What the insert does
The insert fills the opening in the table around the blade. It lifts out so the blade can be changed, and it sets how much gap there is between the blade and the table surface. Both SawStop and DEWALT are blunt: never operate the saw without the insert in place, and DEWALT adds that it must be locked down, to reduce the risk of a thrown workpiece. SawStop's insert has a lock-down lever at the front for the same reason — to stop it rising unexpectedly.
Standard, zero-clearance and dado inserts
| Insert | Opening | Use | Limits |
|---|---|---|---|
| Standard | Wide enough for the blade at any height and tilt | General sawing | Leaves a gap beside the blade where fibres are unsupported and thin offcuts can fall |
| Zero-clearance | A slot cut by the blade itself, the width of the kerf | Cleaner cuts on the underside; thin rips and small parts | One blade width and tilt per insert; replaced when the slot widens |
| Dado | Opened for a dado stack | Dado, groove and rabbet cuts with a dado set | Required for dado sets on saws that allow them |
SawStop ships its cabinet saw with a zero-clearance insert whose slot it cuts at the factory after aligning the saw. Saws whose blade tilts need a standard insert, or a zero-clearance insert cut at that angle, for bevel cuts.
The insert maker Infinity Tools puts the case for zero clearance plainly: by filling the gap around the blade, the insert supports the wood fibres right up to the cut, which reduces tear-out on the bottom face, and keeps thin offcuts from dropping into the saw. Its limits follow from the same fit: each insert is cut for one blade width and one tilt angle, and once its slot has widened enough that it no longer supports the work at the cut edge, it is replaced.
How high an insert sits
The insert must not stand above the table where the work arrives, or the leading edge of a board catches on it. Makers set it slightly differently:
- SawStop: set the insert just below the table surface, using its front and rear leveling screws, and adjust the positioning screws so it slides in and out easily but does not rattle.
- DEWALT (DWE7491): the front of the throat plate flush with or slightly below the table; the rear flush with or slightly above.
Both keep the front edge — the side the work meets first — at or below the table. Use your own saw's setting and its adjusting screws; check it with a straightedge across the table and insert after fitting.
Fitting a new zero-clearance insert
A blank zero-clearance insert has no slot; the slot is made by raising the blade through it. Infinity Tools' method is to lower the blade fully, fit the insert flat in the opening, clamp it in place and raise the spinning blade slowly through it. Never hold an insert down by hand while the blade comes up through it. Follow the insert maker's instructions together with your saw's manual — SawStop warns against inserts with metal or other conductive parts that could touch its blade — and do not improvise a method with your hands near the blade.
Zero-clearance inserts help with clean edges on veneered panels and with thin rips. DEWALT's manual suggests clamping the work when using a zero-clearance insert where practical, which frees both hands from the work. For blade choice on the same jobs, see table saw blades; for dado inserts, dado blades.
Fitting an insert
- The saw is unplugged
- The insert is the one made for this saw — standard, zero-clearance or dado for the job
- A zero-clearance insert's slot matches the blade and tilt in use
- The front edge is at or just below the table, as the manual sets it
- The insert is locked down and does not rattle
- No metal parts of the insert can touch the blade
Sources
Insert heights are each saw maker's setting for its own saw, and the two differ; follow your saw's manual. The zero-clearance description is an insert maker's; the procedure for cutting a new insert's slot should be the insert maker's and your saw maker's, not improvised.
- 1.
Owner's Manual, 10" Professional Cabinet Saw, Model PCS31230. SawStop.
Used for: Never operating the saw without the table insert; the zero-clearance insert shipped with the PCS, fitted just below the table surface with its slot pre-cut at the factory; front and rear leveling screws, positioning screws and a lock-down lever; the separate dado insert required for dado sets; no inserts with metal or conductive parts that could touch the blade.
- 2.
DWE7491 10" (254 mm) Job Site Table Saw, Instruction Manual. DEWALT.
Used for: The throat plate locked in place at all times, with the front flush with or slightly below the table and the rear flush with or slightly above it; a dado throat plate for dado blades; clamping work when using a zero-clearance insert.
- 3.
Table Saw Zero Clearance Inserts. Infinity Cutting Tools.
Used for: What a zero-clearance insert does — supporting the fibres up to the cut to reduce tear-out on the underside, and keeping thin offcuts from dropping into the saw — and its limits: each insert cut for one blade width and tilt, replaced when its slot widens; the insert maker's method of cutting the slot.
- 4.
Creating a Dado Sled — safety instructions. Freud Tools.
Used for: Obtaining the proper insert for the saw before using a dado set.
About this guide
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