And here it is in spirograph. http://tomas.rokicki.com/somsky-spiro.jpg (This may not be exactly the solution I calculated but it does work in plastic). On Wed, Jul 22, 2015 at 8:33 PM, Fred Lunnon <fred.lunnon@gmail.com> wrote:
Please specify -- at least roughly -- the sun centre offset and locations of planets you have in mind.
With (minimum) offset 8/2pi teeth, and planets 32, 40, 42 all (somewhat impracticably) on the same side of the axis through sun 24 and ring 96 centres, I compute belt lengths
86.99579621, 47.00420379, 100,
omitting first, second, third planet resp. Note alternative values arise via subtraction from the tooth sum of those gears involved.
The discrepancy of one part in 10,000 could no doubt be absorbed by slack in the gears; however, this configuration at any rate seems not quite exact.
Fred Lunnon
On 7/21/15, Tom Rokicki <rokicki@gmail.com> wrote:
This is, I believe, a perfectly meshed Spirograph/Somsky solution.
I'm not positive the real plastic pieces will have gears small enough to prevent clashing, but the math seems to work.
On Tue, Jul 21, 2015 at 5:00 AM, Fred Lunnon <fred.lunnon@gmail.com> wrote:
Retraction --- bug detected! WFL
On 7/21/15, Fred Lunnon <fred.lunnon@gmail.com> wrote:
Not sure what "four sets of planet gears" means here.
Anyway, I compute that it is impossible to mesh 3 distinct planet radii from this set exactly with the sun and ring.
WFL
On 7/21/15, Tom Rokicki <rokicki@gmail.com> wrote:
I believe we can make a set of Somsky rigid planetary gears that work using an original Spirograph set.
This set includes wheels of size 24, 30, 32, 40, and 42, and a ring of size 96. Putting this together you should be able to use a sun of size 24 and four sets of planet gears 30+42 and 32+40. I believe this is the only combination that works with the default set of gears.
It's quite possible there isn't enough space to do this without the gears overlapping. But it would be fun to try.
Does anyone have an original Spirograph set?
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