GearHeads Corner

Hi all,

Firstly, thank you for making gearotic, its fantastic, and I appreciate that it's been in existence a while, so many thanks for continuing to support it.

I am an Orrery maker, and am collaborating with another orrerymaker to try to come up with, to the best of our knowledge, the first mechanical model of Halley's Comet which obeys true Keplerian motion (the speeding up of objects as they approach the sun, and slowing as they move away). Short story is that mathematically generated ellipses approximate Keplerian motion well for eccentricities near zero, but fall away from ideal as the eccentricity rises. Halley's Comet has an eccentricity of over 0.9, and so ellipses are good, but not great at modelling motion. We would like to do as well as we can.

The gear shapes needed to model true Keplerian motion can be calculated (the method is complex and computationally intensive - which is easy these days, but previously really hard) but we have the shape - the shapes look like slightly 'fat' ellipses.

The question I have is, can gearotic take this shape, or two of them, and add teeth so we can then make the gears? I guess I'm really asking, can a shape be imported for teething?

Many thanks again!

Chris

Hi Chris:

Unfortunately, I didn't put in a way to tooth your own shape, this was primarily because its very difficult to ensure a shape CAN be toothed when drawn by another. This is specially true of ellipses, or near ellipsoids as no formula exist for their length, and teeth must fit in integer multiples.
That problem is solvable of course as an integrated depth from the curve is usually close enough, but allowing any input at the time seemed unsolvable in the general sense.
You could try to make the functional match your shape with knot edit, ignoring the mate of it, and put a round gear of the same module to run around that toothed shape of the master. Usually, a round will run on the master gear made by the functional. It tries to create from your knots, a circular Bezier ( which should be able to match many shapes, but hard to do knot by knot), it does try to constrict you to a solvable shape, but it could work..

Regards
Art