Biscuit vs. Domino Joinery

[Alan Lightstone]

I use Dominos, and yes I have made the mistake of putting them too close to the edge and having to repair that area.

I also almost always use cauls, so when I am done, the boards are very level with the joints solid.

As Prashun said, no question that good jointing of edges is very important to avoiding gaps.

A couple of quick passes through my wide belt, and the boards look amazing.

Belt and suspenders approach - absolutely. But I'm not selling my work, and don't have to worry too much about time and productivity.

[Brian Holcombe]

I use neither, waste of time in my estimation and it adds a point of hydraulic locking during the glue up and gives a potential spot for problems later if you take the top down unevenly for some reason.

[Mike Cutler]

For a person working alone, in a home shop, either method will work. It's hard for a person working alone to glueup, align, clamp, caul, an edge joint only by themself. It only gets harder as the panel gets bigger.
What you want to avoid is using the biscuits, domino's, or splines, to "pull" the material into flat. The material should already be flat, and ready to glue, prior to using some type of "mechanical alignment" help.
I've used them all at one point or another. I prefer a stopped T&G joint, done on the shaper. It's quick, easy, and very consistent. A reversible glue edge cutter is nice if the edge is of no concern.

[Jim Dwight]

I have a domino XL and would probably use a 5 or 6mm domino for aligning boards but I haven't used it for that yet. I've used a lot of biscuits for this and I think it's a good tool for this. I have not used a spline and probably will not, I worry it would actually be a bit harder to align the boards with the spline but I could easily be wrong. My boards usually are not perfectly flat and I choose to use the this way because they are not thick enough if I fully flatten boards wide enough and long enough for things like a table top. I put biscuits 6-12 inches apart usually. I have never had them telegraph their location but I usually allow the joint to dry overnight before flushing up and final sanding. I have had them show their location on a curved table top when I got them in the wrong place.

Dominos extend further into the other pieces, usually anyway, although you can adjust this. That could help pull things together but you should not need that much help. I can align the boards by hand as I tighten the clamps with the amount of bow I consider OK but if there are several boards that is hard to do within the setup time of the glue (usually Tite Bond 2). The number 20 biscuit only goes 1/2 inch into each board but that is plenty to align IMHO. If your biscuit jointer makes nice tight slots, I don't think you need to use a domino but it makes tight mortises consistently as long as you move it slowly and smoothly. Someday I will probably try it and I suspect I will like it. But I don't really use my biscuit joiner for any real joints so my only excuse to keep it around is for the alignment task so I may not. I am also frugal and biscuits are cheap.

[John Makar]

I own and have used both a Domino and a biscuit. Now days I mostly use the domino, simply because I work with smaller dimensions and a 4mm/5mm fits a little better, also, because I have used it a lot I am simply better with it. Probably some day during a cleanout the biscuit will end up with my son-in-law. Early on Festool was exceptional for precision. It's still as good, but biscuit jointers have come a very long way. Knowing what I know now, if I had to buy just one I would go with the Festool, I'm now over the sticker shock.

I own other Festools, and like them, but the inovations they introduced a decade ago have been copied by many other vendors. A prime example would be my plunge router. I have the PC690, which 15 years ago was the goto machine. Among other things is has a complete lack of the dust collection that is pretty much standard in a router of its class today. Yeah, there are add-ons, but a new Makita, Festool, etc., comes with it built in and functional. I struggle with whether it should also go to son-in-law, or whether I should just suck it up and vacuum up the mess like I have for over a decade. The odds are self-indulgence wins, but it would help if he did a project with a need for a router.

I feel that the competition from Festool forced a lot of that improvement. Earlier this week I bought a DeWalt oscelating saw. Great precision, light weight, excellent Lithium battery. So now the others also have those features, and usually a lower price, tho I think Festool also taught those guys they could charge a lot more.

[Kevin Jenness]

The easiest way of doing this is a shallow-depth tongue-and-groove on the router table, provided you have pressure rollers attached to the fence etc. to hold the slot etc. even to the table (or else that defeats the whole purpose.)

Biscuits are a bit more expedient for the impatient. Provided they fit right.

I have been doing just this for glue-ups with concealed ends. I use a powerfeed and a 4mm slotting bit. I currently have my left wrist in a cast which makes operating a biscuit joiner or Domino problematic, but this is a good solution regardless. I have no concerns about unduly weakening the glue joints on the stair parts I am making, and the surfaces are flush +/- .005".

[Edwin Santos]

Look at it this way; a biscuit joiner is a machine for making spline joints. A Domino is a machine for making mortise and tenon joints. There are similarities in the form factors of the two machines but they are as different as spline joinery is from mortise and tenon joinery.

So with this in mind, to your question, it would not be a traditional practice to edge join boards with mortise and tenon joints. At least I've never seen it recommended in a woodworking textbook or credentialed source. Traditional practice would be to use splines or simply glue well prepared edges using cauls and good clamping for alignment control.

[Derek Cohen]

The way I see it is this.

Before there were machines such as biscuit joiners and, more recently, the Domino, panels were created by simply jointing the edges with a hand plane (before power jointers), and then glueing then up. Once the glue dried, the tops were planed flat and coplaner. This is the way I worked for some decades before I owned a jointer and thicknesser/planer. No methods of alignment other than edge-to-edge. The underside of panels was treated expediently. It was never seen, so why bother.

The first machine I owned to mechanise this process was a jointer. Get one side flat. Square the edges, and then glue together. A caul on the flat side aided to achieve coplaner, and then hand planed the top side. Some argued that a thicknesser/planer was a better choice of a single machine, since it could be used as a jointer as well. Perhaps. Just a different method of preparing rough boards. I wrote an article on this for Popular Woodworking magazine some years ago.

Biscuits and dominos are used to align boards which have been machined to a precise thickness. The aim is to align them so that there is no further work needed to finish, other than polishing the surface with a sander or hand plane. Boards which have been machined to a final thickness no longer have any leeway to further refinement. Either join them evenly, or lose the dimension.

I have no idea why Ishitani used double rows of biscuits. Biscuits do not offer any strength. And double rows of biscuits do not do a better job of alignment. I see in his most recent work that he has discarded the biscuit joiner for a Domino.

I have both a DeWalt biscuit joiner and a Festool Domino. They do better at different tasks. The biscuit is, as you all are aware, shallow and long. The domino is narrow and deep. Dominos are best used for mortice-and-tenon joinery. They can also replace dowels. Biscuits are better for alignment, can be less intrusive if using the shallowest ones, and are better for mitred joints. They are essentially splines. I did raise my eyebrows when many ditched their biscuit jointers for a Domino. I guess that they could not tell the difference

Regards from Perth

Derek

[Chris Fournier]

Based on the comments so far it seems to me the best system to join long grain together would be one thin and continuous spline. It would provide alignment along the entire length but not take up too much surface area for the glue. It may however be more difficult and time consuming to accomplish if cost and production is a consideration. That's my take on it so far.

Take a look at the edge of a biscuit, that and a wee bit more is what material you are removing from the joint. Now look at the face of a biscuit, that is new long grain gluing surface that you are adding to the joint. Face minus edge surface area is positive and makes for more good gluing surface. You would have to try really hard to mess up an edge joint with biscuits. Biscuits are super fast, super cheap, very strong and a real aid in the wood shop.

[Warren Lake]

Any old school trained guy would be done while you are still fussing with your gizmo. Ive likely had a lamello 40 years. I worked for an Austrian guy who might have had the first one in canada, other europeans had not heard of it when he had one. Brain said it and others, waste of time

[Prashun Patel]

I am the most impatient of woodworkers and use cauls often and to good effect. The issue is this:

To keep large panels flat, say 100 lb 8/4 slabs flat with just cauls is not altogether simple. You need decent clearance below and above, and you need to work fairly quickly to get everything clamped up. Putting a few dominos in there - even 5mm ones, allows me to use fewer panel flattening cauls, sometimes none.

I've sweated enough table top glue ups to believe it's a valuable arrow in my quiver.

One more thing: some have noted that this is a great help in mitered glue ups. It also works very well for coopered chair seat blank glue ups. In these cases, the joint has to be clamped skew or offset to the mating faces and having a way to keep things aligned is invaluable. So, if you choose to buy a tool for a this, give extra consideration to those tools with an adjustable angle fence.

[Robert Engel]

In my work, I view biscuits as alignment aids, not joinery. I view Dominoes as both.

For simple panel glue ups, I don't use anything.

I think the thing to keep in mind is that splines, dowels, biscuits and Dominoes add little strength to a long grain glue up.

[Rick Potter]

Finally, someone mentions dowels. Doesn't anyone use those anymore? Seems like every old piece of furniture I take apart for wood has them.

[Mike Henderson]

Finally, someone mentions dowels. Doesn't anyone use those anymore? Seems like every old piece of furniture I take apart for wood has them.

The problem with dowels, for me, is alignment if you use more than one. If one hole is just a bit out of place you can't get the dowels to fit. With biscuits and dominoes the mortise is just a little bit wide so if one is a little out of place it will still fit.

The factory made furniture is made by machine so the dowel holes fit.

Mike

[Jim Becker]

Finally, someone mentions dowels. Doesn't anyone use those anymore? Seems like every old piece of furniture I take apart for wood has them.

I mentioned thim in post #5