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Zero-clearance miter saw fence

A zero-clearance miter saw fence, mounted with WoodAnchor sliding nuts

Overview

Zero-clearance miter saw fences mount to the front of a miter saw's factory fence, or sometimes to the saw's base.  After mounting the ZCF, the saw blade cuts a zero-clearance slot.

A zero-clearance fence offers three major benefits.

  1. It increases cutting accuracy, by showing exactly where your saw will make the cut.  Simply align your workpiece layout marks with the zero-clearance slot.  With a good miter saw, your cuts will be split-the-line accurate.
  2. It supports the wood fibers on the backside of your workpiece, providing clean cuts with little to no tear-out.  
  3. It prevents even the smallest cutoff pieces from passing through the gap in the factory fence, so they can't become dangerous projectiles.

Most miter saws have mounting holes for zero-clearance fences.  But they're not commonly used, and for good reason.  If you simply mount a ZCF with wood screws, the zero-clearance slot will be opened up the first time you change the miter angle.  And it will be completely destroyed if you change the bevel angle, unless you remove the ZCF and then reinstall it afterward.   Even the small amount of saw flex from inadvertent side pressure on the handle can open up the clearance slot, requiring tedious fence remounting and a fresh cut to restore it.

Using a WoodAnchor fixturing slot and sliding nuts to mount zero-clearance fences makes them tremendously more practical.  If the zero-clearance slot widens after use, just slide the fence segments inward a bit, and recut the slot.

How it works

A WoodAnchor fixturing slot is milled in the backside of the zero-clearance fence segments.  Then the segments are mounted to the factory fence using WoodAnchor sliding nuts.  This provides for infinitely-adjustable positioning of the fence segments.

Rear quarter view of a zero-clearance miter saw fence, showing the WoodAnchor fixturing slots

To mount the ZCF to the factory fence, loosely install the WoodAnchor sliding nuts and their mounting screws in the factory fence.

WoodAnchor sliding nuts installed on a compound miter saw fence, ready for mounting an adjustable zero-clearance fence

Then slide the ZCF onto each sliding nut, position it as desired, and lock it down.

A zero-clearance miter saw fence, prior to cutting the kerf

Make the zero-clearance cut, and you're finished.

A zero-clearance miter saw fence, after cutting the kerf

When you're ready for a fresh zero-clearance cut, just loosen the WoodAnchor mounting screws, slide each fence segment inward, and retighten.  Make the fresh cut, and the fence is as good as new.  You've shortened it by only about one kerf width.

The WoodAnchor advantage

The WoodAnchor system is ideal for mounting sacrificial zero-clearance fences.

  • The sliding nuts are infinitely adjustable in the fixturing slot.
  • When you change the miter angle, you can quickly realign the front face of the sacrificial fence segments with the saw blade.
  • There's no metal T-track in the path of the saw blade.
  • The 1/4"-20 fasteners fits most miter saw fences perfectly
  • If your mounting holes are the same height on both sides of your factory fence, you can easily swap the two zero-clearance fence segments, and use their (normally) outboard ends for bevel cutting.
  • Sacrificial fences are usually made of scrap material, so they're essentially free.  You can keep different fences on hand for different bevel angles, if you wish.

Summary build notes

There's not much to say here.  Choose some flat scrap material that's at least 3/4" (or 18 mm) thick, and cut it to the desired length and width.  Mill a WoodAnchor fixturing slot at the same height as the mounting holes in your factory fence.  If the holes are at different heights on each side of your fence, mill the two sacrificial fence segments separately.  Install it and use it.