After the more or less ugly printouts of the front sections of the model, the printing of parts was passé again. It went back to the computer more intensively and the "redesign" began. As before, the first printouts were more than ugly, but you still held a piece of the model in your hands. The euphoria was unbroken and even increased a little by the will and the certainty that we could do it even better.
First of all, the method of connecting the individual sections had to be rethought. Since I wanted to be on the safe side, simply gluing the sections together wasn't really my thing.
I had an extremely bad experience on another model. Here a model, which consisted of 6 ABS deep-drawn half-shells, broke apart. The model was finished and completely painted. The first trip was imminent and I had it on my table and wanted to lift it up when the bow section broke off along with the adhesive tabs behind it. It was a 1.50m long model kit. It may be that I should have picked it up more carefully, but it was still a shock at first. I don't want to experience that again. So things just get more stable here.
When dividing up the print sections of the first attempt, I threw a lot overboard and came up with something more sensible instead. The principle of dividing the sections was also the same as in the first attempt - NO CROSS JOINTS UNDER ALL CIRCUMSTANCES.
On the first try, I not only divided lengthwise and crosswise, but also cut horizontally. This has made it significantly more difficult to comply with this principle. It also ensured that inaccuracies due to the pressure were recognized too late, which led to problems with the pass. I don't know anymore why I cut it so confusingly. That was gone in the new version. I only added vertical cuts and provided these cuts with the appropriate connecting flanges. Since my printer has a realistic print area of 190x190x180, I had to at least halve each section lengthways. In order to comply with the fugue principle again, I had to alternately halve and third each section. I also added two bulkheads or bulkheads to the hull. These are located between sections 4/5 and 8/9.
The reason for including the two bulkheads was simply the size of the ship and the weight distribution of the ballast in the ship. While the front part of the ship will receive little ballast, but also due to its shape can generate less lift, the rear part will receive motors, servos and co. and can thus contribute a bit to the ballast. The middle part is the part where the bottom and the outer walls are maximally straight. This means that batteries and ballast can go in here. The partition walls have the advantage of sealing off these parts from the drive parts.
I also took all the struts I had installed earlier out of the fuselage. This took a long time because I had to rework each frame individually. Sometimes I had to reconnect the polygons manually to generate a clean surface.
I made the frames a bit thicker. With the thickening of the frames, I also added holes in them to use the frames as connecting flanges for screwing the individual parts together. These were sealed by gluing and the screws took over the mechanical load.
I also made sure that the downward-facing surfaces were never aligned horizontally, if possible. I always provided these surfaces with bevels - if it was possible. This made the printing of support structures on the inside of the hull superfluous, as the deck above built itself up as a result of the gradually widening slope. The whole thing probably needs more material than the support structure itself, but at the same time a much more stable structure was created. In addition, it saved tedious rework.
For the printing order of the new sections, I followed the construction of real ships. Here the middle sections are built first and laid on the keel. I did the same now. Also under the aspect that sections 1-4 were still standing. I didn't have the heart to dispose of these, especially since section four was still being used as an experimental section. So I prepared to print Section 5. To do this, I cut out the individual section assemblies from the overall hull and arranged them next to the "whole" ship. With that, a lot of sections were ready for printing
At the same time as I started printing, I ordered 400 pan-head screws, washers, locknuts, and two-part epoxy. I deliberately made the holes that were intended for screwing in the frames smaller. After printing, each individual hole had to be drilled out accordingly. In this way, I was able to ensure a precise connection of the individual assemblies. In practice, this turned out to be a good solution, since the assemblies were held together with a perfect fit when glued. I coated the frames thickly with epoxy resin glue, put the screws through and put the parts together. The screws held everything in place well. The excess adhesive was pressed out of the joints by the subsequent screwing and the components were pressed together well. The excess adhesive could be spread over the seam. So the connection point was guaranteed waterproof. To prevent the parts from bulging upwards when gluing, I put them upside down to dry the glue and weighed them down with a weight.
The printer needed about 2 days per component. So that the printer prints the individual layers well and cleanly and the new layers connect well with each other, I throttled the print speed from 60mm/s to 35mm/s. The result was a significantly cleaner result. In addition, it was ensured that the layers run well together due to the slow pressure and are really waterproof. While the printer printed part by part, the ship continued to be expanded on the PC. This time I concentrated on the stern area of the ship.
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