Onshape Parameterized Rail

[Stereo]

As a fun project, I decided to parameterize the Lego rail system in CAD.  The main impetus was talking to a couple people modeling narrow gauge, who are aiming to replicate real yards, not stick to MILS plates, and thus have particular interests (like R200+ curves) that certainly aren't available in stores, but also might not have 3d designs to print anywhere online.

I won't say that I've replicated the original rails exactly, but I hopefully have all the features to make curves compatible with original parts and the Lego system. 

As yet I haven't printed any parts, but I'm getting close to a design I think matches up.

For most purposes, the 3 basic variables are all you would need to change:

- #Gauge:  Studs covered by the rails.  Regular L-gauge track is 6 studs wide, of course.

- #Radius:  Stud radius of the track piece.  Centre of track to centre of circle.  Official track is R40, aftermarket usually goes up by 16s (56, 72, 88, 104, 120)

- #PerCircle:  Number of curves to complete a 360 degree circle.  R40 track uses 16, higher tends to go to 32 above R72. (64 above R152?)

But, to make it more flexible, I also have the advanced variables (I haven't tested these as much, so cautious use)

- #LDU:  Lego Design Unit.  If you wanted 2x scaled track, you might use this?

- #Stud: Width of a 1 stud brick.  Probably don't touch this.

- #Plate: Height of 1 plate.  Also don't touch this.

- #Tolerance: Tolerance around the edge of plates to make Lego easier to put together.

- #TieStuds:  Width of tie in studs.  By default this is gauge+2, minimum would be equal to the gauge.

- #TiesPerPiece:  Total number of ties (ends count as half each).  By default this autocalculates to space them roughly 4 studs apart, but you can pick any number 2 or more.

- #ClipSpacing:  Number of studs centre to centre on the end clips on the piece.  This is 2 for all official tracks, but it made sense to me to make adjustable.

I've split the model into 3 sections so it's also fairly easy to remove the ties if that's desired:

For example, here is a narrow gauge half R40 curve with the middle ties disabled.  It's also possible to turn off the end ties and get bare rails with the end profile to connect to regular tracks.  You do this by right clicking the folder and choosing "Suppress".  I don't know how well they would attach to track in that format.

I've built this in Onshape and it's the first time I used their platform, so bear with me, but I believe you can view the 3d model at this link, and if you have an Onshape account, you can create a copy for yourself, so you can edit the parameters.

 Onshape Curved Track

To a reasonable degree, if you want a particular size to print, you can ask in this topic, and I'll enter the parameters, make sure nothing's too wrong with the result, and share an stl file.  Though to reiterate, I haven't tested it myself, no warranty that it's useful.

 

Other sample outputs:

8-gauge R8, 90 degree curve, with 8 stud ties.  Maybe useful for a crane on rails?

5-gauge R120, 1/32 circle.

7-gauge R88, 1/32 circle, 8-stud ties.  As you can see, if the ties are half-offset from the rails by mixing odd and even, it automatically removes the studs that would interfere.  "UCS Hogwarts Express" curve, though the model doesn't articulate, so other changes needed.

[Berthil]

That's a great effort! I don't have an Onshape account and am looking for standard curves but in the narrow track radius (not sure what the radius is). I'm using tracks within the narrow track curves for narrow radius in this GBC setups at shows but trains derail frequently at the connection points with standard tracks.
 

If would be great if you would have an STL file available for me with a curve piece with a smaller radius that would fit exactly inside the R40 with a crossover pieces inside (or switch with a curve). I don't know what radius that is but maybe you can calculate please? I recently got a Bambu P1S and the print quality is great so would be very nice to be able to print and use on small tables at LEGO events.

[L-Gauger]

I like where your work is going, @Stereo. I've been examining some alternate gauges for Lego trains myself, and found some interesting things: 

- As you noted, a 6-stud-long plate will carry a pair of 4.5V rails at the correct L gauge. However, measuring gauge in the conventional way (between inner edges of rails) L gauge is 12 plates (4 bricks or 4.8 studs.) 

- One stud wider than L gauge (what you call "7-stud gauge") is similar if not identical in gauge to the conventional model railroaders' Gauge 1. 

- One stud narrower than L Gauge (what you call "5-stud gauge") is the same gauge as conventional Q gauge or Proto:48 trains. (Realizing this has made me think it would be cool if some fans of 8-wide trains would try converting their models to Q gauge...) 

- Lego narrow gauge track is the same gauge as S scale track. American Flyer trains will run on Lego narrow gauge or roller coaster track (I have tested this,) and presumably vice versa. I'm hoping to someday convert one of the official LEGO 6-wide trains to run on S gauge track, as that is the correct gauge for 6-wide, 1/64 scale standard gauge. 

Hopefully this information about compatibility is helpful!  

[Stereo]

2 hours ago, Berthil said:

That's a great effort! I don't have an Onshape account and am looking for standard curves but in the narrow track radius (not sure what the radius is). I'm using tracks within the narrow track curves for narrow radius in this GBC setups at shows but trains derail frequently at the connection points with standard tracks.

If would be great if you would have an STL file available for me with a curve piece with a smaller radius that would fit exactly inside the R40 with a crossover pieces inside (or switch with a curve). I don't know what radius that is but maybe you can calculate please? I recently got a Bambu P1S and the print quality is great so would be very nice to be able to print and use on small tables at LEGO events.

The narrow track radius is 24 studs, which does have a small availability on stores (eg. TrixBrix).  Anyway, with the understanding that you'd be a guinea pig in the process as I've not yet tested printing these, here is a link to an STL file for an R24 curve on Google Drive.  I think the most likely problem will be the clips needing tidying to work, as I've designed them at exact size, no extra tolerance added.  They are as far as I can tell 4mm diameter, so it should be easy to drill them open if needed.

41 minutes ago, L-Gauger said:

I like where your work is going, @Stereo. I've been examining some alternate gauges for Lego trains myself, and found some interesting things: 

- As you noted, a 6-stud-long plate will carry a pair of 4.5V rails at the correct L gauge. However, measuring gauge in the conventional way (between inner edges of rails) L gauge is 12 plates (4 bricks or 4.8 studs.) 

- One stud wider than L gauge (what you call "7-stud gauge") is similar if not identical in gauge to the conventional model railroaders' Gauge 1. 

- One stud narrower than L Gauge (what you call "5-stud gauge") is the same gauge as conventional Q gauge or Proto:48 trains. (Realizing this has made me think it would be cool if some fans of 8-wide trains would try converting their models to Q gauge...) 

- Lego narrow gauge track is the same gauge as S scale track. American Flyer trains will run on Lego narrow gauge or roller coaster track (I have tested this,) and presumably vice versa. I'm hoping to someday convert one of the official LEGO 6-wide trains to run on S gauge track, as that is the correct gauge for 6-wide, 1/64 scale standard gauge. 

Hopefully this information about compatibility is helpful!  

Yeah, to get specific, the way I've modeled it, it's 37.6mm gauge (inside edges of rails).  5 studs centre to centre, and the railhead is 2.4mm wide, reducing that from 40mm.  I am open to naming the gauges a different way (eg. call standard 5-stud since it's closest to correct, or 4 since that's the brick that fits between the rails), but I haven't really seen common usage, and I think this is easy to understand.  As you observe, +8mm makes it 45.6 which will run 44.45 trains on it, -8mm is 29.6 which nearly matches Proto:48 at 29.9.

I didn't actually mention it in the post, but it's possible for this to generate non-integer track - if you wanted exact O-gauge compatibility at 32mm, you could enter 5.3.  And so on... N gauge would be 2.3 studs, which is obviously not very useful, as the railhead would be about half the height of rolling stock, but does appear printable. One problem is you end up with more gaps between the studs.  And of course once you're in the weeds like that, you really depend on these files providing the entire ecosystem of tracks - which they don't, yet, only curves.  The antistud portion of the ties also doesn't really handle this gracefully yet - the outer ends of the ties are usable, but the middle needs to be over tiles.

[Berthil]

@Stereo I got the file, thank you! I'm waiting for Black Friday to order filament that resembles DBG and will print when I get it. I will let you know how the fitment is.

Edit, I can print a few in black PLA tomorrow and will let you know, it's only 24 gr. per track with 4 wall loops and 15% Cross Hatch Infill. 

Edited 6 hours ago by Berthil