laser beam?

I know some users of plywood bases put a linking web somewhere between the timbers. I put the sprues option on the timber ends so that they could be easily trimmed off after tracklaying without distorting the timbers. But they have similar problems to the above in complex formations. Some users put a web under the rails, where it is very difficult to remove after tracklaying without distorting the track, but if not removed it makes ballasting very difficult and destroys the realism of bullhead track -- no webs between the timbers here:


View attachment 5166

A noticeable detail in that photo is the clean square end on the check rail. One of the advantages of the loose-jaws option is that you can have such neat flat rail ends, because the chairs never get threaded onto the rail.

cheers,

Martin.
Hi Martin,

To answer your questions in reverse order:

3. It is reasonable to assume most (if not all) laser users will have access to CAD software. That is to say the laser driver software (I use Lightburn) has some CAD functionality, and it is not difficult to adjust/delect vectors within that environment. I suspect that most (if not all) will also be using CAD software such as AutoCAD or Fusion360 etc. which they are using to create their own files. In which case they are probably more likely to use that to adjust the .dxf file Templot produces.

2. I hadn't given thought to the bits dropping out of the chair sockets when we spoke before, but these fiddlesome bits are the most likely to drop into honeycomb bed holes. But to attach them with nibs would likely require a modification to the chair plugs, as the remaining 'half-nib' which is left behind after breaking-out the waste will be difficult irksome to sand away.
I hope that makes sense, here's how I suggest the chairs might need adapting:

Modified Plug Chair.JPG You will see I've added a clearance groove up the end of the plug.

I think that to modify the chairs to suit perhaps a minority of users with as laser might be to the detriment of the FDM/Milled plug track and if I were you I'd discount chair modification.


However, having just written that, and produced a drawing of a modified chair, I'm now having second thoughts, the half-nib would almost certainly compress - it might even help the bash-fit quality of the plug.
So, after all that I'd say a single "nib" in a chair socket would be a good way to go. Preferably on the 'long side' to avoid compressed nib residue affecting the gauge.

1. Given my answer (3) above, I'd say option 1 of the five you present would be the most useful and the one which I personally would like to see as a default, with the option to switch it off to leave an option 3 situation. If there was the facility to adjust the length of the upper vectors which cross I should think all bases would be ticked. It would be no hassle whatsoever to make further adjustments to these in CAD post Templot if someone chose to do so.
I'd be happy to do some testing, I can recreate what you have proposed above in CAD or can cut something from a test file which you produce.


With regard to the timbering falling apart when lifted from the laser bed, there are a few simple solutions, I'd suggest that either of the following would do the trick.
A. Draw a rectangle around the timbering, so that in-effect becomes the fret, The additional nibs we are discussing here keep the whole thing together, and importantly allow the fret to be snapped away either after the timbers have been glued down or the turnout built. The rectangle could be produced in Templot, or drawn in the laser software mentioned above (3).

B. Stick a line of making tape over the plywood across the timbering after it has been laser cut to keep all the bits together.

As I mentioned before, I think Templot currently has all that is required for laser cutting to be useful. And that most people doing the laser cutting themselves will have the skills to achieve what they required with everything as it is. Personally though, I'd find the nib function really useful and I'm sure others would too.

Finally, I couldn't agree more regarding sprues between the sleepers/timbers.

I hope the above is clear/useful,

James
 
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If there was the facility to adjust the length of the upper vectors which cross I should think all bases would be ticked. It would be no hassle whatsoever to make further adjustments to these in CAD post Templot if someone chose to do so.
@James Walters

Thanks James for the detailed reply. :)

A setting to adjust the length of those vectors is already there:

nibs_snibs6.png



For the sockets, I think nibs in the corners might be the best option, because there is already a setting to increase the corner relief on the plugs (for CNC-milled sockets with radiused corners):

nibs_snibs7.png


Would 4 nibs be too many to push out, or do you just make them smaller and weaker?

I'm getting a bit nervous about talk of most users editing the Templot DXFs. I know folks have been doing that with the DXFs for 20 years, but they haven't been mentioning Templot plug track in the same breath. If lots of technical posts appear on the forums and YouTube about CAD editing of Templot Plug Track files, I just know it is going to put a lot of potential users off the whole idea. I'm getting frequent emails along the lines of "I would love to try building the plug track, but I'm a complete computer numpty". I keep reassuring them that if they are capable of printing paper templates from Templot on a 2D printer, they will be able to make plug track on a 3D printer.

cheers,

Martin.
 
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I think those adjustments are all that is needed, when the time comes I'll have a play.


I understand your concerns Martin re laser cutting, and I wouldn't want to add to any confusion. Hence why I've not previously mentioned my experiments on the web.
When I mentioned most users, I was referring to most using a laser cutter. These are likely to be the people who fiddle with the .dxf's - who on the whole are less likely to be computer numpty's - but more likely to post about about their experiments.

I don't know what to suggest really, as it's my guess that those who feel confident to experiment with the .dxf's will always do so. In the same way that someone with confidence in 'traditional' techniques might have cut-up and curved a paper template in the way things were done pre Templot.

I totally agree, and would defend that the plug track concept can be produced successfully with a 3d printer with no more computer skill than using an office printer. That is the joy and genius of the system which you have created.

Best,

James
 
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Laser cutting is not an area that I have much knowledge of, but I believe that it's possible to partially cut/burn away some of the timber, like a half-etched tab, when etching brass or nickel silver. If that's indeed possible, would that help in creating a gap under the rail, when using under the rail webs.
 
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Laser cutting is not an area that I have much knowledge of, but I believe that it's possible to partially cut/burn away some of the timber, like a half-etched tab, when etching brass or nickel silver. If that's indeed possible, would that help in creating a gap under the rail, when using under the rail webs.
@Phil O

Hi Phil,

I think that's done by changing the colour in the DXF file. I'm not too clear how you burn away an area, rather than the normal process of cutting a thin line. Presumably an area 1mm wide would need 5 lines 0.2mm wide, at half-power. Or maybe the beam-width (focus) can be adjusted while cutting. I doubt the depth can be set with much precision, although it is presumably repeatable on the same material with the same settings. Over to James. :)

What I do know is that adding such tabs in Templot along the existing rail lines is out of the question, unless you can find me an extra year or two of coding time. :( Such half-tabs would need to be created separately, although they could be placed under the rails manually if desired.

Anyone who is using under-the-rail tabs at present is editing the DXF file in CAD to achieve that.

cheers,

Martin.
 
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@James Walters

Hi James,

I should perhaps have mentioned earlier that if all you want to do in the CAD or laser software is to add a few extra cut lines, you can do that quite easily in Templot, without needing any CAD.

shape_snibs3.png


shape_snibs4.png



Then just draw lines with the mouse, in the background shapes:

shape_snibs1.png


shape_snibs2.png



The result in the DXF is:
shape_snibs5.png


A bit tedious to do, but not difficult. It would make it possible to prepare for laser-cutting a complex track formation without needing any other software.

It's much better for me to answer questions with "click this, set that..." rather than "get software X and learn how to use it".

(Note that this works only in the 2-D exports -- in 3-D exports the background shapes are used for other functions.)

cheers,

Martin.
 
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When I received my experimental laser cut ply sheets from the lasercutting bureau, one side was covered in masking tape and all the "chads" from the sockets were still present, and all the timbers/sleepers were still present.
If the "chads" did fall into the honeycomb bed would it matter?
Could you not just vacuum them up, or use some other method to remove them?
I just sent the .DXF files as output by templot to them, having first set the colours of the lines using the Templot settings.
Sockets were set to a coulour that meant "inner" cut, Timber outlines to the coulour that meant "outer" cut, and the Timber numberings to the coulour that meant engrave.
Next time I would not bother with the Timber numberings as I would just use a printed copy of the same template to identify the timbers.

I used https://modelshop.co.uk/Static/WorkShop/Laser-Cutting-And-Engraving

ps James, I have ordered your ballast vacuum device to help in my experiments:)
 
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Martin,
Thank you for the instructions above - all very useful.

Steve, the "chads" issue is not a big problem, but they can become wedged-in and get missed by the vacuum cleaner, especially where the bed frame creates blind pockets. Over time they become truly carbonised which whilst not a big problem it does tend to lead to increased staining of the underside of parts.
A honeycomb bed can be tricky to keep clean at the best of times so anything which reduces the need for a thorough wash and brush-up gets an upvote from me. :)

Thank you for your order. I'm afraid I missed the post this morning but it's ready to go and will be with the post office as they open on Monday.
 
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When I received my experimental laser cut ply sheets from the lasercutting bureau, one side was covered in masking tape and all the "chads" from the sockets were still present, and all the timbers/sleepers were still present.
If the "chads" did fall into the honeycomb bed would it matter?
Could you not just vacuum them up, or use some other method to remove them?
I just sent the .DXF files as output by templot to them, having first set the colours of the lines using the Templot settings.
Sockets were set to a coulour that meant "inner" cut, Timber outlines to the coulour that meant "outer" cut, and the Timber numberings to the coulour that meant engrave.
Next time I would not bother with the Timber numberings as I would just use a printed copy of the same template to identify the timbers.

I used https://modelshop.co.uk/Static/WorkShop/Laser-Cutting-And-Engraving

ps James, I have ordered your ballast vacuum device to help in my experiments:)
@Steve_Cornford @James Walters

Hi Steve,

You kindly sent me some samples of your commercially laser-cut plywood sheets some while ago. I was unable to do anything with it because you had reduced the socket width to 1.7mm, so my chairs with 2.0mm plugs wouldn't fit.

But I did notice a few things:

1. the underside of the sheets was covered in masking tape, and no loose parts were missing.

2. the masking tape showed no signs of burning, so must have been applied after laser-cutting.

3. removing the masking tape caused the loose parts to fall out freely.

4. the cut lines on the underside were noticeably finer than the cut lines on the top.

5. the result of that was that the timbers were slightly wedge-shaped, being around 4.04mm wide on the underside, and 3.97mm wide on top. (design size is 4.0mm)

There are 2 possible explanations I can think of:

a. the laser lens was focused on the bed of the machine, not the top surface of the plywood; the bed of the machine is a flat heatproof surface; after cutting, the top surface was covered in masking tape, or some other sticky surface, or a vacuum lift plate of some kind to retain all the loose parts; the cut sheet was then turned over; masking tape was then applied over the underside of the sheet; finally whatever was on the top surface was removed.

or b. the sheet was cut twice, once from each side mirrored; the laser lens was focused on the surface of the plywood; after half-cutting the underside it was covered in masking tape; the sheet was turned over; accurately re-registered on the bed, and the top surface was cut again, without adjusting the focus for the thickness of the masking tape.

I have no idea how plausible or likely any of that is, or what other clever tricks or devices are used. What I do know, as with everything else in plug track, is that the only way I can know anything for sure is to get one of these machines myself.

At present I don't have anywhere I can safely use such a machine, so getting one is going to have to wait until I have made a safe space for it. It certainly can't go in the 3D printing den, with gallons of IPA sloshing about!

In the meantime I must get on with the chairs. I'm feeling some urgency to get a finished FDM turnout done and visible to the world, before the whole thing unravels in all directions!

cheers,

Martin.
 
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I think your first explanation is the most likely.
The tapered 'kerf' is typical with laser cutting and can be minimised (but not entirely eliminated) by focussing on the centreline of the material. Although that does depend upon the type of laser, and the speed at which it was cut.

I'm really looking forward to seeing a completed turnout Martin, so please ignore all of this distraction for now. :)

In the meantime I'll laser a piece of plain track using just the settings in Templot, to prove it can be made to work with the plug track chairs and publish the results and laser settings 'recipe' on here for others to try. Once its been proven, we could come back to nice-to-have laser tick boxes etc when the chairs are all done.

My best to all,

James
 
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I think maybe I was over-thinking the chair fixing problem. The chairs don't need any adhesive to fix them initially, they are a firm bash-fit in the FDM timbering base. We just need a sealant of some sort to penetrate around the tapered plug to prevent them coming loose months later.

Yesterday I found an unopened Humbrol tinlet of white enamel paint which must be at least 25 years old. It had completely settled in the tin, so I stirred it clockwise for a fortnight, and then anticlockwise for a week, until it looked usable again. I found the loosest chairs of those I had been testing -- almost loose enough to fall out of the timber if turned upside down. I added a drop of the white enamel using a cocktail stick into the underside of the sockets around the plugs, and left it for 6 months to see what happened. Well actually I left it overnight in a warm place. :) The result this morning is that I can't budge them with any normal level of force. This is how the tapered plugs fit the sockets in the timbers:

index.php


One week on and I can report that the chairs are now solidly fixed in the timbers. I can't push them out by hand. It needs a hammer and punch to push them out from below.

So it seems Humbrol enamel paint is the sealant of choice for resin chairs in FDM timbers. Apply with a cocktail stick into the underside of the sockets after fitting the chairs. One little tinlet would probably do the whole layout. :)

cheers,

Martin.
 
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.
Just adding this while I'm working on it -- it's very unlikely I shall ever remember to mention it again.

If you create plain track with a continuous check rail, the first check-end chair from CTRL-0 (flare in) will be created, and all the middle check rail chairs. However, no final check-end chair (flare out) will ever be created.

(That doesn't actually matter, because continuous check rails on plain track are added by mirroring the template somewhere in the middle. Such templates are created as approach track on shortened turnout templates.)

Martin.
 
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I have done some experiments this morning using the 2d .dxf export from Templot, with the specific aim of testing the 'kerf' settings to attempt to establish a suitable default when laser cutting plywood for the plug chairs. I have (mostly) avoided using any other CAD input as so tried to replicate how someone with no CAD experience might approach the job.
The chairs were straight out of Templot, printed on an Elegoo Saturn with standard Grey resin on default settings.

I'm using 3.2mm plywood as that was to hand.

Here are the results:

Test 1.jpg

The top loose sleepers were cut with the default 0.2mm kerf using the file straight from Templot. Because they weren't fixed into a fret, they tended to move about whilst cutting as so neither the sockets or timber outlines were cut accurately. I tried cutting the sockets first and it helped, but even so the results were not ideal.

Next up, I took the same file, bunched the pieces together and made a small 'nib' between them to stop them moving about.
I did this in the laser software (not CAD per se.). To do this I drew a .5mm radius circle between the bunched sleepers, deleted the line bridging the circle, and then deleted the circle to leave the nib. I also removed the overlapping lines so that the long edges didn't get cut twice once the timbers had been bunched. I added the kerf legend to the sleepers and cut again (with a .2mm kerf). To reiterate, this was done with the laser software not a dedicated CAD program.
The top-left sleeper plate was the result. The chairs were a bit loose and fell out when I turned the piece upside down.

Next I tried again with a .4mm kerf. This time the fit was good but not tight - I'd say ideal with a little glue.
Next up, I tried .5mm kerf (by increasing the kerf I was closing the socket slightly). This time the chairs were a bash fit and it took quite some force to squeeze then in. A little more than I was comfortable with - although I didn't break any chairs. :)

Next I tried a .45mm kerf - this time the fit was excellent. They pushed in firmly, but could be removed without damage if care was taken. The outer width of the sleeper was 3.39mm, I couldn't measure the length as I only have a 25mm micrometer to hand. A little over width, but not that anyone would know.

So what has been the learning?
Well, theory would seem to suggest that .2mm kerf ought to be ideal. But variables such as cleanliness of the laser, exact focussing, etc. all come into play. What has been proved is that it is completely possible to produce the data directly from Templot, and that the kerf adjustment is all that is required to produce repeatable results. There is no need for CAD.

I'm going to produce a test .dxf with different incremental 'kerf' offsets ranging from 0 to 0.6mm in 0.1mm increments. I'll post it on here.
I'd suggest all that one would need to do is use it as a test cut before each cutting session/material - try fitting the chairs and see which works best. Martin, if such a test piece were available within Templot then it would save others experimenting such as I've done.

Secondly, it has confirmed my suspicion that some form of fretting is essential. Not just from the perspective of retaining the pieces from movement during cutting, but also in terms of accurate alignment when they are glued down. If 0.05mm of adjustment is the difference between good and optimum fitting tolerances, then I'd suggest that sticking down individual timbers to that level of accuracy could be potentially difficult.
Of course the 3d printed track bases avoid that worry and are good to go as-is.

I hope that is of some use.

This system is excellent. Martin you are a Genius.

Best,

James

p.s. Yes I know that the chairs on the 0.4 and .5mm versions above are the wrong way round. :oops:

Test 2.jpg
 
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Next up, I tried .5mm kerf (by increasing the kerf I was closing the socket slightly). This time the chairs were a bash fit and it took quite some force to squeeze then in. A little more than I was comfortable with - although I didn't break any chairs. :)

Next I tried a .45mm kerf - this time the fit was excellent. They pushed in firmly, but could be removed without damage if care was taken.
@James Walters

Hi James,

Many thanks for taking the trouble to do all that. The results look great. :)

Can you clarify what you mean by "some force to squeeze them in"? For bash-fitting in FDM timbers I use a pin hammer. On the loose-jaw chairs, with the aid of a punch made by snipping the ends off a cocktail stick. For the solid chairs by inserting the rail, and a sharp tap on a hardwood block placed on the rail top. I would imagine similar methods for plywood, but maybe not?

For the plain track sleepers the socket is 2mm wide in sleepers 3.3mm wide. With the result that there is only a weak 0.65mm of ply in the side wall of the socket.

For the 4mm wide timbers there is a stronger 1mm side wall on the sockets (except for L1 bridge chairs).

Do you suspect that the side wall is flexing in the sleepers, making the fit seem easier than it otherwise would be? I'm wondering if the optimum kerf width might differ for sockets in sleepers and in timbers? While remaining the same for the timber outlines? I can see 3 kerf settings being needed instead of just one -- for timber outlines, timber sockets, sleeper sockets (and L1 chairs).

If the result of a firm bash-fit is that the side wall of the socket stretches, this would affect the track gauge. There is a gauge-tweaking adjustment in the exported socket positions, but for consistent gauge results in say P4 we may need to accept a looser fit than a firm bash-fit.

Thanks again,

Martin.
 
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HI Martin,

I too used a pin hammer to bash the chairs in, gently of course with a bit of shaped timber given the lack of cocktail sticks here.
In my experiments I found the .45mm kerf gave a nice feel when inserting the chairs. .5mm felt too tight. Neither has flexed the sockets - I've checked (as best one can) with a micrometer. Either would work fine.

Just tried some timbers in-between jobs here, but made a mess of it. The outsides were fine but the chair sockets too loose. I must have done something wrong in my haste. I will investigate later when I have more time.

I will check the gauge of the examples above this evening when I have access to my gauges.

Best,

James
 
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@Steve_Cornford

Hi Steve,

The Templot setting doesn't change the width of the cut kerf -- that's a feature of the machine laser.

The Templot setting controls how far Templot shifts the cut line from the true line. Shifting it further into the socket moves the laser into the socket, which reduces the size of the socket.

cheers,

Martin.
 
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Agreed Martin,

Steve, where I have mentioned the 'kerf' above I have been referring to the adjustment of the 2d kerf width in the .dxf output settings of Templot. My apologies if that has caused any confusion. The actual kerf is of course a laser factor.
Perhaps that setting ought to be renamed to 2d Cutter Kerf Off-Set or Kerf Compensation? Just a thought.

James


2d Cutter Kerf.JPG
 
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Thank you Martin, I understand now.
Come to tnink of it, I produced the .DXF files for the bureau with a vsersion of Templot prior to your adding the laser kerf options.
I Was advised by the bureau to aim for a minimum distance between cuts of 0.8mm, so for 3.3mm sleepers that meant reducing the socket width from 2mm to 1.7mm.
Looks as though James has managed to get down to 0.65mm between cuts, thus maintaining a socket width of 2mm.

James,
Are you able to laser cut 3mm cork sheet on your machine?

Steve
 
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