Profintern Build

Discussion in 'Warship Builds' started by Bob Pottle, Sep 14, 2015.

  1. Bob Pottle

    Bob Pottle Well-Known Member

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    Yesterday I finally started to build the Russian CL Profintern (pre-WWII name for the Krasni Krim).

    The hull is the first from a mold I had built for me on commission in 2007, but on inspecting the plug before giving the go-ahead for the mold I missed a major error. The splinter shields at the side sponson positions were made twice as high as they should have been, but with the excess being below quarterdeck level, placing the angled plating beneath the sponsons nearly 1/2 inch below the 3/8" deck stringers.

    I didn't want to sell the hulls with that error so with the first hull cut off the excess splinter screen sections and the sponson supports below, leaving the correct splinter screen height above the quarterdeck and holes in the hull sides below. The holes were dealt with by reglassing the hull sides and the plan was to have builders make the angled sponson supports from wood. The fiberglass modifications took so long it was not economical to sell the hulls, though one captain in Florida didn't mind the sponson error and bought one.

    Two years ago I decided to redo the hull plug, which had been sitting in the basement for 6 years. it was completely reskinned, correct sponsons were made, minor errors in the bow shape and a slight asymmetry between port and starboard forward casemate decks were corrected. The hull plug was donated to Strike Models in 2014 and the hulls are now in production.

    Before redoing the hull plug I'd corrected the bow shape on my hull, using gelcoat and fiberglass. The bow was a bit too narrow, and the forecastle was supposed to be level but sloped forward and was 3/32" too low at the bow. I held the hull at correct beam using brass rods and added fiberglass cross-members between the two forward and the two aft casemates. Then the hull sat gathering dust.

    This weekend it was marked and taped for penetrable areas and the port side was cut-out. (Photos to follow.) The starboard side will be done this week and the running hardware will be ordered. I used my last Robbe rudder kit (now OOP) to make a rear rudder of correct shape but it needs to be extended aft 1/4" to be the right length for the allowed area. The forward rudder will be made from the cut-off section of the deeper than required Robbe rudder and will be scale size, being only 1/2 square inch in area.

    I did an equipment inventory on the weekend and to my surprise found 3 complete Camurati pumps, nearly all the parts for a 4th, a 1/2 unit never-used micro-pump with spare plate to install a 380 motor, and parts to make several BB cannons with stainless steel tight-tolerance barrels.
     
    Last edited: Sep 18, 2015
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  2. SteveT44

    SteveT44 Well-Known Member

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    Looking forward to the build. It's a very interesting looking ship.
     
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  3. Bob Pottle

    Bob Pottle Well-Known Member

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    I spent a couple of hours last evening going through boxes of spare parts I hadn't opened in years; found lots of stuff that can be used for Profintern:

    Raboesch nylon and brass u-joint couplings, 360/385 motor mounts, a never used Robbe servo-operated step switch kit for throttle control (have to disable the faster of the two forward switches that puts two motor batteries in series vs parallel), Tamiya servo-operated speed resisitor, more props shafts and tubes, a dozen more 360 motors of various types, and the missing stuffing tube and rudder arm from the Robbe rudder kit.

    Also found several BB cannons including some for small models. One is a 1.5 unit cannon with stainless steel tight tolerance 4" barrel and Foster breach (I'll need another like it), plus two of my light weight cannons - one's a 1.5 unit spurt gun that fires all 15 BBs at once, the other is a 1.5 unit spurt gun that fires 3 BBs at a time.
     
    Last edited: Sep 18, 2015
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  4. Nick Park

    Nick Park Member

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    wish I had boxes like that!
     
  5. irnuke

    irnuke -->> C T D <<--

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    Stay in the hobby a few years...you will. :laugh:
     
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  6. Bob Pottle

    Bob Pottle Well-Known Member

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    I finished Profintern's main rudder yesterday. I'd found a spare Robbe rudder kit, cut the nylon rudder to match the upward slope of the keel and to fit under the stern without protruding below the bottom of the model. That produced a rudder that was 36mm long and 27mm high at the front, but a bit too small.

    With the 50% bonus for having two rudders the total area would be 2.63 square inches, with 0.5 sqare inch going for the scale size front rudder. To make the main rudder 2.13 square inches it had to be extended aft by 7mm. (I work in metric - 1 square inch equals 645 square millmeters.)

    To do that I cut out the rudder design (including both sides) from 0.5mm styrene sheet, scoring the center at 1mm intervals where it would have to bend around the front of the nylon rudder, and gently pre-bending it. I made each side 4 mm too long to allow room for trimming. The nylon rudder was sanded with 100 grit and the styrene overlay was bent around it and glued on with slow setting CA glue. When that had set the ends of the styrene overlay were glued together with styrene glue and held in a small modelling vice until set. Where the ends were clamped together there was a slight concave depression on either side at the rear of the rudder. A narrow strip of 1mm styrene was glued vertically on each side and the rest of the depression was filled with Tamiya grey putty, which was also applied to the top and bottom surfaces of the rudder. After a couple of hours the rudder was sanded smooth and trimmed to the correct length.

    The front rudder will be next. There is enough of the nylon rudder left (the part I cut off to reduce the height) to make the front rudder by filing and sanding, then inserting a 1/8" rudder post.

    Metric hardware will be ordered from the UK this week: stainless steel prop shafts and stuffing tubes, Raboesch 25mm diameter props and universal joints. RS360 RH motors are on the way from the USA. The drive train will be identical to those in the Canarias and Suffolk, but the props will be smaller.
     
    Last edited: Sep 21, 2015
  7. Bob Pottle

    Bob Pottle Well-Known Member

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    The box of Mabuchi RS360 RH motors from ebay arrived yesterday. First time I've been able to buy this type of motor in more than 10 years. I used them in all of my 1995-2003 models of Class 3 and under except the I-400. The rest of the Profintern's drive train should arrive within 3-4 weeks.

    It's getting dark by 1930h now so by the time I get home from work, have supper and walk the dogs there's less than 1/2 hour of light for cutting out the hull. (You do not want to do that anywhere but outside due to the huge amount of dust generated, and be sure to wear a mask with good filters.) I still haven't finished the starboard side but it'll be done this weekend and photos will be posted.

    The next step will be to install the rudder stuffing tubes. My standard technique is to drill a hole through the extra layers of fiberglass that were added at the rudder locations, install the rudder tube, glass around its base, then solder fore and aft braces made of brass tubing to the rudder tube. The braces slant down to the keel at 45 degrees and are glassed to the bottom of the hull. To help protect the rudder tube from BB hits I add concentric layers of two sizes of plastic tubing to it.

    After the two rudder tubes have been installed I'll add the brass bolts that will hold the 1.5mm thick styrene armour along the sides of the hull. The bolts protrude 1" or more into the hull interior and once CA glued in position the bolt heads are cut off and filed flush with the exterior of the hull. This has been standard in all of my models since 1995.

    If you look at the IJN Ibuki build thread (pages 8-9) you'll see several photos of the brass bolts installed in that hull. They are screwed into slightly smaller holes drilled into the upper section of every second rib - they have to be far enough below the fiberglass deck to reach them easily with fingers to fit or remove the washers and nuts. All ribs that have the bolts have two extra layers of fiberglass.

    The bolts not only hold the sections of styrene armour (which is easily patched or replaced when damaged), they hold the wiring harness on the port side suspended from plastic clips, and the Gold'n Rod plastic steering linkage in the same type of plastic clips on the starboard side. Most of the servos are in the bow of my models, away from the drive and pump motors, so the Gold'n Rod rudder linkage runs most of the way along the side of the hull. It's made of tough plastic (nylon?) and in any case is on the inside of the internal armour.
     
    Last edited: Sep 24, 2015
  8. Bob Pottle

    Bob Pottle Well-Known Member

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    I finished cutting out the hull windows and worked on the rudders yesterday. The main rudder post is in and the small forward rudder was made from the cut-off excess depth of the Robbe nylon rudder. The forward rudder's post and stuffing tube were made last night and are ready to install. I bought some 0.032" thick aluminum at the hobby store and made the piece of armor that sits in the part of the bow that's too narrow to use for internal equipment. You can see a similar aluminum armor plate in photos of the Ibuki's bow on pages 8-9 of that build thread. The splinter screens molded as part of the Profintern's hull were trimmed down in height at the 4 main armament gun sponsons (2 to port and starboard). The screens on the sponsons are 3/16" lower than along the sides of the deck.

    I was going to download the photos taken so far but discovered the old Canon Sureshot (last used to take photos of the Ibuki build 5 years ago) isn't working. Though the batteries were recharged there were just streaks of light instead of images. I didn't notice the camera wasn't working because I shot the photos using the viewfinder instead of the LED screen. I'll shoot some photos today with Kim's new camera.
     
  9. Bob Pottle

    Bob Pottle Well-Known Member

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    I had spare gelcoat from starting the Indefatigable hull yesterday and used it to fill some dings in the gelcoat along the upper edge of the Profintern's hull, and cuts where the Dremel went 1-2mm into 'window' borders. Then there was a big problem with the main rudder. The shaft was bent back a couple of degrees where it exited the rudder (from hitting a rock when it was a much larger and deeper rudder being tried in Hood). When I tried to straighten it the shaft snapped off flush with the rudder's top surface. Not much force was applied so it was weakened in the past - good thing it broke now instead of in competition.

    An attempt to drill the rest of the shaft out of the rudder was unsuccessful due to the slope at the break. With careful measuring I was able to drill up from the bottom of the rudder in line with the shaft, make contact and drive it out with a nail. The shafts in the Robbe kits are quite long so they can be cut to the length needed. Fortunately I hadn't shortened it yet and the piece that broke off was long enough to go through the stuffing tube and rudder arm after being installed in the shaft hole in the rudder. Next steps are to sand the gelcoat repairs smooth and make the molds for the forecastle deck and the quarterdeck aft of the stern embrasures.
     
    Last edited: Sep 28, 2015
  10. Bob Pottle

    Bob Pottle Well-Known Member

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    Four more layers of fiberglass matt were applied inside the hull around the rudder stuffing tube bases this evening. That makes the hull thickness at rudder locations about 1/4" thick so I'll be able to omit the planned angled brass braces fore and aft of each stuffing tube. There's no way they'll be dislodged set in that much fiberglass.
     
  11. Bob Pottle

    Bob Pottle Well-Known Member

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    I've run into a supply problem - the Graupner metric prop shafts and tubes I need are out of stock at all shops I've checked. The next shortest and longest lengths are available but aren't suitable for the Profintern.
     
  12. Bob Pottle

    Bob Pottle Well-Known Member

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    On the weekend I found a pair of Raboesch nylon U-joints with brass inserts for 360-400 motors and 4mm shafts, plus a pair of 8.5" long steel shaft tubes with bronze bearings but minus their shafts. I have no idea where they went but threaded replacement shafts from brass rod (no SS rod available). In another parts box I found a set of spare 4mm retaining nuts for the threaded end of the shafts and an unopened set of 5/32"/4mm shaft collars. I have a pair of Rivabo 4-bladed 30mm props threaded M4 so the drive train is almost ready to install.

    The locations where the working and dummy shafts exit the hull were marked; I have another pair of brass rods to thread for the dummy prop shafts. A set of single strut shaft supports were ordered from BC and when those arrive the shafts will be installed. Took some photos yesterday and will post them tonight.
     
    Last edited: Oct 26, 2015
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  13. Bob Pottle

    Bob Pottle Well-Known Member

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    Completed the drawings for molds of the quarterdeck and the forecastle deck section ahead of the forward pair of casemates last evening. The q-deck will have a narrow (~1" x 3") access hatch recess molded over the two rudder posts and an open area inside the aft section of superstructure, to access the ends of the props shafts and the U-joints. That part of the superstructure will be fiberglass, molded on top of the q-deck using a waxed balsa form (same technique used to build Courageous and Hood and to be used for Indefatigable). There's already a fiberglass wall connecting the port and starboard aft casemates; the aft superstructure will be glassed to that too.

    The forward section of the forecastle deck will have a small access hatch just ahead of the front casemates, where the radio reciever will sit between two sheets of armor. Forward of that hatch is a single sheet of aluminum armor from keel to deck - that part of the hull is too narrow to use for equipment.

    I hope to complete the deck molds and make those deck sections within a week.
     
  14. Bob Pottle

    Bob Pottle Well-Known Member

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    Photo of rudders installed in Profintern. The green stuff is gelcoat used to fill some dings from cutting out the windows and a defect in the skeg. The rudders were made from a single Robbe rudder kit with a spare rudder tube and rudder arm. The rudder was deeper than needed so the cut-off bottom piece was reduced in size and reshaped to use as the forward rudder, which is scale size and 1/2 square inch in area. The rear rudder had to be enlarged and lengthened by wrapping two layers of 0.5mm styrene sheet around it. The area where those sheets were glued together was flat so was infilled with thin strips of styrene on each side and smoothed with Tamiya putty.


    IMG_1623.JPG
     
    Last edited: Nov 2, 2015
  15. Bob Pottle

    Bob Pottle Well-Known Member

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    Another view of the rudder installation. The bottom of the hull was made 1/4" thick at the rudder locations so no supports are needed for the rudder tubes. They'll have a couple of sections of plastic hose of different diameters put over them to prevent damage from BBs.

    IMG_1624.JPG
     
    Last edited: Nov 19, 2015
  16. Bob Pottle

    Bob Pottle Well-Known Member

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    Cut-out Profintern hull next to just laid-up HMAS/HMS Albatross hull, curing outdoors in mold last weekend.

    IMG_1629.JPG
     
    Last edited: Nov 2, 2015
  17. Bob Pottle

    Bob Pottle Well-Known Member

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    Stern section of Profintern. Note the difference aft between this hull from Ralph Coles' mold and the new hull from Strike Models. The latter has a pair of vertical walls along the quarterdeck due to a different technique of making the mold from my revised plug. If those walls are close enough to the side of the hull aft they could form the sides of the aft section of superstructure, but that is much shorter in length than the walls from the molding process.

    Note also the fiberglass wall added between the aft casemates to strengthen the hull and form the forward wall of the yet to be made aft section of superstructure. There's a second wall forward between the first set of bow casemates. The walls also hold the hull sides at scale beam in their locations.

    IMG_1627.JPG
     
    Last edited: Nov 1, 2015
  18. Bob Pottle

    Bob Pottle Well-Known Member

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    Profintern next to newly made Indefatigable hull with its 'windows' marked by auto-stripe tape.


    IMG_1622.JPG
     
  19. Bob Pottle

    Bob Pottle Well-Known Member

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    Bow of Profintern. Part of the 15-gun main armament was in casemates so BB cannons can be installed in them, close to the waterline. BB cannons in the forward pair of casemates will be able to depress far enough to hit the water immediately ahead of the bow.

    Being Class 2 Profintern can have multiple 1/2 unit cannons, so spurt cannons in the forward casemates might be useful in Campaign Lite. Battleships shooting at shore targets are usually stationary so Profintern can approach to within inches and hit them on or below the waterline. Test firing indicates that a spurt gun firing 5 BB salvos at that range will produce a hole ~1/2" in diameter.


    IMG_1625.JPG
     
    Last edited: Nov 1, 2015
  20. Bob Pottle

    Bob Pottle Well-Known Member

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    Amidships: note that the impenetrable area above the 3/8" deck stringer is the splinter shield that ran along the entire quarterdeck between and bow and stern casemates, and was lower around the main armament guns on the side sponsons. I had Ralph Coles incorporate that feature in the original mold I commissioned from him and kept it in the revised/corrected hull plug I gave to Strike Models. You'll still have to cut down the splinter shield height around the sponsons on the Strike hulls, and don't make the mistake of thinking the top of the hull sides is the deck level!

    On the Strike Profintern hulls the supports below the sponsons are present. This hull is the first one from the mold Ralph made for me - he misread the plans and made the side sponsons go 1/2" too far down the side of the hull, then I didn't spot the error in the plug before the mold was made. I had to cut off the too-deep sponsons, reglass the hull sides flat (you can see the slightly whiter shade of gelcoat where that was done), and will make wooden supports to go under the sponson splinter shields. You can see their outlines drawn on the gelcoat. That error is why I decided not to market the hulls from Ralph's mold and to correct the hull plug and give it to Strike to make a new mold. Stephen and I think this will be an effective CL given potential to mount up to four 1/2 unit cannons in casemates.

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