Remaining custom on an effort to use 3D contour

[davef_dci]

Hey kind folks, I'm a bit of a newby to Fusion360 and trying to use it to CNC mill a pretty simple contoured pocket.  I am using adaptive clearing to remove the bulk of the material and then Contour milling to finish mill the part. 

no matter what options I am selecting I am getting a larger "cusp" than I'm expecting at the top surface of the contour where it meets the bounds of the stock.  Is there something I should be doing to complete this cut out to the extent of the contoured surface? 

Thanks!  

[matty.fuller]

Contour projects contour lines onto the mode horizontally, as the name implies. As such shallow areas like this are not well covered... you can enabled "Machine Shallow Areas" under the passes tab, or combine it with another toolpath such as Parallel. You can also just replace it with Steep & Shallow, Scallop etc.

[a.laasW8M6T]

Hi

This is because 3D Contour is a Z level or Waterline toolpath, it makes slices through the part at the specified stepdown, so in steep areas it works great but as the part becomes shallower the Z levels stay the same but the XY stepover becomes very coarse.

There are several better options for that part as it isn't really all that steep anywhere.

Flow, Geodesic and Blend can give good results.

Scallop is a good option too but IMO leaves a less desirable toolpath pattern.

The nice thing with Flow Blend and Geodesic is they have a spiral option too for a continuous toolpath

See attached example file

[davef_dci]

Thank you!  this was very helpful.  I'm using flow which seems to yield pretty good results - one thing that's a bit confusing - when cutting the tapered walls using flow the program will cut a few layers towards the top (but not at the top) of the tapered walls, then progress to the bottom and then index back up to the top of the part to finish the cut. The results are fine but it looks pretty odd. Any idea why it's doing this?  

[a.laasW8M6T]

Hi

Without seeing the file I can't say for sure.

Flow works of the UV curves of the underlying surface, if these are not aligned it can sometimes cause issues.

If you want to share the part here you can Goto File>Export>Save as .f3d/.f3z

then attach to a reply here

[davef_dci]

That would be great. I'd really value any comments on my overall machining strategy as well - I'm pretty new to this. 

Thanks!

[davef_dci]

here you can see the phenomena I was mentioning.  The cutter enters in the middle of the sloped wall - cuts to the bottom and then goes back up to finish the upper part of the sloped wall. 

[davef_dci]

bah... never mind - I think i figured it out - it matters what order you select the drive surfaces. 

[a.laasW8M6T]

Interesting, this isn't something I've come across before but you are correct.

If You select the surfaces top to bottom as you go around the part it works good, If you select all the lower surfaces first, then the upper fillet it breaks into two sections.

@oleg.tikhomirov is this just a limitation of the UV aligning algorithm?

[oleg.tikhomirov]

Hi @a.laasW8M6T and @davef_dci ,

Thanks for feedback. It looks like Flow generates not optimal ordering for connected surfaces. From what I can see, it looks like on the picture below. It should be possible to do a better job in this case, so I'll create an Improvment ticket.

I can suggest two alternative options:

1. Blend strategy as it has been suggested above.

2. Split Flow in 3 operations with the following selections.

[oleg.tikhomirov]

CAM-58357