Model Trains

[andy3055]

This is great! I think I have the parts in hand to build one. Thank again.

[pcprogrammer]

I keep seeing servo motors popping up in this discussion.  Servo motors are a completely different animal.  You send a PWM signal to the servo to specify its desired position.  But, that is the end of PWM.  Servo motors have a angular feedback mechanism from which a comparator drives the motor with a DC voltage in the forward or reverse direction until the angles match.

The more modern servo controllers also use PWM internally to control the motor. This at a much higher frequency then the external PWM signal.

[RoGeorge]

With all the 3D printers (optical ones), would make sense to buy only generic wheels platforms, with/without motor, then to have (free) downloadable models, for various wagons and locomotives shapes.  That will require painting after 3D printing, but that's not unusual in modeling.

I bet the printing resin + platform wheels would cost less than the ready made wagons or locomotives, wouldn't it?

[MarkF]

This is great! I think I have the parts in hand to build one. Thank again.

Depending on the voltage of the power pack, you may need to add a resistor between the pot and the diode to limit the max track voltage to 12V.  I would try to limit the max track voltage between 12V and 12.5V  You could safely go as high as 14V, but I would not.

With all the 3D printers (optical ones), would make sense to buy only generic wheels platforms, with/without motor, then to have (free) downloadable models, for various wagons and locomotives shapes.  That will require painting after 3D printing, but that's not unusual in modeling.

I bet the printing resin + platform wheels would cost less than the ready made wagons or locomotives, wouldn't it?

I don't have a resin printer, but that would be a real chore to print you're own rolling stock.  By that, I mean doing a CAD design for them.  I haven't seen any models that have been made.  Although, there are structures and other small items for can download.  The actual material would be cheaper.  But, I don't know if resin printers can duplicate the fine details and again the time required to do a CAD design would probably not make the savings worth while.

As far as wheels, most people will swap out plastic wheels for all metal ones.  And the better rolling stock already come with metal wheels.

I have been struggling to print a searchlight signal head with my Creality CR-10.  The small size seems to be right at the limit for creating the detail needed.  They are something a resin printer could probably do but I don't have any experience with their capabilities.

[RoGeorge]

I don't have a resin printer, but so far my understanding is that the level of details and smoothness of the prints is much better than in the filament prints.

About the 3D models, it's enough to draw it once.  Another source of models can be made by scanning the real thing with a laser scanner, in a rail station or in a museum.  There is yet another way to reconstruct a 3D model by using many pictures taken from different angles.  Then, there might be technical drawings in archives.  None of these is perfect, but I guess will require less work than making a model from scratch.

In time, more and more CAD models for trains will accumulate.  After all, it doesn't has to be collector's items or copyrighted models, can be fantasy wagons and locomotives that never existed before. 

All is needed is to be enough enthusiasts, and to bring them together in a forum or some similar online place.  There, they can talk to each other, share pics and videos with miniature landscapes and trains, exchange between them info, models and hardware, etc.

[andy3055]

Unless one has a ready "market," I think the effort to create rolling stock from scratch and painting will not be worth as I see it. Even with commercially available stuff the details and painting is not all that perfect.

[MarkF]

Andy,

Since you expressed interest in the AC Fullwave throttle a few posts back, I spent a little time today laying out a PCB that I might build to see how my locomotives respond.  Here are the gerber files if you would like to have a PCB built.

You can remotely mount the pot and run wires to a DPDT switch instead of the relay.

[andy3055]

Mark,
Thanks for that. Is that the same circuit you suggested earlier? Since it is just a few parts, I was planning to use a veroboard but I realized that I don't have the Darlington transistor. I have to order one. I have the rest of the parts. If you do put it together before me, please let me know how it performs.
At the moment I have an old Bachmann controller which to my horror was giving out 20 volt spikes. I have my daughter and her family coming over on Saturday for a week and I just got the basics working for the little girls. 

[MarkF]

Yes.  It should be the same circuit unless I messed up somewhere.

Except, I used a 2N2222 instead of the 2N3904 because I'm have a bunch of 2N2222.

[MarkF]

I found another video on making pine trees that is simple to do.  Enjoy.

[andy3055]

Thanks  Mark. I will check on that circuit once I get hold of the Darlington transistor.
There is a YouTuber in Canada who does some nice work with cheaply available stuff rather than buying from  Walthers etc. I will try to find his page and post it.

[andy3055]

Check this out. He has a few more on creating trees etc.
https://youtu.be/v0rvFaI8fzU

[MarkF]

Check this out. He has a few more on creating trees etc.
https://youtu.be/v0rvFaI8fzU

There is a YouTuber in Canada who does some nice work with cheaply available stuff rather than buying from  Walthers etc. I will try to find his page and post it.

Thanks Andy.  I forgot that I had seen him before. 

Were you talking about Boomer's Youtube channel ?  He indicates that he is in Canada now but he use to work in Hollywood creating models for the movies.  He is very good and explains a lot of insight on the thought process behind the work.  I especially liked his series on scratch building a dinner. 
   

I follow quit a lot of Youtube channels.  Part of my morning routine.   
Here are a few more channels that have been very instructive:
   https://www.youtube.com/@THEBENNETTRAILROAD/featured
   https://www.youtube.com/@ThePixelDepotLLC/featured
   https://www.youtube.com/@EverardJunction/featured

I am just now getting started on the scenery and putting together the last two buildings that have been waiting in a box for 25 years.   
I'm going back to my older buildings to add LED lighting.  I'm also working on moving the mountains and tunnels from my Anyrail design software to layout to see what looks right.  That's why the 3D printed tunnel portals sitting around in some of the pictures I posted.

[andy3055]

OMG! These guys are great at modeling. If you look at them "in the scale," it is like you are in the scene.
Great links.
Thanks for the message.

[andy3055]

Andy,

Since you expressed interest in the AC Fullwave throttle a few posts back, I spent a little time today laying out a PCB that I might build to see how my locomotives respond.  Here are the gerber files if you would like to have a PCB built.

You can remotely mount the pot and run wires to a DPDT switch instead of the relay.

Mark,

What is the value of R1 in this circuit?

[MarkF]

The value of R1 depends on the AC transformer that you use.
For a 9V AC transformer, it would be 0Ω (i.e. no resistor).
For a 12V AC transformer, I believe I calculated something around 150Ω.
It is just to bring down the maximum track voltage.

It's a basic voltage divider circuit:
   

You can use an online calculator to get a value. However, the actual track voltage will be two diode drops (V_BE = 1.4V) lower because of the darlington.
   https://ohmslawcalculator.com/voltage-divider-calculator

Or just put a meter on the output and try some values in the 0Ω to 200Ω range trying the limit the track voltage down close to 12V.  Definitively, keeping it below 14V.


Note:
  If you don't use R1 and you're using a 12VAC transformer, the track voltage will be about 15.5V.  Which IMHO is a little too high for a 12V motor.

Note 2:
  I'm forgetting about all the diode drops at the front end.  So, the voltage will be a little lower.  Just leave R1 out and check the output voltage.  Then adjust R1 accordingly.

[andy3055]

Got it, thanks.

[joeqsmith]

I know, necroposting...   Years ago a I was loaned the book Hackers written by Steven Levy.  It documents some of the early history of computers, starting at MIT.  The term hacking had a different meaning back then, so don't expect the book to be about what we call hacking today.   

The book starts out talking about the model railroad club at MIT and how they were using some of the telephone switch gear to automate the trains.
https://classes.visitsteve.com/hacking/wp-content/Steven-Levy-Hackers-ch1+2.pdf

When I was a child, I played a lot with my old train sets.  I was at a dumpsite an found some sort of electric timer.  Basically a motor with a complex rotary switch attached to it.  I took it apart to sort out how it worked and used it to automate my trains.

I still have a few bits from my old trains that survived.  I remember my dad taking me to an old farm house where a lady showed us her husbands old train sets.  My dad bought them for me.  Shortly after we got home, a person contacted my dad about wanting to buy some of the passenger cars.   My dad sold them off before I had a chance to play with them.  Most likely a good thing if they were collectable (I was rough on my toys).   

Sorry but I have no photos of the old setup.   Imagine an 8-12 year old playing with plaster, paper mache  and spray paint.  You pretty much have it.  Nothing like what the adults put together today.

[andy3055]

Building up the scenery is beyond even most of the adults let alone the young kids. In my case, the stuff was collected for over 40+ years. It is hard at this age to work on these due to the usual aches and pains. I want to complete a fairly basic system I can use to impress the two granddaughters. Pity, there is no grandson.  I sometimes wonder what would happen to all this stuff as my age progresses. 

[joeqsmith]

A friend's GF's dad who had passed away had a large collection of trains.  I met her mom and she let me see it.  It was a large HO scale layout that took up most of their basement.  My guess is it gave her mom comfort or, she didn't want to deal with liquidating it.   I don't have enough parts that survived my childhood to make the cleanup more than taking a box to the recycle bin.   The few parts I have are in rough shape and I doubt would have much value to anyone besides me.

Saw a website where they had restored some of the old cars.  Stripping rust, prime, bodywork...  It was like a car restoration complete with new graphics.   I've looked for used parts to see if I could repair some of mine.  It may be fun to get it running.  Maybe just an oval...

[andy3055]

What scale are your trains?

[joeqsmith]

Mine were mostly O gauge.  I had I think an old S gauge that was a steam bullet.  Similar to this one,  but from what I remember it was a dull silver painted finish. 

https://www.ebay.com/itm/235307468024

I tore one of my engines apart.  This is a Marx 999.  The wheel bearings are all shot.  My childhood custom paint job was in poor condition, not just that I had no skills to be painting at that age, but it had a lot of chips and such.  Chemical stripper....   

I have no idea on the age.  I didn't think I could put a price on my childhood memories, but this site suggest the very common one is worth about $20.    

https://dfarq.homeip.net/marx-999-locomotive-variations/

[MarkF]

My first layout (the test track) was just two ovals. 
One inside the other with a crossover between them.

When my bother and I were kids, our father built a O scale layout
with Lionel trains.  They flew off the rails and onto the floor
most of the time.  When my father passed 15 years ago, we divided
them between us.  He had them running for my nephew for a while.

The new O scale locomotives with sound are all fancy now (electronically).
I don't know anything about them.

[MarkF]

I have no idea on the age.  I didn't think I could put a price on my childhood memories, but this site suggest the very common one is worth about $20.    

I would say more like $120 in pieces.

You can't even get a HO scale box car for $20 now days.
Last year I paid $160 for a non-DCC HO locomotive.

[MarkF]

When I was in high school, my father took me to someone who built
a 1/4 scale steam engine in his garage.  He had two flat cars with seats
and a 12" wide track in his back yard for his grandchildren to ride in.