What a dado set cuts
DEWALT's description is the plain one: a dado is used whenever a cut is needed that is considerably wider than the saw's kerf — commonly to support and line up a shelf in a cabinet or bookcase. The same stack cuts three related channels, named by where they run:
Because none of them cuts through the work, the guard and most splitters cannot stay on the saw for these cuts. That is the main reason dado work needs more care than ordinary sawing, and why the steps below matter.
How a stacked set is built
- Two outside blades cut the walls of the channel. Freud's instruction is absolute: always use both outside blades; never run the chippers by themselves or with only one outside blade.
- Chippers fit between them and clear the waste. Freud's SD508 comes with chippers of 1/8, 3/32 and 1/16 in; its SD208S with three 1/8 in chippers.
- Shims — thin rings — set the width between the chipper sizes, so the groove can match the actual thickness of a shelf.
- Diameter. The sets here are 8 in, and both saws below that accept dado sets limit them to 8 in.
The width of the groove is the sum of everything on the arbor. Freud gives the SD208S a range of 1/4 to 7/8 in. Whether you may build it that wide on your saw is a separate question, answered by the saw's manual.
Equipment notePaid link
8-in Pro dado set, with Dado Lock Down Insert
Freud SD208S
Freud's SD208S from above, here with Freud's dado lock-down insert: 8 in, three 1/8 in chippers and grooves of 1/4 to 7/8 in; your saw's manual decides whether it may be fitted.
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Will your saw take one?
| Saw | Dado sets allowed? | Largest diameter | Widest stack | Also required |
|---|---|---|---|---|
| SawStop Professional Cabinet Saw | Yes | 8 in | 13/16 in | Optional dado brake cartridge and dado insert; arbor washer left off above about 3/8 in |
| DEWALT DWE7491 jobsite saw | Yes | 8 in (200 mm) | 13/16 in (20 mm) | Dado insert, sold separately |
| DEWALT DWE7485 compact jobsite saw | No | — | — | "DO NOT use dado sets, multiple blades or shaping cutter heads on this saw." |
From each saw's manual. The two saws that allow dado sets cap the stack at 13/16 in — narrower than the 7/8 in Freud gives as its set's maximum.
Caution— The saw's manual decides, not the blade's box
Freud describes its SD208S as compatible with all saws, naming SawStop, Jet, DEWALT and Bosch. That is a statement about the blade set. DEWALT's DWE7485 manual forbids dado sets outright, and the saws that allow them limit width and diameter. Saws for different markets can also differ, so check the manual for your exact model before buying a set. Never modify a saw — a longer arbor, a cut-down insert — to take a stack its maker does not allow.
Guarding during dado cuts
- The guard comes off, and goes straight back on. OSHA does not require a spreader during dadoing, grooving or rabbeting, but requires it to be replaced immediately after. DEWALT tells owners to reinstall the guard assembly, anti-kickback assembly and riving knife as soon as dado cuts are finished.
- The riving knife may or may not stay. SawStop tells owners to fit the riving knife for non-through cuts except dado cuts. Follow your saw's manual on this point; designs differ.
- Featherboards hold the work instead. OSHA calls for featherboards or jigs where a standard guard cannot be used, naming dadoing; SawStop and DEWALT both describe featherboards clamped to hold the work against the fence and table.
- Several shallow passes. DEWALT and Freud both say to make deep or wide cuts in several passes rather than one; Freud adds that this reduces the chance of kickback.
- No improvised wobble blades. OSHA prohibits the "wobble saw" made by wedging a blade between its collars so that it runs off-square.
Fitting a dado stack
Setting up for a dado cut
Confirm the saw allows it
Read the dado section of your saw's manual: whether dado sets are allowed, the largest diameter and widest stack, and any extra parts — SawStop's saw needs a separate dado brake cartridge.
Unplug the saw and remove the guard
Take off the guard and, where your manual says so, the riving knife. Remove the standard insert.
Build the stack
Mount an outside blade, the chippers and shims for the width you need, then the second outside blade — teeth facing the direction of rotation marked on the blades. Fit the arbor washer and nut as your manual describes; SawStop leaves the washer off for stacks wider than about 3/8 in.
Fit the dado insert
Use the dado insert made for your saw. SawStop and DEWALT both require one, and Freud's instructions tell you to obtain the proper insert.
Check clearance before power
DEWALT says to check dado blade clearance before plugging the saw in: turn the stack by hand and make sure nothing touches it.
Set featherboards and cut a test piece
Clamp featherboards to hold the work to the fence and table, set a shallow first pass, and cut scrap to check the width before cutting the real part.
Restore the saw
When the dado work is done, refit the standard blade, standard insert, riving knife and guard before any other cut.
Before the first dado cut
- The saw's manual allows dado sets, and the stack is within its diameter and width limits
- Both outside blades are on the arbor
- The dado insert for this saw is fitted
- Any extra part the maker requires (such as a dado brake cartridge) is fitted
- Featherboards hold the work to fence and table
- The first pass is shallow; deep cuts are taken in several passes
- The guard and riving knife go back on as soon as the dado work ends
Freud publishes plans for a dedicated dado sled, with its own guard. Not every crosscut sled may be used this way: POWERTEC's manual forbids using its sled with dado blades. See crosscut sleds for how sleds differ, and the safety guide for why the work must be held flat and against its guide.
Sources
Compatibility figures are each saw maker's instruction for the model named; they are not limits for other saws. The dado set's width range and compatibility statement are Freud's own description of its product; the saw's manual decides what the saw may run.
- 1.
Owner's Manual, 10" Professional Cabinet Saw, Model PCS31230. SawStop.
Used for: Dado use on the Professional Cabinet Saw: 8 in sets only, never stacked thicker than 13/16 in, with the optional dado brake cartridge and dado insert; the arbor washer left off for dado widths above about 3/8 in; the riving knife used for non-through cuts except dado cuts; no molding heads.
- 2.
DWE7491 10" (254 mm) Job Site Table Saw, Instruction Manual. DEWALT.
Used for: Dado use on the DWE7491: no stack thicker than 13/16 in (20 mm) or larger than 8 in (200 mm); the dado insert; guard removed for dado cuts and replaced afterwards; several shallow passes for deep cuts; checking dado clearance before plugging in.
- 3.
DWE7485 8-1/4" (210 mm) Compact Job Site Table Saw, Instruction Manual. DEWALT.
Used for: The DWE7485 manual's instruction: do not use dado sets, multiple blades or shaping cutter heads on this saw; featherboards for non-through cuts.
- 4.
SD208S 8" Pro Dado Set and SD508 Super Dado Set specifications. Freud Tools.
Used for: The SD208S (8 in, 12 teeth, 5/8 in arbor, 6,000 RPM maximum, three 1/8 in chippers and three spacers, grooves from 1/4 to 7/8 in, described as compatible with all saws) and the SD508 (8 in, 24 teeth, chippers of 1/8, 3/32 and 1/16 in, with a shim set).
- 5.
Creating a Dado Sled — safety instructions. Freud Tools.
Used for: Freud's dado safety instructions: confirm the cutter is compatible with the saw; use the proper dado insert; always use both outside blades, never the chippers alone or with one outside blade; make wide or deep cuts in several shallow passes; inspect the carbide before use; and Freud's plan for a dado sled with a polycarbonate guard.
- 6.
Owner's Manual, Model No. 71403 Table Saw Crosscut Sled. POWERTEC.
Used for: POWERTEC's instruction not to use its crosscut sled with dado blades.
- 7.
29 CFR 1910.213, Woodworking machinery requirements. U.S. Department of Labor, Occupational Safety and Health Administration.
Used for: Spreaders not required during grooving, dadoing or rabbeting but replaced immediately after (1910.213(c)(2)); featherboards or jigs where a standard guard cannot be used ((a)(15)); the improvised wobble saw not permitted ((s)(8)).
About this guide
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