Nautilus Drydocks ALVIN (3D printed)

[gboxwood]

I'm done with the printing and this is a big relief... I will post pictures of all the parts during the weekend.

Question about the drive for this build: this is how I envision it, is this a correct assumption?

ALVIN-007 by Giacomo Bosso, su Flickr

The propeller is 120mm in diameter, 5 blades from Raboesch, M5 threaded connection to the main shaft (which I then envision to be 5mm DIA).

[He Who Shall Not Be Named]

I'm done with the printing and this is a big relief... I will post pictures of all the parts during the weekend.

Question about the drive for this build: this is how I envision it, is this a correct assumption?

ALVIN-007 by Giacomo Bosso, su Flickr

The propeller is 120mm in diameter, 5 blades from Raboesch, M5 threaded connection to the main shaft (which I then envision to be 5mm DIA).

You need a seal at the 'short shaft' to keep water out of the cylinder.

[Subculture]

What you have will work, but It'll run smoother if you run a dog bone at each end (constant velocity).

[He Who Shall Not Be Named]

You also need an ahead and astern thrust bearing at the base of the propeller hub.

[gboxwood]

Printing completed, here is the layout of the parts:

Senza titolo by Giacomo Bosso, su Flickr

Senza titolo by Giacomo Bosso, su Flickr

Senza titolo by Giacomo Bosso, su Flickr

Senza titolo by Giacomo Bosso, su Flickr

And the summary of this printing effort:

ALVIN-008 by Giacomo Bosso, su Flickr

[gboxwood]

The lower hull parts are joined first, I start the post-processing by sanding parts with a coarse sandpaper.

Senza titolo by Giacomo Bosso, su Flickr

Then I coat them with the XTC resin by Smooth On, sand them and coat them one final time. Below the first coat of resin:

Senza titolo by Giacomo Bosso, su Flickr

I will reinforce the joints with fiberglass in the process.

[gboxwood]

I tried a very quick video to show the parts, I'm no YT personality and I never do it but I thought it could be quicker this way.

https://youtu.be/v410mNQrb3M?si=DGvMPocBXF3p6lb4

[Subculture]

Looking good. Wonder why those files don't have the lower viewing port- makes a useful potential vent for the lower hull if you leave the port unglazed.

[gboxwood]

Looking good. Wonder why those files don't have the lower viewing port- makes a useful potential vent for the lower hull if you leave the port unglazed.

Yes I noticed it myself this morning as I was working on it...

[Subculture]

Perhaps that port was removed at some point in its evolution. It's certainly had at least one change of pressure sphere in its long lifespan which changed the layout of the ports amongst other changes.

[gboxwood]

I spent some time with the lower hull today, sanding the first resin coat smooth:

Senza titolo by Giacomo Bosso, su Flickr

Senza titolo by Giacomo Bosso, su Flickr

The white spots in the resin mean you sanded all the way back to the plastic. This is why I typically use more than one coat.

Senza titolo by Giacomo Bosso, su Flickr

I also added 4x 30mm draining holes following what Bob did on his model (according to the YT video).

The joint are reinforced with a layer of 110 grams fiberglass cloth. I do this on top of the first coat of XTC resin because the XTC sticks to the plastic incredibly well and probably better than any other laminating resin.

Senza titolo by Giacomo Bosso, su Flickr

This will be sanded smooth once cured and then coated with XTC one final time.

[Alucard]

Great job, good information.

[gboxwood]

Thank you!

One thing I always try to do is "de-feature" the STL files to the extent that it makes printing easier and/or more efficient.

For that purpose, I use the Meshmixer software which is a pain to work with and at which I'm not very good at. However, some times it is easy, like in the example below.

It does not make a lot of sense to print the front hook together with the lower hull, this detail can be rendered much better if printed as a separate part and added later.

So, I removed the one I printed with the hull...

Senza titolo by Giacomo Bosso, su Flickr

Senza titolo by Giacomo Bosso, su Flickr

... and I then separated the two parts in Meshmixer:

ALVIN-009 by Giacomo Bosso, su Flickr

ALVIN-010 by Giacomo Bosso, su Flickr

Then I can print the hook separately and use real screws to attach it to the hull for added realism and scale detailing.

ALVIN-011 by Giacomo Bosso, su Flickr

[gboxwood]

Hi Guys, I started thinking about the dive system for this application and I would like to pitch it here for your feedback.
I'm thinking simple here and maybe it will be too simple but let's give it a try...

Now, in the following diagrams, RED means CLOSED/NOT RUNNING and GREEN means OPEN/RUNNING.
Also, the ballast tank only is shown.

These are the states I envision at the moment.

ALVIN-012 by Giacomo Bosso, su Flickr

1. Surface trim
- snorkel solenoid closed (normally closed)
- pump not running

2. Diving
- snorkel solenoid open
- pump runs and fills the ballast tank with water

3. Submerged trim
- snorkel solenoid closed (normally closed)
- pump not running

4. Surfacing (below snorkel depth)
- snorkel solenoid open
- pump runs and empties the ballast
* the snorkel diameter shall be chosen so that it is way smaller than the tank in/out line diameter
* this way, the snorkel will let in some water but less than what the pump pushes out... until a balance is reached
* hopefully, when that balance is achieved it will be enough to raise the snorkel above water
* testing will confirm the above scenario

5. Surfacing (above snorkel depth)
- snorkel solenoid open
- pump runs and empties the ballast

6. Emergency surfacing
- a completely independent system opens a valve that releases compressed air into the tank
- an equally independent valve should open as well in order to let the water out of the tank form a different route than the pump in/out line

Does any of this make sense?

Thank you in advance!

[RCSubGuy]

A pump, three separate solenoid valves and a pressure vessel? Why are you making this so complicated?

Alvin needs next to no positive buoyancy. You want a precision systems such as a piston or water pump (I'd go the pump route as you outlined). Just have a sealed tank, a geared pump and one solenoid. Wire the solenoid and pump in parallel so the solenoid opens with pump power. This is an Eden/Sheerline/OTW style system that is simple, reliable and very precise.