Biscuit vs. Domino Joinery

[Steve Mathews]

In an Ishitani video it shows him using 2 rows of biscuits to join some wood slabs together for a table top. In a Rob Cosman video he explains that 2 rows of splines were used to join the pieces to his workbench top. I've also seen where the Domino system is used for this purpose. As a novice woodworker I haven't used either methods yet but would like to know which one is better and why. Anyone?

[Prashun Patel]

To join edges of a workbench or slab top, those guys are only using dominos, splines, and biscuits to help align the joint. The majority of the holding power will come from a properly jointed and glued edge.

It doesn’t matter too much which you use.

The choice of floating tenon would be more critical if one of the edges were end grain.

[Andrew Hughes]

I think every little bit of long grain that’s taken away reduce the chance of having a very strong glue joint.
Some are will to trade that for aligning the tops of the boards.
What side will you take. :)

[Steve Mathews]

I think every little bit of long grain that’s taken away reduce the chance of having a very strong glue joint.
Some are will to trade that for aligning the tops of the boards.
What side will you take. :)


Cosman mentioned that the double spline he used to align/join his workbench top was somewhat problematic. Some of the glue between the splines became trapped and prevented some of boards from joining properly. Makes sense.

So, as far as joining boards together the least amount of space taken up on long grain by a biscuit or tenon while providing alignment is better?

[Jim Becker]

Using too many fasteners might take away from the strength of the glue joint, but the few that are "typically" used by folks for alignment, etc., are not going to materially be an issue, IMHO. I use Dominos, although I still have a biscuit joiner, because I happen to love the system. In addition to the alignment they honestly help me as a solitary woodworker to get something together assembled and glued up. 'Kinda like a few small extra hands. Regardless of the fastener type, the single rule is always to index from the same surface point on all pieces. IE, the top on a table is common. Any minor variation in thickness between boards is then on the bottom/other side from the surface you've indexed from. Dominos, dowels, biscuits, splines, whatever...that rule works.

[Steve Mathews]

Using too many fasteners might take away from the strength of the glue joint, but the few that are "typically" used by folks for alignment, etc., are not going to materially be an issue, IMHO. I use Dominos, although I still have a biscuit joiner, because I happen to love the system. In addition to the alignment they honestly help me as a solitary woodworker to get something together assembled and glued up. 'Kinda like a few small extra hands. Regardless of the fastener type, the single rule is always to index from the same surface point on all pieces. IE, the top on a table is common. Any minor variation in thickness between boards is then on the bottom/other side from the surface you've indexed from. Dominos, dowels, biscuits, splines, whatever...that rule works.

If you don't mind me asking what is it about the Domino system that you enjoy?

[Jim Becker]

I like the precise fit of the system, the variety of Domino sizes that can be sized to be appropriate for the intended joinery, the ease of use, the excellent dust collection and so forth. I happen to use the larger 700 XL because most of my use is larger things like doors and big furniture things, but I have the Seneca adapter that lets me use even the tiny 4mm Dominos. 10mm, 12mm and 14mm get the most action in my projects so that's why I chose the larger one for my work. I've also used the knock down connectors (14mm) for a client project and would use them again in a heartbeat if that was a requirement for something I'm building.

I'll make no secret about the fact that I'm a very satisfied Festool owner. My only regret was waiting several more years than I should have before buying the Domino and I'm not saying that to show off. I really like and respect the tool...

[Steve Mathews]

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.

[Jim Becker]

A spline is a perfectly valid way to do the deed. It can be easy, too...use a slot cutter with a bearing in a router and run it down the edge of both pieces, again, indexing on matching surfaces, such as the intended tops. That puts your spline at the same level from the top of the boards. Make a spline that is a snug fit for the slot you cut with a little room for glue behind it in the slot. Glue and clamp up. Done.

[Prashun Patel]

“Best” in this case is moot. All those methods will work fine and You will not be able to tell which was used.

A continuous spline is probably used not because it’s stronger but because it’s easy to cut the slot.

I am no pro, but I have made enough panels To know that a gappy joint is almost always caused by improper jointing and gluing - almost never because of the choice of reinforcement.

[Matthew Hills]

Would your spline show at the end of the joined panel?
(this sometimes happens with the other joinery systems as well, but usually after trimming to length and realizing you cut into one of the biscuits)

Gluing up a flat panel is also a good technique to develop. (or get a big J/P or get good with hand planes :-)

Matt

[Warren Lake]

neither, its just wasted time, on top a lamello will not give you consistent 100 percent flush every where joint.

[Mike Henderson]

If what you're concerned about is alignment of the boards in the panel, use cauls and skip any of the other things to align the boards.

Mike

[Doug Dawson]

A spline is a perfectly valid way to do the deed. It can be easy, too...use a slot cutter with a bearing in a router and run it down the edge of both pieces, again, indexing on matching surfaces, such as the intended tops. That puts your spline at the same level from the top of the boards. Make a spline that is a snug fit for the slot you cut with a little room for glue behind it in the slot. Glue and clamp up. Done.

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.

[Jim Becker]

Would your spline show at the end of the joined panel?t

Not unless you make the mistake of running the slot full length rather than as a stopped groove. Of course, for some, that would be a perfectly valid design element.

[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 :D :D :D

[Rick Potter]

OOPS.

color my face red:mad:

Guess I need to justify my new Jessem dowel jig.

[Mike Cutler]

No need to justify a good doweling jig.
I've repaired many turn of the century doors through the years, and after each one, I look at doweling jigs. I never bought one, but should have 20 years ago.
A dowel is easily a 100 year joint.

[Patrick Walsh]

For laminations and glue up I never use them. For a long mitered joint in say a wood counter I’d go for a large stopped spline. But dominoes will do just fine probably just don’t put like 3 in in 24”.

I’ve built some huge stuff laminating big heavy long boards. Proper material prep goes a long long way. I have never struggled working alone to get things glued up. Just have to have a good system breath deep, stay calm and work smart.

I don’t care much for the domino or the biscuit joiner or dowels. But that’s Just my opinion clearly it’s not popular and that’s ok with me. I do however use all three in my work regularly as I’m a employee and do for the most part what I’m told. From what I’ve seen for the life expectancy of the average piece someone is paying most of us to build these days any of the above is probably sufficient. I have to build a bunch of church altar furniture in the near future and I will be using tradition mortis and tenon as it’s not intended to go in a dumpster like a kitchen in 20 years or some trendy piece of furniture your wife wants.

One thing I have noticed myself included is people make statements like and interject hard fast oppinions like “this is the way I do it, and then argue some superior or inferior way of doing it and what is right or wrong”. In some cases they might be right but who cares. You gotta figure out what’s right for you and ignore the chatter. Generally we are trying to have fun right. Some if I take pleasure in pain, some of us just like a finished product. Some can be happy with imperfections, some wanna break stuff over imperfections and or can never actually enjoy the piece or be satisfied with having built it the result of imperfection. Only you know where you fit.

If your having a hard time aligning your boards I’d make sure your stock is laser flat, not kinda or almost flat. Next I’d make sure you bench is also laser flat as when you lay your clamps down it might affect things, next make sure your clamps are clean and not covered in globs of glue. I tend to start at one end and work my way across the board, I’ll get a end clamped then make say a 12-18” jump to the next clamp and get it good. Work backwards filling in. If I have issues I can cut the furthest out clamp free and use the board as a lever to get the joint just so as I tighten the clamp using fingers to check for perfect alignment. Don’t bother trying to glue more than two boards together at a time. Glue dries fast, how important is a good result to you....

Good technique and planing and preparation means I have never needed any of the above.

But if none of that works for you both machines will work but they also will not insure a perfect glue up. In my experience if anything they hinder perfection. It’s weird sometimes I find it easier to get things aligned more reliably repeatedly with a biscuit joiner. Other times the domino. Not sure what that’s about, as others say each has a place. You gotta just build a bunch of crap with both and you will intuitively start to know what one you wanna use. However a biscuit is not a replacement for a tenon. And again any of them will in theory work for alignment..

[Bruce Lowekamp]

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

What I like about dominoes is the adjustable width. You can make a narrow one that aligns precisely like a dowel or you can make wider ones that are a bit more forgiving. I've never done more than two of the narrow ones per board....

Bruce

[Curt Harms]

I don't have a domino, I do have a P-C biscuit joiner. I was making a technique error early on which caused joint misalignment. I didn't keep the face of the machine exactly perpendicular to the work face so the biscuit would be at a very slight angle. When two pieces came together there was a slight misalignment. Not very much but enough to notice/feel. When I worked on that the joints were better/more flush.

[Mark e Kessler]

I didn’t read the whole thread so maybe the below has been mentioned but biscuits and Dominos essentially will do the same thing but excel in certain areas, I have only ever used either as a professional cabinet maker and furniture maker as an alignment aid and rarely use glue in the slot/on the biscuit/domino. I personally never found biscuits to be that strong.

As far as a biscuit joiner goes owning a business with 5-7 employees I had quite a few from cheap ones to several Lamello top 10 and I can tell you without a doubt the Lamello is the best of the bunch and worth the money, it’s been a while so maybe the lower cost brands have caught up.

I have found that for miter joints I prefer the biscuit over domino if anything, seams to allow for some tweaking/adjustment whereas the domino really locks it in place and is unforgiving

Other tip with biscuits, if you are doing a thin top say 3/4” or under (or really any thickness and you prefer to use glue on the biscuit) be sure to place the slot low, below the mid point. In the umpteen thousands of biscuits placed in my lifetime i have seen a lot, one thing that can happen is the biscuit can swell from the glue and you end up with a football shaped witness mark on your top, early in my career I even had a callback once or twice due to this. I have even seen telegraphing when not using glue. I also found that the Lamello brand biscuits were superior than the others for consistency and didn’t seem to swell as much if at all.

As far as slots diminishing the strength of an edge glue joint, in theory probably due to less surface area but for all practical terms I say no. Now a domino on a end grain joint like a m+t I would say is stronger than biscuits, like I said earlier I have never found biscuits to be that strong but I have only really uses biscuits and dominos for alignment.

Mk

[Edwin Santos]

OOPS.

color my face red:mad:

Guess I need to justify my new Jessem dowel jig.

The Jessem dowel jig is an excellent tool that far exceeded my expectations. I have never experienced a dowel misalignment problem using that jig, and I have done rows of dowels as long as maybe 15 or 20 dowels spaced perhaps 6" apart.

I use dowels very often when face gluing just to register the parts and prevent the slipping and sliding that happens during the glue up, often right when you turn your back. My workbench was a glue up of three sheets. Two 1/4" dowels per sheet kept them in alignment while I glued up with a lot of cauls, everything stayed aligned. In this case, the dowels are not for strength or joinery, just to register the parts.
Where the Jessem jig struggles a little is when you need to install dowels in the field of the work, far from the edge, and it does not lend itself well to angled or curved work, but other than that, it is excellent IMO.

[Patrick Walsh]

Took these pictures today as I just happened to end up doing some edge glue ups.. Before anyone saiz yeah the boards are on 60” long I say I do the same thing with a 12’ board.

It took me all of 10 minutes to mill this stuff up from 5/4 to 1” and be ready for clamps. My bench is perfectly flat almost as good as a surface plate ;)

Wee bit of glue smeared with my finger.

435191

The result, perfect like actually perfect. Good material prep goes a long way but that should be a given. It took me maybe 90 seconds to put these in clamps ok 2 minutes.

435192

And another same as above,

435193

And here they are in clamps drying. You don’t need to leave them overnight, doesn’t hurt but...

435194

Here they are out of clamps with pretty much zero need For anything than a quick run over with the number four or as most of us would do the orbital.

I ended up taking these down to .875 so one more trip over the jointer then through the planer. I always plan my glue ups this way but honestly normally laminations are good enough out of clams I could just send em through the planer flipping them..

435195

It’s really only as complicated as you make it. Anything for alignment imop is just a hinderance. With dominoes or biscuits you can’t cut the last clamp free and lift on board or push it down to get perfect alignment.

Tip is don’t tighten your clamps all the way as you go. Tighten them just enough to hold as you move onto the next clamp. Then when the whole thing is in clamps carefully go back and tighten them all.

And wipe your dam glue how else do you know how shitty a job you did..