A machined finger joint assembles two panels with through fingers cut directly into their outlines, with no screws and no corner hardware. It demands one thing the drawing does not show: a relief in every internal corner, without which the finger never seats fully.
A cutter is round. It therefore cannot machine a sharp internal corner: it leaves a fillet of its own radius there. A square-cornered finger entering a round-cornered socket lands on those fillets and stands open by 3 mm with a 6 mm cutter.
The fix is to remove material where the eye does not see it: in the corner, inside the socket. That is the relief — a dogbone, two circles set diagonally into the corners, or a T-bone, a perpendicular slot. The joint then closes completely.
The dogbone is faster to machine and removes less material, but it shows at the end of the joint on exposed work. The T-bone hides in the thickness and is invisible from outside, at the cost of a little more material removed.
The generator places one or the other in every internal corner of the outline, sized on the declared cutter diameter. Changing cutter in the settings resizes every relief in the job.
A finger joint binds or rattles within a few tenths. The generator applies an adjustable allowance between finger and socket, and you should set it on an offcut before running the job: it depends on the machine, on cutter wear and on the material. Plywood and MDF do not behave the same.
Two circular bores set diagonally into the internal corners of a machined socket, so the square corner of the mating part has somewhere to go despite the fillet the cutter leaves. Without it, a finger joint stands open by the cutter radius.
Not with a straight cutter: a dovetail needs a tapered cutter and machining at an angle. Cabinet·CNC produces only finger joints, which are what a straight cylindrical cutter can do flat on the bed.
Yes. The fingers give the glue area and the registration, the glue gives the strength. An unglued finger joint holds at assembly but moves and eventually loosens.
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