FixedChamfer: the tool cuts into a wall where the chamfered edge ends against it

Chamfer: the tool cuts into a wall where the chamfered edge ends against it

Affects: Takshak CAM 1.0.7 and earlier, 3-axis Form Chamfer and Mill Chamfer.
Status: Reproduced, fix in progress.

What happens: when a chamfered edge ends against a wall, the chamfer path runs the tool to the very end of the edge. An example is the top edge of a low step that runs into a taller block. With the tool's centre at the end of the edge, half the tool is inside the wall. On our test part, a 6 mm 90° V-bit cut 3 mm (0.12") into the wall, and a 6 mm end mill cut about 2 mm.

Picking one edge and accepting the width extends the chamfer along the connected edges until they meet a wall. Both ends of that chain can then run into the wall.

Also found while reproducing it: Mill Chamfer on a chain of edges that doesn't close into a loop cuts up to 0.8 mm (0.03") too deep at the outside corners. The error tapers off along each edge.

Not affected: closed loops, such as a part's outer rim or the rim of a closed pocket.

The fix: the chamfer will check what each end of the edge runs into.

Against a wall, it stops the tool short and tells you how much of the edge is left unchamfered. A round tool can't reach right into that corner.
At a free end, it runs past so the end is finished cleanly.
Mill Chamfer will also get the corner correction that closed loops already use.

Until the fix ships:

Don't chamfer an edge that ends against a wall.
For chains of edges that don't close into a loop, use Form Chamfer rather than Mill Chamfer.
Reported by dbtayl on the LinuxCNC forum. Thank you.