How to draw / model an epicycloidal curve in autocad or inventor

[Dale gribble]

Hi, I slowly building a 4th axis for my router and one of the item's I'm looking to make is a roots blower. My problem is that i don't no how to draw epicycloidal curves in autocad or inventor. I found a formula here on wiki

http://en.wikipedia.org/wiki/Roots_type_supercharge

Any information on this matter would be gratefully received

Kind regards

Dale gribble

[Dale gribble]

I managed to work out a method in inventor see uploaded pics. 1st pic is of the construction which is a copy of the wiki diagram, to create the epicycloidal curve i used a 3 point curve. I not 100% if it's a true epicycloidal curve but animates well in an inventor assembley.

[PCFlyer]

I had the same thought - no luck yet with Inventor. I found a routine for Solidworks that generates an epicycle. Need to convert to VBA to work in Inventor.

How's your blower coming?

PCFlyer

[Dale gribble]

Hi, I'm have to re-design my rotary axis, need to change it from worm gear to a toothed belt drive and add taper roller bearing all round. Then I'll give the shape I've created in inventor a try.

Regards

Dale