I’ve started on the top of the sail. Since I quickly discovered that the light was wrong and that I needed to redo it, I started there. If you think adding stuff is hard, taking stuff off is way harder, at least with my knowledge of AutoCad. I decided the easiest way to do it would be to simply slice off the top on the current model and one I have from before I did anything to it. (It is always wise to save and rename so that you have the model at various stages along the way, in case you mess up, which I seem to do a lot.) I could then cut and paste the old one in place of the discarded wrongly modified one.
That’s what I did, but man it was a bee-otch. It didn’t want to slice, no matter what I did. After trying numerous ways of doing it, I finally tried just lowering the cut surface a fraction of a fraction of an inch and tada it worked. I figure since I was trying to cut on the original join line, where I joined the top and bottom originally, AutoCad didn’t like that, so it acted like a 2-year old and said, “NO!” Anyway, after that was done, I realized that I had to redo the vents at the top since I had cut them up. All said and done, the entire process to get a new top ready to go took 5 hours.
In pictures I have been graciously sent and those I have found myself, I have decided that the location and configuration of the snorkel induction mast was pretty much as shown on the Permit plans I have, so I’m going to go ahead and start adding it. There is one major difference between the mast on the two ships, that plays to my advantage, and that is that the ID light is on the top of the mast on Greenling and the other large sail ships. This may make it easier to deal with the light, but we shall see.
I’ve decide that on this stage I will give a detailed description of what I am doing as I am doing it. Here we go.
I’m fortunate to have been provided plans that contain good details of the snorkel induction mast.
I started by copying the cross-section at the top of the image above, importing it into AutoCad, and then scaling it and moving it where I wanted it. This I did totally by eyeball and guess work, using no known dimensions. The next step was to trace the outline using circles, ellipses, arcs and lines. The cross section I used shows the bottom side, which shows the outline of the top that matches the cutout in the sail (Red), the masts themselves (Magenta), and a support bracket (Blue). Each will be handled completely differently.
So that is where I am at this point. I’m going to start with the outline, which means that I need to do a couple of things. I need to both cut a recessed hole in the top of the sail in the shape of the outline and create the outer surface of the mast. This requires that I make a copy of the model and the line. I also turn off the plan layer at this point and delete the sail planes as they can always be recopied and pasted.
For some reason my drawing has a line that shoots off into space. It doesn’t seem to effect my model though, and I can create what appear to be good STL files that are needed to print on the stereolithograph (SLA) system I’m making the parts with so I haven’t been worried about it, but it’s just wrong.
Anyway the next step is to cut out the recessed area of the shape. We do this on the model we are going to keep.
I start by extruding the shape longer than I need it. In this case I have arbitrarily chosen to make the recess 0.1” deep, so I have drawn a line perpendicular to the surface at 0.1” from the bottom. I then move the 3-d shape and the line until the line just starts to disappear into the surface. The SUBTRACT Command is performed and Tada, we have our cut out.
Now, going to the copied part, we again extrude the shape, but this time what we are eventually trying to create is the shell top surface for the mast. For the time being I am going to make it 0.01” thick at the shallowest place. It will eventually be trimmed, but we will deal with that later. After we get the shape sunk into the sail, as before, we run the UNION Command and Tada we have a bicycle seat. I always wondered how they came up with that shape.
Seriously though, this piece (Modified a bit) will become the top of the mast. At this point I save the bicycle and traced lines into a new file “Part21-SnorkelInductor” and the sail into a new file.
I’ll get to the the snorkel later, but first, I want to finish the sail part, which means drilling the mast holes into the sail. To make sure they are stout, I’m drilling in 0.5”. The same procedure as before is used.
Since I am going to be running wires up the mast, I also need to drill a 0.04” diameter hole all the way through the sail.
The sail part is completed, so now it’s time to address the mast. This is when we will find out if lights are even feasible, but it will have to wait for the next post.