The Ship Model Forum

Hi all

I have been working on a solid hull (wood) RC version of 1/200 Tirpitz for about 30 years. The hull is done, but I could never find a system that I could stick with for the superstructure, I tried card, wood, etched brass, plastic etc and while they all have their good points, they also have their disadvantages.

I also tried 3D printing.

I have been doing 3D printing since it first came out mainly for work related stuff. These early FDM printers were extremely useful, but the print quality left something to be desired. It didn't go well for the Tirpitz.

Recently I upgraded my old Prusa I3 to the semi latest Prusa MK3S with the bears extended Z axis. For work stuff, its fantastic so I looked at modelling with it again.

I found a cool looking Tie Fighter and printed it out. At the time, I was mainly using PETG.



Not bad (shocking is probably a better word in hindsight) then I played around with PLA (which I haven't used at all in the past due to its mechanical properties).



Hmmm, I think I should try this again...with the Tirpitz!

So,

I printed some superstructure parts for the wooden hull which came out OK, but trying to get detail to print on the side of the superstructure (Ladders, Portholes etc) didn't go well.

Then I tried printing just a basic structure and laminating the details onto it.

Here is an example of one of the funnel hangars of Tirpitz:



This works reasonably well, the laminate is only 0.5mm thick (I might even try thinner in future)

For 3D design work I used 123 Design (Abandoned Autodesk Project that was eventually merged into Fusion 360) in the past and it soon became apparent that this was not really up to the task.

So first step was to start using Fusion instead. I tried it out and found it was not a big learning curve from 123D to get what I wanted from it. Having said that, there was still a bit of a learning curve and I am only just now (2 months on) starting to get good results from it.

I also considered that just doing the deck for the existing project was not much good for someone who did not just happen to have a hull lying around. So as part of the learning curve, I included the hull files as well.

The hull is not as good as I would like, but I also have to balance out that I don't want to spend 2 years designing it.

The Bears extended MK3S has a print volume of 25 X 21 X 31 and at 1.27 metres, I can't print the hull in one piece, Must admit, that CR30 is looking good!

This means, the hull has to be printed in sections and, as I hate supports, created the sections to keep supports to a minimum.

Joining the sections, without a built in part locking system (which usually means supports) is a bit tricky, so I thought I would try joining them with an "interface" part. This allows the parts to be joined with sufficient surface area to keep it watertight (if you want to make it an RC version) and also provide enough rigidity to keep the sides from accidentally being crushed in while handling the model.

As an example, between the Hull Piece 1 and Hull Piece 2:



Becomes



I'm also suspicious of layer separation in 3D printed parts in the Z plane. I added capacity for additional strengthening in the form of a 3 X 20 mm length of flat, There is also provision also for longitudinal strengtheners at deck level.

So, the steel keel support is a flat steel bar 3 X 20 mm, 1055 mm long. The angled cut-out at the rear is to accommodate the centre prop shaft and housing for an RC version.



BTW, in case you were wondering, I have been at this for around 2 months now. Currently the model looks like this:





It is currently held together by gravity, friction and 2 pieces of masking tape so I really need to start putting it together, hence this build log.

As it is put together, errors will be encountered on the files and I will correct them along the way. By the time this build log gets to the above stage they should be OK to print as is.

What I am going to do with these files is at this stage unknown. Hopefully a solution will come along in due course.

I've built two ships wholly by resin printing. About the longest hull section I could print was about 9" so a 1:144 DE or DMS requited 4 parts. I joined the hull sections with epoxy, which seemed plenty strong. No internal bracing was necessary, but the deck is attached, adding considerable rigidity. My construction methods would not be useable for RC, requiring an open deck. A number of bulkheads, with necessary openings for machinery might do. Alternatively the printed hull could be used as a plug for the standard method of making RC hulls. The closest I came to doing RC was my 1:192 Missouri, which came to nothing RC wise after my ex wife to be tossed out all the RC stuff.

Lots of Bismarcks out three and lot of info. Even detailed info on her entire war career! So good luck and have fun along the way!

Cheers: Tom

That's looking really nice! I've been working on 1/144 scale RC hulls with my FDM printers and have had to work through some of the same issues you mentioned. So far, I have a Liberty ship, and an pair of Invincibles. I'm debating what to try next and thinking of trying Bismarck. I'm curious what software you used to design the hull?

Hi Tom, Xanthar

I'm using Fusion 360 for design work. I particularily like that it plugs directly into PrusaSlicr for printing objects, so you are looking at an solid in Fusion and just click Print and voila!

My printer is also hooked up by OctoPrint so the printer pretty much just starts printing down the back of the house. Scary stuff.

Or at least, that's the way it should work (It has worked that way in the past its just that I have reverted to Sneakernet and SD cards)

Turns out OctoPrint over USB does not stream data fast enough to the printer and, particularily where curves are involved, does not produce best results.

Reference files used are various ones that I have found over the years on the net, but mainly a full set of plans I purchased from BestShipModels.com.

Finally a bit of movement..





Nothing much to do here really. Generous smear of Epoxy and start putting pieces together then checking the alignment of everything.

Your "interface" parts between hull sections is an interesting idea.

How well do these parts fit into the hull sections? I have tried to build things in sections with one part having tabs of a protrusion that fits inside the other part (but much smaller than your hull sections). Sometimes there were problems because the thickness of the parts varied with temperature in the room where the printer is located and other effects and the pieces didn't mate properly.

I suppose it would be fairly easy to sand the surfaces of the interface to get a good fit.

Phil

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A collision at sea will ruin your entire day. Aristotle

Hi Phil,

As I mentioned, I will "try this" so taking it as it comes at the moment. What could possibly go wrong? Here, hold my beer

This photo may be a bit clearer:



We are lucky here as the earlier sections of the hull were printed in a lighter Gray, than the later sections. (Not a biggy as this will be painted in any case)

You can see that the light hull section was printed with an "interface" (Bulkhead) built in. This has the added advantage of an increased footprint area and better bed adhesion.

The darker section is created by taking a slice of the end of the section 10mm in, then projecting from the end cross section and lofting between the 2 profiles. The fit is pretty much exact and follows the curvature of the hull nicely.

The hull is semi rigid so the interface can be inserted in either direction. If the hull were to be any thicker, or cut from aluminium (and thus not flexible), the interface would need to have tolerances added and be inserted from "inside out"

This gives a 10mm section of hull which gives plenty of purchase for the epoxy to grab between the hull sides and the interface and also plenty between the bulkhead and the interface.

I don't think it would work without the reinforcing keel bar.

Time will tell, and our lake is shallow!

In the meantime, some more progress:





Hull section 5 is the transition between the forward half and rear half of the boat, No interface is between these 2, the bulkheads themselves being already in place.

Slightly more progress.

Unfortunately a gap has developed between sections 5 and 6, its not terrible but will need to be filled. I'll do this either by 3D pen, plastic putty or filler.

Perhaps a very thin inside coat of fiberglass cloth (like model airplane guys use) and resin on the inside would obviate any issues of strength and water tightness.

Good luck! Tom

Thanks Tom,

That would definitely be a possibility. I have a heap of assorted glass cloth lying around from rocket building days. I think I even have some carbon fibre as well.

I think once the upper bracings go in there won't be an issue with hull strength and the hull will need priming and filling/levelling before paint. I'm not that much into RC boats so it will probably only have to survive a couple of pond outings before it goes up on the permanent display. So I'm not too worried at present.

A bit more progress. Work is getting in the way

Really, I honestly don't know why I go to work. My wife tells me its something about needing money to pay bills blah blah blah... All I know is it gets in the way of fun too much!!

Finally, the hull is complete:



For securing the hull sections in place I tried:

Super Glue
2 Part Epoxy
3D Pen

And the winner is (by multiple furlongs AKA Country Mile).....3D Pen!

In terms of part join strength its remarkable. The hull parts deform and collapse before the join fails (I had a few spare hull parts to destructively test), and I haven't seen a join fail as yet. It sets quickly and is fairly easy to control.

The Only issue I have is that I find my current pen feeds filament too quickly (you want to make sure the parts to be joined get fairly gooey so the pen needs to move slowly to spread the heat around) and only has three speed settings, so I have ordered a new one with 8 speed settings. Hopefully that may get around the problem.

Definitely thinking of making future designs 3D pen friendly for jointing.

Ahoy!

I am now on my 3rd 3D printed and assembled ship and have been very pleased with how standard Cyanoacrylate glue has done holding modules together during building.

I've assembled with CA, filled with standard body putty, and coated with fiberglass resin to provide a complete seal.

Inside the hulls, I've used spray paint (standard gloss enamel) or epoxy spray (as used on appliances for repair/painting) and found that both seem to work fairly well.

I've only used PLA for my assemblies, I tried using PETG, but have had considerable trouble getting it to stick to the print bed reliably.

Printers have varied, but my favorite is the Prusa MK3S+. Reliable as heck.

NS

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Ex RCN, HMC Ships Gatineau, Athabaskan, Charlottetown, St. John's, Montreal, Charlottetown, Summerside, Montreal.

NS:

Your hulls are from a filament printer? With resin printing CA sometimes seems less reliable in my experience, sometimes? But that might be similar to the occasional issues with paint and resin.

Good on both of you for your successful hulls! I at one time was going to make my 1:192 Missouri RC but decided the detail I wanted to include would not survive outdoor usage.

Cheers: Tom

NS: I certainly do like the MK3S+:



Thanks for the kind words Tom

I forgot to mention I also tried friction welding with a rotary tool and UV resin. They all have pros and cons, but I'm fairly happy with the 3D pen results so-far.

Here is a gap that needs some work (Sorry to hurt your eyes like this):



With my preferred amount of preparation (none) a weld bead is inserted:



I could choose to leave my "stack of dimes", like any good welder should, to demonstrate to the world how amazing my welding skills are but craft side cutters are a better option in this case:



And lastly a light sand and its ready for final prep and painting.

My apologies, been a bit quiet.

The Arado 196 took nearly as long to model as the whole ship.



Doing some test prints now, so far so good...

I've been hiding out of sheer embarrassment, so my sincere apologies.

I simply cannot get the detail that I want from filament printing and so have decided to turn to the dark side and try resin printing instead.

Quick trip to Jaycar and came home with a basic Protech printer and have been playing with it virtually non-stop for weeks.

Finally got it to where I want to be and must say I am totally impressed with the detail of print.



Now the problem is deciding what to print in filament (which is still heaps stronger) and what to print in resin.

The anchor and chain is still my favourite. It zips right off the supports and is fully articulated. Mind blown...