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Layout Basics I Ne
 

Layout Basics I Ne

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Basic Layout Study Guide

Basic Layout Study Guide

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    Layout Basics I Ne Layout Basics I Ne Document Transcript

    • Layout Basics By James D. Thompson December, 2005 I. Connecting two points ................................................................................. 2 II. Erecting a perpendicular............................................................................. 5 III. Compasses and lead ................................................................................. 10 IV. Bisecting a line ........................................................................................... 12 V. Constructing a hexagon ........................................................................... 13 VI. Making equal parts.................................................................................. 15 VII. Constructing 4 or 8 parts of a circle.................................................. 18 VIII. Centering Stock for Turning................................................................ 21© www.OldToolsShop.com 1 January 14, 2006
    • I. Connecting two pointsRemember as you read this that I make no claim to be an expert. I am simply acompetent journeyman, and the methods I use are my own. Others may use differentmethods, and those are probably as good as mine.I was taught most of my basic layout in the late 1950’s by a journeyman Millwright whowas dirty, smelled badly, and was constantly spitting tobacco juice on everything andeverybody near him. He was almost illiterate, and spoke like an illiterate, and cursedconstantly. His only saving grace was that he knew what there was to know about layout,and was willing to teach me. I will always be grateful to him for the knowledge heimparted to me. His teaching was the basis for me learning more advanced layout laterand earning my living doing layout work. A good portion of the pipe in the mammothCalifornia Water Project was laid out by me.Layout is accomplished using one or both basic methods: Centerline layout and/orbaseline layout.In centerline layout the center of the object is found and a line is drawn through it,usually vertically. A horizontal centerline is also often used in conjunction with thevertical line, or alone. Measurements are mostly made from these 2 lines.In baseline layout a base line is established, usually on or along one edge of the object.Another baseline can be established, usually at the end of the object, and this line isusually perpendicular to the first baseline. Measurements are mostly made from these 2lines.Notice that I said, “mostly made” from these lines. You can use any combination of baselines and center lines to get the job done. There are no hard and fast rules, justguidelines that you may or may not choose to follow.Lets take a look at a few simple layout methods.One of the first things I always tried to teach my apprentices was how to connect 2points with a straight line. Here they are points A and B.© www.OldToolsShop.com 2 January 14, 2006
    • The first thing to do is put your pencil point on one of the points as shown below.Bring the straightedge up to the pencil, and then use the pencil (or scribe) as a pivotpoint to move the straightedge to the second point.© www.OldToolsShop.com 3 January 14, 2006
    • Then draw the line.I have watched many apprentices trying to align the straightedge with both points at thesame time, without using the pencil for a pivot, and it is always a struggle. This way isquick and accurate.© www.OldToolsShop.com 4 January 14, 2006
    • II. Erecting a perpendicularHere is how I establish a square line at the end of a line without using a square. I learnedthis when I was laying out large steel plate. The ends of a large steel plate are rarelysquare, so a square line has to be established near the end. A framing square is not largeenough to draw a line all the way across a 12’ wide plate.You, of course, are not going to lay out any large plate using this method. And on mostof your work you will simply use a square. But you can impress people at parties byshowing them how to do this. It is pretty cool, and if you can do this you can say thatyou can do your entire layout without a square.Draw a line parallel to the side of the plate or other work.Set your compass or divider at any convenient distance. Usually this will be slightly lessthan half the distance across the plate. Swing an arc back across the line.© www.OldToolsShop.com 5 January 14, 2006
    • Here is the arc.Using the same setting on the compass, swing an arc to intersect the first arc.© www.OldToolsShop.com 6 January 14, 2006
    • Draw a line of indeterminate length through the 2 points. Indeterminate length meanslonger than necessary.Still using the same setting on the compass set off another point on the line.© www.OldToolsShop.com 7 January 14, 2006
    • Draw a line from the starting point up through the last point you established. This line issquare with the base line.PSI received a post from John Lederer showing me another way to erect a perpendicular atthe end of a line.Take a line A--B.Place your compass center above the line, and draw a circle that intersects the line at Aand at arbitrary point D. Now draw a line from D, through the center of the circle, till itintersects the circle again at point E. From E to A will be a line at right angles to A-B.© www.OldToolsShop.com 8 January 14, 2006
    • Just goes to show that you are never too old to learn something new.© www.OldToolsShop.com 9 January 14, 2006
    • III. Compasses and leadA word about compasses and lead. This probably should have been the first page of theseries.There are a great many different types of compasses and dividers. This picture showsone of my sets. The tool at the bottom right is for making very small circles.Lead comes in packages as shown above. It is available in a wide variety of hardness’s. Iuse HB which is pretty soft. I break off a piece about an inch long and put it in thecompass.© www.OldToolsShop.com 10 January 14, 2006
    • The convention is to sharpen the lead on the inside only. A piece of sandpaper on a flatsurface works great. It is necessary to sharpen the lead quite often for best results.If you always sharpen the lead on the inside you will always be able to come back to yourlayout after sharpening without having to readjust your compass. It is just a timesaver.© www.OldToolsShop.com 11 January 14, 2006
    • IV. Bisecting a lineOne of the most basic things in layout is bisecting a line. This simply is a way to find thecenter of a line, or anything else for that matter.On line A-B, set the compass to any distance greater than half the length of the line.Then using both A and B as centers, swing intersecting arcs above and below the line.A line drawn through the intersections will cut line A-B exactly in half.© www.OldToolsShop.com 12 January 14, 2006
    • V. Constructing a hexagonAnother basic layout procedure is laying out a hexagon.Draw a circle of the desired size and then draw a centerline. With the compass set to theradius of the circle, swing arcs both ways from both the top and bottom intersection.© www.OldToolsShop.com 13 January 14, 2006
    • Now connect all the points on the circle and the result is a hexagon.If the centerline is drawn vertically, then the hexagon will have a point on top. If thecenterline is drawn horizontally, then the hexagon will have a flat on top.© www.OldToolsShop.com 14 January 14, 2006
    • VI. Making equal partsAnother basic layout technique is dividing things into a number of equal parts. This canbe quite frustrating when done any other way.Let’s say that I want to divide this page into 6 equal parts. I ask myself what numberscan be divided by 6. And the answers are 6, 12, 18, 24, and so on. So now I check to seewhich of these numbers of inches will fit diagonally across the page. In this case 12inches works.So I divide 12 by 6 and get 2. That means that the equal divisions are 2” apart on themeasuring rule. So I mark every 2 inches.© www.OldToolsShop.com 15 January 14, 2006
    • Now I use a square to draw lines through each tick mark I made along the rule. Thus thepage is divided into 6 equal parts. No fuss, no muss, no bother! :>) (This is one of thefew times when a square is essential.)Ah, but what if the number of divisions is an odd number?Well, then you are just out of luck! No! Just kidding!If you want 5 equal spaces, just ask what numbers are divisible by 5. They are 5, 10, 15,and so on. Use the one that will fit across the page on a diagonal. If 10” will fit, then themarks will be 2” apart on the rule. If 15” will fit, then the marks will be 3” apart on therule. December, 2005The numbers don’t have to come out as even numbers. Here I want to divide the width ofthe page into 10 equal parts. But 20 inches will not fit in the distance across the page.© www.OldToolsShop.com 16 January 14, 2006
    • Oh, me! Oh, my! What will I do? I cannot spin the straw into gold!Oh, yes I can! 1 1/2 inches times 10 equals 15 inches, and 15 inches will fit diagonallyacross the page. Sometimes you have to put on the thinking cap, but this method alwaysworks.Measuring using metrics makes this method even easier.© www.OldToolsShop.com 17 January 14, 2006
    • VII. Constructing 4 or 8 parts of a circleThis one is a double feature because one leads into the other.A couple of years back I read in the Tips and Tricks page of a magazine a tip from areader who had discovered a very complicated way to lay out 12 equal spaces on a circle.He was using 2 framing squares to accomplish this. His ultimate reason for doing thiswas that he wanted to make a clock face.I was flabbergasted at the complexity of the process, so I wrote in with my solutionwhich is shown below. I received a check for $100 for my effort.Draw a circle of the required size and draw a centerline through it. Set your compass at adistance approximately the diameter of the circle.© www.OldToolsShop.com 18 January 14, 2006
    • Swing intersecting arcs from both intersections in both directions.Draw the line which is now the horizontal centerline. The circle has now been quartered.That is the first part of the solution.© www.OldToolsShop.com 19 January 14, 2006
    • Now set your compass to the radius of the circle. Swing arcs on both sides of eachintersection. The result is a circle divided into 12 equal parts.Logic tells you that if the radius can be used to lay out a 6-sided figure, that it must alsobe able to describe a 12-sided figure. So what would be the result if you were to dividethe circle into 8 parts?(Old trick for getting the apprentices to do something for themselves.)© www.OldToolsShop.com 20 January 14, 2006
    • VIII. Centering Stock for TurningThere are several devices for sale which are supposed to help you find the center of apiece of stock that you want to turn in your wood lathe. And they work just fine, as longas the stock is round or square.But usually the piece I want to turn is NOT square or round. It is likely to be almost anyshape. Like the piece shown below.So how do I find then center of irregularly shaped stock?I use a pair of dividers.I set the dividers to an approximate size and put one leg on the approximate center.© www.OldToolsShop.com 21 January 14, 2006
    • Then swing the divider to another side. Then check all 4 sides and adjust the divider untilyou have found the largest circle you can draw. Push the divider leg into the wood tomark the center.© www.OldToolsShop.com 22 January 14, 2006
    • Now draw the circle. I do this on both ends of the piece. If there is a defect or damage tothe wood I can often move the center on one end to avoid it, particularly on a handlewhere one end is going to be small anyway.Now I double check to make sure the stock is big enough for its intended use.© www.OldToolsShop.com 23 January 14, 2006
    • I use a center drill on the tailstock end where I normally use a live center. (A live centeris one which has bearings inside and spins with the stock. A dead center does not turn. )On the drive end of the wood the mounting method depends on how I intend to drive thepiece, but I always have to have at least a small, shallow hole drilled for reference.I bought and made several different devices for this, but in the end I found that mytrusty dividers are easier and more certain than any other method.As always, your mileage may vary.January, 2006© James D. Thompson© James D. Thompson© www.OldToolsShop.com 24 January 14, 2006