"The animation looks excellent, well done, the pistons and pipes, etc, move better..." 

Thanks for laying the groundwork!

 

 

"Something I can't figure out. What is the function of the placeholder dial, it doesn't do anything and isn't linked to anything."

 

The placeholder is just that:  a placeholder.  I am thinking of rigging each car to sway a bit in time with the train moving; I just put it in the Tender to remind myself because the Locomotive and the Carriage already have ERC code in them

 

 

"1) Open each object file in UV Mapper, save with the "Don't export material file option", and then you can delete the .mtl files from the geometry folder, Poser doesn't use them at all."

 

Ok; I always delete the .mtl file for finals.  I left it in here since its WIP.

 

"2) On some object parts, like the body of the locomotive, you don't want people to use smoothing, it makes the model balloon, so you can turn it off by unchecking that check mark, and saving the model. Or in the CR2 just change:
 smoothPolys 1
 to:
 smoothPolys 0 
for the parts you don't want smoothing. This way you can leave it on for wheels and off for the body."

 

Great!  So I dont have to split all the parts, only the ones that will be smoothed?

 
Correct

 

*"3) You may want to hide dials you don't want people to be turning. For example, if the wheel turns only using the X-rot dial, you can hide the y-rot and z-rot. The less there is for the user to mess up, the better."

Will do.  In fact VK, in his toytrain seems to have deleted them entirely with no ill effect. I also will make the PistonTargets invisible and set to cast no shadows.

No, look carefully at what VK did. I am not sure if that was the method he used, but I taught him to hide body parts. In the CR2, there is a line:
 hidden 0
 If you set that to 1, then that body part doesn't show in the dial section, and that part cannot be selected. So for example, if you don't want the user to be able to select the wheels, then you set them to 1, and they will not be selectable, and their dials will not show at all. I do this with most of my models.

 

"4) The next thing is just nit picking. On a real train, the wheels do not all turn at the same speed. The small wheels turn faster than the large ones. For example, if the large wheel has a diameter of 2 metres, and the small wheel has a diameter of 1 metre, the small wheel will turn twice as fast as the large wheel."

 

I thought they were all covering the same amount of rail distance; I'll look at that again.  For the movement, I calculated the circumference of the drive wheels and moved the train that far in one cycle of 360 degrees.  I suppose I'll need to work backwards from that to determine the degrees of rotation for the smaller wheels.

They are. So a wheel with a 2 metre diameter turns once, and covers 2 meters. A wheel with a 1 metre diameter must turn twice to cover two meters, so it must turn twice as fast as the big wheel. I have an entire tutorial and a calculator I made in Excel that automates all of the calculations for working this out. I will send it to you tommorow.