What Is A Dovetail Jig? | Clean Tight Joints

Ask any woodworker why drawers last, and you’ll hear the same answer: dovetails. A dovetail jig turns that classic joint from a once-in-a-while victory into a daily workflow. With a router riding on a guided template, you cut matching tails and pins that lock together by shape alone. No guesswork, no fancy math, just a repeatable setup that delivers neat joints across a batch of parts.

What a dovetail jig does

A dovetail jig is a clamping fixture with an index template that guides a router or guide bushing to shape the joint geometry. The template’s fingers act like a stencil. Slide your board in, clamp it square, and the router follows the template to form either the tails or the pins. Flip, swap, or shift parts as the jig requires, and the mating piece mirrors the pattern. Many jigs handle through, half-blind, and sliding dovetails; some also cut box joints using a different template.

Two broad families exist. Fixed-spacing jigs use a metal comb with equally spaced fingers, which keeps layout fast and consistent. Variable-spacing jigs let you loosen the fingers and set any pattern you want, so you can spread or cluster tails for a custom look. See how far that flexibility goes on the Leigh Super Jigs page.

Common dovetail cuts and typical bit angles

Joint type	Typical router bit angle	Where it fits
Through dovetail	14° common; 7–10° also seen	Case corners, boxes, visible joinery
Half-blind dovetail	14° with offset depth setup	Drawer fronts to sides; pins hidden at the front
Sliding dovetail	7–14° depending on fit	Shelves in sides, table rails into legs

Bit angles aren’t a law. Many jig users land on 14° because it clears chips well and matches common templates, as noted in Popular Woodworking’s angle roundup. Hand-cut work often follows the old 1:6 or 1:8 slope idea. Pick a bit your jig supports and stick with it across a project for a consistent look.

Understanding a dovetail jig setup

A clean joint starts with square, flat stock at a uniform thickness. Plane or sand to size, label the reference faces, and mark outside and inside so parts don’t rotate midstream. Mill drawer sides and fronts from the same board run when you can; matching color makes the corner read as one piece.

Next comes the router package. You’ll need a sharp dovetail bit and a straight bit if your jig calls for it. Many fixed-template jigs rely on a guide bushing that rides the template while the bit cuts the wood. Variable-spacing rigs often use a bearing-guided bit against aluminum fingers. Either way, keep the collet clean and the bit fully seated with a small back-off for heat expansion.

Depth sets the fit. On half-blind joints, small tweaks in bit depth change how tightly the pins drive into the tails. On through joints, bit depth sets how much shoulder shows after flush-trim work. Make a test pair from scrap milled with the same thickness, and record the final settings for the batch.

Fixed-spacing versus variable-spacing

Fixed-spacing models shine when you want speed and repeatable spacing across many drawers. The Porter-Cable 4216 kit shows this well: one base with multiple templates for half-blind, rabbeted half-blind, through dovetails, sliding dovetails, and small box joints. Clamp, set the stops, and run the whole stack.

Variable-spacing jigs target custom work. You can widen a center tail, push pairs toward the ends, or stack narrow drawers with tight spacing and wide chests with bold spacing, all on the same jig.

Router bits, angles, and bushings

Most jigs ship with a recommended bit list. You’ll see 14° bits a lot, with 7° or 8° options for tight pins or sliding joints. Popular Woodworking notes that 14° shows up often on router-based systems, while hand-cut angles wander more by habit and wood type. Try a 14° first if your kit supports it, then test other angles for looks and chip flow.

Guide bushings matter. A small change in bushing size changes the pattern fit, which is why jig makers pair a specific bushing with a specific bit and template. Keep a dedicated bushing locked in for dovetail work so you don’t mix it up with your round-over or pattern gear.

Dovetail jig explained with real shop steps

Prep and layout

Label parts clearly: LF for left front, RS for right side, and so on. Mark the inside of the drawer with a carpenter’s triangle so the points meet at the front left corner, and keep that mark visible during every swap. This habit kills flipped parts and mismatched corners.

Clamp and align

Set the jig’s side stops so parts return to the same position. Seat each board firmly against the reference surface, then clamp without racking. A light tap with a mallet seats fussy pieces against the stop before you lock them down.

Dial the depth

Make a first test cut with the recommended depth. If a half-blind joint won’t close, lower the bit in tiny steps. If the pins bottom out before the shoulders meet, raise the bit. On through joints, watch the shoulder reveal and the amount you’ll trim flush.

Route with control

Keep the router flat on the template and move against the cutter rotation. For tear-out prone stock, nibble a shallow climb cut along the edge, then finish with a standard pass. Always keep two hands on the base, and pause only with the bit clear of the work.

Joint styles you can make on a jig

Through dovetails

This is the showpiece joint where both tails and pins are visible. After routing, you’ll flush the proud end grain with a plane or sander. Through dovetails suit boxes, casework, and any corner that should broadcast hand-built character.

Half-blind dovetails

Pins and tails interlock, but only the sides show the end grain. The drawer front stays clean. It’s the go-to for furniture drawers because the front sees daily use and you don’t want end grain flashing on the face.

Sliding dovetails

A single tail slides into a long pin socket, often from the back. Use it to anchor shelves, dividers, and web frames. The angle acts like a wedge that resists pullout without hardware. Make a shallow first pass, then sneak up on the final fit with tiny fence moves.

Pick the right size and features

Capacity comes first. Twelve-inch jigs handle most drawers. Eighteen- and twenty-four-inch bodies take wide case sides and deep blanket chests. If you build mix-and-match pieces, choose a larger body once and leave room to grow.

Look for positive stops, clear scales, and finger assemblies that don’t drift when you snug the knobs. Micro-adjustments help when a half-blind joint almost fits but not quite. Thick aluminum templates last longer than stamped sheet metal, and a solid clamp bar saves time across a run.

Dust control helps you see the cut and keeps chips out of the guide fingers. Some jigs offer snap-on hoods; others pair well with a compact vac and a small hood on the router base. Good lighting across the template reduces mistakes.

Jig features that affect fit

Feature	What it controls	Why it matters
Template type	Fixed spacing vs. variable spacing	Speed on batches or custom layout freedom
Depth stop	Pin/tail engagement on half-blinds	Small tweaks make a tight, gap-free drive
Guide bushing size	Offset between bit and template	Wrong size shifts the fit across the joint

Tips that raise the hit rate

• Run matched scrap first. Keep an offcut from the same milling run and do all tweaks there.
• Mark the reference face. Keep the same face against the jig for every mating piece.
• Use sharp bits. Dull edges crush fibers and leave fuzzy shoulders that hide gaps until glue-up.
• Back up end grain. A thin sacrificial board behind the tails tames blowout on exit.
• Label your stops. A bit of tape with “drawer left” and “drawer right” saves you when parts pile up.

Troubleshooting cleanly

Gaps at the shoulders

If light shows at the shoulders on a half-blind joint, raise the bit a touch. If the shoulders meet but the joint won’t close, lower the bit and retest. On through joints, check that the piece sat flat in the clamps; even a chip under the board tilts the cut.

Joint too tight

On half-blinds, drop the bit by a hair or widen the guide bushing if your jig allows it. Lightly wax the pins and drive the joint together to read the bruised spots; those show where the fit binds. On through joints, a fresh pass with a straight bit can ease the socket walls.

Joint too loose

Raise the bit in tiny steps on half-blinds. On through joints, nudge the stop blocks to shift the pattern closer. If only one or two tails feel slack, a thread of veneer in the socket is a quick save that disappears under glue.

Tear-out and chipout

Use a scribe line, a backer board, and that light climb nibble at the edges. Slow down so chips clear the cut. A vac hose near the bit helps.

Where a jig fits next to hand tools

There’s a time for a saw and a guide, and a time for a jig. If you’re making one decorative box, a saw guide and a chisel session feel great and look the part. If you need six drawers for a kitchen island by Friday, the jig earns its keep. Shops that do both keep a small saw guide on hand for odd angles and repair work, and the jig stands by for the production push. Both paths build skill and speed daily.

Proven workflows for common builds

Furniture drawers

Mill the sides, front, and back to one thickness. Cut half-blinds at the front and either half-blinds or through joints at the back. Groove the sides for the bottom after fitting the joints so the groove lands in a tail and not a pin. A single depth tweak across the batch keeps every drawer closing with the same feel.

Case corners

Through dovetails lock carcase corners and telegraph quality from across the room. After routing, flush the proud pins and tails, break the edges, and ease the sheen with a wipe of oil or shellac. A slight round-over along the case front softens the touch where hands reach every day.

Sliding shelves

Cut the sockets first with the router table and a fence. Make shallow passes and sneak up on the final fit. Then shape the shelf tails with the same bit. Wax the tail, press the parts together, and wipe any squeeze-out before it sets.

Care that keeps the jig true

Brush chips off the template fingers, don’t scrape them with a steel pick. A little paraffin on clamp bars makes them glide. Check that index stops are still square after transport. Keep the bushing locknut snug and the router base clean so nothing drifts mid-cut. Store the bit set together with the jig so the next setup starts right where you left off.

Quick buying notes

If you’re new to the game, a fixed-spacing kit with a clear manual gets you from box to first joint fast. If you crave custom spacing and wide work, a variable-finger model with longer capacity pays off over time. Read the bit list, confirm your router collet size, and plan on a spare guide bushing so a lost part never stalls a build.

When you’re comparing, scan for through, half-blind, and sliding support in one bundle. Check that you can clamp workpieces vertically and horizontally without shims. Look for a stable base you can bolt to a board for quick bench clamping. Set it up once, add notes to painter’s tape right on the jig, and you have a repeatable plan every time the next drawer run lands on your bench.