Caboose, Flat Bed, Box Car and a New Version!

Hey there, wonderful people!

I never realised a little desk toy train would get so much love!  I've had lots of feedback, seen so many prints, it's just great!  But there was room for improvement.  First, though, let's talk about some new carriages...

Caboose!

Yes, a caboose!  Apparently every train needs a caboose at the back, so now we can have some closure :)  It's a bit taller than the regular carriage, and slightly longer.

Flat Bed

Just what it sounds like - a flat bed carriage!  It has a bit of texture on top for style :)

Box Car

Well, I'm not sure Box Car is quite the name for this one - I think the file itself is called something like "door carriage", but suffice to say it's a hinged box on wheels, so the name isn't entirely inaccurate.  This prints in place as usual, no supports!

Let's talk connectors!

So, there are actually two versions of all these models.  One has the original connectors that use bolts, and the other has print in place hooks.  

Choose the one you like best, but don't worry if you want both - there's a connector car to attach the new style carriages to the end of an existing set!

So, why the change of connectors?  Well, it seems people (not surprisingly) wanted these to be slightly safer around children, and the bolts were obvious hazards, being small parts.  The bolts are also tricky for smaller hands to manage, so the design goals were:

* make it easier to hook the carriages together, even if that means they come apart more easily!

* avoid firm connections that could be twisted and broken, yielding smaller parts; twisting should simply disengage the connection.

* remain support-free and printed sideways as before

Any 3D printed object has a certain vulnerability to breakage, so I'd always supervise small children with such things, but hopefully this at least removes some of the most problematic aspects!  

Also, the new connector is vastly more sophisticated than the screw bolt!  It still allows for rotation between the carriages, and being printed such that the layer lines are perpendicular to the hook it is quite strong, and should be difficult to break without simply disengaging instead.

Let's talk wheels!

The wheels are different too!  Let me see if I can remember all the differences:

* The tread design has changed to the herringbone pattern used on the Roller Van.  The previous linear pattern allowed for good grip on rough surfaces, but caused flat spots that slid rather than rolling on smooth surfaces.  The new version presents a properly round profile, rather than a series of flats.

* The axle is now completely enclosed so that it can't come loose (this was a problem on one or two people's setups)

* The axle surround has been reshaped to reduce friction - the axle now runs on four small bearing surfaces on the outsides instead of being in contact with the entire cylindrical surface inside the body.  The angled insides of the wheels still have the same contact as before, though, since they help spread the load if the carriage is pushed downwards, making it harder to accidentally break an axle.

Printing Tips

Just like before, these all print on their sides, no support needed!  You'll want to make sure your first layer is nice and neat and that there aren't any print issues like overextrusion or stringing that might bind moving parts together!

File Locations

All the Roller Train files are now in the one dropbox folder - 788 Roller Train

* The "original" style models are directly in that folder.  If you want to keep using the bolts, this is the version for you.

* The "new" style models are in a subfolder called  Roller Train Version 2.  If you want hooks and the new wheels, this is the place to be!

(Dropbox link post: https://www.patreon.com/posts/dropbox-and-are-31697592 )

Final Thoughts

Designing the new connectors was by far the most time consuming part of all this, but also by far the most fun!  There were a few different versions along the way, including a latch that slid in sideways and then forwards, but things ended up in a satisfyingly simple place.

So, where to from here?  I am happy to hear further suggestions, but I'm planning to put these train bits aside and finish off a few other things.  It will take a few moments to literally put the train bits aside, though, since I have so many carriages on the table next to me here :P

Happy train-ing! :)

xoxo

Sven.