Merriman's Submarine Modelling

merriman

David Douglass Merriman lll
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Kudos, Sir - craftsmanship at its finest!
Thank you, sir. I carry on with a Craft taught to me by other, better, Craftsmen. These posts are my humble attempt to keep the ball in play.

David
Student of the Craft
 

Arjen

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Intriguing, but needs subtitles?
 

merriman

David Douglass Merriman lll
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Intriguing, but needs subtitles?

Duan Curtis is a 1/96 scale modeler. His specialty are 1/96 scale aircraft carriers. Here's a link to some of that work:


He came over here for a week so I could help him assemble his kit of the USS JIMMY CARTER. Lots of work has gone into un-warping the two hull halves. Today we're working to perform the traditional Z-cut needed to access the assembled models inner workings.

More pictures tonight. Need amplification? Just ask.

David
 

aim9xray

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Fascinating!

Reminds me of Roy Doty's Wordless Workshop in old Popular Science issues.
 

merriman

David Douglass Merriman lll
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I can waste time better spent in the shop by writing needless narrative. However, if you have an unresolved question, ask, and I'll explain.

David
 

aim9xray

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I can waste time better spent in the shop by writing needless narrative. However, if you have an unresolved question, ask, and I'll explain.

David
No criticism intended. I liked Wordless Workshop and looked forward to it every month. Thank you for posting your work. I'm learning from it.
 

merriman

David Douglass Merriman lll
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I can waste time better spent in the shop by writing needless narrative. However, if you have an unresolved question, ask, and I'll explain.

David
No criticism intended. I liked Wordless Workshop and looked forward to it every month. Thank you for posting your work. I'm learning from it.
No offense taken, aim9xray. I speak bluntly, and by so doing strive for clarity of message. I would be delighted to write up details presented in the pictures but in need of supplementing narrative. Just ask.

David
 

merriman

David Douglass Merriman lll
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In the late 80's Ellie and I introduced to the American continent the concept of the cylindrical, removable water tight cylinder (WTC). We were not the first -- just the ones who popularized the system on this side of the world.



The WTC is a complete system that features a watertight cylinder that contains three major subsystems needed to operate an r/c submarine model: Control, propulsion, and variable ballast. This basic layout applied to cylinders of varying diameter, wall thickness, and length -- each type suited for a specific application.



We quickly settled on polycarbonate clear plastic tube as the material of choice for the cylinder because of its useful physical properties. Lexan is easy to machine, and is much less susceptible to damage than the cheaper (and easier to source) acrylic plastic most people are familiar with.



For twenty years we produced hundreds of systems with no reports of failure of the plastic cylinder. However, about ten years ago, we started to get reports from the field that some WTC's were evidencing cracks -- these usually emanating from a drilled hole adjacent to an internal bulkhead. Should one or more of these cracks in the cylinder run through an internal bulkhead o-ring then flooding of the space within was inevitable.





The rate of these failure reports escalated through the years to the point where, today, I'm seeing a failure rate of nearly ten-percent of the units I produce for myself and friends (I retired from the business about a year ago). The situation was most unacceptable!

A situation that was only resolved recently as Bob Martin, of the Nautilus Drydocks, developed a new line of SubDrivers; a product that cleverly employs a modular scheme of Lexan cylinder segments which do not require drilled holes in the Lexan plastic cylinder.

I just could not let this cracking problem go. So, I did some reading and found that I could easily anneal my Lexan cylinders in the kitchen oven, thus stress relieving the materials crystalline structure, likely caused by some bean-counters implementation of frugal production practices -- I suspect, as a coast saving measure, that either the chemistry of the plastic and/or the post extrusion temperature control protocol had either been eliminated or curtailed.

Bottom line is this: today's Lexan plastic cylinder (and this varies from manufacturer to manufacturer) is much more brittle and prone to cracking than the Lexan products of old.

The solution was to anneal the Lexan cylinders here, in the kitchen.





I found that preheating the oven to 240-degree F, then loading it with cut-to-length cylinders, then waiting twenty-hours for the oven temperature to creep back down to room-temperature did the job of re-organizing the crystalline structure of the plastic to the point where stress forces imparted during manufacture were relieved. I no longer observed significant cracking of the Lexan cylinder, no matter how tight I made a fastener running through a drilled hole.



A few months ago I cut two lengths of 2" diameter Lexan cylinder. One I annealed, the other was not. I then mounted an internal bulkhead and emergency ballast blow cylinder within each, tightening the screws and retaining collar with unreasonable force. Show time!



Recently I examined the test articles: Sure enough, the annealed one evidenced no cracking; the one that was not annealed had cracking.



So. Problem solved. Henceforth all WTC Lexan cylinders will be annealed!
 

merriman

David Douglass Merriman lll
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Of the many facets of radio controlled modeling, r/c helicopters and r/c submarines stand out as the two types that demand the most user involvement in their construction and maintenance. This screed describes just some of the 'after action' procedures that must be performed on an r/c submarine after a days outing at the local lake or pool.



maintaining an r/c submarine (and I'm talking about hand crafted, fully capable submarines, not Walmart or mail-order ready to run toys) requires work before, during, and after a days outing. I've broken these tasks into three parts: pre-mission, mission, and post-mission.

Pre-mission is what has to be done to ready, check out, and assemble the WTC to the models hull and get the two sub-systems to work as one. Mission checks are done at the boating site during the operation of the model submarine -- it's during this phase that problems encountered are either corrected or logged for later referral and action once the model is back home. Post-mission operations deal with the preservation and, where required, repair of faults identified during the mission phase.

This discussion will focus on the post-mission checks and operations.

Unboxing the model(s) after running at the local lake or pool. A little appreciated necessity -- and a vital element in support of the safe stowage and transportation of the model -- is manufacture and use of a well padded, stout box, as seen here. Think about it: you put so many hours of work and laid down so much money to achieve the model, why risk it all to a simple fender-bender on the highway (ain't' that right, Johann!?...). It's not enough to wrap the model submarine in a blanked, and toss it into the back-seat. No. You place it into a well designed, purpose built storage-transportation box!



This 1/96 LOS ANGELES class model submarine had been operated at a distant lake that was thick with duck poop, leaves, and algae. As there was no fresh water on site to give the model a preliminary rinse-down the model went into its shipping box for the trip back home covered in lake gunk. Obviously the first post-mission check would be to clean off the crud.



Cleaning is a simple matter. Some soapy water is prepared and the model hull and WTC, outside and interior, are aggressively scrubbed with a soft-bristle paint-brush to break loose all the gunk.



The removed WTC gets the same treatment. Not forgetting to get plenty of soapy water into the ballast tank as well.



And the hull and WTC get a complete rinsing with fresh water applied as a low-pressure shower.





The cleaned hulls and WTC's are left to dry off.

At this point each WTC is taken into the shop, opened up and any issues identified during the mission phase addressed. The WTC is made safe by venting off the gas charge in its emergency blow bottle, and the battery removed and put into storage. The forward and after bulkheads removed and the entire unit put into a dry, dark environment for storage.



And the hull returned to its transportation-storage box which in turn is taken inside and placed in storage.

 

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