Biscuit Joiner Basics

Not all that long ago, mid nineties. So I guess that is a while ago, the only biscuit joiner you could buy was a Lamelo biscuit joiner. It was a very, very expensive tool. It was about 600 bucks. We had one at the cabinet shop I was running, but honestly, it was, you know, you kind of let people use it if they promised to take very good care of it.

Today, biscuit joiners have become really, really commonplace and shops. Affordability is there applications are there and we're gonna talk about where you can use biscuit joiners. So let's have an overview of a biscuit joiner. Make sure yours is doing everything you need it to do. And then I'm also gonna give you some tips on specifically using the biscuit joiner.

So first off, what's the deal? A biscuit joiner has in it. A blade that when I plunge against my material, that blade is blade is gonna project out and cut kind of a half a football shape into our material on the side of the biscuit joiner, there's a depth gauge and the numbers on this correspond to the sizes of biscuits that we can get tens, twenties, zeros. So when we're using the biscuit joiner, we wanna set this relative to the size of biscuit that we're gonna use with it since the biscuits are here. Let's talk about those a little bit.

Most commonly these are made out of beach. One thing that can happen to them is that if they're exposed to just ambient moisture, high humidity, they can swell a little bit. So when you're storing these biscuits, you wanna make sure they're stored in a relatively airtight container. So they don't swell to a point where they won't fit into that slot that we just got done cutting. Again, our common sizes are zeros are the smallest tens are in between and then twenties are the biggest ones we could get on the biscuit joiner.

What you'll find as we start using it is that there's a line on here or a hash mark or a divot something that indicates the center of the blade and that'll be really, really important. So that when we want to register for the cut, we know where we are on the material. When we make that plunge, the fence is adjustable angularly. So we can set this to different angles. It's also adjustable vertically.

So depending on the thickness of stock you're working with, we can change the position of the slot in our material. First thing we wanna do is check the biscuit joiner and make sure the slot we cut is right for the biscuits that we're using. The next thing we're gonna do is make a test cut with a biscuit joiner to make sure it's cutting deeply enough. The slide is deep enough. In order to do that, we have to make a cut in order to make a cut.

Let's talk about making a cut. So a bunch of things going on, there are some commonalities regardless of what brand biscuit joiner you're using. So one is that most biscuit joiners make it easy when you're working with three quarter inch material to get the fence in the right position relative to the cutter. So when this is loose, I can rack and pinion this up and down. When you look at the scale right there, there's a little hash mark that indicates 3/8 of an inch.

So you can see that half is there right below that, that's 3/8 because they know we work commonly with three quarter inch material. If then I put the pointer right there that puts the fence in the right spot relative to the cutter to be centered on three quarter inch material. From this perspective. Let's also look at this line down here. Generally on the side of the housing, you'll see something like this that shows you where the center of the cutter is and that can be helpful as we're laying out other joints that's gonna come into play later when we look at the biscuit joiner in this direction.

We already talked about this a little bit. There might be a hash mark, there might be a detect, there might be a divot, there's some kind of indicator like this one right here and this one right here that again indicate the center of the cutter on my material. I've got a layout line. That's where I want to make the cut, that's the center of it. So those marks are gonna get located on that pencil line.

Now, a couple things about using the biscuit joiner. The way I like to do this is I never use this handle except to carry this around. I find and from teaching classes, I've seen this when people are gripping like this, there's a tendency to roll this up. It's better if we ignore this with one hand, I'm dominant right handed. So my right hand is back here.

My left hand is gonna go on this fence and I'm gonna kind of rock that, roll it forward until I feel the fence flatten there. Then I'm ready to make the cut and that cut, that push is just gonna come from my right hand. So part of what I'm working real hard to not have happen here is for this to walk up and down while I'm cutting. If you do that, it's gonna widen the slot and reduce the effectiveness of the biscuit. We gotta go straight in, straight out.

Notice that I've got this clamped. We wanna use a clamp, not your hand as a clamp as we're cutting. If we don't have this in place and we're really relying on my left hand to hold it. If something slips, there's a chance that cutter could come forward and catch my left hand. So make sure you're securing your work to the bench, you need to have hearing protection and for these.

So let's go through that procedure again. I line up my hash marks, I start to roll forward. I feel that here with my thumb flatten out, then push straight in so rock flat, straight out. Now, our test is we're cutting for a number 20 biscuit here, put a number 20 biscuit in there, draw a line, take this out, turn it around, do the hokey pokey. And what I'm looking for is that line needs to go beyond the edge of the material just like this.

Imagine if, when I did this second insertion, if it were sticking out here, that means the slots not deep enough. And when I put two boards together, the biscuit is actually gonna hold them apart. There's gonna be a gap between those two pieces of material. So this simple test is making sure that we're beyond center here and we can see that when we flip and check it here. If this isn't the case for you read your owner's manual, everybody hates hearing those words.

But in your owner's manual for your machine, it's gonna show you how to adjust that depth of cut. And if it's right for the 20 it's gonna be right for the 10 and the zero. So it doesn't matter which size biscuit you do this test with. Once you correct this, it's gonna be right across the board. But if you've not done it yet with your machine, this is a really important test to do to make sure your machine is set up, right?

Pretty common application for biscuits is edge to edge joinery like I'm doing here now, dose of reality, I'm showing you how to do edge to edge joinery with biscuits. You really don't need them. If the joint is manageable when you glue it up a size that's manageable. And if it's a good joint, meaning they come together seamlessly, this joint will be stronger than the surrounding wood without a biscuit in there. But the benefit to knowing how to do this is when boards are really, really, really long.

I did a dining room table that was over 6 ft long and that was a glue up. I put biscuit joiners in there to register the surfaces together because it would have been really hard in the glue up to hold everything perfectly flush on that big of glue up. So I added them not for strength but for um a registration perspective, that's why it's important to know how to do this. But we don't have to add them in order for this to be a good joint. So question number one frequency of biscuits.

If you have a biscuit about every eight inches, 6 to 8 inches, that's gonna be great. Laying out. One of the beauties of using a biscuit joint is there's a lot of flexibility here. There's a lot of latitude. So when I do something like this, all I do is mark boom, boom.

Those are the centers of my biscuit slots. Now, if I had a bunch of boards, this would be something like a B CD. So I can keep the line straight. I know which board goes with which board, but laying out your biscuit joints just like that is gonna be fine on my biscuit joiner like we've already talked about, I've got the pointer set at three eights. That's gonna center me on this three quarter inch thick.

Stuck. One of the things I just did when I secured that board of the bench is I can't lever it over the edge. So don't biscuit joint three quarter in stock with it sitting on a table. And the reason for that is if that's a little under three quarters of an inch thick and you don't know it doing it like this could cause that fence that we're relying on for repeatability to be up off the surface when I can't deliver it like this. I know the fence is down tight to the face down, tight to the face.

Same thing here. And one of the things that biscuit joiners provide, but you have to do, right? Is that uniformity of spacing top down, top down to all four of these slots? And that's what's gonna allow that registration to work. If we change that registration somewhere along the way, we're messing up the system.

Same deal. Get your hash mark on the center line, rock forward, feel the flat plunge the gut rock flat. Now, I remember that latitude I was talking about when these babies come together, biscuits are in there. But was this see how far I can slide from left to right? And the joint still stays closed.

The biscuits are still doing what they're supposed to do, but it gives you a lot of wiggle room in this direction. But the tolerance in this direction is good is tight. That's what's keeping me flush across the surface and again, adding them on an edge to edge. This is probably why for me, I'm doing that is because I wanna make sure these stay flush. So I have less flattening to do after the glue up is complete.

That's how we would put an edge to edge together another application. And this is probably one of my most common applications for a biscuit joiner is if I've got a Plywood shelf and I wanna put solid wood banding on it so we can start out the same way, which is by getting our parts together. And then remember we have a lot of wiggle room left to right. So if I want a biscuit to be there and there, there and there, now, the reason I really love this process is that when you look at Plywood, the veneer on this face is Uber thin. It's like a 24th of an inch thick.

When I put solid wood banding on here, if I misplace that banding a little bit, if I get the banding just a little bit too low, there's really no wiggle room in sanding here to sand this flush with that edge. So I really need to lock these in nice and tight, meaning they're flush across the top. So this is stuff you've seen. It's getting to be old for you already secure your work. We're still set at 3/8 on this machine and getting a feel for that plunge is really, really important to make sure that as I said earlier, you're not rocking as you go in and out.

Now, this is a little bit different scenario when you do this, we're still gonna rock and go flat, but don't put your thumb way out here because there's a propensity to pull it too far. Really important. Don't put your support hand back here because now you're in line with that biscuit cutter. I'm gonna stay off to the side, feel it rock flat there. The other thing I'm being real careful about is making sure that when I turn the machine on, I'm still in a relaxed, not me, but the machine is still in a relaxed position.

Meaning I haven't inadvertently kind of kissed it against the face of that board. If it's pushed a little bit forward and I turn this on, it's gonna climb. So we want to let those springs do their job, let it be relaxed, rock, feel the flat, straight in, straight out. And again, what I love about this particular scenario is the way that this buys me flus across that face. Like I said, there's no sanding room in that veneer.

So getting these flush at glue up is really, really, really important that for us takes care of edge to edge and banding to plywood scenarios. I like biscuit joiners a lot. However, there's no such thing as a free lunch. So there are some limitations. Let's talk about the penetration on a joint that we get from biscuits compared to other stuff.

So there's our zero or 10 and our 20 that's the 20 that we marked out earlier. That's the approximate center. So what that means is that out of this football shape about that much is going into our mating piece when you cut a traditional Morrison tenon joint, a very standard rule of thumb is a tenant should be twice as long as it is thick. So a quarter inch thick tenant is a half inch long. So when we look at this, on the number 20 biscuit, the biggest one, we already have less than that when it comes to overall penetration of this biscuit into our mating piece, even less here, even less here.

So we really don't get a good job out of these, out of simulating Morrison 10 and nothing like what we get if we compare that to a dow because on that, that much of the dow is gonna be in the mating piece with a bead lock. And again, about that much is in the mating piece or something like a fest to domino. Same deal about that much in the mating piece. So from a strength perspective, this is better than nothing, but it doesn't give us the same rigidity as we would get from other loose tenant or traditional mortis and tenant joinery. So people have probably built chairs with biscuits.

I would not, I would trust any of these joints or traditional mortis and tenant more than I would trust a biscuit joint for something like a chair. When it comes to thin stock. This is a little bit of an urban legend, but it's kind of theoretically possible when glue hits a biscuit, it swells. And that's part of what helps make it work is the glue hits this beach, the moisture from the glue gets into the beach and that increases in thickness. If you're in stock, that's half inch or less.

It's possible that this swells so much that actually telegraphs the football shape through to the surface of the material. Now, in reality, I've used biscuits in half inch stock. Never in anything less than that. I've never seen a biscuit telegraph so far. But I'm just warning you, it could possibly happen more likely in a softwood than in a hardwood.

You need to be aware of it. You need to be experiment, you need to experiment with it. If you are gonna use a biscuit in thin stock. The other thing that we're up against is that if we glue something up and we use biscuits as part of the assembly and we're machining into it later. There's some possibility we're gonna reveal a biscuit and this isn't a cracker jack box.

We don't want to reveal the surprise inside. We want this to stay hidden. So imagine if for some reason, you used biscuits on a panel for a raised panel door and then later you raise the panel with a router bit, maybe suddenly you're looking at a biscuit. So you have to be aware of that. You just got to be conscious of your layout.

The other thing that we run into with biscuits is that on something like a face frame, one might think, wouldn't this be a great place to reinforce that end grain joint? And the problem that we're up against is that even with the smallest biscuit, even with a number zero biscuit in this two inch wide stock, the slot that we cut for, that exceeds the width of our material or it's really, really close. So coming in here with the biscuit joiner and cutting a slot such that it doesn't blow past these edges. It's pretty impossible to do. And again, that's with the smallest biscuit as we go up in size, it becomes more obvious, we can't even use a number 10 on a two inch face frame piece, two inch face frames, inch and a half wide face frames.

Those are pretty common dimensions. So not just in face face framework, but in your other woodwork in general, you gotta recognize the slot required for the biscuits is slightly longer than the biscuit itself. So it's possible that you can't use it simply because of the limitation that the joint is gonna show on an edge when you put everything together. So overall biscuits are great, be aware that they have their limitations. Like anything in woodworking practice with the machine before you use the machine, make sure that you're coming in dead straight, going out dead straight.

We've got other stuff about biscuit joiners. So make sure you work, watch all the videos in this series to really fully understand these machines.