Might be just be the picture, but is there an impossible to cut trench around the boss thingy?

Dave

Is it just a facing cut?

Martin.

It's one of those seemingly simple jobs which are a PITA. If you trying facing the system will machine the outside perimeter with no problem but will overcut the boss. Conversely if you profile between the boss and outline it won't completely machine the corners of the outline.

A simple but very inefficient solution is to profile the boss but have a number of 8mm stepovers such that the whole of the blue area is covered.

Alternatively one could create a rectangular outline more than 10mm from the outside of the blue area and profile between the rectangular outline and the boss.

Andrew

use "2D Pocket"

Select 10mm flat bottom endmill

For geometry click the face you have in blue

Set stepover at say 6mm and zero stock to leave

Press Go!

Tool will take off a series of 5mm wide cuts, blue line indicates ctr of tool axis which will automatically work out that it needs to be offset 5mm from edge of boss, you can play about with directions, stay down etc if you want

Click the top right icon on the F260 screen and select "share" then "publick link" post link here then we can play with the actual part, this is the simplified example I used which you can open in fusion

Edited By JasonB on 27/06/2020 13:34:36

Pocketing doesn't work in my CAM software, which is why I didn't suggest it:

It sort of does what is sensible, ie, keeps within the outer boundary and outside of the inner boundary, even if it isn't what is wanted. Presumably Fusion360 has extra knowledge of the part geometry and knows it can go outside the outer boundary?

Andrew

Andrew, I wonder if it is because you are selecting two boundries and not a surface? F360 won't do it if I select the outer edge and edge of the circle.

On some types of cut F360 allow you to select cutter inside, on or outside the boundaries and also add an +/- offset to any of those options

This would be another option which is actually quicker for this part, first a parallel path to remove most metal but it leaves scallops around the raised boss so a followup contour around the boss is needed to clear that up, this snip shows the cutter part way through the contour cut.

Not sure if I have understood the problem but I would run Op 1 as a face from Stock Top to Model Top

Second op could be a 2D Contour from Model Top to Selected Contour to clear perimeter shape to bottom of overall 'keyhole' shape

Third op is 2D Adaptive from Model Top – 0.4mm (anything below model top) to Selected Contour (the top keyhole shape edge) with either zero stock to leave or some stock left for a Rest Machining clean up depending on finish.

Op 2 and Op 3 could interchange position.

But maybe I misunderstood.

That is interesting, you learn something every day; thanks very much.

It works fine in my old version of VisualMill:

I had in mind that using a facing operation with bosses would overcut the boss; but obviously that's not the case. I think it arose from my experiments with pockets that are open on one side. Pocketing doesn't properly finish the corners that meet the open edge. But facing overcuts the three sides that are not open. I'd better go back and do some tests.

Andrew

I use option 2.

Andrew