What is a T-bone fillet?
It is a corner relief whose arc centre lies on one edge, one radius out from the vertex. The cutter still removes a full radius of interference. It just does that along one wall instead of on the diagonal.
How it differs from a dogbone
A minimal dogbone centres the arc on the angle bisector. Both edges lose √2 times the radius, and a small bulge shows past the corner. A T-bone spends 2× radius on the facing edge and nothing on the other. Compare both on the dogbone vs T-bone page.
Where the overcut goes
Auto picks the wall that still has room after the opposite corner is accounted for. You can force X or Y in the tool above. The file you download is the finished pocket contour. CAM generates the toolpath from it with the same bit.
When a T-bone is the cleaner visible result
Shelf dados, drawer openings, and any joint where one edge is on a show face. The square edge is the one that was not consumed.
When a T-bone does not fit
The facing edge must be longer than 2× radius plus the opposite corner’s share, with 0.05 mm to spare. A short wall will not take a T-bone. Use a dogbone, turn that corner off, or drop to a smaller bit. The tool names the edge and blocks the download rather than emitting a self-intersecting contour.
Export
SVG carries millimetre width and height plus a matching viewBox. DXF R12 coordinates are millimetres. See SVG vs DXF before you import into LightBurn or Carbide Create.