The simplest dado routing jig is a straightedge with a sacrificial edge trimmed by the same router and bit you’ll use for the cut. For a dado that fits a shelf or panel, measure the actual stock first, then set the guide width to match it—not its nominal size. A paired-rail jig is another option when you want adjustable guides, but its edges must be calibrated to the specific router and bit.
Choose the jig that suits the job
| Jig type | Useful when | Check before cutting |
|---|---|---|
| Straightedge with sacrificial edge | You want a simple guide that can also guide grooves or rabbets. | Straightness, support length, clamp placement, router-base offset, and condition of the sacrificial edge. |
| Paired adjustable rails | You want an adjustable two-sided guide and can build it accurately. | Base flatness, parallel rails, router-and-bit-specific edges, and preserved router orientation. |
| Commercial adjustable jig | You prefer built-in adjustment and the model fits your router. | Bushing and base compatibility, maximum cutter diameter, width range, included parts, and number of passes. |
Make a straightedge jig with a sacrificial edge
This approach uses a straight guide and an oversized strip of thin hardboard. Trimming the strip with the router and bit that will cut the dado creates a reference edge showing the cutter’s path. Woodcraft describes making the straightedge about six inches longer than the workpiece; treat that as an example, not a fixed requirement. The guide should support the router base before and after the cut and leave room for secure clamps. Woodcraft’s “Perfect Router-Cut Dadoes,” published February 5, 2012 and updated May 30, 2026, describes the straightedge method.
- Prepare the guide. Choose a straight, stable straightedge longer than the workpiece. Attach an oversized thin hardboard strip along its edge; leave enough material to trim it with the router.
- Clamp and trim the reference edge. Secure the assembly on a stable surface. With the intended router and straight bit, run the base along the straightedge to trim the hardboard. Keep the base supported throughout the cut. The fresh edge now marks the cutter path for this router setup.
- Set the dado width from the mating stock. Measure the board or panel that will fit into the dado. Position the guide so the cut matches that measured thickness, accounting for the router-base offset and any guide or spacer thickness.
- Set the depth and test. Set bit depth using the router adjustment, accounting for any jig base that raises the router above the work surface. Make a test cut in scrap from the same material and check the fit before cutting the project piece.
Woodcraft describes using sacrificial guides and the mating shelf stock to establish the dado width. Its method also calls for accounting for guide thickness when setting bit depth. A narrower straight bit can make a wider dado in multiple passes; the fence position and spacer method establish the final width.
Set the dado to the actual board thickness
Measure the stock that will enter the dado rather than relying on a nominal label. Woodcraft reports that hardwood plywood is typically undersized from nominal thickness by 1/64 to 1/32 inch; that is the magazine’s reported range, not a guarantee for every sheet or brand. Ryan Reese, a contributor to that Woodcraft article, describes the basic setup as “a bit that’s a smaller diameter than the desired dado width, a couple of scraps of wood, and a straightedge fence to guide your router.”
#1 Best Overall
- PRECISION DADO CUTS: Achieve perfectly straight and accurate dado cuts with this Router Dado Jig. Effortlessly create grooves from 1/4" to 1-1/4" wide, or any width in between, using standard 1/4", 3/8", and 1/2" router bits. Require 1/4", 3/8", and 1/2" straight bit sold seperately
- PERFECT FIT GROOVE: The adjustable fence allows you to set the jig using an actual workpiece sample, ensuring consistent, precise groove widths every time - no guesswork required.
- EASY ALIGNMENT: The built-in cut line indicator ensures precise alignment for grooves ranging from 1/4" to 1-1/4", giving you professional results with minimal effort.
- BUILT-IN DUST PORT: The 1.5" OD dust port connects to a 1.5" ID hose, minimizing dust and debris for a cleaner, healthier workspace. Use with the POWERTEC 70356 Vacuum Hose Kit (sold separately) to enhance dust collection while you focus on your woodworking projects.
- UNIVERSAL FIT: This router dado jig is compatible with any router base plate that accepts Porter Cable Style Guide Bushings. A 1" bushing is included with the jig.
One width-setting method uses two spacers: first place a spacer matching the bit diameter against the fence and make the initial pass; then replace it with a strip of the mating plywood held on edge and make the second pass. This lets the actual stock establish the final fit. Another method, described in the POWERTEC jig manual, uses a straight, unwarped spacer from the material intended for the dado. Capture the spacer without play, lock the adjustment, remove the spacer, and use the resulting opening as the jig’s open position. Check that the assembled guide slides freely.
Build a paired-rail adjustable jig
A two-rail design can guide both sides of the router base and adjust to different dado widths. One documented homemade version uses a thin MDF base split into two pieces and aluminum angle rails. Its builder’s example is about 700 × 200 × 30 mm overall, with roughly 500 mm of cutting length, and was made for a 6 mm straight bit and a DeWalt trim router. These are design-specific dimensions, not a standard or a guaranteed fit for another router.
Rank #2
- MAKE STRAIGHT, ACCURATE DADOS AND RABBETS – Woodworkers asked us for a router guide / router jig that would make precise Dados, Rabbets, and Mortise cuts
- WORKS WITH THE BORA WTX and NGX CLAMP EDGES – The perfect addition to your woodshop, this dado router guide will help with all of your woodworking projects
- WORKS WITH ALMOST ALL MAKE/MODEL ROUTER – Includes a 1” standard guide bushing for easy mounting (works with almost any routers). No drilling or bolting necessary
- VERSATILE CUTTING FOR WIDE DADOS – Cutting adjustment allows for cutting wide dado’s with a 1/4" 3/4" or 1/2" router bit
- LARGE PLATE SIZE FOR EASIER HANDLING – The large plate size ensures your router stays steady, and is easy to handle
- Build a flat base and parallel rails. Use stable material and check for twist or bow; a distorted base can undermine accuracy. Align the two guide rails so the router slides without binding or side-to-side play.
- Create the zero-clearance edges with the intended setup. Use the router and bit that will make the dado to establish both guide edges. Mark the jig halves and router orientation so you can keep the correct sides paired.
- Calibrate before changing equipment. The documented design warns that a different router or bit requires adjusted dimensions. Re-establish the guide edges for another setup rather than assuming the original calibration transfers.
- Set width with a measured spacer. Use a straight, unwarped piece of the mating stock, capture it without play, lock the rails, then remove it and verify that the router moves freely through the guide.
The documented build and its router-specific calibration are described in “How to Make a Dado Jig for Router.”
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Check router, bit, and guide compatibility
Follow the router maker’s instructions for collet size, bit installation, maximum cutter dimensions, and operation. Do not assume that a bushing or base that fits one jig will fit another. For example, the POWERTEC manual lists 1/4-, 3/8-, or 1/2-inch straight bits for its jig and says some routers may need a base adapter for its included 1-inch guide bushing. It also warns that an off-center bushing can cause size deviations.
Rank #3
- INCLUDES - You will receive a 24 inch Woodpeckers Exact Width Dado Jig.
- HANDY SCALE - The built in handy scale set stops limiting travel of your router. It also slides out of the jig to set depth of cut on your router. Offset compensates for thickness of jig.
- LARGE CLAMPING PAD - The built in large clamping pads secure the jig for accurate cutting.
- PRECISE - Trim cut matches edge guides to your router bit and guide bushing precisely.
- MADE IN USA - Like all Woodpeckers products, these Exact Width Dado Jigs are proudly machined and carefully inspected in our Strongsville, OH facility, just south of Cleveland.
For its PGD-1, CMT lists a 30 mm router-bushing opening and a maximum cutter diameter of 19 mm. The guide template is included; some baseplates and straightedge clamps are recommended separately. Those specifications apply to that product, not to homemade jigs or other commercial models. Confirm fit and included parts before buying. CMT’s PGD-1 product page lists the model-specific details.
Quick Recap
Rank #4
- INCLUDES - You will receive a 32 inch Woodpeckers Exact Width Dado Jig.
- HANDY SCALE - The built in handy scale set stops limiting travel of your router. It also slides out of the jig to set depth of cut on your router. Offset compensates for thickness of jig.
- LARGE CLAMPING PAD - The built in large clamping pads secure the jig for accurate cutting.
- PRECISE - Trim cut matches edge guides to your router bit and guide bushing precisely.
- MADE IN USA - Like all Woodpeckers products, these Exact Width Dado Jigs are proudly machined and carefully inspected in our Strongsville, OH facility, just south of Cleveland.
Secure and test the setup
- Clamp the workpiece and guide so neither can shift. Confirm the router base remains fully supported along the cut.
- Before powering on, slide the router or jig along its guide. It should move freely without binding, friction, or lateral play.
- Use an undamaged, compatible bit and follow the router manual for installation, depth, speed, handling, and personal protection.
- Turn the router off before changing settings. The DadoWiz manual extract says to turn off and unplug the router during setup or setting changes; follow the exact procedure in the manuals for your router and jig. DadoWiz user manual.
- Make a test cut in scrap from the same material. Check both width and depth, adjust the guide or depth as needed, and test again before routing the workpiece.
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