1/48 scale Type VIIC U-201 build

[Monahan Steam Models]

I feel like a dung beetle pushing an elephant turd up a hill with this build. The small things that make a difference I guess. Finally got the forward dive planes working again with the new servo in the wet design.



Kept the magnetic coupler design as it is still relevant for quickly removing the forward servo equipment mount as a unit without pulling the whole launch tube assembly out too.

Here is a short video of it working. https://youtu.be/TikVaWcqAxA

The servo is not waterproofed yet and I plan to upgrade the bow plane cross shaft to something similar to what I did for the aft planes but hey it’s progress so far.

At this point, all the control surfaces are functional and the props spin. The torpedo systems are functional and the new WTC is almost complete. The original design worked great so the new one should be also good. Still lots of little details to address before the cosmetic part of the build can start hence the uphill turd battle still. It’s getting there.

Nick

[rwtdiver]

Thank you, Nick,

It certainly does help! You sure do things the right way. I cannot believe what you are doing to your Vll, and the quality in the design and the manufacturing of the components. "Perfection in motion"

If I can just get all control surfaces to work properly, and have the boat operate and descend to periscope depth, then I have achieved my goal. I am going to follow the YouTube that Bob has out on how he weathered and applied the finished his Vll. This will be my first true submarine weathering process that I have done, so I will look forward to that as well.

Thank you again, Nick. I do appreciate your help, advice, and expertise.

Rob
"Firemen can stand the heat"

[Monahan Steam Models]

Nick,

I have a question for you. Dose the Arkmodel Vll kit come with the prop shafts, and if so, what size they are? I know the 80 mm WTC that I have coming for my boat has a 4 mm dual shaft.

Thank you nick,

Rob
"Firemen can stand the heat"

Yes the Arkmodel type VII that I purchased from Bob did include the 4mm prop shafts. The stuffing boxes that come with the kit are nylon tube and are junk. I replaced them with stuffing boxes made from K&S .250” OD brass tube and oil embedded bronze bushings. The bushings had a 5/32” bore and a 7/32” OD. The bore of the bushings was opened up to 4mm with a high speed steel multi-flute ream.



Here are the bushings and the part number.

I keep the bushings in place in the tube with blue locktite applied to the OD of the bushing prior to inserting it into the brass tube. The bosses that are molded into the Arkmodel hull for the original nylon prop shaft tubes have an ID of 6mm or .236”. These were opened up a couple thousands at a time with a series of reams till I arrived at a ID of .250”. You could open the ID up more for a looser fit or to have some play to get the new stuffing boxes aligned with the outer supports and then glue them in place also.

Part of the reason I did it the way that I have is during this whole build, I have been measuring and documenting all the critical features of the hull in CAD trying not to disturb the alignment or placement of the original moldings. This allows me to know in a 3D environment where everything is in relation to other features. Comes in really handy when designing the all the new junk that I’ve been putting into the build. LOL! Anyways, hope this helps.

Nick

[rwtdiver]

Nick,

I have a question for you. Dose the Arkmodel Vll kit come with the prop shafts, and if so, what size they are? I know the 80 mm WTC that I have coming for my boat has a 4 mm dual shaft.

Thank you nick,

Rob
"Firemen can stand the heat"

[Bob Gato]

You tend to give us more information from smaller updates- Also easier to eat the elephant one bite at a time -BG

[SubDude]

Smaller more frequent...really liking the updates.

[Monahan Steam Models]

Well I managed to get project Flying Spaghetti Monster transferred over to the new forward water tight section. It’s in the initial assembly stage. Will need to break some of it down to add sealant to some components for final assembly and finish connecting wires to the 17 pin data bulkhead plug.



I am already enjoying the modular style of each compartment with more components being fixed into the hull not needing to be removed. The way the forward compartment end cap clicks into place with the forward alignment dowels in the hull is easy and everything feels rock solid.



View of the equipment installed on the upper shelf. Slightly different arrangement than the original design with the servos removed and the LPB now moved to the center. The eight color ribbon cable will be replaced and routed to the 17 pin data plug. So that will be a much cleaner look.



The underside of the lower shelf that holds the trim tank pumps is less busy than the original design since the power cable connection and harness has been removed.



Here’s a view of the forward end cap. The counter sunk wells around the brass nipples are for the flexible potting epoxy to fill.



Overall view of what the new forward dry compartment looks like currently.

Do those of you following this build enjoy these smaller more frequent progress updates or do you prefer less frequent but more major milestone updates?

Nick

[Monahan Steam Models]

It looks like the Flying Spaghetti Monster currently but I’m just starting to transfer the guts from the forward dry section over to the new WTC.

[Monahan Steam Models]

This is roughly where I was trying to get to yesterday with the work being done on the forward data cable connection.



The gold plated 10 pin header is soldered to a printed circuit board and the 6 wires are connected. I chose to use a gold plated pin header for the excellent corrosion resistance properties. The majority of the time, these pins will see no current flowing through them and when they do it will only be for a second or two.



View of the connections to the board.



This header pin retainer keeps everything positioned in correct place until the cavity is filled to the top with the epoxy potting compound. The 2mm stainless screw holding the retainer in place is counter sunk below the housing’s edge, so it will also be no longer visible once the potting compound is poured into the cavity.



Before the potting compound is poured, all connections will be tested one last time to make sure there are no issues before everything is permanently entombed in epoxy.

That’s about all for now.

Nick

[rwtdiver]

Thank you Steve!

Rob,

The Arkmodel type VII is a great model. You’ll enjoy building it. The 80mm cylinder from Bob will be perfect for this boat and the top of the cylinder will be just at water line or slightly below depending on how you mount it in the hull. I’m using a 90mm in my build like the kit was designed for which sits in the hull’s molded in cradles, but this puts the top of the cylinder slightly above waterline which starts to work against you. It’s not much of a problem in my build because I have extra trimming capacity from the forward and aft piston tanks that sit below waterline.

If you have any questions during your build, please ask away, I or others who have or who are currently building this model will be glad to help. I went a bit overboard with the way that I chose to build my boat but that is just how I decided early on to build this particular project.

Nick

Thanks Nick,

I am sure I am going to have a lot of questions. I do appreciate your willingness to lend a helping hand!

Rob
"Firemen can stand the heat"

[Monahan Steam Models]

Started work on the forward data cable water proof connection this morning. Didn’t get very far as the day took a sudden dramatic turn early on but here’s what was accomplished.



These are 17 pin IP68 rated connections that I use at both the forward and aft WTC sections. The connection itself is water and pressure tight but where the cable sheathing enters the molded plastic connection housing, I’ve found is not water tight. So let’s perform some surgery.



This first starts out as carefully sawing into the plastic connection housing just deep enough around it’s circumference where it meets the flexible cable sheathing.



Once the cut is done, the cut off portion of the plastic housing is slide back and removed.



Here’s the connection with the cut off plastic housing portion removed. The next step is carefully cutting away a section of the cables sheathing.



Here I have carefully removed about an inch and a half of the 17 wire cable’s sheathing.



The cable ends are then fed through the forward junction housing for water proof harness. Six of the seventeen data wires are cut from the cable pack which will be connected to a ten pin male connection at the forward end of this junction. This will provide one common five pin connection and five separate connections for the five torpedo solenoids.




Another look at the cable junction assembly. Those loose wires will be connected to a ten pin connector yet to be shown. The whole housing and assembly will be potted in epoxy to water proof it.

Nick

[Monahan Steam Models]

Thank you Steve!

Rob,

The Arkmodel type VII is a great model. You’ll enjoy building it. The 80mm cylinder from Bob will be perfect for this boat and the top of the cylinder will be just at water line or slightly below depending on how you mount it in the hull. I’m using a 90mm in my build like the kit was designed for which sits in the hull’s molded in cradles, but this puts the top of the cylinder slightly above waterline which starts to work against you. It’s not much of a problem in my build because I have extra trimming capacity from the forward and aft piston tanks that sit below waterline.

If you have any questions during your build, please ask away, I or others who have or who are currently building this model will be glad to help. I went a bit overboard with the way that I chose to build my boat but that is just how I decided early on to build this particular project.

Nick

[rwtdiver]

Hi Nick,

Well, I just purchased the Arkmodel Vll kit and 80 mm WTC from Bob! As you know if you were following the Kilo build that I started, it did not work out for me for many health and shop related issues. I just wanted to say this on Bob's behalf. What an honest and extremely fair man he is! He did give me a (MORE THAN FAIR) partial refund on the Kelo kit towards the Arkmodel system. I am sure that anyone on this forum that has ever had any dealings with Bob knows what kind of person he is as well!

I am going to go over your build and pick up on every little morsal of information I can use towards my build. I am sure my build will not even come anywhere close to what you are doing here on this build blog! Thanks for sharing your build!

Rob
"Firemen can stand the heat"

[SubDude]

Dang, you do nice clean work Nick!

[Monahan Steam Models]

Quick build update.

Work has been progressing on the design and build of the new water proof data and power cable harness. Last I recall there was something like 48+ wire connections that needed to be made and sealed up.

I turned my focus over to the forward end of the hull to work on a mount for the bow plane servo and other parts.



The way I designed the original WTC was to be inserted into the hull through a vertical split separation of the aft hull section. Because of this all the equipment that lived outside of the WTC had to be attached to the forward end cap shown above. The servos for the ballast control and bow planes were inside the WTC and these fancy linkages made everything work outside the WTC.



Another view of the original forward equipment.



Here’s the new forward mount for the bow plane servo and pressure regulator for the torpedoes.



The new equipment mount has two stainless steel alignment dowels that interface with sockets in the forward end cap.



These are the two brass sockets in the forward end cap that mate with the stainless dowel pins.






Here’s forward end of the new sectional WTC inserted into the hull and mated with the dowel pins. This simple connection does a number of things. It locks the forward end of the cylinder at a vertical height in the hull while also keeping it from rotating on its axis. The forward section of the hull does not feature a cradle molded into the hull from the factory to support the cylinder so this takes care of that. Due to the way I split the hull at the waterline, the hull relaxed in a spread apart manner. These pins when mated to the cylinder also pull the two hull halves back together where they originally were. The last jobs the alignment pins perform is keeping the cylinder and forward mount in perfect alignment with each other which later in the build, I will show how this helps with the new data cable connection and how it works with only removing the aft section of the WTC.



The new forward mount was designed to use the existing molded in features of the hull. The stainless steel fasteners I use through out this build are the thread forming type and not the thread cutting type. This reduces the threads in the plastic from becoming worn out quickly if at all.



Starting to populate the forward mount with the gear.



The torpedo launch solenoid pressure regulator installed and the bow plane servo installed.



The forward mount reinstalled into the hull with the bow plane pushrod. Still need to make up the connection between the servo and the pushrod but this is where I got with the build as of today.

Going to jump back over to the external water proof wiring harness part of the build. There is some cool stuff with that part of the build that I will hopefully be able to share next. Once all this mechanical and technical part of the build gets done I can hopefully move on to assembling the dang kit! It’s gotta run good before it looks good.

Nick