Milling a Crankshaft on a VMC

[MetalMarvels]

I have posted a simple one-throw crankshaft on the ftp site under MC8/Crankshaft.mc8. The A-axis center of rotation is through the end journals (parallel with the x-axis). I figured out how to accomplish the machining of the blue surfaced center journal using full 4th axis rotary motion and produced a decent part (in 6063-T6), but it was rather painfull getting there. The boss said that there was "no way" to do it on the VMC!!!!

 

I ended up using Multiaxis/Flow5ax with a surface that was one tool radius short of each of the side walls. The other challenge was producing a single diameter journal with an end mill that is not flat-bottomed (generating a concave or convex shape occurs without any further help due to the tool geometry).

 

My question: does anyone know a relatively easy way to generate the blue-surfaced journal on a VMC with full 4th axis using a flat or bull type end mill? Without having to "cheat" on the surface width????

 

Personally, my 1st response to the above would be "get a lathe", but where would the fun in that be?

 

GRW

[P_Scott]

Gary,

 

I've attempted a Curve 5-axis toolpath with 4-axis output operation. You can download it from the FTP site as your original part name with _SFA added to the end. I translated one of your arcs to the center of the surface and used it for the drive curve on the surface. The tool used doesn't matter however you will not be able to rough out the material with this toolpath. You may have to simply rough it all out first from the Top plane and then change to another plane to continue the roughing with standard 3D surface toolpaths before attempting to finish with this method. I also don't understand why it starts the curve from the center and works down from there. Do a simple Backplot and Step it through and you'll see what I mean.

 

HTH

[MetalMarvels]

Thanks, Peter. As soon as I make it home I will download the file and check it out. I didn't even think about using an arc rather than a surface. One problem that I had in going right to the journal is that most endmills are not flat-bottomed and will cut a barrel-shaped journal. I approached it by using a small tool and stepping along (x-direction) the journal in a finish pass.

 

GRW