REFURBISHING THE NAUTILUS MINISUB

PAGE FIVE

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J

 

 

Wednesday, March 27, 2019:  Refurbishing 4 became large and slow to load so  I've started Refurbishing 5.

NAUTILUS MINISUB DRIVETRAIN: The blue cast-iron flange bearings shown on the previous page are for setup and testing purposes only.  For the actual installation I bought a pair of these stainless steel flange bearings.  This way the entire drivetrain is stainless steel; bearings included.    Better longevity in seawater than cast iron.

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7/8" ID Stainless Steel four-bolt flange bearing.

 

Sunday, March 31, 2019: Lots of work this past week; check THE CLIPBOARD for more info.

Last night I did this diagram of the pressure compensated propeller shaft  housing / manifold with a cutaway showing the internal carbon-ceramic shaft seal.  Simple drawings like this help me in the design process.  I'm not going to win any drafting competitions but they help me check the fit of component parts before I order them or they arrive by mail.  This is what we did before we had CAD, kids!  J

The mottled black / gray represents the submarine's pressure hull, fins, and rudder.  The blue is water and the white is inside the pressure hull; dry at 1 atmosphere pressure.  The prop is yellow because it's brass.  The cap nut and two of the flanges are chrome but everything shaded with gray pencil is stainless steel. 

PROP MANIFOLD DIAGRAM.jpg

(From left to right: RUDDER; PROPSHAFT CAP NUT; WASHER; PROPELLER; COLLAR; SHAFT; BEARING; 1/4" AFT BEARING MOUNTING PLATE; FLANGE; REDUCER BUSHING; INTERNAL SHAFT SEAL; CUTAWAY BELL REDUCER; CLOSE NIPPLE; CROSS-TEE WITH REDUCER; NIPPLE; FLANGE; 1/4" BULKHEAD; FLANGE; NIPPLE; FLANGE; BEARING; SHAFT; COUPLING TO GEAR REDUCER AND MOTOR.)

All of the parts for this manifold are in the mail and arrive next week; should be able to start assembly and testing soon.  Film at eleven.  J

UPDATE, TODAY: Here's another example of how a pad and pen aid my design process.  This is my new bilge sump pump and tank schematic.  By controlling the valves, I can either pump the bilge overboard when running surfaced; or to a storage tank from whence it can be pressure-purged overboard while submerged.  You don't have to get fancy.  At this point; simple sketches like this are all it takes.

Easily over 98% of the prospective subbers I've talked to get what I call "analysis paralysis"; they never get past the design phase.  For them, being a subber means being part of a discussion group and sharing pictures and conjecture with others on that same level.  They are just playing with their computers and they never get to the point of cutting steel.  Analysis paralysis. 

I'm exactly the opposite.  Simple concept schematics, graph paper drawings, and templates are all I need to produce steel parts from which I build submarines.  I prefer to spend minimal time drawing and maximum time fabricating.  In contrast with others, I guess you could say I have "fabrication motivation."  Works for me.  J

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Crude initial bilge pump system concept diagram.

 

 Even so, I still generate boxes of drawings and research notes on a project like this; some basic and some more refined; whatever's needed at the time.  Here's a look at what I've generated in the past several weeks working on the drivetrain, bench test setup, guidance control through-hulls, 12V electrical accessories system, and now the bilge pumping system.    Every idea that occurred to me; everything I need to buy, make, or otherwise acquire; and how I was going to proceed is all documented in pages like these. 

People say they "can't imagine what it takes" to do something like this.  For me, working under these conditions, this is a big part of it.

Conceiving, designing, and building a submarine is a lot of work, but I don't feel as though I've "got" to do it; I feel like I "get" to do it.   When you love what you do; it's not really work.  J

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R&D notes.

 

Wednesday, April 03, 2019:  TEST BENCH: salvaged an old 3x9' sheet of siding from which I'll cut a 2.5 x 6' base plate for the test bench; cleaned it up and laid it out to dry.  Also got the 10' 2X10" mounting board ready to go.  Still have to buy a 4x8' sheet of plywood to make the water tank. 

DRIVETRAIN: The propeller shaft went to the Machine shop on Monday and might be done tomorrow, but you NEVER rush a machinist.  J

 

Needed a few more parts for the propshaft housing / manifold; they are in the mail and some actually arrived today.  No unusual delays there.

Bought some heavy duty brackets at Home Depot (to support the propshaft bearings on the test bench) that were $30 each and the quality sucked.  Taking them back for a refund.  But first, I've  used them as templates on a piece of 6" x 6" square tube and I'll cut and drill my own brackets to fit the bearings and flanges precisely.

The thing about making these brackets is the propshaft height above the 2x10" base board must be exactly the same from the motor through two brackets and bearings, and to the propeller.  I tried guestimation and then got a better idea.  I cannibalized an old 7/8" drill bit; chucked it up in the drivetrain shaft coupler; positioned the template-marked bracket stock in front of the bit; and spun the motor. 

 

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An old 7/8" drill bit; shortened, sanded, and secured in the propshaft coupler; to be used as a drill.

 

Now I know exactly where the center of the propshaft will be when motor is mounted on its mount and the propshaft bearings are mounted on 6" brackets atop a spacer made from a 1.5" thick piece of 2x10" lumber.

MARKING MANIFOLD BRACKET 1.jpg

ME1117 and Gear Reducer driving 7/8" drill bit to mark centerline on mounting bracket stock.

 

In this pic you can see the guesstimation marks I made with a scribe, using one of the bearings as a guide.  Didn't measure anything; just eyeballed it.  The little round circle near the center of the X is the actual centerpoint for the propshaft.  I would have only been off by a 16th of an inch, but when you're talking about something that's  heavy and spinning at thousands of RPM; even that small variance is unacceptable if I can prevent it.  This looks like it's working out just fine.  Me likey!  J

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"Best-guess" scribe marks and actual center of drive train comparison.

 

Next, I'll put that piece on the drill press and that's where the pilot bit of my  carbide hole saw will go.  Once I have drilled a nice 7/8" hole, I can position the flange, bearing,and shaft to precisely mark where all the bolt holes must go.  Easy peasy!  J

TEST BENCH WITH WATER TANK: Here's a crude drawing of what I'm building: its based on a 2X10; has a 2X2' water chamber around the prop and manifold.   The MOON EYES are a "note to self" to notice something on this page.  Here, it was that I'd decided to eliminate the 1/2" neoprene pads I've presently used under the motor mount.

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Basic schematic for test bench / water tank; showing manifold, mounts, motor, and struts.

 

I know from past experience: bolting everything down securely and minimizing chances for vibration are critical.  Not only will I not be using rubber pads under the motor mount;  I'm making struts of angle iron that will be welded onto the top of the manifold brackets and bolted from the forward bracket to the already drilled-and-tapped motor mount.  It's not enough for the mounts to be fastened to the foundation; the tops of the mounts must be rigidly connected to prevent them from flexing fore and aft under load, when things get spinning and it all gets crazy.  J

 

Saturday, April 06, 2019: Got the basic drivetrain running on one bracket and bearing last night.  I used the old tailcone plate because it's already sized and drilled to match the tailcone bulkhead boss.  I roughed out a bracket to position the tailcone plate in alignment with the gear reducer output shaft.  Marked the center point and drilled a 2" hole with my carbide hole saw.  Worked fine. 

I have to make one more like this out of mild steel; about 5" square to serve as the propeller bearing mounting bracket.  Once I have it all worked out, these old 3/16" mild steel parts will serve as templates from which I will make final versions from 1/4" stainless steel. 

OLD TAILCONE PLATE.jpg

3/16" mild steel Nautilus Minisub tailcone bulkhead; circa 1991.

 

Also, assembled the propeller shaft housing / manifold and hung it in position with some wire to check the fit.  In this pic it's hand-tightened and still only 3/8" longer than it needs to be to fit between the tailcone bulkhead and propellershaft mounting brackets.  I won't have any problem getting it to final fit using a wrench.

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Stainless steel propshaft housing / manifold in position on Nautilus Minisub.

 

Next, I'll make a prop bearing mounting plate; attach a bracket so it will bolt onto the bench; size it next to the gear reducer output shaft, and mark the centerline.  Cut a 2" hole around the center point; insert the shaft, slide the bearing on the shaft up against the plate, mark the bolt holes, and drill 'em.  Once that's done I can bolt the brackets to the bench; bolt in the manifold, insert the propshaft, connect to the gear reducer, install the propeller and cap nut, and test it all for clearance of rotary parts.

If it's okay, I install the pump seal on the shaft, reassemble the drivetrain with a temporary water jacket around the pump seal housing vent holes, and wet test the seal.  No leaks?  We're ready to put it into the submarine.  J

 

Monday, April 08, 2019:  DRIVETRAIN: Had to redesign the propshaft manifold and ordered a new set of flanges over the weekend.  

Built an internal seat for the carbon ceramic shaft seal; made it out of PVC parts of a swimming pool pump hose, a rubber hose grommet; and a couple odd pieces of PVC.

Today I made a rudder bearing mounting plate out of 3/16th mild steel; modified a piece of 6" angle to support it on the testing bench; aligned it with the gear reducer output shaft; and set up the basic drivetrain (motor, gear reducer, L mount, shaft coupling, shaft, tailcone bearing and mounting plate; propeller bearing and mounting plate; shaft collar; propeller; cap nut) positioned and held together with a combination of bolts and clamps. 

It turns but I don't dare run it until I get everything "trued-up and screwed down" as they say.  J

Didn't drill the bearing mounting plates to receive the bearings yet; waiting until the new manifold flanges arrive.  I believe the bearings and flanges share a common 4" bolt pattern and I'm hoping to get by with only one set of four bolt holes per plate.

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Here's a look at the propshaft sitting in the tailcone and propeller support bearings.  These old steel parts will serve the bench testing process and become templates from which I'll make better ones out of stainless steel.

Speaking of stainless steel; those fittings in the lower right quadrant are the basis for the manifold now.  That white PVC material in the bell serves as a watertight support for the mechanical shaft seal seat holder.  That black and white rubber thing in front of the threaded nipple (like a lot of what I do) got cobbled together from available hardware and parts of other devices adapted to my purpose.  That's been the theme of this project since day one back in the 1980's.  No great big shop or supply source here; just a shadetree mechanic making do with what's available.  J

 

Tuesday, April 09, 2019: The propshaft manifold flanges don't arrive until later this week; can't drill the bearing mounting plates until then.  Meanwhile, I've laid out the lumber to make the test bench (this is my workbench) and did a little cleanup work on that vintage brass propeller.  I'm not saying it would pass Brass Inspection at MCRD San Diego, but ya gotta admit it does look a little bit better.  J

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"Hi-Speed" 12 x 13 RH brass propeller

 

Wednesday, April 17, 2019: Went around in a couple circles getting the parts together for the propshaft manifold, but this is the final incarnation; pretty much exactly as originally designed.  The bolt pattern on the bearings and flanges match so I can bolt them to the tailcone bulkhead and propeller bearing bracket via the same four shared holes; which is very fortunate (less work) for me.  J

MANI 2.jpg

Stainless steel propeller shaft housing manifold.

 

Below is another view of the manifold with the functional areas indicated and explained.  A turbine-type high-speed carbon-ceramic shaft seal is in the bell-chamber and the cross-T will comprise a pressure-compensated chamber between the seal and the pressure hull / motor compartment.  Between the flanges and bearings goes the 1/4" stainless steel tailcone bulkhead and propeller bearing brackets, which bolt to the hull with rubber gaskets.  I have two 1-1/4 to 1/4" NPT reducer bushings for the cross-T; to which the fittings for the air inlet and one-way exhaust valve will fit, but they're not shown here.  I (at least) need to shorten them for height clearance and may actually have to weld them in. 

I'm confident the shaft seal will work but have some concerns about whether the pressure in the air-compensated chamber will defeat the seal.  That's why we're going to put the drivetrain together on a test bench; wrap a water jacket around the shaft seal chamber (after we drill some vent holes in the center nipple); and test it for leaks before it gets installed.  If the seal is as good as I think it will be; might not even need the pressure compensation.  We'll see when the time comes.

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L to R: Bearing; flange; close 1-1/4" nipple; bell; close 2" nipple; bell; 1-1/4" close nipple; cross-T; 3" nipple; flange; bearing.

 

And here's a pic of the manifold sitting in the tailcone of the submarine.  This isn't precise but it shows about where it will sit when the drivetrain is operational.  And for our new visitors: yes, the submarine is rusty and dusty.  It's all surface rust and that's why they have sand blasters.  J

MANI 1.jpg

Propshaft manifold positioned in tailcone / motor-mount area of NAUTILUS MINISUB.

 

I think the visual contrast between the rusty steel and the stainless manifold is interesting: depicts this as a vintage (old) homebuilt submersible being refurbished with new parts and technologies.  That's kind of what this refurbishment is all about.  The NAUTILUS MINISUB is an old warhorse being reborn.  When complete, all that "crud of ages" will be blasted off and she'll receive a new exterior covering of acrylic resin, acrylic cabochons (rivets), and acrylic enamel paint to compliment all the beautiful new stuff being installed.

UPDATE TODAY: Here's better looks at the manifold.  I think this exemplifies the spirit with which I've approached creative technologies right from the start: "Adapt what's available to accomplish what you need." 

This is a fairly sophisticated device of my own invention: a propeller shaft housing that combineds a  turbine shaft seal  with pressure compensation.  Most people would need to have something like this made for them and/or machined from scratch.  I found a way to do it using available hardware and things laying around my shop.   This is what you call backyard submarine boatyard ingenuity, folks.  That's what I'm all about.  J

 

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Side elevation view: NAUTILUS MINISUB propeller shaft manifold.

 

The fasteners look long but will come out just right when there's a 1/4" stainless steel mounting plate and rubber gasket between the outer bearings and flanges.  The reducer bushings in the cross-T go down to 1/4" NPT to accommodate the airline and exhaust valve fittings.  The entire assembly (including the plates that mount it to the submarine) are all stainless steel so there will be virtually no chance of rust contaminating the mechanical seal or bearings.

 

SS MANI 2.jpg

Planform view: NAUTILUS MINISUB propeller shaft manifold.

 

I want to get the reducer bushing bosses down flush with the top and bottom of the cross-T.  If it gets too tight trying to thread it down that far; I'll either shorten it and redress the threads or weld the hex head on.   Getting very close to having the drivetrain running on the bench with a functional water test of the shaft seal.  Progress!  J

 

MORE TO FOLLOW…

 

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