thibaultron

I am not and expert, by any means. I just started using SketchUp about 3 months ago. There may be way better ways to do some of this. The content of these posts is what I have learned of its features, while doing these projects. I have been drafting for my own use for several decades, though.

I would say, just dropped. It would be to heavy to throw. I've never seen a picture, or any written material, on how they did it.

My next task is to redraw these frames, for a 1/64th scale skipjack. Even with the minimum print size limits, it will be near scale cross section. I could not even come close trying to fabricate them. I'm thinking of drawing up the trailboard base, and a railing that was misshapen on the kit. Buying material small enough for the railing has been elusive. I have a couple of kits that to save money, they do not include all the cannon, another plastic kit where one cannon was misshapen. Other small detail, barrels, fish traps. I saw one that was a whole bunch of blocks for a 1/200th scale modern warship, not sure which one. If you are really talented, scale crew figures. Not all of us can fabricate every detail, like the big guys, nor at my age, am I likely to have the time to develop such skills.

Part 09E Next I copied this frame, and flipped it to get a mirror image. Next I moved them together, for the finished frame sides. I think that next time, I will show how I connect a cylindrical part to a smaller rectangular type part. There are probably better ways, but this is what works for me. That should finish the operations that I think were good to use the frame to illustrate.

Part 09D Now I need to cut away the second stub of the frame. Because the cylinders of the lower leg of the frame were larger in diameter then the top ones, and I made a cutting plain joint where the upper cylinder met, the lower ones connected further back. I need to preserve this area, for my final frame master part. I used the same method of drawing a rectangle, intersecting the faces, and erasing the unneeded cylinder stub. In the picture below you can see the flat area of the lower cylinder that we need. It is the larger , nearly horizontal curved surface. After cleaning it up and removing the unneeded surfaces, we end up with this, as the end of the frame the new nose will be attached to. Next I made a copy of that good looking Follow Me nose extrusion, and pasted it in place. Wait a minute, what happened!! Remember that Follow Me creates intermediate surfaces that are perpendicular to the path? The surface we started with was not perpendicular to the downward curve of the path, only in the straight. Z axis, direction. So Follow me used the reference surface as the outline of the extrusion, but created a new starting face that was perpendicular to the first line of the downward curving path. It then deleted our original surface, leaving this gap. Looking at the two extruded noses from the side, you can see the difference between them on the right hand end (the area where it will connect to the frame) So despite having missing surfaces, the Upright Extruded nose is the correct one to use, in this case. The Upright Extrude draws all the intermediate faces parallel to the original one. After pasting this nose on the frame, and filling in the missing surfaces, we have this, as the part for one side of the finished frame.

Part 09C With the nose separated from the frame, and the centerlines saved, I erased the nose area. This last area had to be erased line by line, as it was too close to the rectangle, to select them together, and most of them contacted the rectangle, which means that you would have to select the rectangle, and any parts on the other side of it that were inside your selection box needed to capture the whole object, will also select . Finally a clean section to start over with. To save what I had here, I copied the whole frame, and worked on the copy. I will have to delete the rest (back) of the frame, when I finish the nose, so I can paste the nose onto the frame I copied from. This gives me the rectangle, with the cylinder outlines, and the old centerlines, to begin building a new nose. I drew in the straight lines between the circles to represent the eventual sides of the welded area. Sorry I forgot to make a graphic of this step. To get the outline as a single surface, I had to draw over all the lines that made up the outside outline I wanted. SketchUp should have already made this surface a separate one, but for some reason did not. This happens occasionally, and you have to fix it manually. Most likely some very small line was lost during the removal of all the frame parts. Rather than try to find it, redrawing was quicker. I then removed the outside rectangular surface, and the unneeded half of the new nose outline surface. In the above picture, I have also drawn lines connecting the original centerlines, in preparation to draw the line I will use for the extrusion path. I drew from the endpoints along the segments that make up one line to the matching endpoints on the other line. Next I drew a line along the midpoint of each cross line. This gives me a curved line that follows the downward curve of the centerlines, but is straight in the other directions, and perpendicular to the surface I want to extrude. I then erased the extra lines between the old centerlines, the centerline that does not touch the surface, and most of the other one, just leaving the section closest to the surface. I left this line segment to use as a reference point when I paste the nose back onto the rear frame section. The line down the center curves downward in what will be the vertical axis (Y axis), but is straight in the horizontal axis (Z axis). I used the “Shift” key feature of selecting, to select all the line segments of the extrusion path. Then I extruded two new noses, using both Follow Me, and the Upright Extruder. For Follow Me: you select the path, Follow Mw, and then the surface to be extruded. For Upright Extrude: you select the path and the surface, then Upright Extrude. The results from the Follow Me The results from the Upright Extruder. Keep both! The Follow Me extrusion looks like the winner, hands down, but you will see later why I saved both.

Part 09B I need both the centerlines of the lower rods, to use later to create the extrusion path for my new frame nose tips. To do this, I selected all the line segments that make up the centerline. When you need to select more than one object, you select the first, then hold down the “Shift” key, and continue selecting things, Each new object will be added to the previous ones that were selected. Clicking on one of the already selected objects, will remove it from the group you are building. I erased the end surfaces of these rods, for better viewing while doing the selecting. I selected the centerline, zooming along its length, through intervening surfaces, until I had passed the rectangle surface. I then made them a group, then locked the group from editing. Both operations are accessed by right clicking, while over the object, and selecting the operation from the pop-up menu. The group has been made, shown by the objects being displayed in blue, and the box that shows what overall area the group occupies also in blue. The red Group Box and objects, indicate that that group has been locked from editing. A group can be Unlocked, and returned to individual objects (Explode), using the same pop-up menu.

Part 09A Mirroring An Object I have a bone to pick with SketchUp. Most every other program I’ve ever used, has used some form of the word ”Mirror”, in the command to create a mirrored image of an object. Not SketchUp, they use “Flip”, which, to me, means turn over like a pancake, while keeping it the same. Their explanation of “Flip” sounds like they were trying to explain it, and the word Mirror was patented, and they had to avoid it like the plague. Just be aware. Making A New Nose For The Frame I will show all, or at least most, of the steps to create the new nose piece. There are lots of good techniques shown. Because of this it will be a very long post, but bear with me. In the end after writing this section, it has to be posted in 5 parts, A through E Now, last time I told you that I was throwing away all the work I did on the welded nose of the frame, and starting over. When I drew the frames, I started with the main body flat, and angled up the nose. I tried to make the tip curve in one direction, while remaining straight in the other. Well, my geometry calculations were off. When I went to paste the two sides, together, the tips curved away from each other, rather than running alongside. In order to get them to form a mass, they overlapped so much, the nose became only a single frame thickness wide, rather than two. Then it hit me, angle the frames and draw the curve on the flat horizontal surface! So that is what I did. This time instead of two cylinders I made the extrusion one solid piece. To do this I went back to the flat frames I’d started with, before angling the tips, rotated them and combined them, into the proper configuration. I used the straight frame sides, so that I could get the proper flat curve, for the nose. You will see what I mean later. Then I drew in a rectangle where the upper frame leg cylinders just met, to use as the line to cut the tips from the frame. Notice, above, that the larger diameter lower frame leg cylinders connect before the joint on the smaller upper ones. This will come into play later in this process. The upper and lower rods are a single cylinder were the joint will be. I cannot erase the left side on the tip end, without erasing the portion on the right. To solve this I needed to cut the frame cylinders where they meet the rectangle surface. This is what happens if I do not cut the surfaces that cross the rectangle’s surface. There is a function Edit – Intersect Faces. That can be used to do this. When you intersect the faces, all the flat surfaces that cross the rectangle, or any other type of surface you choose, are cut in two, forming two new surfaces. This acts like a saw, cutting through the part. First I selected the area I wanted to work on (including the rectangle). Then I choose the command. Now when I select a surface on the left hand side, it is unique, not part of a surface that spans the “cut”.

In Part 27, I said the drawing of the dredge frame showed a tapered point. I was incorrect, what I thought was a tapered point, is in fact the ring. I've corrected the post.

Most times it's not that bad. I had to create some graphics for the posts, and in this case, just deleted a section, to use as an example. If it had not been as fiddley as it turned out to be, you would have gotten as intense an example. It just happened to come out like that, so I went with it. It turned out to have quite a lot of good operations to be done.

Part 08B You also have to check for missing surfaces, at junctions of shapes. The pictures below, are the interior of one of the cylinders. I zoomed through the end wall and scrolled along its length, checking for problems. And found some. I managed to fix most of them, until I got to the bottom of the large lower triangular area. When I was filling this area, from the angle I was looking at (a view I could not get back after finding the problem), it looked like the area was closed properly. When I panned away, however, I saw that I had messed up. Instead of a flat surface, I had created a pocket by connecting to a lower surface, that looked like it was flush, at that viewing angle. I deleted this and by changing the view, I was able to connect to the right lines. Sometimes the endpoints are not terribly visible. In the picture below, that endpoint at the base of the triangle, was only shown when I ran the cursor along the bottom line. In the next part, I’ll explain why I threw all this careful work away, and used a different method to simulate the welded front of the dredge. This is why I save to new file name versions frequently (Dredge Frame _45, Dredge Frame_46, etc.), as I talked about in a previous part.

Part 08A Some times when you go to fill in a space or missing section, you cannot see all the endpoints. They may be very near one another, so that you cannot distinguish between them, or otherwise hidden. Sometimes SketchUp should fill, but does not. When this happens, you have to resort to creating many triangles, sometimes to minute proportions. I will use the example from the last post, but intentionally make a mistake that forces me to use this method. Here I’ve drawn the upper line to an edge rather than the endpoint. This creates the situation I talked about. I will ignore the endpoint that I should have connected to. I continue to draw in triangles. I generally try to use a go from one corner, to the midpoint of the other line for the second end of the line. When I drew that last line to the right (see below), SketchUp filled in the rest of the space (see below). This happen often, and you can just be thankful that you are done. Don’t look a gift horse in the mouth. The last line drawn. The highlighted area, is what SketchUp finished filling in, when the line was drawn. Remember from the last post that the ends of the cylinders in the example, did not line up. So all the lines here enclose surfaces that differ in orientation, and cannot be deleted, without also deleting some of the surfaces. However if they had formed surfaces that are in line (entire surface should all be one flat plain), you can delete the extra lines, to clarify the drawing. To show you this, I will use example from the first two pictures of Part 7, where the ends did line up, and the entire end should be a flat surface. We can erase most of these lines. But, be careful. Not all the lines can be erased! The lines that form the circular rim of the cylinders cannot be erased, without losing the adjoining cylinder surface. If I delete the highlighted line above, I will delete a surface, on the cylinder. This is the end with most of the lines removed. Even here I had to leave the line (actually 2 lines very close together) inside the left cylinder end, or the upper or lower surface was also deleted. Check frequently!

Thank you for the suggestion.

Part 07B Now on to filling in along the length of the cylinders. A few things to note. Notice that the lines running along the length of the darker cylinder are dashed. SketchUp many times treats these as not lines when it comes to doing this filling in. You can see that in the area of the closely spaced surfaces, I have drawn a line over the edges along the length. Without the new lines, SketchUp would not create the surfaces. Yet on the longer sections, it did. The lines on the lighter cylinder are solid, and I did not have to draw over them. I do not know why SketchUp uses the two different types of lines, but be aware of the difference. In the picture below I have filled in more of the area. I drew triangle between the narrow surfaces, but ran out of matching ones on the dark cylinder, I attached the rest to the other end of the larger space. I could have done the same at the left, by continuing to connect to the left end point, as in the second picture. . I continued filling in the surfaces, until I ran into a spot where I had to change gears. As I went along I reached a point where the two cylinders had changed level, and I had to change the surfaces to another lower edge. Look at the right hand line, in the picture below. As you can see it dips below the surface of the lighter cylinder, I had to go down to the next line to eliminate the interference. I also drew a line from here to the upper line to connect the space. I then continued using the new spacing. Looking at the picture above, you can see extra lines on that first panel, where I change which lines were being used. These indicate that there is still some minor inference, but without a lot of effort to find the exact right spot for the line at the right side of the surfaces, this is good enough for our purposes. It will not hurt the finished printed part. More tips on filling in surfaces in the next post.

Part 07A Now I will discuss filling in missing surfaces, and filling in new surfaces between parts. There are two problems that may be causing the missing surfaces. The surface is really flat, but the program did not fill it, or the surface is not flat, and should be made up of two or more flat surfaces. Below is an example of both. The white end of the part is the first type, the horizontal surface is the later. Both can be fixed the same way, by drawing in triangles. By definition – any triangular shape encloses a flat surface, take my word for it. So the solution is to draw in triangles. Connect the end points to each other with triangles. The end shown has one end of the cylinder too long and in the next shot I will remove part of it to show the flat surface. What is an Endpoint? SketchUp endpoints are the end of lines making up an object. Look at the rim of the cylinders above. It is made up of a series of straight lines, that form a circular shape. The end of each individual line is an endpoint. When you are drawing lines, arcs, circles, etc. SketchUp will indicate when you are over, or very near an endpoint. If you click, it will snap to that point and set that is a point on your line. Then as you continue each time you are near and endpoint the program will show that to you. SketchUp will also show when you are near the middle “Midpoint” of a line. Notice that the Midpoint is not the middle of the line from one side to the other. Because the two long lines cross, (when on the same plain), SketchUp breaks them into four individual lines. So the Midpoint shown is the middle of that new individual line, of the four. SketchUp will also show you if you are on a line, but somewhere other than the above two points. This is indicated by “On Edge”. These aids will only be shown while you are drawing something. During normal mouse movement in other operations, they will not be displayed. These indicators are vital as you build your part. Navigation in 3D space takes learning, and a lot of patience. Unlike 2D drafting, where everything is on a single plain, and where your mouse is, is actually where you are. In 3D space your mouse may actually be touching something in the far distance. When you draw a line, you may think you are drawing a horizontal line, when it is actual also going away from you, so it goes in an entirely different direction, and may be connected to a point far behind, or in front of the place you want it to go. Frequent checking is required. This line looks to be horizontal from this view. But when we scroll to a view from a different angle, we can see that it really runs down along the face of the side of the cylinder. Navigation in 3D space takes some getting used to, and can be quite frustrating at times, but SketchUp is not unique in this problem. Maybe someday we will have 3D holographic displays, but while we still have flat screen monitors, it will be a problem. For the discussion of filling in a surface, I will use the following drawing. The task is to draw a surface across the two ends, like we had glued a sheet of paper over them, and to connect them along their length. On the dredge frame, this represents the ends being welded together. I will start with connecting the ends. You will notice a difference in the finished product from the example above. In the picture above, the end is truly flat, as in the first and second pictures in this post. To save time and effort on my part, I will be connecting the ends, but they are not on the same plain. The darker cylinder is slightly longer, in this earlier version. So what I will end up with is a series of flat surfaces that fill in the area, but are not all in a line. In the second picture I show where, with a flat surface, the end of the cylinder can be erased, to bring the end truly flat. Is does show that you can connect parts that do not line up. I will fill in the space by drawing in a series of triangles, until I have connected the area I wish to fill. When drawing the triangular surfaces The best way to get a good surface is to draw the lines so they end on an endpoint. I will show later what can happen when other points are chosen. To start a line is drawn for the bottom of the area to be filled in. Normally I would draw in the line for the top of the area, in the hopes that they might line up, and I would be finished. In this case I tried that, and failed, so I erased the line, and will fill the area , piece by piece, to show you the process. Remember connect endpoints. I drew in a line from an end of the line for the bottom of the area up across to the endpoint just up from the other end of the line. Right to left, in this case. I then starting from the left end, where I had just finished, I drew a new line up to the next endpoint on the right. Continuing in this fashion, I continued to fill in spaces.

I though I might be going into too much detail.

Is this tutorial going in the direction you guys want, or would you like me to take a different course?

Part 27 The wood for the mast and boom have not arrived yet, but I finished the drawing for the dredge frame in 1/32nd scale. I’ll order a set at the beginning of the month. This is the frame drawing from the Willie Bennett plans. It has decent detail, but not as much as I think it should. This is from an old stereographic print Of course there is the dredge in the hand winch photos. And even a picture of a dredge that was on sale on EBay! Wish I could have bought that one. This is the print from the Fisheries' book, that I showed in a previous post. I bought a book “Images of America Maryland’s Skipjacks” that had several photos showing a dredge. After looking at these pictures, I decided to draw a more complex frame, using some of the details from the pictures. What I got from these pictures, is that there were many different designs, and just about anything resembling a dredge would be correct on a model. In the first book picture, showing frames at the docks in Baltimore, some of the dredges have bottom braces, and some don’t. I particularly like eyelet and hook arrangement for the bottom brace on this last picture, and decided to use this on my dredge. The dredge in the winch photo also has a hook and eye arrangement, though of a different design. Having the dredger bar bolted to the frame, then welded to the bottom brace, making removal impossible, also did not make sense to me. What I settled on was a frame like the Bennett drawing, but a bottom brace like the last picture above. The front of the dredge in the Bennett drawing is a blunt end, with a ring. I made the front end a mass of the upper and lower bars welded together, with a blunt point which is the common configuration in the pictures. I will still use a ring, rather than a welded eye for the cable connection. This is my completed dredge frame drawing in 1/32nd. I have to redraw almost all of it for the 1/64th one, as I will have to make the diameters of the bars larger, to meet the printing requirements, though not a whole lot. The 5/8” upper frame bars will only have to be made a little large than ¾”. I want to increase the size of the rest of the bars, to keep the proportions correct. Close ups of the bolt area and the nose. This is a screen shot from the Shapeways site showing that everything is acceptable (all green, no yellow, or red). The only thing that worries me is that the model may sag during the printing process. If that happens I will have to break it up into sub-assemblies.

Part 06B Next is a bit more complex a path. One thing I will have to tell you here is that the surface is not perpendicular to the path, it is angled off somewhat in the vertical direction. You can see above that the path angles up, but the surface is vertical, not angled back somewhat to be perpendicular to the path. SketchUp should as you draw a line, snap when you are close to perpendicular to the line, and tell you so. With this complex line there were too many small lines for it to be able to do this, and I had to settle for vertical lines to make the cross. We are not making parts for NASA, so the slightly oval shape of the final solid will not be a problem for us. Anyway, back extruding. Follow Me makes this shape. From a higher viewing angle it looks like this. Using Eneroth gets this shape. The shape is distorted at the sharper curves. The distortion shown is a depression forming a sunken area. So if you can, use the Follow Me operation, and ways check for missing surfaces. To fill in missing areas may take some work. It could be as simple as drawing over an existing line like in Part 5, or it may take a lot of lines to convince SketchUp to fix the surface. The next part will discuss ways to fill these missing panels.

Part 06A As you can see from the label, this will again be a two part post. There are three main ways to extrude a flat surface into a 3D object. The ones that come with SketchUp are: “Push/Pull”, and “Follow Me”. The third is from one of the add on plug-ins “Eneroth Upright Extruder”. They operate in different ways to extrude the surface. What is extrude? Think of the press Play-Doh makes were you force the Play-Doh through a shaped hole to make a column with the cross-section of the shape in the Doh. The three tools above operate in a similar fashion taking the surface and extending it along the path you choose. In this part I will talk about the differences in the way they work. While “Follow Me” and the Eneroth extruder work in a similar fashion, there are differences in what you end up with. The “Follow Me” more frequently gives you a 3D shape that is truer in cross-section than the Enenroth, though the Eneroth will sometimes times work, where the “Follow Me” will tell you it cannot do the operation, and visa-versa. The Eneroth will also many times give you a better shape than the Follow Me” for complex paths. I generally try both, and pick the one that looks better. The difference between the two are how they extrude the surface. “Follow Me creates a new face, at the junction of the lines, perpendicular to the line(s) that are the path allowing the surface to angle up or down with the path, if it is angled. Follow Me then connects the faces The Eneroth always keeps the face vertical, so some distortion of the shape may occur. After creating all the new faces, both then connect them with surfaces to fill in the shape, and delete the interior faces, leaving you with a hollow solid.. Note: that sometimes both commands will leave the inside faces, giving you a series of chambers inside the shape. These can sometimes act as the hidden interior walls I talked about in the previous post, when you go to export the file for the 3D printing. This happened to me on a ring I made as part of an eyelet for the dredge frame. I would export the file and the ring would show up, the another time, it was missing. Deleting the interior surfaces solved the problem. It took awhile to find this. Both “Follow Me” , and the Eneroth one will sometimes leave a shape with missing surfaces, that you have to manually fill. Let’s start with a simple flat curved path. The Push/Pull command will only extrude the surface in a straight line, not what we want for this. The Follow Me creates a solid like the one below. Each of the joints where the solid has a joint, are where the lines changed angles to make the curved path. The Eneroth extruder creates a solid like the one below. You can see that the outside shape of the solid has many more surface segments, giving it a slightly more rounded shape. These two solids come out looking similar after the extrude. Next we will see what happens if the path is angled up. Using Follow Me creates the shape below. The above is how it looks with the Hidden Geometry turned off, this is how it looks without the outlines of the surfaces shown. This is what your printed part would look like. Now to see the difference in the Follow Me and Eneroth operations see the two shapes created. The Follow Me shape. The Eneroth shape. Notice how the joints are vertical in the Eneroth shape, not following the slope of the path, as in the Follow Me. As I said above I generally try both ways, and choose the one that either is the only one of the two that worked (obviously), or the one that produced the better shape. Next we will create a hooked shape by extending one end of the shape using Push/Pull, to see what happens in each type of shape we made. Extending the Follow Me does this. While the Eneroth looks like this. Generally, but not always the Follow Me comes closer to what you want. One thing to note is that all these commands will only extrude a flat surface, not a curved section, which is really made up of several surfaces.

Part 05 B There is an option in the “View” menu – “Hidden Geometry”. This shows the lines that the Part is created from. You can see the lines that run the length of the cylinder, which is really a circle of flat walls, the boundary of which are the dashed lines. If I erase one of these walls you can see what I mean. By the way, the cylinder is no longer a solid part. It is just a collection of walls. To be a solid a part must be closed. This also happened when I deleted the top of the end to show you what was happening. To make the cylinder whole again, we need to restore the walls. Draw a line over one of the existing lines around the open area. This may also restore the top of the end, if not you can do the same to it by, either drawing a line over the line we drew earlier across the end, or by drawing from any point on the rim to any other point along the rim. With the end restored, this way it is now three surfaces, just delete the two lines to make it one surface. If you do this to some part on your drawing, to clean it up visually say, and some surfaces disappear, what you are seeing is not one flat surface but one made up of two or more surfaces, that are slightly different in orientation, like the side of the cylinder. Remember to check your whole drawing regularly for accidently deleted walls. Next time I will show some of the ways you can extrude a part, after that we will get back to the winch drawing.

Going From A 2D drawing To A 3D Printed Part Part 05A I’m going, in this part, to show how one of these interior walls can accidentally be created. We’ll start by making a cylinder, that follows a line. Here is the line with four lines perpendicular to it, all the same length, and at 90 degrees to each other. Basically a cross. There are several ways to draw a circle, centered on a line. The easiest one is to use the “Circle” command that comes with SketchUp. You can see the icon for it at the left of the screen shot below. The trouble with using this, is SketchUp will pick one of the axis to be the plain the circle is going to be drawn in, and generally, it will be the wrong one. It most times will pick a circle that is in the XY plain. The pictures below illustrates what I mean. If you are drawing the circle on an existing surface that is parallel to one of the X,Y, or Z axis, it will generally choose correctly, but not always. These are pictures of drawing a circle with this command. This was the only axis that it would allow me to draw it on. To continue with showing how an interior wall can be created. We need a vertical circle. The way I use is to draw a cross on the line, then draw the circle using the “Draw – 3 Point Arc” command. I connect three of the legs, to make half the circle, then another for the other half. If your line is angled, this is the only way I know of to draw the circle, perpendicular to the angled line. The process is shown below. Line with cross drawn. Same as above, just looking at it a little closer. Top half of the circle drawn. Drawing the lower half of the circle. Note that SketchUp will tell you that this is a half circle. If the lines in the cross are not at 90 degrees from each other, or at least the same length in the same plain, the circle will not be correct, and you will not get this message. You can look for this to check your work. There are other ways you can still use to draw a half circle, but this is a good check. The circle shown above, is presently four different surfaces, one in each quarter of the circle, because the lines of the cross separate each from the other. We need to make it one surface, by erasing the lines. SketchUp will then combine them into one piece. Here are the lines erased, but this can cause a problem. For this example, I only want to create a cylinder to the right of the circle. With all the lines gone, the center line is all one piece, and the following steps would draw the cylinder in both directions, so we need to put one of the lines back. With this line touching the centerline, SketchUp breaks the line into two different lines, at the meeting point. Now you see only the right side of the line is selected. Now we will draw the cylinder by extruding the circle to a 3D shape, using the “Follow Me” command. Now let’s say we need to add something to the right hand side, centered on the circle. We need to find that center, so we draw a line down the center. By doing this we have completed a rectangle inside the cylinder, that SketchUp makes a wall/surface from. The sides are the one line we left on the circle, the centerline, part of the new line, and one of the lines that run along the cylinder. Remember it is really made up of several flat surfaces, and hollow inside. With part of the end removed, you can see the wall. See Part 5B for the rest of the post.

Found the problem, too many pictures for one post. I thought the limit was 16, guess its 15.

There seems to be something wrong with the site. It says that I've posted more pictures than I am allowed to. This is strange, as I have seen many logs of extreme length. I'll try again later.

Yes scale models can be made. I saw a video from a car show, where one of the car companies had a huge 3D printer, printing out a full size car body. A finished body was then sent over to a robot, that sanded the body to remove the ridges left from the 3D printing process.