Q&A with George: Finish for Kitchen Tables & Precise Cutting
George VondriskaDescription
Al stopped in the shop recently and had a few questions for George. He was looking for help choosing the best finish for a kitchen table he’d recently completed; how to get more precise cuts; and how to best calculate angles. George provided answers for Al that might help in your shop, as well.
Finishing
Knowing how to finish wood is, possibly, more important than knowing how to make the project. No one wants to lose the countless hours that have gone into making a woodworking project by choosing the wrong finish, or not applying the finish correctly. In addition to helping Al decide on the best finish for a kitchen table, George provides application tips, too.
Precision wood cutting
Woodworkers sometimes struggle with accuracy. There are a handful of things that can be done to help with this. From pencil selection to pencil sharpening tricks to marking knives, George provides Al with some cool ideas that’ll help you do precision wood cutting in your shop, too.
Knowing the angles
Laying out angles can be tricky, and confusing. George explains how to calculate angles, and goes on to show some great tools that can be used for laying out and measuring angles. You may not have known it, but even the miter gauge from your table saw can be a great lay out tool.
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We've got some more Q and A coming your way today. My friend, Al Duchnowski is in the shop. And Al, what's your woodworking dealio? Why are you here? Why am I here? Hobbyist woodworker, you do a lot of work on your cabin up North. I do. We do a lot of stuff. After I ask you, I do projects, like make tables and furniture at home. Let's see, the last thing I remember was a big hickory table. It was. It was for your cabin up North. It was. Came out okay? It did. Which leads to my first question. All right. All right. So here we go. We're launching right, I see no time for banter. That's right. Going for the throat right away, okay. The first question is, on hard surfaces like that, what finishes do you find work best for tables and furniture? Okay. So, finishing is always a great question. One, it's scary to do and you sure don't want to mess up a project. Two, you want it to last a long time. So, let's talk about some different stuff. Shellac, lacquer, varnishes. Of those three stuff in the varnish family, like the polyurethanes, are gonna give you the best water and alcohol protection. So a good question would be, well if polyurethane and varnish is so protective, why not use it all the time? No such thing as a free lunch. The downside is the drying time. So when you don't have a dedicated finishing facility, you have to be kind of careful about your environment. As you brush it on, it could be 40 minutes or more before it's dry to the touch. Which means, any little dust mites that are coming down in the air are gonna stick to it. Okay. A real important thing to remember with most varnish, is that when you put second layers on to build up the finish, it relies on a mechanical connection between the two layers as opposed to a chemical connection. So, if I put on a coat of shellac and I put on a second coat of shellac, coat number two actually melts into coat number one and they'll bond, no matter what you did or didn't do. With most varnishes, read the manufacturer's instructions. But typically it'll say, be sure you sand between coats. And that's not just to get the dust nibs out. That's to put a little tooth to the finish. So that the second coat can lay on. Otherwise it's like two layers of acrylic. Two layers of plexiglass, one on top of the other and they're not really bound to each other. So, short answer is, if you want to be able to put a glass of water or something else on your table. Beverage. A beverage. And not worry about leaving a mark, varnish and polyurethane, great choice for that. Heat sensitive, not? Can be still. So it may not protect you from, you know, still put a trivet or coaster under a cup of hot coffee. It's pretty hard to get that kind of protection out of any of these finishes we talked about. Okay. 'Cause I did make the mistake of putting on the bar top finish. Yeah, yeah, yeah. On the table. And I noticed when you set a plate on there, a hot plate, it'll stick to it. Yeah. Kinda melts its way in. We don't have any of these issues with the varnish or the poly. Yeah. And not if it's especially, part of it is cure time. Make sure that it, whatever they say, if you need four days cure time, make sure you allow that. But then it shouldn't be, you know, this is the stuff that the high-end polyurethanes like Spar varnish is the stuff they're putting on boats. If it can take UV and salt water, you're gonna be in pretty good shape on a kitchen table. Okay. And not as sensitive to heat as your epoxy based finish was. Okay. Good. Can I go onto the second one? Okay. I was hoping we were done. I'm really worried now. I know. Second one is, whenever I cut something, it's never consistent. And I know you guys in the carpentry trade, the master carpenters, are always, your cuts are precise. Give me some hint here. See that, he always knows my cuts are precise. I want you all to remember that. Well part of it is some subjective stuff. Part of it is kind of, experience of how I do my layout, how I do my cuts relative to how I do my layout. So, let's see if I can get a couple of things here. One is, I try to teach all the time. Consistency is more important than accuracy. So I try to not get hung up on, I have to cut this to 15 and a 16th, so much as, if I'm making two of them or four of them, they all need to be the same. Now, sometimes that doesn't work. If I'm making an inset drawer front, it probably has to be a very specific size. And that's where we've gotta figure out how to cut to the line. If I'm doing stuff with a tape measure, one of the things that helps me a lot, you were talking earlier about big fat pencil lines. Right. We'll talk some more about the pencil in a second. I try not to make a line. I make a V. I'm gonna do it on this side. So if I'm laying out to nine inches, I put the tip of the V at nine, so that I have that, instead of just that. 'Cause now when I look at that line, if I wanna square that off, which part of that line am I trying to hit with the square? So that with the V, it gives me a distinct point and I can do that. Now, when I cut to the line, for most of what I'm trying to do, I'm gonna try to just skin right along the edge of that very sharp line, resulting in that being the length I'm trying to hit. The very sharp line part is important. Which means keeping your pencil sharp. If I'm doing real meticulous layout, it's not uncommon that I'll have a little bit of self-adhesive sandpaper on the table. And then I'll very frequently roll my pencil across. And it gets really a needle tip on there. And we might even see a difference between what I had and what I do now. Get them a little closer. Pretty close. But if the pencil is sharp. And then the other thing is, there's pencils and there's pencils. Don't skimp on your pencil. We want, it's a number two pencil in this. A number two lead. But we want it to be a hard lead. And I find that if I do this and that pencil bends like a piece of rubber, the graphite inside there is real marginal and I'm gonna make like three lines and the pencil will be done. And it'll be like drawing with a crayon instead of a pencil. If it's nice and crisp like this, it's gonna hold up better and that's gonna give me more accuracy. So these are a lot more expensive than, you know, they may be twice as much as crummy pencils you should send to school with your kids. But they're much better for in the shop. Then if we wanna go a step further, you can go to marking knives, instead of pencils. And a marking knife is not the same thing as a utility knife. On a utility knife we have a bevel on both sides. And on a marking knife there'll be right-handed and left-handed. This is a right-handed marking knife. So the idea with that is that, when I make a line, the flat side goes up against the square. And the bevel as I cut, is actually helping to push the flat side against the square. So it stays nice and tight. And now I haven't drawn a line, I've incised a line. I've cut a line across that surface. And that's really crisp. A lot of people who do hand tool work, that's how they do all their layout. To get a hand cut dovetail to fit together, there's not a lot of wiggle room, you know, it's either right or wrong. So we really need the precision of something like this, over what we can get from this. Excellent ideas. That help you? Do kids still use pencils at school? I think it's an app on the iPad called Pencil. Okay. My third question was angles. I'm the worst person in the world. I thought you knew all the angles. I've heard a rumor of that, but. What's the tool you use that's easiest for doing angles, figuring angles, making angles. Okay. It depends. So, well. So, depends on what you're doing. If you're gonna make an octagonal frame. The geometry is, there's 360 degrees in a circle. And if we want an eight-sided thing, we would divide that into 360 and then divide that number by two. So because, what we're doing when we divide eight into 360, we get 45. And that's the entire angle. We wanna cut half of it on this board and half of it on this board. So 22 and a half here and 22 and a half here, will give us the 45 we need to come up with an eight-sided octagon. So that's kind of the calculation deal. On the layout side. If I'm transferring measurements, this is a bevel square or sliding bevel or T bevel. So it's not uncommon that if I've already produced an angle or maybe it's an existing piece I'm trying to match, I can set this to any angle, lock it in place. And then I can transfer that to my work. Or if it's like this, I could transfer that to a table saw blade to get that angle matched up. And it's another one of those cases where, in this case, I don't care what the angle is. I just want this to match whatever I've already done. Setting up something like a table saw. I'm unlikely to use only the protractor on the table saw for the angles. I'm more likely to use some kind of a setup device for that. Another kind of a cool way to do angles is because most woodworkers have a miter gauge in their shop for their table saw. Is, to use your miter gauge, just like a big layout tool. And if I set this to the angle I want, so we were just talking about 22 and a half. So let's do that. I can flip this over and use that with my really sharp pencil to lay out a 23, 22 and a half degree line. So it's a pretty specialized layout tool that you don't have to pay any more money for it because you've already got one hanging on your table saw. Good idea. And because of its rotationality, it's also depending on what you're trying to match up, you might be able to put this on an existing item, set this. In order to find then, what angle you're already at. Okay. So it just adds a little diversity to what the miter gauge would do for you. Perfect. What else? That's it. Really? Everything else I know George. All right sir, thanks very much for coming in. I know lucky Al is heading to Northern Wisconsin from here. It's probably to do a little work on the cabin. Yes. And a little. Yeah, yes. And maybe a little. Shhhhh. Oh, I don't know. Yeah. All right. Thanks Al. You're welcome, thank you. All right, more Q & A next time.
I forgot to ask: What happened to your left pinky finger?
That was a great video! I have not found a way to cut accurate enough angles and that means using a miter saw, table saw or even a router with pattern bit. For example, I cut 15 degree angles for a 12 "identical" trapezoids to form into a "wheel." When forming them all around on the work bench, the 12th piece is always too small to fit properly. Then, when they are glued together, they tend to slide around on the glue, making that 12th piece always needing to be sized differently (every piece can't have the same amount of glue between it and the pieces next to it. Basically, there are 24 angles. If they're not exactly 15 degrees, if the lengths of their longest edges are not exactly the same, the error is then multiplied many times. The wheel is then cut round with a band saw, jig saw for the inside, using MDF templates with a router and pattern bit. The size differential in the 12th segment then isn't noticeable. Cutting just parallel on a table saw is easy unless the piece is long. I was cutting leaves for a formal dining room table. The table was 40" wide, the leaves were something like 18" wide and 40" long. The leaves are supposed to be square! Do you have a 40" long T-square? Probably not, and what if the sides of the table are slightly curved? So, let's suppose a very small error, just 1/2 degree, on the cutting angle. Trig: The sine (or tangent - they're about the same at small degrees) of 0.5 degrees = .0087. Multiply that times the 40" and that's you horizontal error, 0.35", which is almost 3/8". You can draw the lines, make sure everything "measures" parallel, but the best you can do is cutting a parallelogram. It will not be perfect, track saw or not, with the equipment you have. Finishes: Building the work piece is often the easy part. Finishing can be difficult. I put shellac on nearly everything after staining. It can be sprayed but it tends to dry on the sprayer tip, which is very annoying, and that gets worse with increased temperature because it's an alcohol-based product. It is fully dry in a few hours. It tends to dry rough and I recommend smoothing it with 4-0 steel wool. Beware of water-based polyurethane. It goes on very nicely, dries quickly and drips are easy to manage. But it's acrylic and won't tolerate any kind of alcohol (the shellac needs to be really dry). A bowl of cooked string beans will sink into it. Cold glasses will leave water marks. It is easy to spray if diluted with distilled water. It adheres well to dried and smooth shellac. It's surface tension helps it fill in gaps. I used to use lacquer a lot, but it's a terrible finish unless you're working in a factory where time is money. It needs to be sprayed no warmer than 75 degrees temperature, the colder the better. It boils at 90 degrees! It will start drying coming right out of the spray gun and many substances cause it to fish-eye and other unsatisfactory appearances. It dries extremely fast, but it's also extremely toxic. You need to use a good respirator, then then vacate the area afterward and wash your clothes separately. The problem is that lacquer is very brittle and it will craze due to changes in temperature and humidity. The crazing will look like broken glass. If used for large items like a table, expect the item to out-gas for a long time after it has "dried" and some will object to the smell. So-called dried lacquer can still stick to Styrofoam, so be careful how you transport it. Deft is a type of lacquer that never seems to dry. It is painted on. Perhaps it's good for making guitars and chess pieces, but not for tables because it is not hard enough. Real, oil-based polyurethane can be sprayed if you thin it with real mineral spirits 50:50. It adheres well to shellac and water-based polyurethanes (acrylic). If you respray at 24 hours, it doesn't need to be roughed up. If you need to fix the surface, you need to wait 48 hours until it will be hard enough to handle smoothing. Drips are hard to manage. Coating all size sides of a rectangular work piece can be a real challenge. Painters pyramids DO leave marks. In my experience, 1 of out of every 10 pieces will give you a problem no matter what. If it looks great, you were lucky. Sometimes, you have to just start over, sanding it down, re-staining it, re-sealing it with shellac, etc., and it still doesn't look exactly like the others. Polyurethane cures and doesn't dry. It gets harder with time, all the way out to infinity. It cross-links with oxygen, which means that it will gel in the can. You can delay that by washing out the room air oxygen in the can with something besides oxygen. I use nitrogen. Those little spray cans of Argon don't hold enough gas unless the can is pretty nearly full. The displacement of the oxygen is purely by flow and volume, not the weight of the gasses. A nitrogen set-up is not cheap (cylinder, regulator and any hose that'll fit on it) and aren't worth it unless you do a lot of polyurethaning. You need a dedicated spraying space, a virtual clean room, to spray these in and don't forget that you need to be able to breathe in there as well! I spray all pigmented paints outside, not in the spraying room, which requires reasonable weather and no vehicles down-wind.
When I took Mechanical Drawing in high school, it was important to always have a sharp point. We were taught to twirl the pencil in our fingers as we drew a line. This help to keep the point sharpened much longer. This is especially useful on long lines. Now, I use a .5 mil mechanical pencil. :-)