Episode 1 Wood The Apprenticeship: Woodworking Techniques and Tips



hey I'm John Landis years ago I served as an apprentice and a journeyman to a fine furniture builder and have been a professional woodworker for the past 18 years as the saying goes if you give a man a fish you feed him for a day if you teach a man to fish you feed them for a lifetime in my series of instructional videos I'll teach you not only the techniques of woodworking but why and when we use those techniques making you essentially my apprentice so let's get started you you hey welcome to Episode one that we're in titling would I feel it's an important subject to cover before we get into the woodworker before we start milling before we start joining before we start doing anything that has to do with building furniture or building things out of wood I feel we need to learn about the material itself hey you wouldn't be a writer if you didn't understand the language in which you wanted to write you wouldn't be a painter if you didn't understand oil paints and how it's going to react on the canvas and you sure as heck shouldn't be a woodworker if you don't understand wood and how wood is going to behave what it's going to do under certain circumstances how we can glue it how can we join it how can we finish it how can we sand it we need to know what wood is and how it's going to react before we can start all that so we're going to take you back a little bit maybe to biology class high school biology class maybe you don't love the subject but you're going to love this because this is going to tell you why wood behaves the way it behaves and this is going to be ongoing information I'm going to give you information here that you may not catch all of and it may not sink in entirely especially since it's not hands-on this is something that's going to happen inside of your brain I'm giving you information that somewhere down the road as we're woodworking something's going to click and say hey I remember that I remember when I was taught that and now it makes perfect sense a lot of what I'm going to say today will make perfect sense but somewhere down the road is going to make more sense it's the same thing as doing arithmetic if you learn the two plus two is four you learn that two times three is six but then you build on that so that you're doing calculus later on you're doing higher math later on you're building on the fundamentals so what I'm giving you today is the fundamentals of wood from a cellular structure to how it's going to behave and you're going to take that information and the more you go throughout your woodworking career the more you're going to understand what it is I'm teaching you today so it's going to be a great foundation you got to have it before you can move on how else will you know what joint to use how else will you know how to join two pieces of wood together how will you know which way to sand something what kind of finish to put on it you can't know that until you know wood itself so we're going to get started all right so we're going to start on a sort of a molecular level first I have here a bundle of dowels to represent wood on on a microscopic level this would be better if this were a bundle of straws but I'm a woodworker so I've got dowels I don't own a diner so I don't have a bundle of straws here but the Dow's will work just fine so if you picture a piece of wood on a microscopic level this is what you've got here these straws on a scientific level and you won't be quiz later so don't worry about remembering this they're called lumens and a whole bunch of this bundled together these are all micro fibrillar space there are spaces between their cell walls around the straw but this is the this is the microscopic level of what wood looks like now the most important thing that you need to realize about wood is that no it's not the romantic living breathing thing once you cut down a tree it's dead in the wood you're working with is dead but what we'll continue to do throughout its life as you've turned it into furniture before you turn it into furniture it is going to react with the environment around it it is going to exchange moisture it's going to take on moisture if put into a more humid situation it's going to eject moisture if put into a drier situation and that is the key thing that I want you to learn today that it exchange moisture takes it in and takes it out how it happens why it happens is what I'm about to teach you now it's at a very very high moisture content it may be 100 percent moisture content what that really means that 100 percent is that the amount of moisture in the wood equals in weight the weight of the tree 150 percent moisture content with me that did water in the tree weighs one and a half times the weight of the wood and so forth and down 50 percent moisture content would mean that it weighs half and so on and so forth once the tree is cut down and the lumber is milled and then sent to a kiln hopefully when you get it by the time you get it as a wood worker it's been kiln dried so its moisture content is going to hover somewhere between six and nine percent as as kiln dried lumber somewhere maybe around twelve percent is air dried lumber and the reason this is important to know is because at that stage at six to eight percent six to nine percent 12 percent moisture content all of the moisture that was in these lumens inside of these straws is gone that water is gone in that moisture hopefully never to come back again but the moisture that were worried about which is called the bound moisture or the bound water is that water or moisture that hangs out between these straws that hangs out in the cell walls of these straws because it's that moisture that affects the size of the wood is that moisture change that will cause the wood to shrink or expand now when a board is at its fiber saturation point that means strictly speaking that the moisture in the wood has completely filled the microfibril space it has completely filled the cell walls but there is no moisture inside of the Lumines it's at its at its saturation point which means the wood is at its largest its largest size at that point it's when the moisture starts to leave these cell walls it starts to leave the microfibrils that the wood will begin to shrink and this is the important part so it's six to nine twelve percent moisture content it's going to have an amount of moisture that you should be used to that that's that's the amount of moisture that's going to be in this board when you get it from your lumber supplier from the lumberyard from wherever it's going to be in at six six to eight percent of kiln dried twelve percent of air dried and you're going to work with this wood you're going to build something out of it and then this wood is going to move into a situation into someone's house it may move into your finish room it may hang out in your shop for a little while whatever the case is this wood is going to adjust to the atmospheric to the relative relative humidity that is around it and when that happens the size of the wood is going to change so this wood that has moisture in it again we're looking at the cellular structure here all the moistures trapped between these lumens it's inside of the cell walls and and we take this board and we've milled it to this effect and we take it inside to a house that's dry may be the wintertime the heat might be running it's going to slowly over time and not a long time but not in a moment it's going to start to eject this water it's going to try to reach an equilibrium it'll have an equilibrium moisture content it's going to try to get with eject where it's ejected all of its moisture it doesn't need to eject anymore it's trying to become – at equilibrium – its surrounding environment when it ejects that water this board is going to shrink the space between the microfibers will get smaller and this board is going to shrink it shrinks across the grain likewise the board that is dry introduced into a more humid situation is going to take on moisture and it's going to take on moisture through the ends of the lumens here for sure but also just through the cell walls and as it takes on moisture that moisture is going to fill the space between the microfibrils it's called hydrogen bonding it's going to fill with moisture and it's going to force these lumens apart and this board is going to grow and it's going to grow and width across the grain like this and it's that growth and that's shrinkage that we need to worry about as well so let's talk about wood on the reality level here we have a board of chair here that's about twelve inches wide about thirty inches long it's grown like this it's its cells structure it's lumens are growing in this way you can actually see that in some woods if you looked at the end grain this is the end grit if you looked at the end grain of some woods oak for example Wayne Gaye I don't know if you're familiar with Wayne gay but Wayne gays one where you can actually see the cellular structure you can see the straws because they're they're large enough that you can see them with the naked eye you can actually see the straws on some of those woods so the straws are grown the lumens are in this direction when the lumens take on moisture that is when this board which is now at an equilibrium moisture content when it takes on moisture when the relative humidity around this board is higher than the board itself this board is going to expand in this direction it's going to move in this direction and become larger in this direction it's also going to grow in this direction although it'll feel like not as much because we're only starting at about an inch wide in the first place so it's going to expand a little bit but it's going to grow in this direction and it's going to grow in this direction it is not going to grow in this direction it's not going to grow in its length that's called longitudinal and it's not going to grow in that direction reality is it does grow but so very little that it's negligible it's negligible and every time you build furniture you don't ever have to concern yourself with growth that happens in the longitudinal direction you do need to concern yourself with growth across the width and that's the reality of wood so now you understand why wood shrinks and expands it's because on the cellular level that moisture goes into the space between the microfibrils into the cell walls through hydrogen bonding it enlarges that space between these lumens and these straws causing moisture to cause us wood to grow across the grain like this in the same respect put into a dry situation the moisture escapes it's pushed out and that space between these lumens gets smaller and this board gets tighter why do we have to concern ourselves with that in the woodworking industry very easily actually very simple the explanation is simple because we're always joining one piece of wood – another piece of wood let's say we're talking about building a table and we have to join aprons to legs the apron needs to be able to shrink and expand the legs need to be able to move and in the most important situation in a tabletop situation is a solid wood tabletop that may be 30 inches wide it may be 44 inches wide maybe five feet wide whatever width you're making this tabletop that tabletop is going to shrink and expand and at that size at 44 inches 48 inches it has a movement depending on species it may be as much as a quarter of an inch and if you bind that wood if you put if you join that wood in such a way that you hinder that woods ability to move that that woods ability to shrink and expand then you're going to cause a problem with the wood either it's going to crack or it's going to blow a joint in the next episode we'll continue a little bit more about the shrinking and expansion of wood but we're going to talk about it as it relates to quarter sawn lumber versus flats on lumber or plain sawn lumber and we're going to talk about how it relates the cellular structure of how we can glue wood together and therefore what kind of joinery we're going to have to use so thanks for joining me I hope you learned a little bit about something about wood keep it tucked in the back of your brain because this is the kind of stuff that's going to stick later on we're going to come across a situation where I'm going to refer you back to this and say hey remember when I told you that this wood is going to do this this is what we have to take into consideration watch it again maybe it'll stick a little better this time but definitely put it in the back of your pocket and we'll talk about it again many many times thanks for watching see you next time

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