Akula 1/144 scratch build

david f wrote:Lovely work Bart!

I was interested to hear about your conclusion that the sub could not float.

This happens - I believe it happened to a 1:1 Spanish sub recently!

With small subs you can easily run out of buoyancy. I think that can justify a dry-hull concept rather than a WTC.

I was impressed by your use of plexiglass (perspex). I found that the darned stuff used to fracture too much and so I started using polycarbonate. Do you use a particular grade or mix of plexiglass perhaps?

David

Thks David,

I needed 400gr of buoyancy. the piston tank that I have designed forced me to make use of the full length of available internal space. After calculating all the weight of the bits and pieces the buoyancy was slightly negative no problem if you can add some foam. But that space was not available in my case. Also the piston tank was designed as a separate tank within WTC what resulted in a decent own weight. All together my bad….No problem I love challenges like this. And it’s done before just have to steel the one that’s suit me best.

No special grade. I reduced the pointangle of my drills to 90° +-something instead of 120°, and you have to have solid support to prevent chipping. That’s the reason I had the hickcup,  the piece was not supported. I also use the slowest RPM available on my drill press. To cut the darn stuff I use a fine-toothed scroll saw blade.

Can you glue polycarbonate with acetone?

Grtz,
Bart

You quite possibly can - I have never tried it.
I find that I get very good joints with polycarbonate using Solventweld (A very volatile liquid in a brown bottle.)

David

PS I should have called it Plastic Weld (available from E.M.A Model Supplies in the UK)

polycarbonate can also be glued using chloroform if it is available.

Test on a scrap piece first of course and apply all the normal safety precautions.

It softens the surface of the material and allows them to fuse together.

Its not always easy to obtain though as it is classified as a substance hazardous to health.


John

I have been doing some scribing practice on my master. As a novice I had no idea how it suppose to look.
After some gentle corrections by David Merriman I reduced the point of the finishing tool from diameter 0.9mm to 0.5mm.
The difference is significant.

Grtz,
Bart

I have started with the fabrication of  all the small bits and pieces for the sub.
The first challenge were the lights on the upper rudder and tow array pod (three pieces in total).
I used a 0.2mm rod bent into shape cut it at the desired length pushed it into molding clay and applied CA glue. The base is 2mm in diameter.









Next challenge were the SOKS. Here I used a 1,5mm brass rod, drilled a 0.5mm hole into it, turned it down to 1mm and made a radius with a needle file.











Grtz,
Bart

bart...

you make it sound so simple.... start with 1.5mm, drill 0.5mm hole, turn it down to 1mm... i would snap half a dozen tiny drillbits trying to make the hole for a single device, let alone the four that are in the picture.

tsenecal wrote:bart...

you make it sound so simple.... start with 1.5mm, drill 0.5mm hole, turn it down to 1mm...   i would snap half a dozen tiny drillbits trying to make the hole for a single device, let alone the four that are in the picture.

Viewed through the magnifier lamp that drill moved like crazy when it made contact with the rod, still get nightmares from it (I only have two drills of 0.5mm).

Ok FINALY some progress:

Readdressed the rudders and planes,
​When I made the transition with the hull to much material was removed a slight reses was the result. Two coats of primer (red colour) iwo the curve solved the problem.




all parts in the Paint box




Horizontal SOKS 6 needed 2 spare; body 2.5mm brass rod support 1mm styrene::








Vertical SOKS: 3 small SOKS, 2 big protectors; 2x1.5mm styrene sheet:








Inlet Scoops (round instead of the fin type), 2x4mm styrene sheet inlet still to be opened up:








Grtz,
Bart

I have been working on the aft escape hatch.

The round body is made out of 2mm (0.078”) acrylic sheet.
The hatch cover is made out 1mm (0.04”) acrylic sheet.
The  valve handle is made out of 0.2mm (0.0079”) diameter wire and glued together with CA.
The hinge is made out of 1.5mm ( 0.059”) diameter brass rod made scuare 0.8x0.8mm (0.031x0.031”).

As I don’t have a 0.004 diameter endmill I was not able to make the small flood sleeves in the hatch nor the slot in the hinge.

Typhoon hatch


Valve handle




Body and hatch cover


All parts ready


The assembly






grtz,
Bart

A fiddly bit of soldering there Bart! Thank goodness that you didn't show the handle being made with 4 separate spokes and a  spindle!!!!


                                                   Trevor

Bart,
Nice details! You are really doing some great work.
Peace,
Tom

Crossie wrote:A fiddly bit of soldering there Bart! Thank goodness that you didn't show the handle being made with 4 separate spokes and a  spindle!!!!

Trevor

Thanks Trevor.....conserning the spindle......I engraved "open" "close" on the handle instead.....but the picture didn't picked that up.....LOL.

Tom(ADMIN) wrote:Bart,
Nice details! You are really doing some great work.
Peace,
Tom

Thank you sir.

Grtz,
Bart

I decided not to scribe the air intakes in the sail they are too small to get the necessary detail into it.

I decided to make them.
Could I squeeze 92 slots divided over 4 columns and 25 rows in a 11 x 6.5 x 2mm piece of acrylic sheet……NO I COULDN’T……I calculated that I only could squeeze in 88. Distance between the slots is 0.25mm.
And NOOOOO…… that’s not 3D printed…..it’s hand crafted. 22pc and 1 endplate and your done.









Grtz,
Bart

Previous I made “in-between” masters of the rudders, diving planes so I could cut out the surfaces without any risk, if it went wrong I could cast other ones.
At that time I made separate tools for each part.

For some parts I crafted only one although I need two pieces. Of those items I need to cast an additional piece, this time I wanted to try multi part casting.

Pre development I AGAIN had a look at the pictures and explanation from David Merriman.

My preference goes to making reusable box for the tooling, this works best for me and it’s supports the silicone very well so I can keep it’s thickness to a minimum (it’s expensive stuff).

I made a tool to create the alinement wholes with ease. This was also a good test to work with cores so this was again a very nice learning process.

Picture below show the process from the creation of the tooling till the actual casting result. Parts involved:

- Aft dive plane
- Fwd dive plane
- Shark fin scoop (not going to use it, but it ad’s quantity)

As I have decided to make an earlier type AKULA, which carried a circular cross section scoop, had to remake them.
Picture below show the process of creating the new scoops.

Grtz,
Bart

The old shark fin and the new with circular cross section



Scoop Root adapted to hull shape



The inlet was opened up with a handheld grinder.



Grating test fitted (to small on next two pictures)



All seems smoothed out with filler (grey on top of scoop)



On done one to go



Finished scoops, painted and with new gratings

I now have all the parts that need casting, so I’m in the process to create the tools for them.

I will have tree tools

One for the little parts on witch I will use David’s vacuum casting technique

one for the tow array pod (the pod has to be hollow) so I will try a sort of lost wax method with the use of a core. Did some test concerning the melting point of the wax and the behavior of casted resin when heated up. Should work, will keep you informed.


And then the last one, the “normal tool for all the other parts (still have to complete)

Vacuum casting tool







Lost wax tool





Grtz,
Bart

Some progress

Received SubSriver......fits perfectly.



All internals installed



Details









The DepthController needs a pressure pickup tube the requirements are:

• It must run vertically for at least 2 inches at the end
  
• Open end to be as for as possible to the bow.
  

The pickup tube is made out 3/32 brass tube. Soldering the tubes at an 90 degree angle would not be strong enough so I made an corner piece.
The right angle corner piece is made off 2 pieces of 2,5mm aluminum. Temporary spot glued together to drill the holes and permanently glued together when the tubes were inserted.
















Marking out the hull for scribing
I tried several ways to see what was suiting me the most (yes I’m crazy).

Lofted the info from the drawing and foto’s and

• directly transferred them onto the hull
  
• transferred them to GRP made laid-up stencils from the hull
  
• Transferred them to brass sheet 0.010 x 4 x 10”
  

The last option I liked a lot so I cut out the transferred shapes. The disadvantage is that it takes ages to do it right and You have to bent them into shape after you are done.

The GRP made stencils...will not be used



The brass sheet stencils, one is shaped to the hull, trimming still to be carried out.







Scribing, at last.
Started with the bottom flood-drain holes.
Nevertheless I have to open them up afterwards I scribe them first for practice purpose.
All went well, and I’m pleased with the result, pictures showing scribed lines without cleaning or touchup.









That's it for now,
Grtz,
Bart

WOW Bart, great work on the panel lines!
You make this look easy.

Thanks Tom but You will have noticed that I postponed this till the very end, I wasn’t really keen on doing it. Spent A lot of time to figure out what method suited me the most, inclusive the walkups during the night pondering on it, try and error you know the stuff.

Then I spent around two months on the stencils, and that pays off big time now. The guidance of David regarding the thickness of the scribing tool was the missing link I needed to get to this result.

But I’m aware this is the easy part of the scribing the upper deck will be the hardest part with those awkward shapes, no victory yet.

Grtz,
Bart

Lovely work, Bart!

(How did you get the brass stencils?)

Great model all ready for summer? (Come to Norwich??)

David

david f wrote:Lovely work, Bart!

(How did you get the brass stencils?)

Great model all ready for summer? (Come to Norwich??)

David

Thks David,

The hardest part was to transfer the 2D shapes into a shell expansion thing.
I enlarged the plans on my computer till they match the dimensions of my model, transferred the shapes onto a circle that I had drawn to a piece of paper, now I had the real dimensions needed to transfer them to the brass sheet. (the drawings that I have are printed on A4 and glued together, and do not meet the scale).

The opening up of the stencils was the easy part of the process, for 90% of it I used the drill press with a handful of 1mm mils.
For the remains I used diamond needle files.The whole took some 2 months.

My aim is to get her sailing an April....not sure now because the flue hit the house......the backbone of the family is sick in bed......the household is now on my shoulders. I estimate the build will be Idle for two weeks.

I preserved some holidays for Norwich, it’s in July, isn’t it?

Grtz,
Bart

Get well soon to the mainstay of the family!
Norwich is end of JULY (see the events section on here)
Norwich is the main 2 day event now in the UK and has a good pond. Include it in a little holiday?

David

I'm sorry that I was running behind with my post....I will make multi postings :-) to make it up enjoy

Half a day work......she is turning into a real sub now....slow but steady












more scribing  I used autoCAT as a support.......the hull is almost finished now......will apply air-dry putty to touch up paint damages/chips from scribing.







Grtz,
Bart

Used 2mm ball nose end mill & diamond needle files.

Pic 1 Different stages in the process
Pic 2 Used tools
Pic 3 Also opened up and fitted the reactor outlet gratings


Grtz,
Bart

Ok guy’s I’ have done some more work on my tooling.

As previous stated I have three tools for the sub, all three are finished now, the finish is not what I wanted to be but I’m forced to be left handed for the moment.

N°1: The towed array pod tool is a straight forward the wax is in place

N°2: The small parts tools for vacuum casting, this tool is a little special as it’s is a pocked tool what I mean with that is that three of outer edges of one of the tool halves was not sprayed with release agent and consequently both halves are permanent fixed together at those places. The tool only can open were the castings are positioned in order to get them out.

N°3: The third one is the largest tool I made so far. I have dimensioned it so it will just fit my pressure pot. I had some trouble to get both halves of the tool leak free when I squeezed them together. (YES I ALWAYS TEST MY TOOLING USING WATER AND YES I’M CRAZY BUT SPILS ARE EXPENSIVE). I normally used David’s way by applying rubber bands bud it failed I could not reach enough pressure to prevent water pouring out in some areas.

As space is very limited in the pressure pot I fabricated some clamps that, when in place, just fitted in the pressure pot. The clamps made out of some wood leftovers and 4mm threaded studs. The test was OK now no more leaks.















Today I have done the casting….....no leakages........……the vacuum casting worked well David Merriman, MANY thks for your explanation on that. After degassing the tool I placed it in the pressure pot together with the rest of the tools.
I have to wait some days to see the result (it takes 7 days to fully harden). Hope the prep work pays off.
The picture is showing the cores in place together with the bushings witch will be embedded in the parts.



Today after 6 days of curing I could open the pressure pot and see the result.

I was very happy everything worked out very well.....It's all in the prep gents.
The overkill bushings were encapsulated perfectly and the vacuum casted tiny pieces are incredible, no air bubble what so ever.

Lets not forget that I could not have accomplished this result without the help/guidance/instructions of David Merriman.

Grtz,
Bart