Trying new scales: from 1:220 down to 1:720

[martink]

I find I need to plan one layout ahead, so with Penzance coming along nicely I have been trying out some preliminary ideas for next year's project.  This includes some experiments with new prototypes and/or scales.  These are all just rough test builds, but hopefully might be of some interest here.

 

https://youtu.be/uBcmRts7tYk

[Colin_McLeod]

Some fantastic modelling in such tiny scales.  I like the use of linear motor technology.

 

 

[DGO]

Just wondering if this could be adapted to move some small vehicles at H0 scale circa 40mm x 17 mm in size would be really nice to have the hotel electric taxis go to and from my alpine station, and there is not enough room to do a magnorail setup, but I suspect the linear motors would let me do a setup to achieve a 3 point turn at the station and maybe a hidden turntable at the other end of the street 

[martink]

I was deliberately pushing to find the upper and lower size limits with this round of experiments.  My version of the track was optimized for T scale, so N scale plastic car-sized vehicles really are as big as it can go.  For HO, IDL's track could probably do it - it is inherently about twice as powerful and you can also use larger magnets which boost it further.  However, you would have to rip out some of the electronics and build a new control system from scratch - not a simple task.  I know somebody who has done a simple version of that using IDL's track with a Z scale front-end loader, doing  a 3-point turn back and forth between a coal stack and an unloading point. The turntable would be straightforward, but would have to use a brute-force approach (drive into a cradle which then forcibly turns the car around without moving the track).  Overall, doable but non-trivial.

[DGO]

Possibly silly question, but could you have a straight section of track with the turntable below ,drive the vehicle over the turntable, switch off the track and switch on the turntable spin the vehicle around then set switch off the turntable and switch the track back on ?

 

Since there are no actual above ground tracks it strikes me that this might be possible given that the turntable is hidden anyway 

 

[Colin_McLeod]

Agree @DGO.  That's exactly what railways gave been doing for nearly 200 years.

[martink]

6 hours ago, DGO said:

Possibly silly question, but could you have a straight section of track with the turntable below ,drive the vehicle over the turntable, switch off the track and switch on the turntable spin the vehicle around then set switch off the turntable and switch the track back on ?

 

Since there are no actual above ground tracks it strikes me that this might be possible given that the turntable is hidden anyway 

 

I do exactly that with the turntable on Penzance (there is a video in the T Gauge section of the forum), but it has its challenges.  The track has overlapping coils on the top and bottom, so joints and the turntable need special arrangements to provide an extra coil to span the gap. There are also more polarity reversal issues than a conventional system.  I had to make some custom track pieces to do the job; trying to adapt a standard piece would be tricky.

[DGO]

Ah I think I may have been misunderstood, I will try explaining again, there are no rails involved here just a smooth surface (like a road) as I understand it, so let us say the road surface is 0.5mm thick plasticard (or similar) and the "track" (yes I understand its actually overlapping coils) is directly beneath this surface, so to make this simple let us say the road finishes in a garage, the car drives in and stops, now let us say that inside the garage the road has a pair of kerbs on either side that hold the wheels of the vehicle in alignment, now let us take the floor (not the track below it) and spin it 180 degrees, the vehicle is now pointing in the opposite direction to how it entered, now reverse direction of the track and switch on and the car comes out and goes back down the road,  thus the long road section needs no breaks at the far end, for that matter I can leave the floor smooth and have the walls of the "garage" turn so that the wheels just slide across the plastic floor which is probably even easier as I can use a central shaft from above.

 

However what I'm not sure of is how you effectively get the equivalent of points at the other end in order for me to have my reversing wye so I can do the three point turn  does anything in the track actually move to do this or do you simply have two sets of coils one over the other going in different directions ? And if that is how you do things how do you stop the current in one coil feeding back to the other (though I guess thats not an issue because otherwise you could not get smooth running from one coil to the nest) Am I over thinking things ? I'm a Mechanical not an Electrical Engineer LOL

[martink]

6 hours ago, DGO said:

Ah I think I may have been misunderstood...

 

However what I'm not sure of is how you effectively get the equivalent of points...

With the turntable, that is exactly what I meant by a "cradle" - something that physically grabs and turns the car without doing anything with the track.  My fault for not explaining it more clearly.

 

I build points as two pieces of track, one on top of the other, then switching power between them.  As always, there are a number of complications.  The main one is that the lower piece is further away from the car's magnets so the drive force is roughly halved, a possible showstopper for a heavy HO model, which I solve by doubling the current (which quadruples the generated heat).  Other ones are getting the track surface back to the same level with packing pieces or another overlapped pair, ensuring that the coils line up perfectly where they do overlap so that the model doesn't jerk when you switch tracks, keeping the joins at the end of each track piece from getting in the way, and limiting the track heating problem.  Unfortunately, I am not able to sell you any of my track, so you would need to adapt IDL's.

IDL's track pieces are designed so that each turns on as a vehicle approaches and off after it departs, and are hard-wired for one-way running. You would need to tap into and override the on/off control wires on each piece and drive them from an Arduino or similar.  You may as well use the same Arduino to completely replace IDL's controller and drive the track directly.  One nice thing about the linear motor approach is that everything runs in lockstep, so the vehicles move a fixed distance for every drive pulse from the controller.  This makes automation remarkably easy.  The end result would be a program built around a movement script where each step turns on two specific sections (the one the car is in and the one it is going to), then generates a certain number of drive pulses either forwards or backwards until the car is fully in the next section, then optionally delays for a few seconds or immediately continues with the next movement.  Solid mechanical, electrical and programming skills are all needed. 

 

Bluntly, it is certainly doable, but it would be a big and challenging job, especially for a first-timer.  Back at the beginning I did look at adapting IDL's track for my own projects, but the associated difficulties and limitations meant that starting from scratch and completely reinventing the wheel was actually the better option.

[DGO]

The HO model is likely to be a 3D printed resin part so pretty light, basically a microvan like this  

that's used as a taxi service to take people between station and hotel, it's a bit on the small side to use a faller road system setup and 3 point turns would be difficult, likewise the magnorail system probably needs more space than I have by the station so a linear motor seems like it might be the only choice if I want movement, do IDL have a website ?  I suspect it still might not be practical due to the tight turns required to go around the street corners

 

Edited October 25, 2021 by DGO

[martink]

That size & weight of van seems reasonable.  IDL's website is www.teenytrains.com.