Machine cavities not working for me

[sendithard]

New to cam. I'm practicing on this part. Decided to do a 3d adaptive roughing with .5mm stock left and boring out the hole. Then I wanted to do another 3d adaptive with .2mm stock left and a finer stepdown.   For the 2nd operation I wanted to leave the hole alone and do a 2d contour much later on it.  So I chose to uncheck 'machine cavities'. Problem is in the geometry tab if you set it to 'none' it still machines the cavity. A duplicate operation simply selecting silhouette resolves this issue and the cavity is successfully avoided. Any thoughts on why?   In my attachment I suppressed the operation that has 'silhouette' used. The one active shows the cavity being milled.   Thanks.

[engineguy]

@sendithard 

Seems to work OK here, all I have done to the first operation (3d Adaptive) in your file is toggle the "Machine Cavities" to off and it toolpaths correctly without the hole. 🙂

So not able to replicate your problem 😞

I added a new 3D Adaptive operation from scratch with the "Machine Cavities" toggled off and smaller stepdowns and that also seems to work fine without the hole.

When you toggled it to off did you try "Re-generating" that toolpath ???

File attached

Stay Safe

Regards

Rob

[sendithard]

@engineguyI believe you changed the first operation in your mod to not machine the cavity. I am trying to do 2 separate operations. The 1st machines the center hole, then the 2nd ignores the hole and just does a finer stepdown of the previous operation. For simplicity, I have uploaded another file with only 2 operations. Notice the second operation has 'machine cavities' unchecked, yet it still goes into the cavity. If you go into the geometry tab and change 'none' to 'silhouette' it will then avoid the cavity. Very strange.

[engineguy · Accepted solution]

@sendithard 

The second toolpath is going into the hole because you have told it to go there !!

The reason is that you are using "Rest Machining" for the second toolpath but you left "Stock to leave" so what you have done is to tell Fusion to leave some stock on the first toolpath so the second toolpath is removing what the first toolpath left, so if there is stock left in the hole then the "Rest Machining" function will go and clear that stock out, which is exactly what you told it to do.

This appears to disable the "Machine Cavities" function as it makes no difference whether it is toggled on or off 🙂

Now, as you have found if you create a boundary by using the Silhouette then the second toolpath has been told it can not go into the hole. Of course this means that there is still stock left in the hole which you will need to remove another way, 2D Circle is just one option, up to you how you clear the hole out 🙂 🙂 🙂

What you could do is use the 2D Circle to clear out the hole immediately after the first 3D Adaptive toolpath and you would not need to use the "Silhouette" in the second 3D Adaptive, there are of course other ways but I think that is the simplest way if that is what you want to end up with 🙂

Example file attached.

Stay Safe

Regards

Rob