4×4 Post Notch Router Jig
3D-printable guide jig for cutting precise ½″ deep notches in 4×4 rough-cut lumber with a router.
router 4x4 notch jig 3d-print
Cut clean, repeatable ½″ notches in 4×4 posts without a fancy machine setup. This jig slides over the post, registers flush on two sides, and guides your router bit to the exact depth — every time.
What’s in the box
- PDF guide — step-by-step setup, bit selection, and technique for cutting post notches safely
- STL file — print-ready for any FDM printer with a 130mm+ build plate (fits Bambu Lab H2D in one piece)
- SCAD source (separate) — fully parametric; tweak cavity width, wall thickness, and slot depth for your stock
Specs
- Internal cavity 4.25″ × 4″ — oversized on width so it drops over rough-cut 4×4 stock that runs heavy
- Jig length: 12″ for stable registration, even on short offcuts
- Wall thickness: 3/8″ printed PLA — stiff enough to shrug off router downforce
- One continuous opening across the top and 2″ down both side walls — your bit and base have a clear, unobstructed path
- Notch depth: ½″ — set on your router’s own depth stop (3/8″ plate + ½″ notch = 0.875″ bit protrusion)
- Prints flat, open-bottom up — no supports needed
Using the jig
- Slide the jig over the post and clamp it down firm — no slop, no walking
- Set your router bit to 0.875″ protrusion (3/8″ plate + ½″ notch)
- Run the router across the opening in light passes — the jig registers the depth, you just drive it
- Lift, slide to the next mark, repeat. Every notch comes out the same
Works with any standard straight or spiral up-cut bit (¼″–½″ diameter). A spiral up-cut clears chips fastest and leaves the cleanest notch walls.