Why not just set up your lock-miter router bit this way?
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The mysterious hidden groove joint
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Lock Mitre Router Bits
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The common misunderstanding of safe router feed direction
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New locking miter joint by Microjig.
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How To Use A Miter Lock Router Bit From Zokmok Tools
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I wish I'd made these 2 Router jigs when I started out!
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The Genius Miter Trick You Were Never Taught
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