thibaultron

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!

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.
 

 

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.

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.

I'm so sorry for your loss and the stress that you and your family are undergoing. I trust that your sister-in-law's surgery goes well ask without complication. We can wait, as family and  friends are far more important.

As if I had not been slow enough on this log the last month, due to a friends death, and other family emergencies, it will probably be at least a couple weeks until I can get back to working on my model.
 
The other problem I'm having, is that with my expansion of the shop, the heater can no longer keep up, and it has been a high of about 50 F in there. Next month I'm going to install more insulation.

Ron, that doesn't sound like good news but I hope it all turns out well.   Take care.

I will probably be away for a week or too, due to family emergencies. See you when I get back.

So sorry to read that, Ron. I hope all turns out better than expected. Best wishes until your return.

I am finding out that the drawing for a 3d printer can be very hard on ones nerves.  I remember when we got our waterjet at work ad the ork our supervisor had to do to learn how to draw for the program. and he was just doing a 2d drawing.  I The home office had an extra CNC lathe for maching plastic ad almost sent it to us.  He almost had a heart attack.
David B

Part 10C
 
The back side was treated as with the others. On this side I cut away less of the curved area, As this side already slopes more toward the tab's surface.
 

 

 

 

 
 
The last side was then connected. Note that I again redrew the corner to include the full length of the adjoined curved surface.
 

 

 

 

 
These are pictures of the completed end.
 

 

 
Looking at the end, I decided that the slope of the first side was to sharp, so I redrew it going one line of surfaces back.
 

 
Next time back to the winch drawings, and the point I had originally planned to start, before I decided that I needed to cover the previous material first.
 

Part 10B
 
Next I took a face, and decided where the best line was to start the transition on the side. I started with the hump of the curve, as that will be the side with the most difference between the curved and flat surfaces.
 
I removed the two surfaces that touched the flat, at the point I wanted to start.
 

 
Then I drew a line between the two intersections, to use as the end of the transition slope.
 

 
Next I erased the surfaces between the ones I just deleted.
 

 
I erased the orphaned end of the bar, and extended the line around the entire tab. I will use this as the ending of the slopes around the finished transitions. If a blacksmith flattened the end, this would be how he treated all the sides, making them line up at the start of the flat area. At least, that’s how I would.
 

 

 

 
I then connected the corners of the curved surfaces, to the edge of the line on that side. This ties the curves to the flat, and will serve as two of the corners of the transitions. When I am done the top section of the tab will have been erased, above the bottom of the four transition slopes.
 

 
I connected the endpoints of the curves to the line, forming the outline of the transition.
 

 
Using the triangle method I filled in the slope.
 

 
Starting on the second side, I erased one row above the first, I erased one row above that of the first side, as the curved surfaces were closer to the flat surface of the tab. I also erased the upper area of the tab.
 
On the left you can see that there is a corner left on the last curved surface, of that first side.
 

 

 
 
I erased the sloped border line, and redrew it to include the full length of that surface.
 

 
I continued in the same manner as for the first side, to fill in this one.
 

 

Part 10A
 
Selecting an Object Hint
 
In the tutorial below, I have to erase a fair amount of surfaces. To make it go quicker, there is a trick. If, for example you want to erase two adjoining surfaces, select the line that separates them. It and both surfaces will be erased. Without that line the surfaces now have an open side, and cease to exist.
 
If the surface has one side that is a dashed line, select it, and many times the surface and the solid line will also be erased. I’m not sure why the solid line is erased, but it is.
 

 

 
Transitioning from a Round Object, to a Flat Sided One
 
This is how I did the transitions from the round bar stock of the frame, to flat sided shapes that represent the end that is bolted to the others. There may be better ways I don’t know, but I chose this method, it was simple and straight forward.
 
On this frame the ends of the bars are flattened and bolted together. I figured that in the 1890s, this would be done by a blacksmith. I assumed that he would flatten the ends, making them a little wider. This would not leave smooth machine formed modern looking transitions. This allows me to justify my crude transitions. :-). In 1/32nd and 1/64th scales, they will be all but invisible any way.
 
Here is a finished transitions on some of the smaller bars.
 

 

 
For this part of the tutorial, I will be making the transition between the 1 ¼” diameter dredge bar, to its tab.
 
The next three pictures show the starting point. The round bar overlaps the flat sided tab.
 

 

 

 
In the picture below, I’ve erased all the other parts, to give us a better view of the operations.
 

 

Decided to scrap the dowels for the mast and boom. I'm taking the advice and will try making them from square stock. Today I bought some basswood square stock to practice on, and ordered boxwood strips, for the final parts.
 
Been working on the dredge frame 3D plans, I'm fairly sure I may be able to print them as one piece in 1/32, and likely in 1/64th. I'm up to version 136 in the drawings. Probably be at 200 or so when done. I save increamently as I go. I've restarted 3 or 4 times as I've progressed, and come up with better ways to draw them.

Frank, thanks for the information and the picture. .............feathermerchant

Here's what my Waterman friend says about the question:  "There was a piece of guard to protect the side. There was also a steel ½ round approximately 1 inch wide by maybe10-15 long nailed at the spot where the chine and bottom met. Yes the updown roller would help keep the dredge off the boat as it was wound in but even more important it helped make the cable last."
 
Hope this answers the question.
 
He also gave me some information on the use of the drudge (his term for it):
 
 "He would either alone or both guys together in one motion would kind of push and throw at the same time roll the dredge over the roller. As the nose of the dredge (and btw it’s really a drudge J ) approached the roller one guy would push the nose downward while still pushing out to get the bag to flip up (see pic). This way the bag does not get caught in the teeth and you get no catch in the drudge, in which case you had a very unhappy captain (it was called throwing her fowl)."
 

Part 10A
 
Selecting an Object Hint
 
In the tutorial below, I have to erase a fair amount of surfaces. To make it go quicker, there is a trick. If, for example you want to erase two adjoining surfaces, select the line that separates them. It and both surfaces will be erased. Without that line the surfaces now have an open side, and cease to exist.
 
If the surface has one side that is a dashed line, select it, and many times the surface and the solid line will also be erased. I’m not sure why the solid line is erased, but it is.
 

 

 
Transitioning from a Round Object, to a Flat Sided One
 
This is how I did the transitions from the round bar stock of the frame, to flat sided shapes that represent the end that is bolted to the others. There may be better ways I don’t know, but I chose this method, it was simple and straight forward.
 
On this frame the ends of the bars are flattened and bolted together. I figured that in the 1890s, this would be done by a blacksmith. I assumed that he would flatten the ends, making them a little wider. This would not leave smooth machine formed modern looking transitions. This allows me to justify my crude transitions. :-). In 1/32nd and 1/64th scales, they will be all but invisible any way.
 
Here is a finished transitions on some of the smaller bars.
 

 

 
For this part of the tutorial, I will be making the transition between the 1 ¼” diameter dredge bar, to its tab.
 
The next three pictures show the starting point. The round bar overlaps the flat sided tab.
 

 

 

 
In the picture below, I’ve erased all the other parts, to give us a better view of the operations.
 

 

Nice model! I moved to Baltimore in 1977, and followed the Pride's journeys and visited her many times, when she was in port.

Hi Everyone - I'm working on the Niagara masts and have a few questions. This is really the first time I've looked at the mast plans closely.
 
1. Plans show quite a few chocks (masts & spars) most are less than 1/16" tall. I'm debating whether to use wood (easy but would damage easy) or brass cut from strip (would take longer but more durable)
 
 
2. Plans show sheaves in the masts - even one in the skinny end of the top gallant. At 1:64 scale trying to do something like that ain't gonna be easy. Suggestions?
 
 
3. I've got the main top assembled, cheeks on the main mast and was going to glue down the top. The main cheeks provide an 11* angle. The main is also tapered. How in the heck do you get the top horizontally squared with the mast? I was just going to "eyeball it" but I'm afraid even a slight variance will come back to bite me when I start the rigging.
 
 
4. The plans keep using "P/S" i.e.  chock P/S, cleat P/S .  What is P/S?
 
 
I also made a jig that helped me with cutting octagonal sides on a tapered stick. There are plenty of pix showing a 90* notch taken out of a long piece of wood. You drop your square (maybe round too) stick in and file the side facing up. My problem with that is I would need quite a few different sized notches for the various sized masts and spars and a tapered stick presents some problems. Below are some pix of my solution. Maybe everyone does this but I SWEAR I didn't purposely steal it. It has helped a lot as I have all my masts shaped using just the 2 jigs - one small & one large.
 
All you do is tighten or loosen the nuts on the ends so one end is a little wider than the other. You put the fat end of your tapered stick in the wide end of the jig. With a little adjustment, the side of the stick facing up will be parallel with the top of the jig. Then you can file or sand from one end to the other. The springs in between the wood pieces of the jig keep them from moving once they are adjusted.  Not scientific or calibrated. You still must adjust by eye, but I do a lot of that anyway. You can see in a few of the pix, I get nice sharp edges.
 
 

in the drawing that Cap'n'Bob included you can see a piece of molding on the side of the hull just below the dredge rollers, called a "guard" that you referred to, on the Willie Bennett plans.  My assumption is that this, combined with the sharp incline of the hull, helped protect the hull from the dredge.  I have a good friend who actually worked on skipjacks (he's still a Chesapeake waterman) and I've sent the question to him.  I'll post his answer when I get it.

I am just trying to help others who can use this info. I think of this as another type of build log.

I am just trying to help others who can use this info. I think of this as another type of build log.