Scratch Build Project 685 Plavnik K-278 Komsomolets NATO: Mike

[greenman407]

Hardrock, ............what is that? It looks like a Japanese sub. For an instant , I thought it was a 212 ....but the sail is wrong.

[HardRock]

You must, she's wild machine...

[Davidh]

Hi Scott,

The silicon will just peel off. You seem to be busy in the building department. I'm going to have to have a look at this soryu of yours...

Dave

[HardRock]

Looking good Dave. What are you using to ensure that the silicon releases once dry?

[Davidh]

Thankyou all.


Red boat to answer your question the SD is 63mm /od. Yes its a single screw. Its the same SD that I have in my R esolution that I completed last year. I like a modular system where I can run any number of boats off one SD.

The last couple of days have been busy. Work periods in between dad's taxi service to the shops and Christmas stuff I have embarked on the most arduous part of the entire exercise. I find that laying up and creation of the two hull mould halves is messy, smelly, tedious work, but if you don't want you submarine to consist of purely appendages its usually good to create hull moulds. Kinda helps....

The last batch of pics showed the kiddies doing a bit of labour. It was good that my kids could help and found it enjoyable, I do however get sad when I think that there are some kids in India or China who actually do this every day to survive. I know David's jokes are in jest.

After checking that the hull is secure we continued using the modelling clay all the way around the equator of the hull. I am pouring RTV silicon around the edge of the master. I thought about using the Thixo-M to thicken up this silicon but then decided on using a silicon without thickener and simply making a shallow wall all the way around the base. The initial pour could simply create a moat around the outside of the hull. I just need a draw bridge now. I drilled holes into the side of the mould board about 10mm out from the hull. Earlier last week I found some scrap in the waste bin at school and cut some barriers for the silicon to run up against. I cut grooves into the side of the walls to create indexing areas for the silicon to run into. Once this layer is poured I would then mix up a batch and add thixo-m to thicken it and paste it over the rest of the hull.

Enough for now

David H

[redboat219]

Hi Redboat,

Thanks for the comments, the boat is 1/120 scale and it is made for RC. ( I do not build models that don't function) I will be dropping a subdriver into it. I am going to put it into production.

David h

2" dia. Single screw SD?

[He Who Shall Not Be Named]

Good stuff, David. Slave labor: much to recommend it.

M

[Davidh]

Hi Redboat,

Thanks for the comments, the boat is 1/120 scale and it is made for RC. ( I do not build models that don't function) I will be dropping a subdriver into it. I am going to put it into production.

David h

[redboat219]

Hello David.
Wonderful build you got going here.
BTW, What scale is your Mike, can't recall seeing a post about it's scale anywhere.

Are you going to do an RCable hull?

[Davidh]

Hello all,

Thanks for the feedback David, there wasn't much else on offer but I took your advice and did a smaller silicon hardback mould doing a copy of the Resolution sail. It worked out well however I really learnt that you need to make sure that the silicon mould is thick enough. Other than that the mould worked well and as I don't have a vac /pressure chamber I couldn't get the air bubbles out however I found that there really was virtually no air bubbles anyway. I did not know how much thixotropic-M thickener to put into the mix. I decided to put a few drops in at a time and mix it and then see if it would cling to walls. It only took a couple of drops. Man.. that tiny jar will last me years!

I have been busy making extra sails for the mike and have made a couple out of Vinyl ester resin. Initially when I used this resin I was sceptical however I have found that it's really good, it just needs longer to fully set than polyester which I am so used to. Anyway the photos here show some examples of sails out of the mould the Vinyl ester being the mossy coloured ones. The detail is just as good as with polyester resin.

Before laying up the moulds there was still a bit of detail work to finally complete on the top and bottom hull. I still hadn't completed all the vent holes on the bottom and there was a tiny bit more safety line to do near the bow. So I etched away at the bottom of the hull and completed the rest of the vent holes. I have actually moved the placement for the inlet scoops further back. My initial position was slightly too far forward. I have finished smoothing the teardrop profile of where the sail is placed too...

I have just commenced summer holidays here and schools out. Today is going to be a 35 degree stinker so a good one for laying up moulds. I put the roller doors of the garage up and work in the shade, in the direct heat is really intense and just too hot. I am at the stage where I am looking at starting the most laborious part of the whole exercise, creation of the two hull moulds. As mentioned I am trying something new and creating a silicon mould for the top of the hull. I have never done a mould this large before and have put a fair bit of thought into it.


Took a break for an hour or two and took the aforementioned kiddies down to 'Soldiers', our local beach here on the coast.

After mounting the hull on the board I then made sure it aligned up and was exactly level. Then I would go around the hull and press modelling clay into the corners. A nice yellow colour that I bought at go-lo for $3. Actually I didn't end up doing it . I had two willing helpers that wanted to "help Daddy with his submarine stuff." The pictures here show Amelia (milly) 6 years old and Noah, 9, pressing the yellow clay into the gap between the hull and the board and then slicing it away with the back of a ruler. Did a good job too. I have decided to make a barrier around the side of the mould and mix up some silicon without thickener and pour around, effectively making a trough. That's what these wooden barriers are for. I have cut grooves into the side of them to help register the silicon mould sides to the fibreglass hardback when I eventually mould it up.

Anyway I may very well be back to it tomorrow and the write ups should be a little more frequent.

David H

[Davidh]

Thank you David and thanks Scott,

I have just started summer holidays. So pace on development should pick up as of tomorrow. I have now just the two hull halves to do, fingers crossed....
Dave h

[HardRock]

Great work Mate. Can't wait to see the final product pop out of the mold.

[He Who Shall Not Be Named]

When applying the rubber (glove) element of the hybrid tool:

1. experiment on something small first -- you don't want to commit all that expensive rubber on the hull only to find later that some step(s) in the process were wrong and rendered a useless item
2. vacuum the mix of rubber before trolling it over the hull -- this will eliminate the possibilities of catching air pockets as you troll the rubber down onto the hull
3. apply the rubber with a credit card or stiff piece of plastic sheet.
4. apply multiple coats of rubber, the nominal thickness of the glove should be between 3/8" and 1/2".
5. make the surface of the last coat of rubber as rough as possible -- this will index the hard-shell (mother-mold) GRP to the rubber so they key together perfectly.

M

[Davidh]

Quiet forum,

I haven't had any response to the questions I put up about polyurethane and the need for a release agent on metal parts in a polyurethane mould. Surely someone has an answer?

Anyway back to the build. I have spent a fair bit of time welding up a tube steel frame to make the bench for the lathe that I anticipate getting soon. The top bench plus two lower shelves should store most of my stuff. Will still be a little bit of a squeeze though.

I am about to start the home stretch of this project. I will soon be looking at the moulds for the hull, top and bottom.

Last Sunday afternoon I managed to start construction of the moulding/Splitter board that I will produce the hull mould on. Like with the Resolution, I decided to make the customary box around the outside the ensure that the MDF board is absolutely straight and flat. Then I marked out the profile of the hull on the main board and then got the jigsaw ready to cut it out.

Cutting out the profile of the hull wasn't difficult and MDF is certainly soft stuff. I cut slightly inside of the profile so that I could file down later and make the fit as tight as possible. Once the boat is at the equator in the board I will go around it with plasticine and get it nice and flush. With all my projects be they Submarines or Sailplanes I try and do something new in the building process for the sake of trying something new and expanding the possibilities. Here I will be making the top mould out of a large silicon RTV mould with a fibreglass hard back. This will require thickening of the Silicon and for this I have something called thixotropic-M that will mix into the silicon and allow it to thicken to a paste that will hopefully mean that It will stick to vertical surfaces around the side of the hull. The lower hull has less detail and not railings moulded into the deck. I will probably just do a hard shell Fibreglass mould for this one.

The hull will be supported underneath by two wooden 'handles' that will be screwed up under the underside of the hull making sure that it does not slip down below the equator of the hull.

Although mike fits nicely into the board and I could proceed pretty quickly with moulding the two hull halves I will probably spend most of the weekend just getting the hull just right. There are still many imperfections that I should iron out. I also have to finish etching the ballast tank vents on the bottom of the hull. I need to really devote some time to these so it will be a little while before I finally set up the hull for the mould. It's worthwhile getting the hull just right, that RTV silicon is expensive.

Anyway, enough for now

David H

[Davidh]

Hello all,

As mentioned earlier all the moulds have been made for the appendages. I then got to make the last of the parts out of resin including the rear reactor coolant outlets, probably the most mysterious part of the boat. Anyway the photo shows the masters and where they align on the rear of the hull.

I have also added a raised profile where the sail will be. This will help with positioning the sail when the design is a kit and also will make sure that light will not be seen when you look dead level with the base of the sail if you have not done a neat job of cutting it. Just got to sand it back and get it really smooth soon.

I have received the ordered Polyurethane resin that Dave recommended from Barnes. I got the appendage moulds ready and prepared for giving this new resin a try. I was spooked by the whole degassing thing as I do not have a vacuum chamber or pressure chamber to apply to the resin once mixed. I really wasn’t sure if when I mixed the resin and poured it into the mould whether it would end up coming out looking like Swiss cheese.

Initially I did not prepare enough moulds for the amount of resin I mixed up and had more than I could use so hurriedly scambled to insert brass inserts into more moulds and tried to pour the remaining resin into those. Nuh, wasn’t going to happen, the resin was starting to thicken and was already as thick as thick honey, man this stuff sets fast!
It was interesting watching the colour change of resin, starting off the colour of beer and then going more yellow, eventually to be a nice banana yellow.

After a couple of hours I de-moulded the pieces and did not find Swiss cheese. There was maybe one small bubble and I am presuming lots of tiny pin prick bubbles. I had to look hard to find them. However I am stoked at the result. I have since done a couple more pourings, getting the quantities right and less waste and am finding that there are even fewer small bubbles. These parts look really excellent, maybe that’s just my opinion and maybe David is shaking his head and screaming for me to get a vacuum chamber however I can’t see what the problem is with the bubbles I really have to look really hard to see them. Those vortex pods on the ends of the horizontal planes remind me of Bananas being yellow and all, I might just eat one.

Once the parts came out of the mould then it was simply a case of trimming off the flashing and then a light sanding back. Pulling out the brass inserts has been easy I did coat them with Vaseline to make it easier not knowing originally if there was a need for release agent. Can anyone enlighten me on this? Any advice on this would be good, it’s been quiet lately….
If a part had an insert that fitted into another part like a two piece rudder system then this was easily accomplished as the two parts would fit around the brass pivot really nicely.

I am about to order some of that Stoner E326 release. I have also cut up a MDF particle board to make my mould splitting board for the two hull halves. I will screw down a long straight piece of MDF to make sure that the board is absolutely straight then make the rest of the box underneath. Then cut out the profile of the hull at the equator and mount it to the board. I have also cut out some little holders underneath that will hold the underside of the hull just where I need it.
I am also in the process of making up a small bench to mount the lathe when I finally get it. Some old tubular steel and a borrowed MIG welder. Then I will be able to make propeller hubs and masts and scopes at home. nice!..
Enough for now..

Any comments /advice would be appreciated…

David H