perennial boundary clearance problem.

[freman]

Hi,

I always have trouble with FC not cutting a pocket fully because it's scared to cut air or unused stock.

AFAIKT this is a fundamental limitation of the 2.5D tool design. However, I thought this was handled more ably by the 3D tools.

I've seen posts saying there are options to handle this from time to time but I can't find it when I need it.

If I use 2.5D pocket tool, I don't get any path at all because it gets vertigo passing over the 6mm hole at the bottom.


Can someone help out?

Many thanks.

Code: Select all

OS: Fedora 31 (Thirty One) (LXDE/LXDE)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.22872 (Git)
Build type: Release
Branch: master
Hash: 7c9e0f3a99d94d87e43df9fda09097d62537bb53
Python version: 3.7.9
Qt version: 5.13.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United Kingdom (en_GB)

[GeneFC]

This is what I get from the (2.5D) Pocket_Shape.

Capture.PNG (26.61 KiB) Viewed 197 times

Perhaps I do not understand your request.

OS: Windows 7 SP 1 (6.1)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.22846 (Git)
Build type: Release
Branch: master
Hash: 1f46b72491a0008384a6db4f2615a656249f6f08
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United States (en_US)

[sliptonic]

All the PathArea operations work pretty much the same way:

They first compute a shape to work on. For pocketing it's the shape of the area to work on. For profiling, it's the material to leave behind.
Then they slice the shape at the step-down levels to establish a set of 2D shapes
Next, they use the clipper algorithm to offset each 2D shape by the cutter radius to find the toolpath. For pocketing, the offsetting is done inward and done multiple times. For profiling the it is done outward.

That means for pocketing, the calculated shape establishes the outer boundary of the pocket. The tool will not move outside it.

So we can consider the problem as two questions: Is the offset calculation being done correctly? And, Is the removalshape being calculated correctly?
Here's the removalshape for your operation:

removal.png (11.74 KiB) Viewed 180 times

For 2D pocketing

and here's the removalshape for a 2D pocket with extensions turned on.

removal2.png (18.15 KiB) Viewed 180 times

Path needs a more robust way of configuring the removalshape. Extensions are great but only available in Pocket2D.

[freman]

@GeneFC
Ah, I need click on the Extensions tab and check the faces to extend, otherwise I get no path at all.

What you showed was exactly what I was trying to do. Thanks for the hint.