A Wheel of a Tale

Here are progress shots of the wheelhouse interior I'm building from a static CR kit I am putting together. The methods developed here will be used on the r/c boat I've been describing. While a mini kit in itself, the CR wheelhouse goes together well and has been a fun diversion from some of the more involved tasks of late on the r/c boat.

I've followed the CR instructions pretty faithfully and everything has fit together nicely. While at first glance the project seemed a little daunting, in realityit has been a swift and relaxing build. I've hand brushed almost all the paint except the deck and the results have been more than satisfactory. One of the details I didn't find in the kit was a compass card for the helm's binnacle. Taking a cue from some of the build threads on disneysub.com I downloaded an actual 1:1 compass card image and shrank it in PhotoShop. The hard part was cutting the tiny thing out. But once affixed with a dab of white glue it really looked good -- in my opinion.

Here's a shot with the wheelhouse exterior in place, taken through the aft window. The rails will be added next along with some lighting to make the details easier to see. Collison speed -- full!

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Whale of a Tale

Recently I had the privilege to travel to Honolulu for the remembrance ceremony and activities given by the USS Bowfin Museum for the family of those lost aboard USS Wahoo (SS-238) during WWII. It was an amazing time and the fulfillment of a lifelong dream to visit Pearl Harbor and the Submarine Base. During the trip I blogged a journal of the activities. You can read all about it in the War Fish Blog.

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In The Tank

While certainly speaking to my lack of posting over the last few months, what I'm talking about is a quick snapshot of the new ballast tank actuating mechanism I've worked on over the last few months. Really, not worked on is more like it; a few several day spurts of concentration followed by prolonged inactivity.

Below is the general layout of the new system. The Lexan tube is new, purchased from Small Parts, Inc. They carry short lengths of 3" OD. The stock D&E Propel tank was modified with a new barbed fitting for the gas hose and cleaned and painted. The ballast tank is elongated by 3/4" to add reserve bouyancy, which has always been marginal in my LA. The pass-through tube is of slightly larger diameter to allow more room for the wires. It is glued in place to eliminate leaks and o-rings. The servo is now mounted over the battery in the forward compartment and drives the linkage via a rotary seal.

The brass control shaft passes to a bearing in the back bulkhead for stability. The servo, with metal gears, turns the shaft which rotates the control arms to either vent the tank or hit the Propel blow valve. The vent valve for the tank is not shown but was machined down from a stock Schrader valve. It is screwed in upside down so the arm pushes the pin up and opens the vent -- just like letting the air out of a tire.

As you can probably tell, the mounting tab for the aft bulkhed interfered with the rotation of the arms. After much deliberation it was decided to remove the tab and go with three screws to hold the aft bulkhead. They are basically just to hold everything in place and it shouldn't cause any problems.

Installing the blow valve and arm are the last steps before final assembly. Then it's off to the pond to test things out. Once again, little of this would be possible if not for the kind assistance and expert advice of Gail Phillips. The basic design is modified from his original work.

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Ballast Tank Blow Up

Since the Sun N Fun run I've been working on a major redesign of the ballast tank mechanism which goes in my 1/96 scale boats. I could not get it to blow in College Station and the servo seal has leaked repeatedly. So the time has come to replace the head and handle on my trusty D&E Miniatures axe.

After some disassembly, I found the tank would not blow because the Propel tank's internal discharge tube was plugged. The external fitting was removed and silver soldered closed. A new brass barbed fitting was installed on the end and silver soldered.

Cracks in the Lexan were also discovered around several screw holes so I purchased a new 3" Lexan tube from Small Parts, Inc. They sell Lexan tubes up to 3" od in 24" lengths. This is great because most other places you have to purchase an 8' minimum. Unfortunately, 3" is the largest diameter they carry.

Borrowing heavily from Gail Phillip's modification of his original D&E WTC-3.5, I sketched out the modifications I wanted. With Gail's assistance we turned a new 3" bulkhead master from which I created a mold. Four new bulkheads were cast and I headed back to Gail's where we turned the o-ring grooves on his lathe. I spent the better part of last Saturday marking and drilling holes in the cylinder to mount the bulkheads and tank. I also took the opportunity to lengthen the ballast tank by 3/4" in order to increase the reserve bouyancy for my LA model.

The blow/vent servo has long been a source of leaks so I decided to mount a mini servo on its side in the forward compartment over the battery and employ a radial shaft to activate the vent and blow mechanisms mounted on the after ballast tank bulkhead. The radial motion through the seal should greatly increase the watertight integrity. The diameter of the pass-through tube between the bulkheads was also enlarged slightly to allow the passage of the additional servo lead to the aft compartment along with the battery and speed control leads.

The result should be a much more efficient system, leak free, and maintainable in the field. Pictures will follow as things come together.

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Sun N Fun 2007

Spent the weekend with my sub skipper friends at our SubRon5 meet. Below is some video of my 1/96 scale 688i Los Angeles class boat underway at periscope depth. The site is the indoor instructional pool at the student rec center at Texas A&M University.

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Rudder Linkage In Action

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Course Correction

With the rack and pinion setup in place, I hooked up the control lines for a trial run. I was ready for the satisfaction of an easily flopping rudder. However, upon testing the setup a few observations were made: 1. the rack required a tremendous amount of linear force to move the rudder; 2. the open end of the rack housing allowed the rack to pull away from the pinion gear when force was applied. The similar setups I'd seen in the SCR showed full housings for both the rack and the pinion gear. And they used bellcranks and brass rod to transefer the force to move the rack. Now I know why. My configuration, though sound, would require some modification.

While I chased the new varaibles through my head, an old notion came back to me: why not try an extremely short control tab mounted on the shaft linked to a conventional pushrod? I'd done this in my 1/96 USS Thresher which has a pretty confined tail cone. It would be easy enough to knock together and would settle that particular idea for good -- one way or another.

After a few hours in the shop the end result was a new keyed upper rudder shaft with a small control tab. It's width was dictated by the upper rudder fin dimension. A brass shaft hooks into it via a z-bend and the wheel collar connects it to the nyrod pushrod. Talk about keeping it simple!

A pull on the nyrod control link inside the hull and the rudder answers to port.

A push and the rudder answers to starboard.

The next trick is to finish the upper rudder fin, pour a mold, and cast an new GRP piece. Then everything can be fine tuned to fit inside. However, at present everything is within design parameters and fully functional. Once I figure out the best way to post it I'll have a short video of everything in action.

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Engage The Rack & Pinion!

Spent some time installing the nyrod and fabricating a linkage set for the rack. The nyrod is Sullivan Precision Rod, 91.4 cm diameter, with a carbon fiber 2-56 pushrod. I drilled a hole in the control deck upright and inserted a length of brass tube to stabilize it as it passes through the bulkhead. The final turn is rather sharp so this keeps it from angling upward. Brass rod was cut to length, threaded to 2-56, bent into a Z-bend and screwed into the end of the control rod.


A control linkage tab was cut from brass stock along with a spacer of the same thickness. Both were clamped in place on the end of the rack and soldered. The spacer gave the tab the proper height to engage the control rod. A hole was drilled in the tab to accept the Z-bend in the rod.

One side of the rack housing (a square piece of brass tube) was opened to allow the rack tab to travel inside it. Keeping as much length of the housing as possible prevents slop when the rack moves. At present the housing is set in place. Ultimately it will bolt to the deck.

A close shot of how the rack engages the pinion gear. The shaft is not quite finished but the gear will ride just proud of the deck. The pinion shaft serves as the pin which holds the rudder in place. Another tab will be installed to keep the shaft and the gear from working upward during operation. While holding the rack housing in place, the control rod works easily inside the boat, turning the pinion back and forth. I can almost see the rudder wagging!

The results are very satisfying. This is the first model engineering project of this complexity I've ever attempted and it's pretty cool when it comes together. So far, the only fabbed items I've purchased are the rack and pinion gear. Everything else was made from stock K&S brass items using basic hobby tools (Dremel, disc sander, files, solder). And it all fits within the footprint of the upper rudder piece!

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Quickly I Turned...

Did a check on the travel needed for the rack to turn the rudder. Was surprised to learn that the current setup only requires about 1/8" push-pull to turn the rudder 35 degrees port and starboard of center. Less than I was anticipating. Should help keep things simple as I get into hooking the linkage up and making the rack fit within the confines of the upper rudder.

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Upper Rudder Plate Progress

More progress on the upper rudder control linkage deck. The upright mounting plate was cut from brass stock and soldered to the lower deck plate. The upper rudder fin indexing pin hole was used as the hole for the stainless hex head bolt.

From this angle you can see the access hole for the nyrod control link has not been drilled yet. I want to keep this opening to a minimum to reduce stress on the solder joints. Will probably put brass braces on either side of the hole to add support.

The rack and pinion resting in place. I'll need to finish a few more things before calculating the final length of rack needed. The square brass tube serves as a guide and support. With a little grinding and experimentation it should all fit. The new GRP upper rudder fin will fit down over everything and actually bolt onto the control linkage deck.
My benchtop 5" disc sander has been a life saver. It grinds down the soft brass easily.

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Rudder Mods - Part 1

In order to increase the room in the upper rudder fin for control linakges I've decided to use the cast resin piece to create a master for a new GRP (Glass Reinforced Plastic, or fiberglass) piece. To create an upper rudder master with more internal volume, the sides needed to be widened.

The first step was to mask off the area to be altered. Then a small piece of styrene was glued in position as a guide for both contour and to set the maximum height of the filler.

The masked area was then filled with a layer of Evercoat Metal Glaze. This automotive grade polyster filler dries quick and can be worked extremely well. I globbed it on with the stick then scraped it smooth to work it the proper height and shape.

The modified rudder fin in position for a check. The sides were widened 1/32" on either side in the center, then faired back towards the tail after the rudder hinge point. Red putty and sanding finished out the imperfections. All it needs now is a coat of primer, some rescribing in places and rivet replacement. The square access plate on either side for the rudder hinge will be masked off and simulated with a few applications of primer to build up the panel.
Here is some initial work done on the rudder linkage mechanism. The brass plate will mount to the hull below the hole drilled for a nyrod control line. A keyed shaft fits through it into the upper rudder to secure it to the plate. The gear at the top of the shaft will mesh with a rack (not pictured). The nyrod will link the rudder servo in the WTC to the rack transferring the servo motion to the gear. The hollow GRP upper rudder fin will mount down over this assembly.
More to come as time, and progress, permits.

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2000 Words

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Seam Stealing

No pictures at present but I've been working on the seam between the upper hull hatch and the lower hull. It came fairly tight but there are the occasional gaps up to 1/16" in spots and I thought I'd try to hide them.

First, I made sure the upper hull hatch would not stick to the filler material. I did this by brushing on a layer of PVA which I use as a mold release agent when laying up Type XXI hulls. When this was dry, I also applied a thin film of bearing grease down the edge of the hatch. Just in case.

Then, I sanded the lower hull lip for good adhesion. 3M painters tape was masked around the external edges to keep from spoiling the rivet detail. I also put the tape along the edge of the upper hull hatch as well.

The filler of choice was Evercoat Metal Glaze. I mixed a small amount up on a plastic putty spatula and applied it sparingly to the lower hull lip with a popsicle stick. No need to glob on too much and watch it ooze down the side (this stuff isn't cheap). The upper hull hatch is then installed and securely fastened. Only small sections (4" - 6") on one side are filled at a time to ease separation once the Evercoat cures. Any excess filler is scraped off to leave a smooth seam.

After an hour or so, the upper hull hatch is unfastened and gently pried loose -- snap! The result is a nearly invisible separation line between the two hull halves.

NOTE: for those who've lost any of your tiny button head socket cap screws used to secure the upper hull hatch the size is #2-56 and the length is 1/4". A pack of 50 in stainless steel can be bought from Micro Fasteners for $5.50. I'm switching out the kit supplied alloy steel screws to prevent rust in the field.

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The Reason For Resin

A quick update on some work done using kit-supplied parts. While the stock pieces were well made and could be used as supplied, I made molds from them instead to cast new parts better suited to planned r/c operations.

The standard diving planes came with watertight bushings. As mine will be a wet hull boat the bushings were unnecessary. Also, the shafts were keyed into the resin during manufacturing and could not be removed (I tried, and broke a shaft). In order to facilitate easy removal of each plane from the boat for servicing or replacement, I wanted to make the shaft removeable. This required making a mold from the original and casting up duplicate pieces in polyurethane resin. You can't see it due to the white resin but the rivet detail came out great on the new parts.

With the planes installed, the side keels trap them in their well. The solution for freeing them is to make the shafts removeable. Casting them with a round shaft as before was easy in the new mold. However, to prevent any slipping of the plane around the shaft, a new shaft was modified from square brass bar stock and brass tubing. Each plane was cast with the shaft in place. Once cured they were removed with a gentle tug. They seat firmly, do not slip in the part and provide for quick removal of the plane.

Molds were also made from a white metal prop guard and guard support piece. Duplicate parts were cast in resin. Carbon fiber rod was placed in the mold and cast into each part to reinforce the plastic. Once cured the parts are extremely tough. They are also significantly lighter - the reason I made them in the first place. The white metal parts weighed 11.5 ounces. The resin ones total 2.5 ounces. Eliminating 9 ounces of weight from the end of a heavy boat will help make trimming easier and enhance performance.

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Riveting Development

In the course of working on the forward seams between the main hull and the removable upper deck, several rows of rivets were lost. And the thought of restoring them bit by bit with tiny drops of JB Weld reduced with lacquer thinner made me ill. Fortunately, through a wonderfully timed post at disneysub.com, a much more user-friendly solution was found. Tichy Train manufactures tiny plastic rivets in a size that works well with the 1/32 scale Nautilus.

To install them, one needs only to cut a rivet from the tree and drill a pilot hole in the correct spot. I used a twist drill.

At first I tried placing them in the hole with tweezers. But the plastic was very slick and they had a tendency to make a break for the floor and the plastic these rivets are made of has the unique property of instantly becoming invisible upon contact with concrete. I settled on dabbing them with a piece of masking tape and then sliding them into the pilot hole. A drop of thin CA secures them in place.

They come in packs of 96, enough to lay down a healthy line of rivets. I'm even looking at replacing some of the droplet style rivets molded into the hull. For the price ($2.50 per pack) you can't beat them.

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A Tip Of The Cap

Every r/c submariner knows headgear is an essential part of the patrol experience. I've long had a vision of the ideal cap to wear while running the Nautilus: dark blue low profile baseball cap style with the patch from Nemo's captain's hat embroidered on the front. Since the boat was so far off from completion I never got serious about having one made.

Until, that is, I saw a post on disneysub.com about the Nemo cap badge design. AlphaRed6 had a line on an eBay embroidery vendor who could make the design. I contacted Tracie Henson (eBay Seller ID: the_house_of_henson) and she produced the following results:

Cool, huh? Tracie did a wonderful job, answered all my questions, and made and shipped my cap immediately. If only finishing the boat was that easy!

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Side Keel Fastening - The Final Solution

In the beginning there were wheel collars. They slipped over the side keel pins which ran through the side of the hull into the interior. They held the parts in place, but there was slop. Not a snug, tight fit. But they slipped on and off with ease and allowed me to check the fit of a particular piece quickly.

But I wanted the side keels secure -- nice and tight against the hull -- when it came time to gluing. So, I bought a die and threaded a pin to accept a stainless washer and nut. This proved a handful when working on the pin in the part. As I worked, the pin slipped out in my hand and voila, another inspiration.

Searching through my bench I found a length of brass rod the same diameter as the pins and I began to thread it. My goal now was to replace all the pins with threaded rod. As the first threaded pin replacement was completed, rather than tapping the pin hole I simply screwed it into the side keel where the pin went previously. The slightly oversized threads bit into the plastic nicely. Trying the new arrangement I slipped on the washer and nut. It snugged the part right down to the hull. Unfortunately the nut was a little oversized and slipped a bit as I played with it but the idea worked in principle.

While contemplating the replacement of the rest of the pins, a picture of all the pin lengths and nuts running down the midline of the hull interior came to mind. Not too pretty. How to make it appear more uniform and precise?

Inspiration came again in the form of a hex socket head cap screw lying on the bench. It was stainless, and of the same thread as the new pins. I pulled another pin from the side keel and threaded the cap screw into the hole. Perfect! It was self tapping, secured the side keel tightly against the hull and would provide a uniform appearance to the hull interior.

I quickly purchased enough 4-40 stainless cap screws and washers to replace all accessible pins (two on the extreme ends, fore and aft, were too hard to get to with an allen wrench to tighten). With some final alignment sanding, all four side keel parts are ready to be permanently glued in place.

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