I have had remarkably good luck with plastic 3D printed barrels with the caveat that you have to undersize the hole and ream with a properly sized reamer. once you do that they work fine. I do tend to design it with enough extra material and infill such that there is not a continuous failure path from the outside of the inside so that a crack does not propagate outside to inside. It's also really cheap to make spares.
Its always something to hold the newborn in your hand for the first time *sniffles* Not trying to throw my plastic boat weight around or anything, but a small list of suggestions if you want them: The periodic cracking along the hull is 100% due to: excessive cooling fan use, too cold of a build chamber temp (or potential cold air drafts INTO chamber), too cold of a filament temp, combination of the 3. If you're printing in ABS I'd make sure you're around 245-260c hotend temp, at least 100F chamber temp, and 0% cooling fan unless necessary for bridging. ABS wants to be hot and cool as slowly as possible. I personally leave my printed items on the print bed, in the hot enclosure, until the print has naturally cooled to ambient. This personally pains me as I'm very impatient, but I've had parts warp after they've been taken off the printer. Nothing quite like a fresh 3d printed battleship section sitting on a workbench that suddenly makes a gunshot sound, scaring the shit out of you, and you walk over and it's got a massive crack in it where it didnt before. Your hull looks pretty susceptible to damage to me. The ribs seem very thin towards the centerline of the ship. Your subdeck also seems very thin in the same orientation (aka the deck hatch is quite large). For the ribs around where the ship has that bulge, I would drop the rib straight down from the more narrow profile at the top vs having the interior profile follow the exterior profile of the rib. Will make it a lot stronger. IMO I make the ribs at the top, where they meet the subdeck, at least as "wide" (towards the longitudinal centerline) as the subdeck.
Unless you're on a strict budget, it's probably worth at least finishing the current hull, just so you can test-fit things and learn a bunch of lessons from it. I generally agree with Will's suggestions though. I like nice thick sub-decks whenever practical. As long as it doesn't interfere with basic maintenance and repair operations, I want my sub-deck as thick as I can get. Same with ribs. Just about the only other thing I can think it might benefit from is a steeper slope on the water channel. Pocket battleships in Big Gun have a reputation for listing when the guns rotate broadside, due to the weight of the barrels. It's generally considered a feature since you don't need depression servos to depress the cannons. The down-side is that with standard water channels, you'll still get low spots that amplify whatever list you've already got.
Please feel free to swing your plastic dick around. Happy to learn from all recommendations! New heater arrived today, and I’m now able to maintain 110-111F all night long. Hard to tell if any cracks are occurring yet. Will come to know in a couple hours. I had Surcouf get shot up with 1/4” BBs some time back, and found that .11” with no infill seems to survive without damage. This is hardly scientific, and not a long term test either. I set the slicer to .15” skin on all sides. I figure I’ll give it a try and see, worse case I have some more printing to do. good point. Will upgrade this. I have also added a lot of fillets everywhere, especially around the rib/deck.
As long as the interface doesn’t change, each section is getting improvements vs the last. You can see the bow had no fillets, where the next section does. The third section is using a different manuf of ABS, to see if I get more consistency. I’ll continue to evolve it as it’s printing. Once I’m happy with enough of it, I’ll reprint it. thanks for the top on the rotate. Sounds like another reason to invest in making plastic barrels… I see I didn’t post anything on the water channel. I’ll have to do that. I’m using a stepped design, thinking it’ll keep more water at the pump & not sloshing about. Admittedly I would probably be better off with more slope, but then the steps won’t be as dramatic….
OK - The NATS videos looked fun, so I decided to try to modify the 'difficult to fix later' parts to be compliant with both rulesets. Most notably the windows. Can you guys double check the math here and LMK what would not be compliant with IRCWCC? Lastly, the stern seems pretty weak... is this really how it supposed to be for fast gun on a CA?
Stern is 45°. I make a centerline jig of a 90° V and mark approximately where it hits the hull at each rib. That said, yeah sterns are usually pretty thin.
Hi, a few suggestions for IRCWCC configuration Most build with 1/4" wide ribs vice 3/8", which allows more ribs and closer spacing. A good rule of thumb is stick around 3" spacing max, larger spacing can lead to more significant blowouts, a weaker hull, and more damage if rammed. For a cruiser, even window spacing works fine For the bottom of the windows along the main length, account for height of waterline tape (1/4"), so measure down 1.125 or 1.1875 from the projected waterline If you're building for the 51.33" model length, here are ribs and spacing with 2" bow impenetrable and 1" stern impenetrable, the boat would get 18.8 1/4" ribs or 12.5 3/8" ribs I would reduce the bow area to 1.94" to allow getting 19x 1/4" ribs, which can be spaced 2.42" center to center If you want 3/8" ribs, I would reduce bow area to 1.82" to allow 13x 3/8" ribs, spaced 3.47" center to center For the 50.83" length For 1/4" ribs, make bow area 1.87" for same 19 ribs, spaced 2.4" center to center For 3/8" ribs, make bow area 1.74" for same 13 ribs, spaced 3.44" center to center I would align one rib with the aft step, it is stronger and makes or cleaner sheeting. This will impact spacing referenced above slightly
@Kevin P. - Did I miss anything? Notes: - The bow/stern are evenly divisible because those windows will be closed for Big Gun. - I kinda want to remove the rib in the stern between the two 1.5" windows, and move it to the middle. However, I'm concerned that will leave the stern structurally weak.
Not sure that 1st rib location is legal. I believe it should be 1" back from the solid bow??? Thanks, Bob
Generally, 1/4" wide (when viewed from the ship's side profile) and then they go about anywhere from 3/8 -> 1/2" deep "into" the hull. Then they are heavily filleted/radius'd into the subdeck and bottom of the boat. The main exception to this rule is the aircraft carrier Wasp. Being a convoy ship it doesnt matter quite as much, so I did 3/8 ribs there. Another exception is on ships with deck steps, if I have some decimal point worth of rib left over, I will normally make the deck step rib wider. Being that we are computer modeling these boats and not working with standardized wood thicknesses, I can add the .2 of a single 1/4" rib that I have left over to the deck step rib for added strength, vs taking it off the bow impenetrable to get an extra rib. Many ways to skin this cat.
Looks good, the swampy fiberglass hull I have is deeper in the stern so there’s more meat to the hull there, when you add the rudder servo mount you can probably can gain some strength in that area
Update- Windows are compatible with IRCWCC and NTXBG. Fillets added for stress relief. Ribs have increased thickness to 3/8", uniformly across the hull. Rib width decreased to 1/4", for more ribs. Prop support is no 3/8" thick (not shown)
Or more, right? All ribs are .25” (except one) and all open spaces are now larger than 1.5”. That should cover me, no? (It’s semi-frustrating to mix big & fast fun rib rules…) I’ll re-post the updated window measurements in a bit…
