A router bit can’t cut a sharp inside corner — every internal angle keeps a fillet at the tool radius, and your tenon won’t seat. The standard fix in CNC joinery is the dogbone relief, but placing them manually on every part gets old fast.
Form2Bone adds them automatically. One command (F2F_Dogbone), three parameters:
Tool diameter — your actual bit
Diametral clearance — added to the diameter (e.g. 4 mm bit + 1 mm = 5 mm relief)
Offset — shifts the relief along the corner bisector. Positive adds play, negative gives you a friction or press fit
You get a preview before committing: deselect any corner you want to keep untouched, then validate. UI is in French and English — Rhino picks your language automatically.
It’s designed to work alongside Form2Nest (flattening + nesting to CNC-ready DXF): unfold and nest your parts, add dogbones, export. Full workflow without leaving Rhino.
Walkthrough video (French, English subtitles/dubbing available):
This looks like a very useful tool, can’t wait to try it. A feature suggestion: rabbet/rebate pocket detection and offset. In order to ensure a clean pocket it’s generally necessary to overcut the sides of the rabbet that reside on the edges of the finished part by radius of the tool being used. Thanks!
Thanks — that’s a well-chosen suggestion, and a real shop-floor rule: on the open sides of a rabbet, the pocket geometry needs to extend past the part edge by the tool radius, otherwise the pocket floor isn’t clean at the boundary.
One precision though: it’s not quite a dogbone. Form2Bone works by boolean cuts on the 3D solid, and the overcut region lies outside the finished part — there’s nothing to cut in 3D. This can only exist as extended 2D curves in the exported DXF, after flattening. So it belongs to the export stage — on the Form2Nest side, which handles flattening, nesting and DXF export — rather than Form2Bone. Same philosophy, compensating for a round tool, different place in the chain.
Adding it to the Form2Nest roadmap as an export option: detect pocket sides coincident with the part outline and extend them by the tool radius. Question to build the right thing: do you draw your rabbets as closed contours, or do they come from a rebated 3D solid that gets flattened?
Thanks for trying it — feedback like this is what shapes the tools.
Hi Jeang - Yup, you described it perfectly. I generally model the 3d solids as they are to appear in reality and extract/adjust my vectors from those polysurfaces, etc. Thanks for taking this into consideration! And while I’ve got you, any chance we’ll see an English language version of Form2nest?
