How to make a helix that matches a cylinder's radius

w_s856

I would like to make a helix that looks like this (source)



I tried the solution found pretty much everywhere: create a cylinder (of radius R), create a helix on top of the cylinder, create a circle in the "corner" of the cylinder and sweep to extrude material. It works, but the final object has a radius smaller than R.

What I would like is the kind of helix above: something that I tightly fit in a shell cylinder and push some loose material as it rotates (this is my cat feeder again, the "loose material" is small pallets of cat food).

My constraint is the body the helix will go into (the rationale was "I start with the body and put parts around"). I can change that it it helps to "I will make a helix and fit a body around".

nick_papageorge073

You need to make the diameter of the circle that cuts away the material less than the pitch of the helix. Then, it will leave some of the original cylinder behind and match the original R value.

rafael_telgmann

Maybe this will help you? 
https://cad.onshape.com/documents/2f2b1fd8dc8d3ed0661eaa32/w/e6a1ca7f22ee9cec293d7af2/e/ea9464267def4cf661a7d5f2?renderMode=0&tangentEdgeStyle=1&uiState=6671df93d77fdf6aa871bab6