Surfacing spotface feature

[JB7280]

I have a spot face feature that has some other features (not shown) that don't allow a direct approach, so I'm trying to surface them with a ball mill.  The issue I'm having, is the toolpath is leaving a "cusp" or peak right along the highlighted lines in the screenshot.  Does anyone have an idea of a better approach?  If anyone has a faster, or more efficient toolpath that would work, let me know!  I've tried a few variations.  The toolpath shown, I removed the check surfaces.  Cusp is gone on top, but it digs in a bit.  With the check surfaces active, it leaves a cusp on top and bottom.

 Thanks.  (I'm attaching 2 screenshots and a Z2G file.) Oh yea, this is on a 4 axis Matsuura HMC.

6452005_OP2SFSAMPLE.ZIP

[AMCNitro]

How about surface them with a flat mill?  Or perhaps try a ramp contour?

[crazy^millman]

Convert to to a surface and extend the surface and call it a day. If a solid copy that part out and use the model prep to extend where you need.

[JB7280]

15 minutes ago, 5th Axis CGI said:

Convert to to a surface and extend the surface and call it a day. If a solid copy that part out and use the model prep to extend where you need.

Enlightne me, just a bit?  I haven't worked with surfaces very much.  I originally tried created a surface, then extending said surface, but it tells me that MC cannot trim edges of trimmed surfaces.

[#Rekd™]

40 minutes ago, JB7280 said:

Enlightne me, just a bit?  I haven't worked with surfaces very much.  I originally tried created a surface, then extending said surface, but it tells me that MC cannot trim edges of trimmed surfaces.

Create your surfaces on a new level. Then use Surface - Untrim command - then extend where required. 

[Chally72]

Just another note- in 2021, all the HST paths, including Raster, have a new option to add tangential extensions that will avoid this extra surface creation and trim step.

[JB7280]

1 hour ago, #Rekd™ said:

Create your surfaces on a new level. Then use Surface - Untrim command - then extend where required. 

Using your suggestions, I untrimmed it, moved the boundaries, and basically made an enlarged version of that surface, but the toolpaths are really goofy.  Any idea why?  or what toolpath would you suggest?  Almost like it's trying to wrap around to the bottom of the surface.  

[crazy^millman]

Change you boundary to contact point verses center and see if that makes a difference.

[JB7280]

16 hours ago, 5th Axis CGI said:

Change you boundary to contact point verses center and see if that makes a difference.

Before I read your post, I actually made a flowline toolpath, and used the gap settings to extend the transition moves.  Looks good on simulation.  If that doesn't work, I'll try the contact point.

[crazy^millman]

11 minutes ago, JB7280 said:

Before I read your post, I actually made a flowline toolpath, and used the gap settings to extend the transition moves.  Looks good on simulation.  If that doesn't work, I'll try the contact point.

That should work.

[JB7280]

5 minutes ago, 5th Axis CGI said:

That should work.

So, contact point vs. tool tip, that designates which part of the tool MC constrains within the boundary?

[crazy^millman]

17 minutes ago, JB7280 said:

So, contact point vs. tool tip, that designates which part of the tool MC constrains within the boundary?

Yes each process has a little different approach to how it handles the tool. Also Silhouette boundary take the shape being cut into account and you don't need a boundary per say. Using a boundary with it can in all reality wipe out the area you want to cut.

[Chally72]

Here's an example of the differences in choice between Tool Tip and Tool Contact Point. Say I want to cut the valley area, including the filleted valley walls, in this part with a raster. 
 

 

I'll set up a raster against those 3 surfaces, and set my containment boundary to use Silhouette boundary, which produces the same thing as if I created a wireframe chain containment area around those 3 surfaces. Using Tool Tip contain, this is what we get:

Note how we drive the tool tip all the way to the containment boundary edge. On this geometry, we're transitioning across a sharp edge at each end, and most of that motion is wasted time, because we already cut as much of the surface as we were ever going to cut by the time the tool was within 0.200" of that edge:

 

 

Changing the method to Tool Contact point trims the path to the point where the tool tangent contact point first completes the surface, and if we turn it on, we get this:

 

On this geometry, that trims out all of our wasted motion 'rounding' the sharp corner. On your collection of extended surfaces, you would turn this on along with silhouette boundary to get the least path motion possible to machine the full surface.

[JB7280]

6 minutes ago, Chally72 said:

Here's an example of the differences in choice between Tool Tip and Tool Contact Point. Say I want to cut the valley area, including the filleted valley walls, in this part with a raster. 
 

 

I'll set up a raster against those 3 surfaces, and set my containment boundary to use Silhouette boundary, which produces the same thing as if I created a wireframe chain containment area around those 3 surfaces. Using Tool Tip contain, this is what we get:

Note how we drive the tool tip all the way to the containment boundary edge. On this geometry, we're transitioning across a sharp edge at each end, and most of that motion is wasted time, because we already cut as much of the surface as we were ever going to cut by the time the tool was within 0.200" of that edge:

 

 

Changing the method to Tool Contact point trims the path to the point where the tool tangent contact point first completes the surface, and if we turn it on, we get this:

 

On this geometry, that trims out all of our wasted motion 'rounding' the sharp corner. On your collection of extended surfaces, you would turn this on along with silhouette boundary to get the least path motion possible to machine the full surface.

Awesome explanation.  Thank you!

[JB7280]

What toolpath would either of you choose for my feature?  I tend to stick to flowline, equal scallop, and raster because they're the only ones I really have experience with.