[MOC] Inverted spirograph

[Peter Nolan]

Hello! I'm a first time poster in the Technic forum, but thought that my inverted spirograph might be of interest. Rather than move the pen, I used a planetary gear setup to move the paper. Different gear combinations give different results, as does the pen position. The pen-holding frame is made up from a lot of 2 x 4 bricks, but the guts of the machine is a hard plastic wheel with internal gear teeth (I'm not sure of the correct name, but this is the part I used: http://www.bricklink.com/v2/catalog/catalogitem.page?id=83393&idColor=11#T=C&C=11). Sadly the spirograph has now been dismantled--my son needed the parts for a Chima vehicle...

Enjoy!

 

 

[captainmib]

That is really cool.

Love the idea.

 

I think you need to brace the pen better, or apply some down pressure. It would make the drawing a bit better.

[Peter Nolan]

Thanks for the feedback--yes, the linework was quite wobbly! The pens were Lego brand (with a cross-section almost the same as a 2x1 brick) but unfortunately they were a little undersized, which resulted in some play in the pen holder. If I was building it again I'd probably include some kind of locking mechanism to hold the pen.

Cheers,

Peter

[Diamabolo]

Great Work, to use a planetary gear to spin the paper.
Do you have any detail pictures?
Her is my planetery spirograph

 

[iLego]

4 hours ago, Diamabolo said:

Her is my planetery spirograph

This one is really nice !

One additional level of gearing is adding a lot to the final images. They look awesome.

[Peter Nolan]

Hi Everyone, seeing these comments got me thinking about what the different gear ratios would do. I've put together a table of all the possible gear combinations and the resultant number of points in a spirograph pattern. I've treated the 14 tooth gear combinations separately, since these can only mesh with double bevel gears (as far as I know). The maximum number of points is 18, when you rotate a 36 tooth gear around a fixed 14 tooth gear. Apologies for low quality image--I had to resort to a low-res jpeg to get the filesize small enough.

[Peter Nolan]

Just worked out some more gear combos--haven't figured out how to post html though... Also haven't figured out how to delete comments--please ignore this one.

Edited January 29, 2021 by Peter Nolan
Tried to test code formatting, didn't work and couldn't delete comment.