Surfacing Plastic

[SpecialtyTool]

I am having trouble surfacing some plastic parts. They have grooves that are large radii with tapered walls and I was trying to do them with a ballnose. When we checked them on a CMM one was way too big and the other was way too small and both were done with the same tool. Locations of the center lines were almost perfect. I've had 2 other people check my geometry and surface and I'm stumped.

[Manuel0822]

Did you go on a single toolpath & single direction like in surface parallel or contour? If so, it may not make sense but from my perspective I would think one of the radius would be cutting using climb milling while your opposite wall would be doing a conventional cut type of milling. It could be that the tool tip is not cutting as much material but in fact rubbing a little on that plastic on one of the walls.

 

Probably split the toolpath in half and make 1 wall per tpath, once they are both the same size, you could then adjust if you keep on getting 2 small or 2 bigger than they should radiuses.

[Mr. Wizzard]

What toolpath?

Check cutter comp (center or tip).

Check surface normals.

[jeff]

What type of plastic?

Some types (UHMW for instance) will distort overnight.

[SpecialtyTool]

What toolpath?

Check cutter comp (center or tip).

Check surface normals.

 

Honestly I don't remember the specifics. I said the hell with it and turned my part on its side and contoured it. I know I was using a parallel toolpath, the normal was good, but I don't know about the cutter comp. Whatever it defaults to I guess. What is typically used because I dont't know the difference?

[Mr. Wizzard]

i usually use tip, but sometimes get better results with center.