Before the first cut
- Pick the biscuit. DEWALT's rule of thumb is the largest biscuit that physically fits; in most stock over 1/2 in that means no. 20. Sizes are explained in the biscuit joiner guide.
- Set the depth. Turn the depth knob or stop to the biscuit's number, then cut a test slot in scrap and try a biscuit in it before cutting the real parts.
- Set the fence. Fence at 90° for most joints, its height set to put the slot near the middle of the stock's thickness. DEWALT's DW682 can instead reference from its base, which centres a slot in 3/4 in stock.
- Unplug while adjusting. DEWALT says to turn the tool off and unplug it, or take the battery out, before any adjustment.
An edge-to-edge joint, step by step
Joining boards edge to edge
Lay the boards out
Arrange the boards exactly as they will be assembled, faces up, and mark the face side of each so they go back the same way. For a table top, this is when grain and colour are matched across the joints.
Mark the biscuits
Draw a pencil line square across each joint at every biscuit, across both boards at once. DEWALT spaces them 6 to 10 in apart on centre, with the end ones 2 to 3 in in from the ends; a 30 in joint can take marks at 3, 11, 19 and 27 in.
Set up the joiner
Depth to the biscuit size, fence at 90° and its height set to centre the slot in the thickness. Check the setting in scrap of the same stock.
Clamp and cut
Clamp the first board, set the fence on its face, line up the joiner's centre mark with a pencil line, start the motor and plunge. Retract fully before moving to the next mark.
Cut the mating board
Cut every line on the other board with the fence on its face side too, so both slots are measured from the faces that must come out flush.
Dry-fit
Put the biscuits in dry and close the joint. Look for a slot cut off its line or too shallow, and clear any chips from the slots.
Glue and clamp
Glue the slots and the edges, insert the biscuits, close the joint and clamp it as for any edge joint. Glue choice and open time are in how to use wood glue; clamping in clamps.
For stock thicker than 1 in DEWALT allows two biscuits at each mark, one above the other, with at least 3/16 in of stock between each biscuit and the nearer face; cut all the upper slots at one fence setting before resetting for the lower ones.
Other joints
| Joint | Where the slots go | Set-up |
|---|---|---|
| Corner (L) | One slot in the edge of one part, one in the face of the other | Edge cut as for edge-to-edge; the face cut with the work clamped and the tool aligned as DEWALT's manual shows |
| Offset | Slots placed so one face sits back from the other | Centre the cut in the set-back part, then raise the fence by the offset for the other |
| Edge mitre | In the mitred faces, laid out on the outside of the joint | Slot towards the inside, where the stock is thicker; a biscuit small enough not to break through; the reverse 45° fence registers on the outside face |
| T-joint (shelf into a side) | In the shelf's end and the side's face | DEWALT's method needs shelf stock at least 5/8 in thick |
DEWALT's procedures for its DW682 and DCW682; other joiners' fences and angle stops differ, so set them from their own manuals. Not a ranking.
Tricks that prevent mistakes
- Watch the ends. On DEWALT's DW682 three marks on the base show the cut's centre and a no. 20 biscuit's width. Keep both outer marks within the work, or the blade can break out through the end.
- Mind thin and narrow parts. In narrow frame members a no. 20 slot can show at the edges; DEWALT moves to a smaller biscuit for narrow face frames and picture frames and in stock 1/2 in or thinner.
- Reference one face. Every cut on mating parts from the same face, with the fence or the base, is what makes the joint come out flush.
- Dust. Fit the bag or a vacuum; chips left in a slot stop the biscuit seating.
Safety— Clamp the work and keep hands behind the face plate
Clamp the part rather than holding it, keep fingers away from the face plate, let the blade stop before lifting it away, and unplug it or remove the battery before changing the depth, fence or blade. See woodworking safety rules.
Other joinery tools — pocket hole jigs, dowel, dovetail and box joint jigs, mortisers — are mapped in the pocket hole guide. Choosing the joint in the first place is covered in choosing a wood joint.
Biscuit joint set-up checklist
- Biscuit size chosen; depth stop set and tested in scrap
- Fence angle and height set, or base registration chosen
- Parts laid out as assembled; face sides marked
- Lines drawn across both parts at every biscuit
- Work clamped; outer base marks inside the work
- Dry fit before glue
Sources
The procedure and every figure are DEWALT's, from its manuals for its own tools; other joiners' depth stops and fences are set from their own manuals. The 30 in layout is a BenchRoot example inside DEWALT's spacing. No figure is given for how much a biscuit adds to a joint's strength, because no source reviewed tests it.
- 1.
DW682 Biscuit Joiner, Instruction Manual (Form No. 632771-00). DEWALT, 2005.
Used for: The largest biscuit that physically fits as a rule of thumb; parts laid out as assembled and a mark made at 90° across both; for edge-to-edge joints biscuits 2–3 in from the ends and 6–10 in apart, depth set, fence at 90° and its height centring the slot in the thickness, the work clamped and the centre mark on each line, then glue and clamps; double biscuits in stock over 1 in with at least 3/16 in of stock outside each; corner joints cut in the edge of one part and the face of the other; offset joints by raising the fence by the offset; edge mitres laid out on the outside, the slot towards the inside and a biscuit small enough not to break through, the reverse 45° fence registering on the outside face; T-joints in shelf stock at least 5/8 in thick; the base's three marks showing the cut's centre and a no. 20 biscuit's width, so neither outer mark goes past the end of the work; turn off and unplug before any adjustment.
- 2.
DCW682 Biscuit Joiner, Instruction Manual. DEWALT.
Used for: The same layout spacing and fence and depth settings on a cordless tool, with the battery removed before any adjustment.
- 3.
Lamello catalogue (English). Lamello AG.
Used for: Biscuit sizes no. 0, 10 and 20 (47, 53 and 56 mm long), all 4 mm thick, and the groove depths they need.
About this tutorial
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