Gear Relation for Internal Gear aka Spirograph

geoff_higginbottom

Hi Team,

I have developed a SpiroGraph that has an adjustable outer ring which auto generates the gear teeth depending on ring size which works great.  However I cannot work out how to animate the rotation of the 'Spiral' Disc within the outer ring.

I have watched this tutorial https://cad.onshape.com/help/Content/materelation-gear.htm but it does not help as I cannot work out how to place the Revolute Mates.

I want the inner disk to move around the outer ring, which I can do using a Tangent Mate, but I also want it to rotate as though the gears were meshing and making it rotate.

Here is the link to the document https://cad.onshape.com/documents/a7d99d6fd77f3294449b23d2/w/856a3f5fad3c42ab9a79fd16/e/a6e7f9715e7b65f03cce206d

MichaelPascoe

Here is an approach that you could take:
Spirograph - MP

• Apply the mates to the parts before you place them into the assembly.
• Create another part concentric with the inner gear. 
• Use two revolute mates. One for the inner gear to rotate around the larger gear, and the other to spin the small gear.
• Then use the gear relation to connect the two revlute mates.

MichaelPascoe

Here is an approach that you could take:
Spirograph - MP

• Apply the mates to the parts before you place them into the assembly.
• Create another part concentric with the inner gear. 
• Use two revolute mates. One for the inner gear to rotate around the larger gear, and the other to spin the small gear.
• Then use the gear relation to connect the two revlute mates.

geoff_higginbottom

MichaelPascoe - you are amazing, I would never have worked this out on my own.  It still took me a good 30 mins to get it to work even looking at your shared example. I missed the fact the Ring was 'fixed' then I had trouble getting the spiral to rotate in the right direction, but I eventually got it so thank you.

geoff_higginbottom

For anyone stumbling across this I created v3 of the doc and shared again https://cad.onshape.com/documents/a7d99d6fd77f3294449b23d2/w/856a3f5fad3c42ab9a79fd16/e/c70bd0c6079a9c3c345319eb