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Ask WWGOA » Joiner Biscuit Size
Jointer Biscuit Size
Posted: September 30, 2010
"I ordered a PorterCable biscuit jointer and was wondering what size buiscuits to order. How do you determine what size buiscuit is used for a particular job. I have read about PC's FF size but am still confused. Your advice is appreciated."
Submitted by: HHolmes
WWGOA Editor Response
The three common biscuit sizes are 0, 10, and 20. You can find these almost anywhere, from home centers to specialty stores. While biscuits are a great joinery solution, they do have a few limitations. One is the length of the slot required to use a biscuit. Even the smallest biscuit, the 0, requires a slot that’s too long to use on the end grain of a 1-1/2” wide face frame rail. This problem is solved by the FF biscuits. They’re round, instead of football shaped, and require a different cutter. Biscuit joiners typically use a 5” diameter cutting blade. Some machines, like the Porter Cable 557, allow you to swap to a smaller diameter blade and use the FF biscuits. If your machine doesn’t allow the change to a smaller blade, you can’t use the FF biscuits.
When choosing what biscuit to use, go with the largest biscuit that will work for your application.
George Vondriska
Managing Editor
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3 Comments
Subject: Glue Joint Router Bit Hi George, It appears that all we ever hear about is jointing boards together with biscuits in the mag articles, and TV shows. How come there is never a mention about jointing boards together with this bit? It appears to me that this would be the strongest. Please explain. I enjoy your articles very much and your dedication to our hobby. Thanks
Pete needs to review your video on the strength of a jointer cleaned glued edge to edge board. I know it is quick and dirty, but biscuts often show shrinkage if the wood is not fully moisture stabilized before final planing / sanding something often not emphasized in selling biscuit systems or even just butt glueing.
The "claim to fame" of glue joint router bits is two fold. They add surface area to the joint, and also help align the surfaces. The bits are a little fussy to set up, but simplify assembly of edge to edge glue ups. Look at the end grain of commercially made table tops, and you'll often see the tell tale finger joint look of a glue joint router bit. That being said, there's plenty of strength in edge to edge joinery if you simply make sure the edges you're gluing are straight, and you join the parts with yellow glue. When I taught woodworking in Africa the kids would hand plane edges and glue them with a rub joint (we didn't have enough bar clamps...). The tops they made were very strong. A great testimony to good joinery and good glue. Biscuit joinery adds a lot to many woodworking projects. I don't think it's imperative to add biscuits to an edge glue up any more than it's imperative to add the glue joint router bit to edge joints. G