Merry Christmas All!
As a gift, on this special day, I’m going to show you how I scribe the depressions for the objects that I plan to make out of metal. For this demonstration, I will use the Access Hatches near the sail.
In this case I already had a hatch drawn, so I copied and pasted it so that it was aligned properly with the plans. To make sure that the object was above the surface I was going to project to I drew a polyline from the point on one of the cleats to a good reference point on the drawing.
The next step is to do a PROJECTGEOMETRY command to project the object onto the hull. I also project the center line of the object I added for reasons that will become evident shortly.
I don’t really need the original anymore, so I delete it and the unprojected lines. I then draw a line from the center of the projected center line perpendicular to the central axis of the ship, and then reorient the axis as shown.
I then recopy and paste the hatch to the center point of the projected hatch, and extrude it. If the surface was flat, I could simply move the lofted hatch 0.01” down into it, but since the hull is curved, it won’t be even. It will be deeper in the middle and shallow on the edges.
If you look at it from the front, you can see the curve. In fact, you can see that the curve is not constant. To cut this out of the bottom of the projected hatch, I draw polylines along both ends of the projected hatch (yellow). I then move each one out (away from the extruded hatch) just a hair.
This assures that when I loft the polylines to make a surface and move it up into the projected hatch, the surface is outside of the projected hatch everywhere.
That way when I slice the extruded hatch, in the next step, it will work. If all sides are not outside the object being sliced, it will not slice. After slicing I discard the lower piece and the surface.
Next I mark off a spot 0.01” up from the bottom, because that is how far I want the extruded hatch to protrude into the hull.
At this stage it is just a matter of moving the hatch and marker line down until the marker line just starts to disappear into the surface…
If there was just one hatch to do, I would simply subtract the hatch from the hull and I would have a nice depression with a uniform depth of 0.01”. But there is another one on the other side of the hull and to save work I simply mirror this one to the other side before subtracting. Then I get 2 depressions for the price of one. Gotta love symmetry!
So that’s it. That’s all there is to it. It’s a little more involved than just etching, but as you just saw, it’s not that difficult and it’s fun.
Oh, and thanks salmon!