What good are biscuits?

[Greg Urwiller]

I've started to build the Limbert style coffe table in the Feb. 2016 issue of Fine Woodworking. The plans call for the end panels to be glued up using buiscuts for alignment. I bought a biscuit joiner years ago and have only used it a couple of times. I thought this was the most worthless way of alignment ever! Did I get a bad cutter? Undersized biscuits? Nothing I've ever tried has aligned anything. The biscuits were always loose enough that I had to align all the edges. I was really surprised that anyone would use biscuits on anything (fine furniture?) anymore. What am I missing about biscuits? Thanks. Greg

[Mike Henderson]

My opinion is that most woodworkers discovered the same thing. Like you, I bought a plate joiner long ago and only used it a couple of times. For aligning panel glue-ups, I use cauls which work well.

I occasionally use the little ff biscuits for extra strength in miter joints when I make boxes, but that's about it. And I cut the grooves for those with a slot cutter on my router table.

I should sell my plate joiner but I never get around to it.

Mike

[glenn bradley]

Bought one because "you had to hae one, right?". Sold it about 6 months later. There are folks who swear by them but, they do not add any value to offset the bother for me. YMMV.

[Von Bickley]

I haven't used mine in years. Should sell it but I never get rid of any tools. I worked too hard to get what few tools I have. When I get a new tool, I keep it. I'll let my son decide what to do with my tools when I'm not around.

[Ted Reischl]

Ah yes, woodworking magazines and must have equipment to build their projects. Uh huh. Anyone surprised by that?

LOOK! LOOK! You need to advertise with us, we are doing a project article that FEATURES biscuits! You don't want to miss out! Just think of all the sales you will get! Not to mention our ad $$$$.

What DOES work for aligning? A router with a slot cutter. You do not have to rout the entire edge yanno. Then you make the splines that actually fit the groove. What a concept. Sounds like biscuits, but actually works. Do NOT do this on a router table. You want the router to register off the face of the workpiece.

Myself? I rarely bother with these techniques anymore.

I think most people have problem with biscuits because they do not get enough glue in the slot. The biscuits are compressed and will expand from the moisture in the glue. But, if you are like me, you put the glue on and before anything can expand and align the surface I start clamping, so much for the biscuit being able to swell up and move anything. Probably works best with a slow drying glue.

[lowell holmes]

Biscuits are used for aligning the boards in a glue up. They add nothing to the strength. They are good to use on able top glue ups.

They add no strength. You need splines to add strength.

[Wade Lippman]

Some biscuits are compressed, but most are not. Well, at least they weren't 10 years ago when I last used one. I agree they aren't worthwhile and sold mine. The every once in a while I need something for alignment, I use a domino.

But when I did use them, I found they fit snuggly. I suspect the OP's cutter is not very good.

They do add strength. Make two joints. On one glue only the biscuits; on the other glue only the edges. Both are adequately strong. It is inescapable that gluing both will be stronger than gluing either. Now.... the added strength is not a significant benefit as gluing only the edges is adequate; but it is stronger.

[Stephen Rosenthal]

Many years ago I purchased a Lamello Top 20 to use for two projects. At the time as part of a package deal it came with a box of 1000 assorted biscuits of their three different sizes. It's a great machine and I still use it frequently. I think biscuits do add strength to an edge to edge joint and find the alignment to be very precise. It's important to use a water-based glue so the biscuits soak it up and expand within the cutout.

[Cary Falk]

Biscuits were created for joining plywood for the cabinet industry if I recall correctly. Glue 2 edges of plywood together edge to edge or make a corner joint(90 degree). Of course it adds strength. You wouldn't build a wall cabinet and just rely on glue only for a shelf. If a biscuit doesn't add strength then neither does a spline because that is what they are, a mini spline. Are they as strong as a mortise and tenon, no. Nobody claimed they were. You are not going to build chairs with them. They also work great for reinforcing picture frame mitered corners. The work great for alignment when you are trying to glue up hollow posts with mitered sides. It is like any other tool. It has its uses. Maybe you don't build anything that it would be useful for but that doesn't mean it is a useless tool just useless to you. As with anything, there are many ways to skin a cat.

[Mike Cutler]

There is something wrong with your plate jointer.
I am not a fan of biscuits by any stretch, but I do own one, and when I do large panel glue ups, it is helpful. For a one person operation it can aid in aligning an edge glue up. I use them with cauls.
Their true purpose is to joint plywood together, whether edge to edge, or edge to face. Their use in making furniture is very limited.

Check your setup. The biscuit should fit fairly snug when dry.

[Chris Padilla]

Sort your biscuits ahead of time. Test fit each one and you'll soon have 3 piles: loose, tight, Goldilocks (jeeeeeessssstttt right). If they are all loose, they might be very very old and very very dried out. You could possibly swell them again if you cared. If too fat, a vise can compress them. Some brands of biscuits are better than others.

Since getting my Domino, I rarely used biscuits anymore but I do like the small FF ones for certain (picture) frames I build here and there. In that case, I think they add quite a bit of strength in non-hardwood to non-hardwood situations (MDF to plywood, plywood to plywood, MDF to MDF, etc.). In hardwood to hardwood, edge gluing is quite strong without the biscuits but they can help alignment or just as easily misalign things if you aren't careful. Biscuits, due to their largish surface area, can swell the wood around it and if you sand that edge too soon before the glue-up has rebalanced in terms of moisture, you made end up with depressions.

Biscuits, like any tool, have their place here and there. I'll hold onto mine...it isn't taking up that much room in the shop.

[Jim Andrew]

I use my plate joiner to align and strengthen the feet on my projects, in the case of miters. Saw an episode of woodsmith, I think where they were making a rabbet miter, and a biscuit joiner would have made the job much easier.

[Larry Edgerton]

Many years ago I purchased a Lamello Top 20 to use for two projects. At the time as part of a package deal it came with a box of 1000 assorted biscuits of their three different sizes. It's a great machine and I still use it frequently. I think biscuits do add strength to an edge to edge joint and find the alignment to be very precise. It's important to use a water-based glue so the biscuits soak it up and expand within the cutout.

Ditto. I have had a Lamello for at least 25 years, and it has cut thousands upon thousands of slots. I have a couple of Dewalts set up for specific needs with custom fences that just stay on the units, one for extension jambs for example. If you are having a problem it is either you or your machine, because biscuits are handy. I would not use them in places where it is not their intended purpose and then blame the tool or cheap biscuits.

[Jim Morgan]

The first biscuit joiner I bought was little more than a glorified angle grinder, a real POS. It was noisy as hell and there was lots of play in the arbor, so the slots were regularly oversized. I upgraded to a DeWalt (at a fraction of the cost of a Lamello, not to mention a Domino), which is tighter, quieter, and has excellent chip collection with a shop vac; biscuits fit snugly into the slots it cuts. There will always be some lateral play in a biscuit joint, but this can be limited by not cutting the slots too deep (I leave about 1/32" overall for expansion). I mostly use these for joining plywood, but when I use them for edge-joining boards into a panel, the misalignment is typically small enough to be cleaned up with a card scraper. However, the quality of the biscuits themselves varies considerably. In my experience, Lamello biscuits - diagonal grain compressed beech - are the best, featuring the best finish and the largest amount of expansion, while Porter Cable are acceptable for rough work. I got a jar of Ryobi biscuits from HD a while back that were 3-ply garbage.

With regard to joint strength, biscuits rely on expansion from water in the glue to achieve their full strength, so comparisons using polyurethane (as in FWW's comparison a few years ago) are inappropriate. Biscuited joints are certainly stronger than simple butt joints, even though they cannot rival true mortise-and-tenon joints or slip-tenon joints like those produced by the Domino. If I were woodworking for a living I would probably invest in a Domino, but since I am not, a good biscuit joiner suits my needs.

[Malcolm McLeod]

Sort your biscuits ahead of time. Test fit each one and you'll soon have 3 piles: loose, tight, Goldilocks (jeeeeeessssstttt right). If they are all loose, they might be very very old and very very dried out. You could possibly swell them again if you cared. If too fat, a vise can compress them. Some brands of biscuits are better than others.

Since getting my Domino, I rarely used biscuits anymore but I do like the small FF ones for certain (picture) frames I build here and there. In that case, I think they add quite a bit of strength in non-hardwood to non-hardwood situations (MDF to plywood, plywood to plywood, MDF to MDF, etc.). In hardwood to hardwood, edge gluing is quite strong without the biscuits but they can help alignment or just as easily misalign things if you aren't careful. Biscuits, due to their largish surface area, can swell the wood around it and if you sand that edge too soon before the glue-up has rebalanced in terms of moisture, you made end up with depressions.

Biscuits, like any tool, have their place here and there. I'll hold onto mine...it isn't taking up that much room in the shop.

I also find them very useful in plywood, especially aligning and attaching face frames to a cabinet. They have their place, and my shop has room for the Dewalt version.

If the biscuits are too tight in your slots, try tossing them on a cookie sheet and let them sit in the oven on low heat for an hour or so. Then use them or store them in an air-tight container.