train gear

please go to

Does anyone have ideas on EXACTLY how i would do this in blender.
clear instructions would be very welcome!

i have done the mechanics and gears tutorials.

Loaded question, this would probably require it’s own tutorial.

This would probably be done with parenting and constraints. You have any experience with these?

This forum is not really setup for people like myself to give step by step instructions for things like this. If you have done the tutorials, and know how to do basics in Blender, then next step is to just wing it. Give it a try with what you know. Search for different modeling techniques (and constraints, etc if you want it to animate like the drawing suggests it would).

If you have any specific questions/problems, this is the place to ask, after making sure it hasn’t been asked before, of course ;).



I invented this method in a few minutes.

Click here to watch Blender-Train-Wheel

It works, but needs to be modified.

Well, I’ve got the whole thing simulated (Using parents, constraints and armatures) but I can’t get the stupid file uploaded… My own site is down at the moment.

@spin: it’s probably easier to just use the “track to” constraint

(File missing, does anybody know if you can upload an image in a reply? It’s an animated Gif)

You can’t upload (attach) animated gifs to elysiun. You have to host them remotely and link to them.

thank you all for your help.

Incidentally, it’s also a tutorial in the blender book:

It’s not exactly what you were looking for (and it’s old), but at the same time it could easily be adapted. ALWAYS check out the manual first, as it does have a lot of good information in it. In fact, if you haven’t already I’d suggest going through the entire manual cover to cover anyway, because there’re bound to be things you haven’t encountered before that might be useful in the future.

I’ve built a fairly complicated simulation of a Civil War era railroad spike-making machine here… I welcome you to look at it and tear it apart. The motions and timing that are depicted by this model are accurate to the machine. (I would also remind you, however, that I consider the file to be copyrighted material that I’m providing for your personal enjoyment only, not for inclusion in a tutorial, and so-on. Thank you.)

One thing to remember, when doing reciprocating-drive mechanics like this, is that it’s usually easiest to let the wheel actually drive the engine. Once you cross that mental hurdle, it basically becomes a matter of constraints.

To start with, the wheel is turning, completing (say) RotZ from 0 to 359 in a straight line IPO which is cyclic. This gives you the “speed” of the engine and it produces absolutely-smooth rotation.

Parented to that wheel, we have (at least) the crank-pin, but we may also use the great friend of the animator, the Empty. (An “empty” is an object, but it’s only an invisible point in space.)

Now we have the crank-rods, which are centered where they connect to the piston and whose other end is constrained to follow the empty or the crank-pin, in a single axis only.

The end of the piston-rod, where the crank-rod attaches, is also constrained to follow the crank-pin or empty, in a single axis only, so that it is made to slide back and forth in a straight line. Since the crank-rod is parented to the piston-rod, the crank is pushed along.

In the same fashion you can build up a network of dependencies that produces the desired motion. You can also, at any time, define separate IPOs for the motion of other pieces, armed with the knowledge that their motion will be described either by a linear curve or by a sine/cosine curve. For instance, the motion of a piston that is pushing a crank is identical to that of a piston that is being pulled by a crank, and the mathematical progression of that crank-pin along a single axis is described either by Sine or Cosine, in that axis, both of which are simply “sine curves.” The default shape of a Blender IPO-curve, between two keyframe-points, is a sine curve.

“Empties” become very useful when the shape of the piece being driven demands that the hinges or center-of-rotation are not co-linear with the driving mechanism, as in the case of this spike-machine model. In this case, the driving mechanism acts upon an Empty, that is co-linear with the crankshaft, and the hammer-assembly is constrained to track its rotation along a single axis. This causes the motion of the hammer to be correct for “something that is turning on a hinge.”

Re cranks etc…
I am told by an expert…

I tried the file with Blender 2.37a and it went
wrong. Seems to be a bug in blender 2.37a because
using Blender 2.40 alphas and CVS versions it works