click on image for larger view
#10 biscuit - 53mm x 19mm x 4mm (nominal)
Package of 250 Biscuits
Biscuits are used mostly for joining sheet goods such as plywood, particle board and medium density fiberboard.
They are sometimes used for joining solid wood, especially when edge joining for large panels such as table tops because of their ability to position two boards perfectly flush.
When manufacturing biscuits, the biscuit material is kiln dried to a very low moisture content and then compressed to thickness. In use, adhesive is applied to the biscuit and/or into the slot. The biscuit is then inserted and the materials are clamped together. The now wet biscuit decompresses (expands) in the slot, which increases the strength of the joint.
The advantage of using biscuits (over dowels) is simple. Unlike dowels which require accurate drilled holes in all directions, biscuits are much more forgiving. Biscuits allow as much as 3/16" movement along their length but through their thickness, they position with high accuracy.
At only 4mm thick, biscuits can be used to join materials much thinner than is possible with dowels. It's not uncommon to join 3/8" thick materials with biscuits.
The slot for biscuits is cut with a 4mm (5/32") cutter. The machines have a cutter 100mm in diameter which reaches beyond the face of the machine. This allows the woodworker to produce slots in the edge and face of sheet materials, perfect for shelving and divider panels Their fully adjustable fence system make them the preferred tool for cutting biscuit slots.
Woodworking routers using 5/32" slot cutters can also produce the required slot. Their large base diameter and small cutter diameter limit their use to cutting slots close to the edge of project materials.
If you've never experienced the advantages of using biscuits, you owe it to yourself to try them out. If you are not prepared to buy a machine, this Slot Cutter / Biscuit Joiner Set for the router will get you started as long as you are joining near the edge of your material.
For easier application of glue into the slot, try this bottle cap.