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1/144 scratch build Akula

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Re: 1/144 scratch build Akula

Postby bwi » Mon Jul 28, 2014 6:47 pm

Hi All,

The work on the Akula is on hold some time now as other projects around the house and garden took my full attention. Also my appetite to build was not so great to be honest.
Never the less I browse the SC forum on a regular basis......tonight though I had a giant bug that kept popping up through the keyboard (She is also one of the new projects that takes a lot of attention)......

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I know its of topic but I couldn't resist sharing this :D Sorry.

grtz,
Bart
Practical wisdom is only to be learned in the school of experience.
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Re: 1/144 scratch build Akula

Postby Ober Freak » Mon Jul 28, 2014 6:52 pm

So cute
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Re: 1/144 scratch build Akula

Postby bwi » Mon Aug 11, 2014 4:28 pm

Hi Gents,

As the appetite for the build slowly returns I'm mentally prepare myself to start scribing the hulls. The process past already several time trough my head....you know the stuff....witch tools I'm going to use, witch stencils I will make, witch floods and vents I will scribe witch ones I will open up, ....

But every time I get stuck when I'm thinking about the bow....how I'm going to project the torpedo doors to the spherical hull so the will end up as circle in a front view. I was thinking about making a mould of the bow in fiberglass and drill holes in it (will not be so strait forward) and use this as an stencil for the bow. But I'm not convinced this is the best way to go.

Yes I could use the try and error method an go for it but I would appreciate it if you guys share you experiences so I can skip the error phase :-).All suggestions are welcome!

Maybe we can list up all the experiences and place them under "Modeling Tips and Tricks"?

Thks and Grtz,
Bart
Practical wisdom is only to be learned in the school of experience.
"Samuel Smiles"
https://www.facebook.com/CleanSweepModels
bwi
 
Posts: 51
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Location: Belgium

Re: 1/144 scratch build Akula

Postby Ralph --- SSBN 598 » Mon Aug 11, 2014 5:42 pm

Maybe I can hep you a little here.

The bow is a compound curve sort of.
If you know cad programs of good with graphics you can make a pattern that is flat and came be bent around the hull to give the correct scribe line to make a circle as viewed from the front.
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Now here is what I would try.
Get a piece of balsa wood that you can turn a round rod from.
Or if you can get a round rod to start with, do that.

Scribe tube center lines on hull.
Make a stand to hold hull stead.
Make a stand to hold wood rods at center of tube.
Then slowly sand the wood rod to the contour of the hull.
You will need a rod for each tube. Well, not each tube.
Some are the opposite of the others.

Once you have a rod that fits tight against the hull, dip it in some thinned wood sealer.
I actually use thinned glue.
Sand rod back to proper diameter and use as a scribe guide.

I might even drill a very small hole center of each tube and put a centering pin in each wooden rod so it can not be pushed off center when scribing.
----------------------
Another way would be to make a guide that has a floating scribe tool over it.
Say a brass rod with a centering pin to go in that hole in the center of the tube location.
Then use another tube that fits tight over the guide rod and put a scribe pin on it that can float with the curvature of the hull as you turn it around the guide rod.

Using the stand to hold the gude rod level and straight to hull, slowly turn the scribe pin until you have a good line.
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Re: 1/144 scratch build Akula

Postby bwi » Sat Oct 18, 2014 3:10 pm

Thks Ralph


Hi gents, the apatite is back….so the build is back on track.

A drill press was missing on my machinery list, and this was an item I needed for manufacturing the rudders and dive planes. I did not need a big machine but I wanted one with high precision. After streaming the WWW I found one for my budget I wanted to spent with a max clearance of 0.02mm on the spindle.

The masters of the rudders and dive planes were still were I left them…sitting in the modeling clay.

For the making of the sprue channels I modified a syringe so I got the desired diameter for the channels. Filled the syringe with molding clay an out came the channel.

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I cut the cylindrical formed clay in half longitudinally and pressed them in place on the mold.

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The mold were closed and the seams were sealed with modeling clay. The poor funnels I made out of paper, put in place and sealed with molding clay.
The silicone was degassed in my DYI vacuum chamber (works Great!) and poured into the molds.

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After curing molds were opened up and master and molding clay was removed. The only thing I needed to do before pouring the other half is making new sprue channels in modeling clay and put them in place together with the masters……and apply release agent . Closed and sealed everything and poured the other halve. The mold worked out fine.

Next step is to pour the resin in the molds, again I made the pour funnels out of paper. After the molds were filled I placed the in my pressure chamber @ 3bar, and let them cure overnight. I was very pleased with the result.

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The only thing I noticed is that the diving plane was slightly bent but the master was straight. Probably I applied to much force when I pressed the master in the modeling clay as the rudder is long and thin it is fragile (lessons learned :oops: ). The deformation small so I don’t need to redo it.

Next step was to cut the control faces out. Everything was marked in pencil. On the real sub all the rudders and diving planes are provided with trim surfaces these are supported by pintle bearings. I want to integrate these bearing in the model. So these were also drawn.

First I had to drill the rudderstock holes (drill press time). As the rudders and dive planes are double curved it is hard to clamp them in a machine vice without a sort of jig. As I had a lazy day I din’t want to make a jig, so I tried……….modeling clay. This works great, just put an piece of modeling clay on both sided and clamp it in the machine vice, the modeling clay squeezes itself in place wen pressure is applied. 2mm holes were drilled.

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The yellow stuff is the molding clay

The surfaces were cut out with a scroll saw. Before I made the cut I had to level the planes in both directions in order to get a nice vertical cut. This was done with modeling clay (yes I seem to use this stuff for everything :D ). A recess for the pintel bearing was also cut in the control surface. All cut surface were sanded. A radius was sanded on the leading edge of the control surface.

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The pintle bearings (3x5x5mm) were made out of a 3mm styrene sheet glued in place and provided with a 2mm hole.
The gaps between the control surface and the actual plane were filed up with the EUREKA putty but not before I thickened up the leading edge of the control surfaces by masking tape (4 layers approx. 0,5mm) and applied some release agent so the EUREKA putty will not bond with the tape.

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pintle bearing in place and tape applied

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EUREKA putty applied

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Control surface removed

After curing all were sanded in shape resulting in a nice small 0,5mm gap. The upper and lower gap between the control surface and plane needed also attention. EUREKA putty was applied on top and bottom and after curing sanded in shape resulting in a nice small gap.

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Bushings will support the rudderstock, I made them out of a 3mm brass rod, the all received a 2mm hole.
• 4pc for the pintle bearings (rudderstock runs through it) Ø3x3mm
• 4pc for the upper bearing (protrusion of the hull) Ø3x10mm
• 3pc for the lower bearing Ø3x3mm
These bushings will be placed in position in the molds prior to the casting process so they will be imbedded in the parts after casting.

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bushings

That’s it for now,
Grtz,
Bart
Practical wisdom is only to be learned in the school of experience.
"Samuel Smiles"
https://www.facebook.com/CleanSweepModels
bwi
 
Posts: 51
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Location: Belgium

Re: 1/144 scratch build Akula

Postby bwi » Sat Nov 22, 2014 3:00 pm

Another update,

Next step was to lineup the planes to the hull and adapt the roots to the hull for a perfect fit. Masking tape and A release agent was applied on the hull iwo the rudders and planes location; EUREKA putty was used to make the curved transition between the hull and the rudder and planes.

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The making of all bushings was completed.

The slightly bent plane was staring at me all the time……Damn I cannot live with it……so I putted it back in the mould and to my surprise it did not fit……the moult itself was straight……probably the casting was not completely hardened out when I removed it from the mould and deformed when it was laying on my workbench. So I casted another one……left it in the pressure pot for 3 days……and yes I got a straight plane.

In between I was pondering about the deaeration gratings on the top of the hull. My intention was that I would try to foto-etch them. But I have no equipment to do so….further more I went already through so many DIY projects (I believe it took 50% of my total building time) to get things done that I’m getting tired of it…..I don’t want to tackle the foto-etch stuff.

Recently, in Paul Crozier’s 1/72nd Revell Gato Wolfpack build report, micro-drills were mentioned. This gave me some hope for the gratings Image. I have purchased a micro-drill set and went calculating the dimensions of the gratings vs the diameter of the holes. What I came up with was a grating with 5.3 x 3.5mm [0.2086 x 0.1377”] and 25 holes of 0.5mm [0.0196”], I believed this was still possible to accomplish.

For test material I used a piece of plywood…..the test worked out fine…I’m very pleased with the test result…..so no need to foto-etch on this project :lol:.....I save it for my next project The distance between the holes is 0.3mm [0.0118”]. I will drill the holes direct into my hull so there will be no need for an insert. I will carry out on more test were I will align the holes in rows just as the real thing and see which one gives the best scale result.

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That it for now,
Grtz,
Bart
Practical wisdom is only to be learned in the school of experience.
"Samuel Smiles"
https://www.facebook.com/CleanSweepModels
bwi
 
Posts: 51
Joined: Sat Jun 01, 2013 12:25 pm
Location: Belgium

Re: 1/144 scratch build Akula

Postby bwi » Tue Jan 13, 2015 5:27 pm

Another update,

All rudders and planes were sprayed with automotive primer and sanded in preparation to the molding.
I would have repeated this process several times but at that moment the winter kicked in and the temperatures in the basement dropped.
Cold hands and small parts don't match.
As my family members voted “against” moving the paint and sanding process into the living room I had to find something else to do.

So I focused on the internals of the sub.
Me, myself and I quickly agreed that DIY was the way we wanted to go. As usual the others left the building and I remained to figure out “how to”.
I had to do some drawing as I also wanted to DIY the piston tank.

I took possession over the laptop and searched the www for some free drawing software.
A former colleague used sketchUp to design his house. So I had a go at it. After I conquered the basics the software was very kind to me (Normally software and myself don’t get along). They have also great tutorials so I quickly learned the tricks of the trade. I really can recommend this software. I'm sure it has its limitations compared to professional 3D CAD software (rendering) but this is really easy in use.

I spent a lot of time searching for the dimensions of all the necessary gears, bearings and spindles. Also I spent a lot of attention to calculate the neccesary dimentions of the components needed (end caps, O-ring groves, wall thickness, discharge opening,……). For this I found a lot of information in a booklet of Norbert Brüggen and for the O-ring groves I used the information that Sub Culture shared on this forum thks for that Andy.

During the process of drawing all the components I decided I wanted one tank with two piston, both pistons working on one motor. When using a single piston tank, there is a weight shift when the piston moves towards the stem or stern, taking water in or pushing water out. So you need to compensate this. As I want to make a static diver I wanted to minimize this shift so I went for the double piston.

I took over the Idea from the webside of Markus Reidegeld http://www.modelluboottechnik.de, he made several of these tanks. Also the positioning of the servo’s I took over from him.

All this information was transferred to the drawing board. (just one sentence but it took almost two months to do it, needless to tell how many times the design changed during the process).

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You will note that there are six servos drawn but that was just to see how much I could squeeze in, the fwd three will be reduced to one piece the aft three to two pieces.
The length of the piston tank needs to be adapted to the necessary ballast volume I have to take in. It will be less than the 500ml I have drawn now, so room will be available for the battery.
The dimension of the WTC is dia 80mm x 550mm [3” x 22”]. The calculated dive time is 5 sec for 500ml (I'm really curious if my math's are correct).

That’s it for now.
Grtz,
Bart
Practical wisdom is only to be learned in the school of experience.
"Samuel Smiles"
https://www.facebook.com/CleanSweepModels
bwi
 
Posts: 51
Joined: Sat Jun 01, 2013 12:25 pm
Location: Belgium

Re: 1/144 scratch build Akula

Postby bwi » Thu Feb 12, 2015 3:23 pm

I managed to spray and sand the parts several times and their ready for molding.

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Initially I didn’t wanted to make use of the Fwd planes, but along the way I have decided to use them for depth control. So I had to fabricate them, they will be fixed not retractable. As above mentioned I first chapped my rudders and planes an afterwards, when I bought a drill press, I drilled the holes for the rudderstock. It was not so evident to get the hole nicely in the centerline.
So I decided to drill the hole of the rudderstock first and then shape the Fwd plane.
I started with two pieces of 3mm of acrylate sheet, cut at the right dimensions and clued together. Then I draw the longitudinal section a a piece of paper, inclusive the position of the hole for the rudderstock, and glued it on the workpiece.

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The workpiece was clamped into the machine vice an de 2mm hole was drilled, as the shape was rectangular and flat it was a piece of cake to drill the hole in the centerline. Next the piece was cut to the longitudinal outlines.

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Then I drew the cross-sections of the plane on paper and clued them to the workpiece, and grinded/sanded into shape.

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As I’m preparing for molding, some other part needed fabrication. The hatch of the communication buoy is fitted with protection for the cable.

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The difficult part was the symmetry between PS and SB protection. I started tag-gluing to pieces of 3mm acrylate sheet. Then drew the longitudinal outline on it and grinded it into shape.

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Next was the cross section this was also grinded in shape, together with my fingernails…..this stuff is small.

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The parts were separated resulting in 2 symmetrical protections

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The Fwd escape hatch was also fabricated, I had a picture as an example.

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The dome was made out of 3mm acrylate, the diameter is 13mm.

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The scoop I initially made was oversized so I narrowed everything down. The inlet was opened up with a handheld grinder.

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Everything was sprayed and sanded afterwards.

That's it for now,
Grtz,
bart
Practical wisdom is only to be learned in the school of experience.
"Samuel Smiles"
https://www.facebook.com/CleanSweepModels
bwi
 
Posts: 51
Joined: Sat Jun 01, 2013 12:25 pm
Location: Belgium

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