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[Geoff]

I have just acquired a 63" hull of a Castle class frigate. Yep 63". All 3d printed, it came with funnel and other parts of the main superstructure. The hull is in multiple sections all glued together.. The surface finish is a little rough so will need sanding.


Ok, a number of questions:


- The hull sections are about 3mm thick with the deck and superstructure components less so. The hull seems "tinny" so I want to install some internal bulkheads as there are currently none. So, what is the best glue to use. I've thought of superglue but in my experience it can be a little brittle so I was leaning towards araldite. Would this work?


- I don't know how the hull sections were glued together so I was thinking of painting a layer of resin inside the hull but would this stick and/or attack the plastic? The plastic is dark grey but I have no idea what type.


- Any other suggestions or advice?


Cheers


Geoff

[Geoff]

Also what would be the best filler to use?

[Umi_Ryuzuki]

I have printed with PLA plastic, and use standard CA cement(superglue) to glue the hull together.
For filler, I use "Bondo Glazing & Spot Putty". The hull is 3mm, but a small model, and the only
treatment to the exterior is filler, primer and paint. The interior of my hull, and some deck areas
are sometimes unpainted. The model has sunk three times, mostly due to humorous circumstances.
So water hasn't affected the PLA at all. Although, heat, as in sitting in the car, has warped a deck, which
was flattened using a heat gun, and then reprinted later. 
 
If you plan on using polyester resin, definitely check a small area to see if it attacks the plastic. Epoxy should be fine.

[Circlip]

Are there any solvent adhesives for the various 'printed' plastics? OK, Ketones work on ABS and the likes to provide a 'Welded' joint but the use of Cyano and epoxies only give a Layer type fixture. Lets also not forget, although water assists initial activation of Cyanos, in time, it also helps joints fail.


  Regards  Ian.

[Umi_Ryuzuki]

How much of those adhesion claims are myth? I have 20, and 30 year old models, hulls and superstructure, assembled
using CA glue, and they are still sailing. Someone also claimed that PLA printing filament will just 
decay, and literally fall apart after three years. Especially if it touches water. The red tiny tug has been
sailing and getting wet for eight years, and shows no sign of decay. Just enjoy your hobby.
 If you have issues with your cement, or 3d print out, let us know. However, if Ian is at all like my old
friend Cliff Shaw, now that he has said something, it will stop working. I used to build all sorts of
contraptions and things for my models and show off how they worked. Then Cliff would look at it, and
declare, "That won't work...", and it would stop working.  Fingers crossed my little tug doesn't fall apart today.

I have had parts printed in ABS, and used Weld-On 3 for acyrlics to cement/weld pieces together.
That seems to work on PLA, but I don't currently have any proper pieces to test the weld strength.

[Circlip]

Sorry Umi    Have mixed a fresh batch of eye of newt and toe of frog to counteract the curse 


    Regards  Ian

[JohnG]

For ABS: i've used  OSMA brand 'solvent cement no 2 ' (ketone based and generally used by plumbers to join abs pipes - this happens to be the brand i had to hand)  to join hull sections i printed with ABS filament,
and Epoxy to hold fittings inside the Hull. 
For PETG: i used Epoxy to join the hull sections.
I used Humbrol regular plastic filler on the  ABS and  the Humbrol Filler and also Isopon p38  on the PETG. All without issues.


To add strength to the ABS hull where there was layer separation in the 3d print i used fine ABS sheet (spare brim [=bed adhesion layer] from 3d prints) stuck to the inside of the hull with the solvent cement.


No experience of PLA i'm afraid - out of what's probably an over-abundance of caution i went straight to abs and petg.


Both hulls are approx 1m long ww1 destroyer models with 5-6 sections .


Hope this helps. do post some pics in due course. is it the bensworx model ? ( https://www.cgtrader.com/3d-print-models/hobby-diy/other/castle-class-corvette )- i've seen some good comments on his 3d models.

[JimG]

Some people think that pla will break down as it is said to be biodegradeable, however this is under quite extreme conditions, e.g. an industrial composting system where it is in very warm and damp conditions. Just getting it wet or even burying it is not enough to make it break down unless left for many years.
Jim