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 Some of the earlier pages of this topic are now out-of-date.

    Some pages of this topic 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.

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

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Hi Martin,
The other even more deliberate mistake is that you have not first threaded the chairs onto rail before "plugging" them into the sleepers!
:):):)
Would the chair distort if it was already threaded on rail?
Perhaps a few boiled eggs are called for?
Seriously though, please keep up the good work on the chairs, as they are looking really good.
Steve
 
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Martin Wynne

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Hi Martin,
The other even more deliberate mistake is that you have not first threaded the chairs onto rail before "plugging" them into the sleepers!
:):):)
Would the chair distort if it was already threaded on rail?
Perhaps a few boiled eggs are called for?
Seriously though, please keep up the good work on the chairs, as they are looking really good.
Steve
@Steve_Cornford

Thanks Steve.

There was rail in them when I inserted them! I removed the rail to show more detail of the chairs for the photo.

For the main rails in a turnout, or plain track rails, the rail used as an insertion tool doesn't have to be the finished rail. You can remove it to create a chaired base if you prefer.

That won't work for the wing rails because of the knuckle bend. Once the wing rail and chairs are in place, the rail can't be slid out of them.

Because of resolution effects in the home printers, the chair plug sizes and socket sizes do vary a fraction. You might be lucky and find that some of the chairs can be pressed home using fingers. But mostly the chair jaws risk being damaged if you do that. Using the rail to press them home applies pressure to the base of the chair and works fine.

The idea is to thread the chairs on the rail, roughly position them at the correct spacings (the printed paper template helps), and locate them loosely in the sockets. Then work to and fro along the rail with a suitable implement such as a wooden spoon, gradually increasing the pressure until all the chairs are pressed fully home. You can feel a satisfying click as they get there.

It works fine, but as with most things, a bit of practice helps.

All the settings are entirely under your control in Templot, so if you prefer to make the chairs an easy fit, and apply some glue in the sockets first, that's fine. But don't overdo it, because the intention is that the sockets set the track gauge. If the chairs are too loose you would need to use track gauges in the usual way and need a fast-setting glue.

Or if you prefer a half-way house with a gentle push fit, the finished turnout can be turned upside down after assembly, and an adhesive such as penetrating cyano can be applied to the bottom of the chair plugs to seal them firmly in place.

At some stage I shall have to write all this stuff up and make some videos.

cheers,

Martin.
 
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Martin Wynne

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I have moved several posts from this topic into a separate topic:

https://85a.uk/templot/club/index.php?threads/building-3d-track.520/

I know a lot of users are getting very confused by all the different options and methods being discussed. I'm hoping that separating actual modelling and track construction topics from the topics about Templot software developments might add some clarity. Maybe. :unsure:

cheers,

Martin.
 
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AndyB

Member
.
It's proving tricky to get the socket sizing right for the L1 bridge chairs where they are close together. Making them a tight push fit means the first one distorts the base a fraction and makes the second one more difficult to fit.
Hi Martin,

If it's possible to reduce the density of the timbers that might help. I've found it's possible to make them very low density.

Andy
 
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Martin Wynne

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Hi Martin,

If it's possible to reduce the density of the timbers that might help. I've found it's possible to make them very low density.
@AndyB

Thanks Andy.

I'm currently using a fill density of 40%. The problem is that there isn't any measurable fill between the sockets, to be changed:

L1_socket_walls.png


My thought was to make that socket wall stronger, rather than weaker? So that one plug doesn't affect the fit of the other.

I can see that reducing the fill density in the rest of the timber would allow the chairs to push apart a fraction, but that would affect the gauge accuracy.

I'm currently using the Cura 4.13 slicer above. The new Cura 5 has some new controls for wall thickness and dimensions, but I haven't tried it yet -- it's next on the list. At present that wall thickness is measurably thicker than the design size, even though the overall Y accuracy is good -- sleeper length is typically 33.98 - 34.03 mm (EM).

I've currently got the plugs with significant corner relief so that the ends of plug make contact with the socket wall only in the middle:

L1_plug_outline.png


I'm thinking of offsetting the contact points a little, so that they are not exactly on opposite sides of the wall. This might prevent one plug affecting the fit of the other, but risks twisting the chair in the socket. I may need to tighten up on the plug side clearance to avoid that.

For the L1 chairs the plug is wide enough to have 2 contact points at one end only, which would avoid any twisting and might work well. But the S1 chair plug is not wide enough to do that.

In the end I might have to accept that a gentle push fit is the better option, with some glue in the socket for long-term strength -- there is space for it in the corners. I think I may have found a suitable glue:

https://85a.uk/templot/club/index.php?threads/building-3d-track.520/post-4755

Always something to think about. :)

cheers,

Martin.
 
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AndyB

Member
Hi Martin,

I see what you mean. Of course I'm printing the chairs along with the timbers using a 0.2mm nozzle which probably makes things quite a bit different.

Have you experimented with round pegs and holes at all? I'm wondering if the rail could provide the alignment. Highly non-prototypical of course although I have noticed some FB fixtures don't define the direction of the rail. They only seem to determine the gauge.

Cheers,
Andy
 
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Martin Wynne

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Have you experimented with round pegs and holes at all? I'm wondering if the rail could provide the alignment.
@AndyB

Hi Andy,

This has been suggested several times. I haven't actually tried it because I can't see any advantage in discarding information which Templot already knows -- the angle of the chair on the timber. And I can see several problems:

1. Using the rail for chair alignment requires a very close fit on the rail. At present the chairs can slide along the rail quite easily, so there is no stress on the chair jaws. The chairs are aligned from the socket, not the rail, and can't be inserted at the wrong angle.

2. With a round peg, how to recover the situation if a chair is accidentally pressed home at the wrong angle?

3. The edge of the chair base is very thin and fragile. The small overhang from the rectangular plug helps to protect it, and avoids any 3D printing problem from a larger flat horizontal overhang -- which would arise from a round peg.

4. Tolerancing a round object on X and Y for a close-fit is much more difficult than a rectangular object.

There is the "exactopips" alternative idea of having a pip on the timbers and a hole in the base of the chair, matching the original Exactoscale turnout kits:

https://85a.uk/templot/club/index.p...3d-printed-cnc-milled-laser-cut.229/post-2437

But that makes the chair very fragile and difficult to support in the printing process to create a dead flat underside. I may look at that one day -- the pip could be round or rectangular. It would be of no relevance to laser-cut or CNC-milled timbers.

Whereas the present design can cover 3 different timbering methods. It would have been 4 if the Cameo cutter had worked. Even more options if anyone tries other methods such as die-cutting, blanking and punching:


cheers,

Martin.
 
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Hi Martin,
With rereference to the pair of L1 chairs in close proximity, I think the thickness of the fillet between the two sockets might be outside the scope of a laser cutter using 1.5mm plywood, so a possible solution would be to implement a solution similar to your proposed check rail chais, where the plug part of the chair(s) is extended sideways so that they touch and in effect replace the need for the fillet between the two chairs.
That way when you "plug" the second chair in in holds both itself and the first chair in the correct position.
Regards Steve
 
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Phil O

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Location
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Hi Martin,

I have been thinking about this problem and my thoughts would be to combine the two plugs and chairs so that the top of the plug forms the timber fillet between the two chairs. The plug will hold the two chairs in the correct orientation. I have no idea if it's feasible.
 
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Martin Wynne

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Many thanks for the comments.

My hope was that the standard chairs, S1, S1J, L1, P, and others, would be generic -- meaning that the chairs would all be the same, and any L1 chair say, would fit in any L1 socket on the template, or in any L1 socket on any other template.

Modifying the plug dimensions where two L1 chairs are close together would wreck that, and those L1 chairs would be specific to that location on that template.

Which is obviously doable, but the whole process is getting more and more complex, and one day I'm going to have to explain all this in instructions and videos. Cue another paragraph to explain the above, and answer support questions from someone saying they have got an L1 chair which doesn't fit the socket for it.

Developing Plug Track is one thing -- and very enjoyable. Explaining it is something else and a nightmare facing me. I'm getting fearful that the whole thing will overwhelm me.

My thinking now is to replace the wall between close L1 sockets (or an L1 and S1 socket) with a loose resin-printed spacer component. This would allow the L1 chairs to be the standard generic L1 chairs, and a fiddly little spacer would be inserted between them in a single long socket during assembly. I haven't tried this yet, so I don't know how practical it would be. For thin laser-cut plywood it would be very tiny.

It has to be yet another option tickbox, because the existing design works fine for CNC-milled sockets, and probably also for FDM sockets where a looser glued fit is adopted. So another paragraph in the instructions to explain that. :(

cheers,

Martin.
 
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Hayfield

Member
Location
Essex
Hi Martin,

I have been thinking about this problem and my thoughts would be to combine the two plugs and chairs so that the top of the plug forms the timber fillet between the two chairs. The plug will hold the two chairs in the correct orientation. I have no idea if it's feasible.


I think this is the best method, that leaves the L1 chairs with the same size plug as the other chairs
 
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I am assuming that for the instance where you have a very close pair of L1 chairs, or a close L1 S1 combo, that you would "plug" the stock rail assembly in first, in which case would it help if there was a temporary L1 sizes peg inserted into the switch/closure rail position thus strengthening the fillet whilst the stock rail chair was inserted, then just before inserting the switch/closure rail assembly whip out the temporary peg.
 
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Martin Wynne

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Every day is a schoolday. :)

When Cura 5 was released I had just spent a lot of time fine-tuning the settings in Cura 4.13 to get the best results for the timbering bricks on my BIBO prnter. So I held off upgrading and starting again, despite the claims from Utlimaker that Cura 5 offered significant slicing improvements in the accuracy of fine detail.

I'm wishing now that I had upgraded straightaway.

Cura 4.13
index.php


Cura 5.1
L1_socket_walls_cura5.png


For the same STL file and slicing settings in Cura. There is now no infill between those problem socket walls, and a few other differences can be seen.

The printed result is very different. The printing is quit a lot cleaner with less stringing and a better top surface.

But the main difference is that the socket walls are much thinner, and the sockets are now much closer to the design size, and more consistent one to the next.

Which means that chairs which were mostly a very tight fit in the brick from from Cura 4.13 (especially the wider plugs on the S1J and L1 chairs) -- are now in the same brick from Cura 5.1 so loose in the sockets that they are falling out, and have to be sealed in place with glue.

So now I must start again a tweak the socket sizes all over again. :(

I'm wondering if I shall have to accept that a fully press-fit design isn't going to work for FDM? I wanted to eliminate gluing because it is messy and time-consuming, and makes it more difficult to make corrections and repairs.

Press-fit works just fine in CNC-milled MDF timbering. But the results from FDM printing seem to be too variable. If I'm struggling to get consistent results from my BIBO printer, I'm wondering how to set defaults in Templot which will work on all other printers?

Perhaps a gentle push fit, with some adhesive to seal the chairs in place long-term, is a more practical approach?

At least this has solved the issue with close-together L1 chairs, and similar problems I was expecting with the special crossing chairs.

There is another test brick printing on the BIBO right now, so I had better go and see how it's doing... :)

cheers,

Martin.
 
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Paul Boyd

Member
Location
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Every day is a schoolday. :)

When Cura 5 was released I had just spent a lot of time fine-tuning the settings in Cura 4.13 to get the best results for the timbering bricks on my BIBO prnter. So I held off upgrading and starting again, despite the claims from Utlimaker that Cura 5 offered significant slicing improvements in the accuracy of fine detail.

I'm wishing now that I had upgraded straightaway.

Cura 4.13
index.php


Cura 5.1
View attachment 4058

For the same STL file and slicing settings in Cura. There is now no infill between those problem socket walls, and a few other differences can be seen.

The printed result is very different. The printing is quit a lot cleaner with less stringing and a better top surface.

But the main difference is that the socket walls are much thinner, and the sockets are now much closer to the design size, and more consistent one to the next.

Which means that chairs which were mostly a very tight fit in the brick from from Cura 4.13 (especially the wider plugs on the S1J and L1 chairs) -- are now in the same brick from Cura 5.1 so loose in the sockets that they are falling out, and have to be sealed in place with glue.

So now I must start again a tweak the socket sizes all over again. :(

I'm wondering if I shall have to accept that a fully press-fit design isn't going to work for FDM? I wanted to eliminate gluing because it is messy and time-consuming, and makes it more difficult to make corrections and repairs.

Press-fit works just fine in CNC-milled MDF timbering. But the results from FDM printing seem to be too variable. If I'm struggling to get consistent results from my BIBO printer, I'm wondering how to set defaults in Templot which will work on all other printers?

Perhaps a gentle push fit, with some adhesive to seal the chairs in place long-term, is a more practical approach?

At least this has solved the issue with close-together L1 chairs, and similar problems I was expecting with the special crossing chairs.

There is another test brick printing on the BIBO right now, so I had better go and see how it's doing... :)

cheers,

Martin.
Hi Martin

I believe I may have mentioned just how much better Cura 5 was than 4, and that was just Beta at the time 😀

I’ve just bought a new PC (they’re so complex now that I’m no longer confident in building my own). I’ve installed Cura 5.1.something and copied the profiles across, but the key thing is that despite having a much better UI, I haven’t reinstalled PrusaSlicer!

Incidentally, this PC is Windows 11, and Templot runs just fine.

Cheers,
Paul
 
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Martin Wynne

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I believe I may have mentioned just how much better Cura 5 was than 4, and that was just Beta at the time 😀
@Paul Boyd

Thanks Paul. :)

Glad Templot is fine on Windows 11. Please let me know if you spot any quirks. Thanks.

Are you saying that you don't like the Prusa Slicer? I've installed it, but not made any use of it.

Another factor in all this is the different reels of polymer. I'm using eSun PLA Plus, but it's not all the same. I have 2 reels of brown, one about 6 months old and one over 2 years old. Both the same part number. The newer one prints noticeably more stringy than the old one. On the other hand the old one has gone a bit brittle with age, and tends to break in the extruder feed if I don't watch it. I assume that after heating the brittleness is removed, I can't see any difference in the strength of the finished bricks.

I also have a reel of grey, which prints much more cleanly than the brown. I've been using the brown for the timbers because it makes a better contrast with the chairs for photos.

Neither of them are particularly realistic for railway sleepers and will need painting (as will the chairs of course), so I may change to using the grey in future.

If anyone reading this would like me to send you a few sample chairs and bits of timbering base, please let me know your postal address and I will see what I can do. Click this link to contact me: https://85a.uk/templot/club/index.php?misc/contact Don't expect it by return of post because FDM printing the timbering bases is quite slow, it might take a few days if everyone asks at once. :)

cheers,

Martin.
 
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Paul Boyd

Member
Location
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@Martin Wynne

Hi Martin

Are you saying that you don't like the Prusa Slicer? I've installed it, but not made any use of it.

I do like PrusaSlicer, and I got better results with default profiles than I did with Cura 4, as well as it having (for me) a nicer UI. It also supports my 3D mouse! However, one flaw for me was that there was no hole size expansion option so getting a hole to print at a fairly precise size (e.g., for pressing in threaded inserts) was impossible. At least, I couldn't find a way to do it. Cura 5 still has that option, but has also leapfrogged PrusaSlicer for print quality in my opinion. I don't like having different programs for the same function, and it's also messy having project files and gcode with the same file extensions but produced by different software, so certainly for now I'm going to stick with Cura 5. That may of course change in the future!

I've only ever used Anycubic PLA, and so far the white, black or blue of various ages have all behaved identically, but none are more than a year old. I've not noticed any difference in performance with age, but I know some people go to quite extraordinary lengths to keep their reels in a temperature and humidity controlled environment!

Thinking about the hole size expansion option, that actually might make press fit sockets usable for FDM by adjusting the socket size to suit, with a bit of trial and error, when printing. The "expansion" can also be negative if needed. Essentially, I'm thinking along the lines of Templot producing sockets to a set size, then the user adjusting the printed size at print time. That's exactly what I do when printing my own designs.

Cheers,
Paul
 
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Martin Wynne

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Thinking about the hole size expansion option, that actually might make press fit sockets usable for FDM by adjusting the socket size to suit, with a bit of trial and error, when printing. The "expansion" can also be negative if needed. Essentially, I'm thinking along the lines of Templot producing sockets to a set size, then the user adjusting the printed size at print time. That's exactly what I do when printing my own designs.
@Paul Boyd

Hi Paul,

I've wondered about that. My thinking was to keep the trial and error in Templot, so that I can make it easy for users and create videos etc., as I don't know which slicer users will have with any printer they might be using, and what options it might have available. Cura can be a bit scary with so many different adjustments.

Also the hole correction applies to both X and Y dimensions, whereas I'm trying to make an easy fit on the X dimension (along the rail), and a precise press fit on the Y dimension (for track gauging).

The downside of doing it in Templot is that you have to go through the full STL export and mesh fix/repair for every iteration. Doing it in the slicer means you can use the same fixed STL for each try.

Regards storing reels of filament, keeping them dry isn't much of a problem at present! But I wonder if the age-embrittlement is related to daylight exposure, and reels need to be stored in the dark?

cheers,

Martin.
 
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Paul Boyd

Member
Location
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@Martin Wynne

Hi Martin

Also the hole correction applies to both X and Y dimensions, whereas I'm trying to make an easy fit on the X dimension (along the rail), and a precise press fit on the Y dimension (for track gauging).

Maybe I've misunderstood something! If Templot outputs a socket dimension with an easy fit on X and press fit on Y, setting a hole size expansion would simply restore that from both X and Y printing (usually) a bit small, wouldn't it? Setting the hole size correction to make Y a press fit would apply the same correction to X, still giving the easy fit. I think...

I think my engineering mind says that the "CAD" output should be to the required size, and it's up to the manufacturing process to ensure those sizes are met. All very theoretical though because I've only printed rail guides on timber bases so far, where the blind socket dimensions are not critical!

Regards storing reels of filament, keeping them dry isn't much of a problem at present! But I wonder if the age-embrittlement is related to daylight exposure, and reels need to be stored in the dark?

I do store mine in the dark, in the original boxes, but that's mainly just where they happen to be stored rather than from any consideration about ageing!

Cheers,
Paul
 
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Martin Wynne

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Maybe I've misunderstood something! If Templot outputs a socket dimension with an easy fit on X and press fit on Y, setting a hole size expansion would simply restore that from both X and Y printing (usually) a bit small, wouldn't it? Setting the hole size correction to make Y a press fit would apply the same correction to X, still giving the easy fit. I think...
@Paul Boyd

Hi Paul,

Yes and no, or maybe. :)

I'm not sure conventional engineering comes into it much. This is my current design:

plug_socket_fit.png


It's not feasible to make a close fit all round and expect consistent results. The X-Y resolution on the steppers is 0.05mm steps, so rounding effects mean some sockets will be 0.05mm larger in one or both directions than other sockets. In a few cases there might be a 0.1mm difference.

The sideways position of the chairs along the rail is not too critical, so I'm allowing an easy fit at the sides of the sockets even if the socket is 0.05mm narrower than the design size. Currently the design side clearance is 0.03mm on both sides. It could be a bit more, but on the shorter chairs it risks the chair twisting in the socket.

The endways position of the chairs is more critical, because it sets the track gauge. Since changing to Cura 5.1 I've set a bash fit interference of 0.03mm overlap at each end. A bash fit allows more tolerance in the components than a proper press fit. The resin is quite a bit harder than the FDM polymer which deforms to contain it. The corner relief reduces the force needed to a reasonable level, allows for radiused corners in the sockets, and provides somewhere for the deformed polymer to go. And also a space for any adhesive if desired.

I've drawn the above square-on, but of course many sockets in a timbering brick will be at an angle, so the clearances will be controlled by both X and Y axes on the printer.

My thought was that users would be adjusting the plug end fit to suit their printers, leaving the side clearance unchanged. I had in mind a built-in automated 3D printer calibration function similar to the one for 2D paper templates. With options for those who prefer a gentler push fit, or an easy fit for gluing.

But that's still a long way off, in the short term changing the slicer settings is easier than frequent trial and error trips to the online mesh fixer.

The above clearances apply to 4mm/ft scale. In theory they should stay the same in the larger scales, rather than scaling up. We shall see.

What shrinkage setting do you allow in your CAD designs? Or on the slicer? For PLA Plus on my BIBO printer I currently have 0.28% on X and 0.16% on Y. That's currently set as the defaults in Templot but again others will need an automated calibration function for that. It's difficult to know how much of that is polymer shrinkage, and how much is a resolution correction for the printer. Obviously some of it must be printer correction, otherwise the two values wouldn't differ. The slicer is set to 100% scaling.

For the Z dimension I have the shrinkage set to zero. This makes it easier to match the various thicknesses in the finished part to the layer setting in the slicer (currently 0.12mm layers). The result means that the finished part is shrunk slightly smaller on Z than the design size, but for the timbering bricks that is of no consequence.

For the resin printer I have the shrinkage set to 1.5% all round, to get the plugs to the design size and ensure the proper rail fit in the chairs.

p.s. many thanks for the contribution to the funds. :)

cheers,

Martin.
 
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Hi Martin,
I would like to try resin printing the timbers WITH the chairs. I can see that I can create/export timbers only or chairs only which is great. I would like to create/export an stl of the chairs in the timbers 'without' the rails. is this possible within the current version by switching buttons on/off?

Terry
 
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