A sacrificial fence is a length of wood (or sometimes plastic) clamped, screwed or bolted to a tool’s actual fence so that the blade, bit or cutter can safely run close to it, into it, or through it without touching the tool’s real metal fence. When it wears out or gets chewed up, you replace the board — not the fence.
What does “sacrificial” mean here?
It means the fence is expected to take damage instead of the machine. A saw blade, router bit or drill bit occasionally needs to travel right up to — or fractionally into — the edge of a fence to complete a cut cleanly. Doing that against the tool’s own metal or plastic fence would nick it permanently. A sacrificial fence is deliberately disposable: a cheap board that absorbs that wear.
It is not a safety guard and it does not replace one. It is closer to a shop-made accessory, similar in spirit to a jig a woodworker builds for a specific job. It solves a fit-and-finish problem — how to get a clean cut right to an edge — not a guarding problem.
Why not just use the tool’s regular fence?
Because the regular fence is a precision part, and most cuts don’t actually need the blade or bit touching it. A sacrificial fence lets you take the one cut in twenty that does need contact without wrecking that precision part.
Manufactured fences are usually machined flat and square, sometimes coated or hardened, and they’re expensive to replace. Running a spinning bit into one — even slightly — can leave a groove that throws off every future measurement taken against it. A scrap of wood costs little and is easy to swap out or plane flat again.
Where do sacrificial fences actually get used?
They turn up on several common workshop tools, usually for the same underlying reason: letting a cutter approach or graze the fence face without damaging it.
- Router tables — an auxiliary board clamped across the metal fence, often with a bit opening cut into it, so the fence can sit closer to the cutter for edge-forming or flush-trimming work.
- Mitre saws — a board fixed behind or in front of the saw’s fixed fence, giving zero-clearance support right where the blade exits, which reduces splintering on the back of a crosscut.
- Table saw rip fences — a board clamped to the fence face for cuts where the workpiece needs to sit unusually close to the blade, or where a slightly wider bearing surface helps keep a narrow or thin piece steady.
- Mitre gauges and crosscut sleds — an extension fence bolted to the gauge itself, which does the same job as the ones described in our guide to what a mitre gauge does and how it supports the workpiece through a cut.
In every case, the sacrificial piece is bolted or clamped to the tool’s existing fence — it’s an addition, not a replacement for anything that keeps the operator’s hands or body clear of the cutter.
How is a sacrificial fence attached?
Most are held on with the fence’s existing clamping mechanism, or with bolts through pre-drilled holes, or simply with woodworking clamps at each end. The method depends on the tool, but the goal is the same: firm, immovable contact for the whole cut.
A sacrificial fence that shifts partway through a cut is worse than not having one at all, because it can let the workpiece move unpredictably. Before cutting, it’s worth giving the board a firm push test by hand to confirm nothing rocks or slides.
Many router tables and some rip fences have threaded holes or a machined face specifically designed for bolting on an auxiliary fence — check the tool’s manual for the intended mounting method rather than improvising with adhesive or single small screws that could work loose under vibration.
What materials work well for a sacrificial fence?
Flat, stable, void-free material is what matters, not exotic wood. Common choices include:
- Plywood — stays flatter over time than solid wood and doesn’t have grain that can split along a thin edge.
- MDF — very flat and smooth, cuts cleanly, but produces fine dust that needs proper extraction and a respirator, as covered in our piece on why fine dust matters more than ordinary sawdust.
- Solid hardwood offcuts — fine for lighter-duty fences, though more prone to warping with humidity changes.
Thickness is chosen for rigidity, not appearance — a fence that flexes under light hand pressure will flex under cutting forces too, and that defeats the purpose of adding it.
Does a sacrificial fence replace a blade guard or riving knife?
No. A sacrificial fence is an auxiliary work-support accessory. It has no bearing on a machine’s guarding, and it should never be used as a reason to run a cut with a guard, riving knife or other safety feature removed or disabled. Those features stay in place and in the configuration described in the tool’s manual, regardless of what fence is attached.
If a particular cut seems to require a guard to be out of the way to fit a sacrificial fence, that is a signal to rethink the setup — a different fence shape, a different jig, or a different tool — not a signal to alter the guard. Our guide to what a table saw’s riving knife does explains why that part stays fitted, and our explainer on what causes kickback covers why an unsupported or pinched workpiece is dangerous regardless of what fence is in use.
What are the signs a sacrificial fence needs replacing?
Watch for a groove or gouge deep enough to let the workpiece rock, a face that’s no longer flat against the tool’s fence, or splintering along the edge that used to give clean support. Any of these mean the board is no longer doing its job of holding the workpiece steady and true.
Because the whole point of the fence is to be cheap and replaceable, there’s no reason to keep using one once it’s chewed up. Swapping in a fresh, flat piece takes minutes and restores the accuracy the setup depends on.
What PPE does working near a sacrificial fence call for?
The fence itself doesn’t change the hazards of the cutting operation — it’s still a spinning blade or bit throwing chips and dust. Eye protection is needed for anything that ejects material, and hearing protection for any sustained run time on a router table, table saw or mitre saw.
Cutting into MDF or dense manufactured board to shape a sacrificial fence produces fine dust that settles deep in the lungs if inhaled repeatedly — a fitted respirator and a dust extractor rather than a shop vacuum makes a real difference here, and the distinction is covered in our comparison of a dust extractor versus a shop vacuum.
How does a sacrificial fence compare to a featherboard or other jigs?
A sacrificial fence supports the workpiece against a tool’s fence face; it doesn’t press the workpiece down or sideways the way a featherboard does. The two solve different problems and are often used together — a sacrificial fence giving a clean, close edge, and a featherboard keeping steady pressure against the fence through the whole cut.
Both are examples of the same general idea covered in our guide to why woodworkers make their own jigs: rather than adapting a technique to fit the tool, a simple shop-made accessory adapts the tool to fit the cut.
What should you compare before adding one to a tool?
Check that the tool’s fence actually has a sanctioned way to mount an auxiliary board — clamping points, bolt holes, or a flat face designed for it — rather than drilling into a fence not meant to be modified. The manual for the specific saw, router table or mitre saw will show the intended attachment points and any limits on fence height or overhang.
For readers weighing up which fence-equipped tools suit a given job in the first place, our buying tools hub covers what to compare across models, and the broader tool guide hub explains how fences, guides and other reference surfaces work across different machines. Browsing the power tools archive is a good next step for tool-specific detail, and the safety and PPE archive covers protective equipment in more depth.
Find Tool publishes general information, not professional advice. Power tools, mains electricity and workshop machinery are genuinely dangerous, and the safe settings, guards and procedures differ between models — always follow the manual and the markings on the tool in front of you rather than a general guide. Never remove or defeat a guard or safety feature. Anything involving fixed wiring, gas or structural work belongs to a qualified tradesperson. Wear the eye, ear and respiratory protection the task calls for.
Featured image: Photo by Shixart1985, source, CC BY 2.0