Lock Miter

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Woodworking Shop

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Lock Miter Bit .jpg
Owner/Loaner: Dave Velzy
Hive13 Asset Tag: None
Make/Model: Meihejia 1/2 Inch Shank 45 Degree Lock Miter Router Bit (google)
Arrival Date: 6/2021
Does it work?: Yes
Certification Needed?: No
Contact: User:Woodworking Warden
Floorplan: Woodshop
Manual: [[media:|Manual]]


  • This Page is a Work In Progress
  • The Lock Miter Router Bit Corner Joint is a strong way to make a drawer body or a hollow column.
  • The well cut joint results in a tight seam at the corner intersection.
  • KEY PHRASE being 'Well Cut'.
    • Many woodworkers have tried out the lock miter joint, with less than satisfying results.
    • This page is a place to record the collective wisdom so that your attempts are successful.

Prerequisites to success with this tool.

  1. You do not need an expensive router bit. The Meihejia 1/2 Inch Shank 45 Degree Lock Miter Router Bit costs under $10. (And we have it.)
  2. The Router Table must be flat and the fence halves must be in alignment. Take care to assure the blue router inset is flush with the white table top.
  3. The black router cut out must be changed to fit the larger router bit.
  4. The setting of the cutter height is critical.
  5. Setting the cutter height and position is an iterative process. Prepare extra sacrifice wood to get the setting correct before making the cut on your critical piece.
    1. Use the Infinity Tool Lock Miter Jig to center the cutter to the center of the board. See photo and [this video]
  6. The wood that you use must all be the same thickness. Any difference in thickness will show up as an error at the outer edge of the joint.
  7. Protect the sharp edge of the routed wood by clamping the workpiece to a sled OR sticking a backer board to the surface of the board with double faced tape.
  8. Refer to [this article for more insight.]
  9. To reduce tear out, as shown in the pine example below, protect the ends of the cut by squeezing the edge between two sacrificial blocks.

Lock Miter Joint examples.

Joint Examples

Lock Miter Joint edges - Dry fit.

Dry fit edge

Lock Miter Cutter

Lock Miter Cutter

Changing the cutters

Changing the cutters

Lock Miter Infinity Jig.

Lock Miter Jig

Setting the cutter height.

Setting the cutter height

When installing the Lock Miter router bit,

  1. Remove the standard black cutter guard (3 Philips head screws)
  2. Raise the router to remove any cutter that was left in the router. Only raise the router high enough to engage the collet with the wrenches. Do not raise the router against the upper stop.
  3. Install the Lock Miter Cutter with at least 1/8" or 3mm of shank exposed above the collet. Install the large hole black guard.
  4. Precisely mark the centerline of your board edge. The centerline will be used to adjust the cutter height to the board thickness.
  5. Use the Infinity Tool Lock Miter Jig to center the cutter to the center of the board. See photo and [this video]
  6. Prepare a holding fixture to assure the position of the workpiece during the cut. You cannot successfully hand hold and guide the workpiece during a lock miter cut.
  7. Your fixture may be a simple as the ones shown, or more elaborate.
  8. An alternate method is to stick a larger guide piece to the workpiece with double faced tape.
  9. Test the cutter settings with scrap pieces of the same thickness board you will use in your project.
Lock Miter Vertical Fixture
Lock Miter Horizontal Fixture