TRAIN TECH Help, General Questions & Talk to the Staff

[Legownz]

I know the general consensus is to not bump posts that are more than a month old, but I forgot about how that rule applies to your own posts if you have an update you want to make to them?

[JopieK]

It is more that most people that bump just say: "Nice work" or ask for instructions, if you e.g. have an update on your build from some time ago I don't think there is anything wrong with that.

[Feuer Zug]

@Legownz We don't mind if you have an update and bump your own post. I've done it a few times. It's always nice to see how things progress over time too. My train shed started out decently and I posted it here. But, as it grew and became more complex, I kept the old pictures and added new.

[Legownz]

12 hours ago, JopieK said:

It is more that most people that bump just say: "Nice work" or ask for instructions, if you e.g. have an update on your build from some time ago I don't think there is anything wrong with that.

1 hour ago, Feuer Zug said:

@Legownz We don't mind if you have an update and bump your own post. I've done it a few times. It's always nice to see how things progress over time too. My train shed started out decently and I posted it here. But, as it grew and became more complex, I kept the old pictures and added new.

Ok thank you both! I tend to do a project in a relatively short amount of time and then call it done. Usually, if there's any aspects I don't like with it, they'll be at the back of my head for the next few months and it will force me to revisit/rethink something. My most recent MOC had a few things I wasn't totally satisfied with and I couldn't just let it be. I think I'll post updated photos soon of my improvements or I may wait a few weeks until I have the parts to make it in real life and just post it all then.

 

[Toastie]

On 3/8/2022 at 7:23 AM, JopieK said:

if you e.g. have an update on your build from some time ago I don't think there is anything wrong with that

I believe this is the core of the matter. EB as forum is fine. But EB serves so many other things as well. One is repository. Of ideas, MOCs, tests, failed attempts. Successful attempts (both are equally important, or - the latter even more so).

Yes, there are the pinned things, the moderator reviewed "lists" of this and that - but there is nothing better to get an update on a 10 years old project - which is still alive, because either the original poster or a fan of that MOC/MOD is showing some improvement - or better - alternatives.

That's the difference between EB and - TickToc. Or whatever the fire-and-forget platforms are called.

My personal perspective only!

Best,
Thorsten

[Ropefish]

I have two questions.

One, When a project is finished do I update the WIP thread to completed or do I make a new thread for the completed project?
Two, Are polls allowed?

[dr_spock]

Depends if you want new readers to follow your WIP progress or not.

I think you may have to be at a certain user level in order to create polls.

[Ropefish]

I have an odd thing i want to try but wish to explain to see if I am crazy or not, if I have a locomotive powered both from the tender and locomotive with a XL motor in the tender and L motor in the locomotive at 1:1 would those even out due to the wheel difference between drivers ( #10 LL ) and tender wheels ( #5 S), i say this as adding two XL motors would require a massive redesign i am not to eager to pull off however fitting the XL in the tender would be far simpler.

Edited June 19, 2022 by Ropefish

[ThePhatController]

I think weight will also affect them. Here is a simple test... Get a circle of track. Separate the tender and locomotive and put them at opposite sides of circle. Start them off at the same time. If they are running at the same speed then they will never catch up with each other. Otherwise you can see which is running faster and tweak to match them.

NB: this may also be a little crazy 🤪 

[Toastie]

9 hours ago, Ropefish said:

i say this as adding two XL motors would require a massive redesign i am not to eager to pull off however fitting the XL in the tender would be far simpler.

Oh yes, I can clearly see this huge re-design effort ...

Now, you are talking about PF gear, correct? If so, as @ThePhatController suggested, his tweaking approach may work.

I believe visiting @Philo's motor comparison page is always beneficial, when it comes to motor questions (and many, many other things as well). The PF L motor makes 390 rpm on a 9V supply, the PF XL 220. Depending on your gearing, this will of course change everything. The motors do also have different load/no load characteristics, so that will also affect the actual rpm at specific power settings, even when tweaked under "locomotive only" conditions.

Another crazy way out would be using PUp gear using 2x PUp L motors - and then use the SetSpeed rather than SetPower function. Then you do the same test as @ThePhatController has suggested and tweak the speed (not power) in a way, that they both run - well - at the same speed. It will certainly not be the same speed setting on the controlling device, as this depends again on your gearing ratios tender:locomotive, wheel size, and friction forces. However, once you figured out which speed setting on the tender matches that on the locomotive, you're done: The PUp hub (make it a 2-port City hub), will now keep the speed of tender and locomotive constant. This should also balance out the electrical stress on both motors a bit, as they "help each other out".

BTW, I find the PUp L motors quite powerful (8.8 N cm). The PF L provides 6.5 N cm, the PF XL 14.5 N cm => 21 N cm total. 2x PUp L (8.8 N cm) results in 17.6 N cm - all without gearing and such. The PUp XL is not doing anything better, as it also provides 8.8 N cm, but is geared differently. I also find their footprint and geometry favorable for integration into System and/or Technic builds.

Crazy? Sure, but I believe it may actually work.

All the best,
Thorsten

Edited June 20, 2022 by Toastie

[Ropefish]

2 hours ago, Toastie said:

Oh yes, I can clearly see this huge re-design effort ...

Now, you are talking about PF gear, correct? If so, as @ThePhatController suggested, his tweaking approach may work.

I believe visiting @Philo's motor comparison page is always beneficial, when it comes to motor questions (and many, many other things as well). The PF L motor makes 390 rpm on a 9V supply, the PF XL 220. Depending on your gearing, this will of course change everything. The motors do also have different load/no load characteristics, so that will also affect the actual rpm at specific power settings, even when tweaked under "locomotive only" conditions.

Another crazy way out would be using PUp gear using 2x PUp L motors - and then use the SetSpeed rather than SetPower function. Then you do the same test as @ThePhatController has suggested and tweak the speed (not power) in a way, that they both run - well - at the same speed. It will certainly not be the same speed setting on the controlling device, as this depends again on your gearing ratios tender:locomotive. However, once you figured out which speed setting on the tender matches that on the locomotive, you're done: The PUp hub (make it a 2-port City hub), will now keep the speed of tender and locomotive constant. The required speed settings depend on gearing, wheel size, and friction forces. This should also balance out the electrical stress on both motors a bit, as they "help each other out".

BTW, I find the PUp L motors quite powerful (8.8 N cm). The PF L provides 6.5 N cm, the PF XL 14.5 N cm => 21 N cm total. 2x PUp L (8.8 N cm) results in 17.6 N cm - all without gearing and such. The PUp XL is not doing anything better, as it also provides 8.8 N cm, but is geared differently.

Crazy? Sure, but I believe it may actually work.

All the best,
Thorsten

Yea the big stinker is if i move to PUp i can't use the PFx brick with it.... well without some hard wiring modifications, i am not bereft of options gladly but boy i have a lot of touch choices.

[dr_spock]

Crazy thought, if you use PU, you could read the rotation sensor in the PU motors.  Knowing each motors' RPM at any moment and the circumference of the wheels, you can determine the speed difference between the loco and the tender and adjust the PWM to one or both motors so the speed match.  Kinda like the ABS/traction control system in your car.

[Toastie]

8 minutes ago, dr_spock said:

Kinda like the ABS/traction control system in your car.

Pretty much so. I believe it would be easier though to use the internal hub "hold speed software", as you also take care of any load changes. Furthermore, the adjusting speed function between the two motors/gears/circumference is more or less linear (as speed is proportional to rpm and this is what the hub's algorithm tries to accomplish, reach constant rpm), so that speed_1 = speed_2 * x ( with 0 < x <= 1, provided the entire drive train and wheel circumference of 2 results in larger speed at identical manual speed_1 and speed_2 settings). Once x is determined, you only have to turn one dial (speed_1).

All the programming of reading the rpm and adjusting power is already built into the hub's firmware, why not building on that.

Best,
Thorsten

[bogieman]

My experience is that you can pretty much use any combination you want and they will work together just fine due the characteristics of the DC motors. All the motors have a negative slope torque-speed curve so that as the motor slows down for a given applied voltage, it draws more current and the torque output increases. So with all motors connected to a single controller and receiving the same voltage, they will find a balance point for train speed for a fixed load (drawbar pull). I've got two steam locos each with a PF L motor powering the drivers and a pair of PF train motors in the tender and they work together just fine. One loco is a 4-8-4, the other a 4-6-6-4 where the L motor powers both sets of drivers. Since all the electronics and batteries are in the tender, I can pull the train with just the tender and it slows down a little compared to when the loco is helping. If they were running independently, the tender would run away from the locomotive. I don't have traction bands on the loco drivers so they occasionally slip when pulling up the 4% grade on my layout as the train slows.

It's not unlike real railroading in the US where a train could have a mix of 4K HP locos with a 1.5K HP switcher in the consist; they all contribute to the total consist tractive effort but not equally.

Dave

[Toastie]

On 6/20/2022 at 5:26 PM, bogieman said:

My experience is that you can pretty much use any combination you want and they will work together just fine due the characteristics of the DC motors.

Oh come on, Dave, you just dwarfed all the programming fun! All the theoretical thinking and worries - but I guess you are right 

There is only one thing left for the theory folks: Optimization. When you let the DC motors doing it by themselves, the most powerful(s) will almost do it all - and it is not that much of a difference (but it still is, as you said!) to have a weaker member in there - it will basically move along. With some programming, you could kick their butt a bit more. A bit. That's all. Again: It does not make the big difference.

All the best,
Thorsten

Edited June 21, 2022 by Toastie
wrote as*, the auto thingy changed that to megablocks, which I changed to butt :D

[bogieman]

You are right Thorsten, that the more powerful will do most of the work. In my steam locos, the L motor is there not so much for tractive effort, just there to make sure the drivers do rotate while being pushed by the tender.

I'm just one to do it the old school way, not much of a programmer, though I was pretty good in my younger days with Fortran. I mostly prefer to be in control though I'm quite impressed by what you guys can do with your programming skill. 

Dave

[Ropefish]

Well this has got me a lot of things to consider, I think the PFx brick has similar control profiles to the PUhub but not the whole... detection thing hahah.

[dr_spock]

On 6/20/2022 at 9:22 AM, Toastie said:

Pretty much so. I believe it would be easier though to use the internal hub "hold speed software", as you also take care of any load changes. Furthermore, the adjusting speed function between the two motors/gears/circumference is more or less linear (as speed is proportional to rpm and this is what the hub's algorithm tries to accomplish, reach constant rpm), so that speed_1 = speed_2 * x ( with 0 < x <= 1, provided the entire drive train and wheel circumference of 2 results in larger speed at identical manual speed_1 and speed_2 settings). Once x is determined, you only have to turn one dial (speed_1).

All the programming of reading the rpm and adjusting power is already built into the hub's firmware, why not building on that.

Best,
Thorsten

That'll work if the user has PU hub.  What if they need to re-invent the wheel for their particular controler?

[Toastie]

11 minutes ago, dr_spock said:

What if they need to re-invent the wheel for their particular controler?

Ahh, now I get it: You mean folks having the PU motors but their own (programmable) controllers, right?

If so, yes, that could do the trick. The main obstacle for me would be to tap into the PU data flow - they have done it and shown it partly on EB; also Philo did that, I believe. To me, this protocol looks like trying to land on the moon without crashing the thing. But I may be wrong.

Best,
Thorsten 

[Darkkostas25]

Where can I find custom train wheels for stud.io? Coz legos 3 standard wheels, is not enough for me and some of my projects :\ 

Edited July 29, 2022 by Darkkostas25

[Vilhelm22]

3 hours ago, Darkkostas25 said:

Where can I find custom train wheels for stud.io? Coz legos 3 standard wheels, is not enough for me and some of my projects :\ 

Big Ben Bricks has the files on their website.  Elsewhere, HA Bricks has solid and boxpok driver files as well - I believe they intend to start producing them later this year.

http://www.bigbenbricks.com/ldraw/ldraw.html

https://www.habricks.com/product-categorie/wheels/

The other railway related studio files I have (if you’re looking for anything else) are custom steam rods at Trained Bricks, knuckle couplers at BMR Shop, and wide radius curves and switches at Bricktracks.  Many of these designers are on this forum if you look around, should you want them.  I find all of these parts incredibly useful in Studio.

https://trainedbricks.square.site/digital-resources

https://brickmodelrailroader.shop/products/knuuckle-coupler-ldraw-studio-cad-files

https://www.bricktracks.com/resources

Hope this helps.

Vilhelm22

Edited July 29, 2022 by Vilhelm22

[Darkkostas25]

7 hours ago, Vilhelm22 said:

Big Ben Bricks has the files on their website.  Elsewhere, HA Bricks has solid and boxpok driver files as well - I believe they intend to start producing them later this year.

http://www.bigbenbricks.com/ldraw/ldraw.html

https://www.habricks.com/product-categorie/wheels/

The other railway related studio files I have (if you’re looking for anything else) are custom steam rods at Trained Bricks, knuckle couplers at BMR Shop, and wide radius curves and switches at Bricktracks.  Many of these designers are on this forum if you look around, should you want them.  I find all of these parts incredibly useful in Studio.

https://trainedbricks.square.site/digital-resources

https://brickmodelrailroader.shop/products/knuuckle-coupler-ldraw-studio-cad-files

https://www.bricktracks.com/resources

Hope this helps.

Vilhelm22

Thanks mate! You are great!

[RuffDraft]

Hello everyone, 

I'm a bit of a train noob – only have the Christmas train in my collection, but I purchased 4 trams from the 10308 Holiday Main Street set, and would like to combine them together to have them running around my Christmas tree. 

My question: does anyone here have any elements that they'd recommend to help me to connect the trams together? And if so, the code numbers for those elements too? 

Thanks everyone! I'm really excited to build four trams – my Mum, Dad and girlfriend are going to build one each, as we put the Christmas tree up etc. and then the last one with the power functions, I'll take care of, but I just have no idea how best to connect them. 

Appreciate your knowledge! Thanks again!! 

[Duq]

Nice idea to build the tram together! I'm afraid you're looking at a bit of a modification job though. Most of the front is built studs forward. You can put something like 32530 on that but I'd be afraid it will get pulled off after a while.

You can remove the bottom row from the front, remove the brick with 4 studs forward, extend the chassis and then use for example the plate 2x3 with a hole, and a 3 long Technic liftarm with two 2L axles.

None of this is tested, I'm just thinking up a suggestion ;-)

[RuffDraft]

On 11/28/2022 at 2:11 PM, Duq said:

Nice idea to build the tram together! I'm afraid you're looking at a bit of a modification job though. Most of the front is built studs forward. You can put something like 32530 on that but I'd be afraid it will get pulled off after a while.

You can remove the bottom row from the front, remove the brick with 4 studs forward, extend the chassis and then use for example the plate 2x3 with a hole, and a 3 long Technic liftarm with two 2L axles.

None of this is tested, I'm just thinking up a suggestion ;-)

Thanks, @Duq! Really helpful of you! Thanks so much for the help regarding different elements too! I may try the 32530 for now, and see how I get on, and if it does pull off quite easily, then maybe I'll have to go with the other solution, but that sounds quite complicated for me. 😅 It might be easier if I have the pieces in front of me and have a go though! Thanks!!! 

Do you know which piece would help each tram attach together with the 32530 element? Thanks so much for your help! 🙌