[itsme]

Hi there,

Well, I finally got my mill working in 2 axes and after a day of drawing pretty pictures with a pencil in the chuck, I decided that I would try some proper machining. Seeing that my z-axis isn't ready yet, I was pretty much restricted to 2D profiles only. The obvious choice then, was to have a go at some wankel parts in aluminium.

I made a small housing as well as the rotor to fit it. I used my Excel spreadsheet to generate the Gcode for the housing and CAD/CAM to do the rotor. I have now modified my spreadsheet to take into account the tool radius when it generates the Gcode, so machining is easy. It can also generate code for a housing that is parallel to a true epitrochoid, which is what a running wankel needs. I needed to include the radius compensation, as I am using TurboCNC which can't do this on its own.

The big test to see if my spreadsheet actually works was whether or not the rotor would fit properly inside the housing. I kind of shocked myself a bit with the results. It is spot-on!

This particular 'engine' has an eccentricity of 2.86mm, a rotor radius of 20mm and the epitrochoid is 0.4mm larger all round than a true epitrochoid. The capacity is 4.12cc and it was cut using a 6mm endmill.

I'm now one step closer to building a running engine! Once the rotor and housing can be made (which they can now), the rest of the engine is relatively simple to do.

I've included photos of the rotor and housing as well as my mill.

Regards
Warren