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Email This Page to a FriendPreview: Fasteners & Fastening, Part 2 – Countersinking Screws & Setting Bungs in Wood
March 3, 2016
Fasteners in action: Proper techniques for putting stuff together using a variety of fasteners.
– Today we’re going to talk about fastening wood together. You know, tips and tricks for drilling, countersinking, making sure you’ve got a right clearance hole, and how to drill for and set a bung. Kind of give you guys a look at the different fasteners we talked about. We’ll start with sheet rock screws. And again, everyone is familiar with your standard sheet rock screw. You can just drive sheet rock screws with a typical drill. You want to make sure your tip fits the sheet rock screw properly, and we’re just putting two two-by-sixes together here. And you can see that that does a pretty good job. You can draw a sheet rock screw right through those two-by-sixes, it will just keep going. And after the wood moves and so forth on staging and scaffolding, it’s awfully hard to find those screws again to get them back out. Sheet rock screws tend to be fairly brittle. And if you’re driving them into a hard wood such as oak or mahogany, and there isn’t, there hasn’t been a proper tapered bit drilled down into it, the friction will overcome the strength of the shank of that screw, and it’ll just snap off. And then you’ve got steel buried into something that you may not necessarily want. So we’ve started to stay further and further away from these, and more towards these what are called GRK screws. Because they’re a star drive, and they’ve got a washered head. These smaller ones you can see, there’s a couple of different styles. There’s actually teeth on this thread, so that it cuts a pilot hole. On these larger style, there’s actually a slot cut into the end of them, that cuts those pilot holes as it goes. Now on these very big ones, there’s a cutter here, and what that does is it cuts a clearance for the shank. You want the right size driver tip for them. So again, one of these GRK screws. And you see as I drive this just through some two-by-sixes, the head of that screw stays visible, it’s a very, very strong grab, and it really draws those two together nicely. Always easy to see. Easy to see the head to pull them out. We reuse these over and over again, and this whole building is put together with these things. It’s just a nice, tight fastener for general type of construction use. Another thing to be cautious of is, especially with scaffolding and workbenches, is the length of the fastener. This is just about perfect, it’s just shy of three inches, which are two two-by-fours together. If we were to use this, just slightly longer screw, that is dangerous as anything, in that the tip of that is going to come through, and then walking by that and you catch your shoulder on that, it’s going to cut you wide open. The very tip of these are very sharp. And you always want to be sure that you’re using the right-size screw, even in something like a sawhorse or a workbench that you’re just kind of screwing together rough. The next thing I’d like to talk about is just driving simple fasteners. We forever are using these taper-style bits. These are made by Fuller, there’s lots of companies that make them. And they are countersink, it’s a cutter for a plug, if you’d like to put a wood plug behind the fastener. More importantly, it’s a nice tapered bit that is very adjustable due to the length of the fasteners that you’re using. You see that there’s just a little Allen screw on either side of it, and that you can take completely off. And you see that that’s just a very standard tapered lead-in for a number eight, it says C8, so this fits a number eight fastener. And you get these for any number fastener. These all happen to be number eights. But that is a very standard taper lead-in for a number eight screw, whether you’re using a wood screw like this, or a self-tapping screw like this, I use these taper bits that match the number screw. These aren’t the end-all. You certainly could get two bits, basically to put a number eight fastener in, you would want two separate bits. One that was a clearance for the shank that every, that the screw goes through. The piece that you’re screwing through, you want the screw to be able to freely come and go. If you don’t, you’ll get what’s called screwbound. And then as it goes into the second piece, you want to step your bit down to the inside of that thread dimension. It turns into a two-bit operation, you know, one for the clearance hole and then one to grab the thread. So that’s why we really like using these. And we’ll just set this right to a one-inch depth. And I just put the shoulder of the screw right at the top of the countersink, and that is where I will set that. Maybe, just slightly deeper if anything, but usually right, right very close to the end of the countersink is as good a way to go as any. Then we’ll start again with our drill. OK, and we talked about two speeds on a drill. Metal you want to be slow. Wood is high-speed. All of these bits when you’re working with wood are very high-speed to get the nicest, to get the nicest cut. We’ll talk about just setting screws flush and on the surface to begin with, and then we’ll get into countersinking and driving a plug. So here I’ve got two pieces. This is Alaskan yellow cedar. And I’m going to use this number eight flathead wood screw. And I’m just going to drill down. Again, get the drill right up to speed, and come down as vertically as I can. And just sneak up on the, sneak up on the countersink. Oftentimes I’ll check a countersink by flipping the screw upside-down, and it’s just shy of the diameter of the head, and I’m going to call that good. I’m going to grab the screwdriver that fits that best, and wind that down in. One thing that I want to check, I’d actually like to show you to see what happens here. Yeah, that’s good. So what’s happened there is as I’ve come down, you can see that those two have spread apart. What’s happened is that has become threadbound, or screwbound. So I could pull and pull and pull on this, and eventually maybe pull those together. But what’s that, what that is caused by is that there isn’t a clearance hole big enough for this number eight to slide through. Now you’d say, well, why doesn’t that taper bit work out? Because of the varying length of these, the adjustability in these, the shorter you tend to go on a countersink, on a taper bit like that, the less likely you are to have enough diameter out at the end here to drill a clearance hole. So oftentimes I will flip that piece that you’re, that you’re fastening through upside-down, and just come in the backside, and make it so that that screw will go through freely. And then they’ll go back together. You want to be very careful, especially with slotheads, that your screwdriver isn’t overhanging here, because as you come in you’ll scar the wood, especially if this is something very dressy. You want to make sure that the screw head is, that the screwdriver tip is not outside of its slot. And that finishes the screw flathead flush we call that. It’s one way to finish a fastener, it can be varnished right over. One thing that is, that is easy to do and, and looks like hell is to over-countersink something, if you’re planning on it being left that way. And you end up with this ring around the wood, and if this is an exterior application, whenever there’s any rainwater or anything, water’s going to pool in these, and they’re going to hold water. And it’s just going to eventually blacken around that screwhead. So being very, very critical on your countersink is key, and usually I stay just a little bit shy, and then draw the screw into the countersink so that it’s just as perfect as can be. So now I’d like to show you a countersunk and plugged fastener. These Fuller bits come with plug-cutters if you buy them in a set. A number eight countersink is a 3/8ths diameter plug. If you plunge this all the way in, it’s going to, it’s going to drill a negative space for a plug. And then you have these plug-cutters that come with them. We’ll talk about those in a second down on the drill press. How I drill for those again is very high-speed, till the countersink is just starting to hit. And then I clear the shavings from my bit. And then I wind it up, full speed, in kind of a single shot in and out. The fewer times that you run a machine in and out of this hole, the cleaner that hole’s going to be, the tighter your bung is going to fit, and the more it will disappear in your woodwork. I just grabbed these three 3/8ths Fuller bits to show you a very common problem with plug-cutters. You can see that both of these plug-cutters, the tips of these four cutters has a burr on them. And that’s from one of two things. It’s from when this was in a drill press coming down through the material and hitting the tabletop or a hard object as it came through, or more often what it’s from is when you’re unchucking that from the drill, this just falling out of the chuck and landing on that metal cutting surface on the drill press, and it folds those in. What that’s going to do is it’s going to cut a plug that is smaller than it should be. And you’ll end up with a loose plug in a hole with a big glue line around it. So one thing that you always want to look at is the condition of the tips of these cutters on your plug-cutters. And if they’re burred like that, you want to get a file and try to clean that up as best you can. It’s really the leading edge of these that is the cutter, not the tip, but you see how those are folded over and that’s going to give you a bogus plug. So I’ve got a good plug-cutter here. We’re going to take it down to the, down to the drill press which is where you want to cut plugs. You can cut plugs with a, freehand with a drill, but it’s better in a drill press. So whenever I’m working on a drill press with wood, I always put a sacrificial piece of wood down on this tabletop, to avoid either this coming through the material that I’m drilling on and hitting that metal, or taking that out with the, with the chuck and having it fall on the metal. Having this sacrificial piece of wood here could be anything, you just want to be sure it’s parallel-sided, so it’s nice and square to the base. One thing to consider when you’re picking your piece of wood. Oftentimes you take a piece of stock, the same wood that you’re actually putting the hole into, you have an offcut that you can cut some plugs out of. One thing you want to think about is the grain orientation, to be sure that the orientation of the grain is the same on the surface that you’re cutting the plug as it is the surface that you’re putting it into. The flat-grain side of a piece of wood has a much different look than the vertical-grain side of a piece of wood. So, something to consider. Another thing to consider when you’re cutting plugs is that you want to have a piece that, looking at the side of the plug, the grain is very naturally horizontal. If you have a gnarly, curly piece of wood that the grain is waving through, chances are you’re going to tap that plug into the hole, and when you go to clean it off with a chisel, it’s going to break and it’s going to shoot below the surface following the grain of the piece that you’re, that you’ve cut it from. So a nice even grain, the same grain orientation, are two key things that you want to think about when you’re cutting plugs. And again, like the countersink upstairs, you want to come down, kind of get your plug started, and then plunge your plug-cutter. You don’t want to up and down. The more times you travel up and down on this plug, the more chances you are to shave wood that you necessarily, shouldn’t necessarily be cutting off and end up with a loose, slobby plug. Nice, high speed. Come right down, and then you feel that bottom out. Nice thing about these plug-cutters is when you get to the bottom of them, it cuts away the shoulder. So it gives you a bit of a lead-in, and that is the side that you want to drive the plug from. I’m just going to pop this plug out so you can have a look at it, and that is what the plug looks like right off the cutter. You can see that when you bottom a plug-cutter out, it cuts a bit of a chamfer on that side. That is the side that the plug wants to be going into your countersunk hole with that chamfer. So it’s important that you go, that you bury the plug-cutter to cut that chamfer. It would be difficult if that chamfer weren’t cut on there. And on a nice, clean piece of wood you pop them all out and you have these, what seem to be parallel-sided pieces of wood. The plugs are tapered, and not just that chamfer. They’re tapered from there, it’s a smaller diameter there than up here, so as you drive them in they get tighter. So, we’ve got our countersunk hole and our plug. I’m just going to look at the backside of this, and be sure that I’ve got a clearance hole, which I don’t. I need to, I need to backdrill the piece I’m coming through so I have a nice clearance hole. You can see, I haven’t put the screw into this hole yet, but all of these others that we’ve put screws into, as those screws have tightened, they’ve actually created a burr and lifted the wood on that surface. The two key things to doing high-end varnished work is that you have a clearance hole through the piece that you’re fastening through, and that you’ve taken off any burr on the piece that you’re screwing into before your final assembly. And that can just be done with a piece of sandpaper. Just like the metal, you get a little burr. OK. And now those two pieces are ready to go together. You can feel when the screw comes to the bottom, and again, tight is tight, and you can see that, that the joint between those is about as good as anything. Now applying the plug, lots of people argue about this. I think epoxy is overused on plugs. There’s nothing structural about a plug. 90% of the time, I use a Titebond two or three glue. It’s just a polyurethane glue. Single-part, dip it, put it in, and sand it out. There’s nothing wrong at all with, and a lot of old-timers, all the Chris Crafts, and all the antique and classic boat gurus, they put their plugs in with a little bit of varnish. And here, the key is to get the plug started right. You want to be able to read the grain on the top of the plug, and line it up with the grain in the wood. And I usually push the plug in as deep as I can with my thumb to get it started. And then finish it off with a hammer. You can tell when a plug is bottomed out by the sound it makes, it’s a tap-tap-tap-thud-thud. OK? You don’t want to whale plugs in, because the harder you hit a plug, it tends to want to split the section of plug that is still above the surface. Oftentimes, I will chisel, if it needs chiseling, to trim a plug off, but I will take a piece of sandpaper and immediately sand a plug. Sand a plug flush. If it’s high, I would chip it off with a chisel, and sand it flush. It’s always good to have a look and make sure that the grain is lined up, and that you haven’t chipped the plug lower than you should’ve with a chisel, and chased the grain, and it’s below the surface now. When that varnish is yet, or the glue that you put the plug in is still yet and not cured, that’s the best time to get a plug that you’re not happy with out using an ice pick or a very small chisel, and simply drive a new one in.