US Navy 5"38 Mark 28 Twin Turret in 1/35 Scale with Full Cutaway down to the Magazines

It's been a while since I updated this post. I have been working on five projects at once; three of which are commission. This technically is a commission although I'm not charging anything for it. When I last left you, I had to rebuild my 3D printer. I installed a new LCD panel which went well although more trouble than I thought. It's printing well now. I also found out recently, when testing my exposure setting with a new test article (Starship from 3DRS) that I was under-exposing my resin by 20% since I got this machine more than a year and a half ago. When I initially calibrated it I used a simple flat calibration piece and derived 2.5s per layer. With this new part, 2.5s didn't work. I printed a test from 2.1s to 3.1s by twos. 3.1 was it! It explained why I was getting such warpage and support breakage. When exposure is too short, the resin doesn't have enough cure time to develop structural integrity. The warpage is due to the amount of hardening that still needed to take place in post-curing. And the support breakage (a resultant delamination) was due to the resin being too weak to perform.

During all this, I was designing the ventilation system that goes into the gun house. It's a tricky design since the drawing is unscaled and undimensioned. 

I had designed the overhead I-beams (wrong, I might add) and then Ryan came through with a passal of images showing the entire ceiling of the gun house (also good views of the ready service room and magazine). I have four beams. There are only two. I also had lateral beams. There are none. I also needed to know how the cross vent passed around the I-beams. They don't pass, they go through. Makes sense since head room is so limited. I drew the assembly and decided to print it all in one go, I-beams included to ensure it all lines up. I did't design the blower system yet as that will be a separate part to glue in.

This was the image that told me what's what.

I placed my assembly into the gun house drawing and kept moving parts of it around until the ducting cleared the guns and nestled into the I-beam.

I scaled it .021, exported as an .STL file and loaded it into the slicer. My first setup used a 100% raft coverage area. The Tall aspect on that little raft started failing about 1/3 through the print. I could see it detaching from the build plate since the plate has risen enough to be clear of the resin level in the vat. I stopped the print knowing it would just be a waste of resin.

I redesigned the arrangement with a more substantial raft. I am having no problem with build plate adhesion and blamed the strange setup for the lost of attachment.

This will off the machine later tonight so I won't know if it's good until tomorrow. Once the ventilation is squared away, I'm going to dig into all the electro-hydraulics in the gun house, and then onto the ready reserve room below. With exposure change, I'm much more confident about fine details and small piping rendering nicely. I may reprint some of the more dubious parts I've produced so far. I haven't glued or painted anything yet so it's just time and some resin.

I'm giving Ryan a choice of how to display the innards of the gun house. My first approach would be a cutaway, but while not to difficult to execute, it doesn't show all that much unless you turn it into Swiss Cheese. Ryan just texted me. It will be the cutaway version which follows the theme of the 16" project.

The second approach could mimic yesterday's photo showing the entire armored casing in the air above the open gun house. This would show almost everything, but would have to be suspended above and it would raise the enclosure height. I could use acrylic rods to support. Lighting would require some visible cabling. In order to raise the casing, the guns need to be elevated, as they are in the photo.

The last is the most elegant and also the most challenging: making the forward parts of the gun house out of clear acrylic. I would leave the curved wall as it is. While I have clear resin, optically it wouldn't be very good and not any value. Acrylic is very clear and shows no distortion. Gluing it together so it really clean is the first challenge. The second is cutting out the small parts with true and square edges.

So I'm also asking all of you. Which do you prefer?

I finished cutting out all the casing parts and trued up all the edges. I cut the telescope holes in the right and left sides, the ofc's hatch opening, and the remaining access hatch opening. I clamped both angled face pieces together so I could finish shape the gun slots so they aligned perfectly.

To cut the telescope holes, I drilled a series of small holes through the drawing, and then used a larger drill to make nice rounded corners.

Here's all the finished parts ready to be assembled.

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Since I don't know which version Ryan will pick, I did some future planning... While all the casing parts were in the flat, and they're all accurate, I clamped them to a nice piece of 0.080" acrylic that I had laying around and traced all these parts so I'm ready to cut them out if we go that way. If fact, regardless of Ryan's choice I may cut out all those parts and see how well I can finish them. Having it clear would be pretty neat. You can barely see the scribed lines, but they're there. Now that I know Ryan's choice, I'm going to try and construct this version anyway since I've kind of wrecked that part of the acrylic with my scribed layout lines.

I also went at the back of the curved wall and removed that lump. I used a cutting disk to remove most of the stock and then my micro-power sander to finish. I may add some filler to hide all the tool marks. 

With the acrylic in the wings, I can continue to construct the regular casing. I won't do the cutaway until after it's built if i go that route, so I won't be getting too far out over my skis.

My new LCD panel arrives today and I've already stripped the old one out of the machine in anticipation. I hope it comes with a new under class plate since I cracked it a bit getting it out of it's depression. It too is held with adhesive stirps. Should be running next week. It has to be running next week. It's on the critical path of two major projects.

Y'all have a nice weekend!

Thanks for the kind words, Steve! There was no leakage, just pressure. I did have a pin hole last week that did leak some on that tempered glass plate. At least in that instance it did its job. 

I spent almost my whole day on the drawing board (well... virtual drawing board). I'm working on several fronts at the same time. Today's work centered on figuring just what kind of cutaway will be needed to show the magazine buried three decks down, while showing some of the intervening spaces. It's not easy and construction will also be a challenge. I also scoped out the wooden base and the plexiglass case. The base will require some lead time so I'll have to get that constructed earlier than one might think. My last base was done by a dear old friend who lives in Albuquerque. He was the bass player in my band and an exceptional woodworker. I'm not sure I want to task him to build another. He's in the process of scratch-building a stand up double bass. Just to clamp the skins requires 54 screw clamps which he just started constructing from scratch also. He's just as passionate about what he does as I am. (or obsessed...depending who you ask.)

There will be lighting to illuminate the shadowed areas. There will aslo be compartments under gun ready service room. The main deck will be planked. There will be no furnishings on the intermediate decks. I think it's pretty neat that V-Ray renders materials that are loaded from my older rendering engine, Podium. I renders much faster than Podium for these test runs.a

It's one thing to cut openings in a SketchUp drawing. It's quite another to cut them in styrene assemblies. In some cases the former is easier, but in others the latter is.

Before I could start gluing together the turret parts cut yesterday, I had to do a few more design steps. I wanted to cut the opennings for the side access hatches and telescopes while still in the flat. I also want to drill for the foot rungs. I also located the officer's hatch on that small flat roof piece. I was able to cut one hatch opening and clean it up. The printed part fits nicely once I spent some time with needle files to finalize the shape. The hatch drops into the opening and the hinges sit on the surface. If I want to open one of these, I'll have to reprint with a different hinge orientation.

BTW: In handling the hatch, the handhold broke off. I'm going to be replacing a lot of these with 0.020 wire.

Here's a closer look at each.

The left side with the hatch out of the opening.

If I would have planned ahead a bit, I would have included these details in the patterns I used yesterday. 20/20 hindsight. "If my foresight was as good as my hindsight, I'd be better by a damn sight!"

Here's the next pattern with the telescopes for the left side. The left side has two openings: the forward one is for the pointer's position, and the rear for the sight checker. The sight checker uses that telescope mostly for training purposes to evaluate how well the pointer and trainer and managing their positions. I will be 3D printing the hoods for these telescopes. Their flanges go around the perimeter of these openings.

And here's the officer's hatch opening. I'm going to fabricate the counter-balance cylinder out of metal.

There's one more series of parts that's required in gun house construction; There are flat shield on each side of the curved gun shields that seal the curved surface from environmental incursions especially seawater. The curve of the shield covers the curved gun shield. There are two per gun side and then a bottom piece to tie it together. The upper edge is connected to the turret roof.

I used the gun shield in SketchUp in a sectioned drawing to capture both the curve size and position AND the interface with the roof. I can be pretty sure that this works since all the prints were produced from the same drawing. While there's some minor size change in the printing process, it's really insignificant.

Here's an interesting shot of refitting the armor on a 5" turret when refitting the Iowa in the 1980s. Based on this picture, I need to slightly change the lower left corner of the telescope opening. It's not a curve, it's just an angular cut. In this image the guns (without barrels) are fully elevated. Really shows how the gun house fastenes to the main frame. Also good views of how the pointer's machinery is fastened to the frame.

Your model is looking superb!

Regarding the damage to your printer, very sorry to see that happen to you.  Hopefully, your next printer will be much less likely to suffer similar damage.  

I've had a few similar events with my Formlabs printers.  When a model has broken up during printing (yes, that happens), the build plate can crush the broken bits through the elastic layer in the bottom of the resin tank.  Most of the time, the damage is small and I just lose the tank (not cheap but not the end of the world).  But if the leak is significant, resin can leak from the tank into the printer, as much as a quarter of a liter of resin.  On my older Formabs Form 2 printers, the motherboard is below the resin tank.  A resin leak onto the motherboard can destroy the printer.  Newer Form 3 printers' motherboards are positioned differently to avoid the potential of a leak destroying the motherboard.

I will keep in mind your experience and analysis when I buy my next printers.

Again, your model is brilliant.

Finished up with the guns for a while until painting and assembly. Added or fixed the broken levers and handles. I permanently glued the gun mounts to the frame. It's okay to do that now since it makes a stable assembly for further work on all the ancillary equipment. I also got the rammer hydraulic lines in place and replaced the first long one with a more properly shaped one.

I cut out my gun house patterns, applied a light coat of MicroMark Pressure Sensitive Adhesive and stuck them onto a large piece of 0.040" styrene sheet. This represents about 2" in scale, close to the scale 2.5" armor on the gun house. Instead of using the right and left side gun house templates, I just cut one and used it to trace the other side. I then clamped them together and sanded their edges lightly so they identical. When possible, I used the corners and edges of the sheet for at least one of the sides.

Here's a closer look at the gun house side...

All four of the top pieces had to be exactly the same width and the gun slots had to line up. So I used one of them to trace the other three, even though I had drawn them and they equal in the drawing. This eliminated the slight variations that would crop up depending on which side of the line I was cutting. I got most of them cut out today. I tried the sides onto the 3D printed curved back wall and was rewarded that the corner rabbett that I printed perfectly blended with the styrene sides. I don't have any drawing stuck onto the side piece that I traced, but I will need the location of the side access hatch. For the actual hatch cuts I will trace the real one. I'm also going to located and drill all the holes for the foot rungs while it's all in the flat. I have to do some finish sanding on the edges and the gun slots. I also have to sand bevels on the mating surfaces of the angle pieces so they mate properly. All joints will have 3/16" styrene angle as does the prototype.

Meanwhile, while printing parts for another project a calamity happened. After a major print failure... and I mean "major" in the sense that the only thing that printed on the build plate was the base raft. All the rest was a series of variously shaped blobs stuck to the FEP teflon film at the resin vat's bottom.

I was able to remove the crap on the bottom without destroying the FEP (I hope), then I looked at the LCD protective plate and saw a series of bad cracks propagating across the LCD. I thought it was the tempered glass protective plate that I bought to protect the delicate LCD below. But when I removed the undamaged cover plate, I realized that the cracks were in the LCD itself. I did a light test and it failed miserably. Half the screen was disfunctional. The cracks are quite obvious in this image. I need to understand why the print failure happened in the first place. I've tried printing this part three times with not very good success before the complete mess that this attempt was.

I ordered a new screen from Amazon which will be delivered soon and I'll install it on Monday and hopefully, all my projects will continue uninterrupted. Elegoo has a new machine out that uses a Texas Instruments DLP chip. This device has been around for a long time and since it projects its pixel image though lenses and mirrors to the resin vat and doesn't get any physical pressure from the z-axis lead screw and stepper motor. It was the plate attempting to compress those hardening lumps on the vat's bottom that caused the damage to the LCD screen. I think my next printer is going to that technology. So this summer I've added a new motherboard, new touch screen and now a new LCD screen. Wish me luck. I can continue to build the sheet work without the printer running, but I really need it.

I found out from Ryan today that the splinter deck is only 30" high, made up a massive series of square compartments with manholes separating each of them. I will only be showing a little bit of that detail. It's only function is too isolate the magazines below from any shrapnal that may attempt to get there from action above. I don't believe any of the Iowas saw any action that involved this structure.

Hope everyone had a nice Labor Day weekend!

I machined the metal trunnions along with the seal for the trunnion bearings on the real thing. Simple turning operation. The pin size was .147" and I had to deepen the holes on the gun housings to give more meat in the junction. I made the pin's depth is just about .200". I machined the first set using a collett for the 1/4" aluminum stock. The collett did not have a thru-hole, so I had to cut the stock fairly short so it wouldn't extend too far out of the collett. I machined the trunnion pin diamter first and the inner surface of the seal. I then mounted the pin in a three-jaw chuck and finished the outside of the seal face. He I'm test fitting the gun frame onto the pin. My little Taig Lathe is in need of a new motor. The lathe is at least 30 years olds and the motor's bearing are shot. There is about 1/4" end play and it's vibrating like crazy. It's amazing that it's not destroying the cut quality, since the whole machine is vibrating together so the cutter and the stock are also vibrating together. It's just very annoying. I can get a new motor from them for about $160.00.

I tried the finished part on the gun in the mount.

There are screws around the seals perimeter, but I'm not going that far.

Here are the four trunnion pins/seals. The two with the holes will accept the manual firing mechanism that feeds through the trunnion center so the gun can elevate without disturbing the mechanism. The manual firing mechanism is quite complex due to the interrupt system that prevents firing the gun when it's pointing at any part of the ship. The gun is only firing mechanically when the entire firing system is out of commission. Normally the firing is electrical and remotely activated from the secondary plotting rooms.

I finished the metal hydraulic tubing on the guns. I removed the one I did last week. It was not the accurate and needed replacement. I also finished opening up the bore for insertion of the gun barrels and the cylindrical loading tray. The hand levers are breaking off due to all the pushing and shoving I've had to do to fit the guns. I will replace with metal.

I need to design more parts before I can go further.

I got the gun drawing done so it's about as good as I'm going to get it. I had Ryan take a look and he said it would work and was surprised to see it all naked.

With a decent drawing I was able to print it. The barrels are already printed. I had a choice to make of printing the entire gun assembly or print the shield separately. After attempting to install it in my mind, I didn't like how it was going and printed it as a single piece. In actuallity, the shield assembly printed reasonably well. I chose to remove the trunnion pins and will machine them out of aluminum to the .147" diameter on my lathe. I drilled the holes a little deeper to accept them.

Notice the phos-bronze hydraulic lines to the rammer piston. My resin printed ones didn't. It appeared that the pipes were not actually joined to their flanges in the drawing and they failed to form correctly. Better with metal anyway.

The trough that accepts the projectile and cartridge did not form. It was paved over with a resin sheet. Not sure where it was coming from. Drawing that trough was difficult for me, so instead of redrawing and reprinting, I used the Dremel with flexishaft and a spherical diamond-coated burr, and carved the channel back in. These will be partially obscured with a projectile and cartridge load. The back left edge of the curved shield was slightly missing, but was rebuit with Bondic.

Another view of the tail of the gun showing the trough. The trough and the sloped shelf next to it are brass on the rear gun to avoid any sparking.

The real test was how well the gun fit the slide and how well the slide fit the mounts. For the former, I had to open the gun opening much deeper. There was some errant resin growth inside. I tried using an appropriately-sized drill, but it wasn't working well and I was afraid I would break something. I then turned to another diamond burr and ground it out. The diameter of the shield and front of the slide was perfect. The gun was a sliding fit.

As to the fit into the mount, it was perfect!

When painted these will look pretty good. I loved how the gear teeth formed on the elevation gear. Out of the four guns I printed (2 R and 2 L) one pair is good enough to use. I have some more metal works to add. A couple of the handles broke off on the side operating lever. I just thought of using some very thin shim brass to actually line the trough with real metal. I will experiment on one of the reject guns to see if that works.

So folks, WE HAVE GUNS!

I also finally decided to build the model exactly as it is in the ship. With the magazines correctly offset and in the correct deck, it will occupy a display space of about 1' X 1' X 1' and that's really not too big and much smaller than the 16" monster.

Next up will be to design and print the hydraulics and sighting gear that really complicates the turret. Then I'll start working on the Ready Service Room and the projectile/cartridge hoists. I don't have any good references on the structural steel that supports the hanging central column and the hoists attached to it. I did get a properly sized piece of brass tubing that will serve as the central column.

That certainly is a valid point. I did reprint the redesigned rungs with the 30% thicker rung and the fixed mounting lug. They printed quite well and I was able to remove a vast majority of them from the backing piece. I can always do a fallback position with the metal wire, but for now, I think this could work. The bolts resovled, although almost too small to resolve with the naked eye.

This shot was taken during the removal process. I've found that using the flush cut tweezers thing that MicroMark sells seems to work pretty well in snipping tiny supports. I also used a very sharp #11 blade. The blade only works on parts that ARE NOT post-cured.

And here they all are ready to go under the UV lights for post-curing. In their native state, they were too flexible to be useful. That flexiblility is imparted by the Siraya Tenacious flexible resin in the mix. The extra girth really added survivability to these delicate parts.

I was at the local hobby shop and picked up the scale I-beams and some 5/32 angle stock to build the gun house.

I'm in a highly unusual situation. I am working five projects at the same time. I usually work one at a time, but not now. I have the turret project running concurrently with the Takom 1/35 AH-64D Apache. I thought I'd get the latter completed in time for my modeling club's regional exibition, but probably won't and will enter some of my previously built models instead.

Speaking of the show (in September), I slated to make two 45 minute presentations on the 16" turret project, the title of which is: "21st Century Modeling: Traditional Skills+3D CAD+3D Printing" That's project #3. 

Project #4 is creating a small n-gauge train layout for the window of the Newtown Hardware House in Newtown, PA. This commission job stems from my creation of an O'scale version of this iconic Newtown building that was a hardware store since its inception in 1869. The store's owner was so impressed with the fidelity of the build that he asked if I could do the RR. I just happened to have built such a small layout with the grandsons 12 years ago and will modify this layout for the store. I'm making an n-gauge version of this model. At that size, I can 3D entire walls in one go, unlike this one where I had to have the walls laser cut.

Project #5 is helping a good friend and fabulous modeler, Chris Bowling, refurbish a 1:15 scale model of the NASA Space Shuttle. I'm tasked with creating the artwork for 1:15 scale vinyl wrap that will have the heat resistant tile design. I met Chris through our modeling club and his work is spectacular. We have sort of a mutual admiration society going. I'm not quite as festidious a modeler as Chris, but I experiment more and push the envelope. I'm sort of the R&D department. The model was originally built by North American Rockwell and will be on permanent display at a new air museum in Bowling Green, KY.

So if tend to drop out from one project or another, don't worry, it's just me doing what I do.

Hello!

As for those ladder rungs I think wire would be a better material for them. Wire rungs would have better chance of surviving "accidents" and if you made a bending jig I bet you could make them a lot faster than 3D printing them and debugging the printing before that.

Good luck with your project and have a nice day!

Paweł

Spent a lot of time without much to show for it. Most of it was wrestling with the ladder rung prints, both in trying to separate them from the supports and backing piece, and then drilling out the jig to use when mounting them. They are too darn thin... scale, but thin. Removing them was quite painstaking and a bunch failed that had to be repaired with Bondic. There was another problem. I made some very tiny drawing errors that prevented the part from being structurally sound. One small face on the mounting lug was reversed and therefore, didn't print. This lead to the failure of the bolt head to print that was attached to this now-missing face. Also, the rung mounting point was weak and failed many times. 

I stopped messing with it and went back to the drawing board, fixed that reversed face, increased the rung diamter by 30% ]and strengthened the mounting point. It's printing now and I'll get them tomorrow. 

I aslo tried the drill jig idea and it worked. Only problem was some of the holes were into that chamfer area. I also changed this part too for the next print. I'm using a #57 drill, but a #56 would be better since I had to push too hard to get the lugs to seat and that leads to distortion and breakage.

I also got successful prints of the two mirror-image side access hatches. Last print failed three-out-of-four times due to insufficient support at the lowest corner. When that support failed, the part distorted in that area. I added more support and the four parts were perfect. Even the grab handle formed perfectly.

With the Fulament spring built plate I'm using, I rarely have adhesion failures, but I do get support failures. It is crucial to put a lot of heavy supports at the lowest (first) edges that form. Not only do you want to have a good, solid start to the print, but the lower supports have to support the ever-increasing weight of the part as it's forming. It's all proportional. A small part may look like this rule doesn't apply. Afteral, how much can it weigh? But it's not just gravity you're fighting. There is also suction created due to the perfectly flat surface created betweenl the FEP when the resin layer is curing. The build plate, through the supports, has to break that seal to lift the part so fresh resin can infill beneath the part. I've printed hundreds of parts in the four years I've been at this, and still have support failures. There are guidelines, but there are no hard-fast rules. 

As the part forms you can lighten the supports on the upper reaches since the amount of mass is greatly reduced. I also add light supports to all details where removing the heavier supports would destroy the detail you're trying to print when you remove them.

I will take your advice under advisement. It will take a lot of styrene sheet to build all the intervening decks and partitions. When I get the upper works done, I'll start designing all the below decks stuff and see what's what. I love that this forum has international participation!

Hello!

Nice progress here!

I like the drawing a lot, but IMO in your model you should add those two empty decks. That would show everybody what a long way the powder and the projos have to travel before they can go boom!

Good luck with your build and have a nice day

Paweł

Thanks guys!

In a messaging session with Ryan Syzmanski, we've decided to model the magazines in an "artistic" rather than prototypical way. Due to the intermediate non-functional deck spaces (non-functional regarding ammunition movement), I'm going to model it based on this iconic drawing.

My model will be more detailed and accurate than this image. I also suggested to Ryan that we display a graphic to show the actual relationship between the turret and the magazines which do not lie directly below any turret. There are two decks between the main deck and the magazines that would not add value to the model.

I tried out my new V-Ray rendering software which came with the SketchUp Studio version that I'm now using. It's significantly better than Podium which I've been using before.

Here are two examples:

First Podium: Podium handles the details okay, but really shifts the color.

Now V-Ray. V-Ray drops out the background based on selections you make. This is actually quite useful for embedding images into documents. Sharpness is the result of the image size you're outputting. In this case I chose a small file size. It also renders much faster than Podium.

And now a screen print directly out of SketchUp: In some respects, the SU direct shot is more descriptive showing all the line work. I can display it without the lines and it looks more like the renderings. 

As you can see, the gun designs are almost complete. I was drawing all kinds of details based on one of my references and then realized that the reference drawing was of the gun slide, not the housing that surrounds it. The flanks of the fixed part of the gun are relatively clean. It saved me a lot of drawing time. The hydraulic piston that operates the ram, which I was trying to depict, isn't simple. The ram is tied to a gear rack which multiplies the stroke length. The rack then operates the ram with another rod. All of that is hidden by the outer housing.

I got a nice print of a gaggle of ladder rungs. Only one did not print well due to on support letting go beneath it. I chose to post-cure BEFORE trimming the supports to strengthen the rungs to better handle the support clipping function. We'll see...

I spaced the rungs on their support bar exactly on the 7.5 scale inch spacing as they sit on the turret. I can then drill at each point after removing the rungs and have a convenient drill jig to drill the mounting holes on the turret flanks. Now that's thinking ahead, ain't it? I designed the rungs with a stub end that is sized for a 1/32 drill size. It should work...

I'm finalizing the cutting patterns for the styrene turret parts. I had some clearance problems which required adjusting the gun slops on the faces. I also printed the size access hatches with their hinges, mounting bolts, and grab handle. Only one out of three printed well. Again, I used medium supports for the base and some failed causing deformation. I'll adjust it and redo. Need to order some more resin.

That is just some insane Detail. My Hat off to you.....Cheers Mark

Can't believe how much you've done on this project since last time I checked in.

Looks to be coming along beautifully, very impresive work.

After studying the part set up AND the part's design itself, I modified the rear panel and then changed the setup on the printer. For the part redesign, I added ribbing and buttressed the corners to stiffen the structure and add more beef so the styrene flat walls have more contact surface. For the support setup, I placed the part on the plate simply tilted back and not slanted. I removed the bottom ladder rung since these broke off almost immediately before, and even then, am printing dozens more that I can apply much later in the build.

This in looking at the inside. You can easily see the added material to stiffen the structure. Top now forms a lip so the roof can set down inside the back wall.

And here's the front view showing the individual light supports picking up the exposed details that showed up as trouble spots in the slicer. I'm making the piece with and open hatch for more interest.

I printed them today and here's the output. I will use this. As I expected, the foot rungs didn't do so well and I lost one door dog which can be substituted with 0.010" wire.

The rear still shows one of those odd bulges as happened in the first attempt, but this one seems easier to remove. It does not show up on the front side. And there are not print lines in the front surface. It's a pretty good print all in all. The inside door dogs printed nicely... amazingly. That delamination on the bottom rib is not a worry either and easily fixed with Bondic. Not worn wasting the resin on another print. This was post cured, but not final sanded.

I have the ladder rungs printing now and have another crack at those powder magazine doors. With these printed I have to get back to the drawing board and produce more parts. 

I'm going to be making a clinic presentation on the Construction of the 16" Gun Turret at our Military Modelers Club of Louisville Regional Modeler's competition being held on Friday thru Sunday, September 21–23 at the Triple Crown Plaza in Louisville. I'm titling the presentation 21st Century Modeling: Model Building+CAD+3D Printing. There are going to many vendors and exhibitors.  It will be a wonderful show.

I finally unloaded that batch of QAWT doors and they did come out pretty well. The handwheel cross bars are almost too fine to hang together, but even there I did get some successful ones. The operating bars are so thin they're kind of floppy and if I were to do them again would make them about 2X thicker. As I've said before, real world material sizes sometimes don't translate successully to the model especially at 1:48 or smaller. Regardless, I'm happy with them. They will work and I don't know where to put them in the model. It gives me confidence that any other doors I produce will work.

And the flip side. All the major supports were on the front side and the only supports on the mechanism side were supporting the dog rollers and removal didn't damage anything to badly. I hadn't don final sanding on the edges.

And here's the second one I cleaned up. I still have four more that I haven't trimmed that are in the spares box. This one did have the edges sanded. When primed and painted they should look pretty spiffy.

When I woke up this morning and did my usual model ideating, I realized that I could use the backing plank that I use for the ladder rungs as a drill jig to add them manually. The correct spacing is 11.5" and I had arbitrarilly a little over 13". I redrew the layout to have that spacing and set it up for printing.

Then, this afternoon, I put the back wall in the printer. 6 hours later here's what I got. It wasn't totally bad, and, in fact, since it's quite an unusual piece to print, I'm not too upset, but there were some weak points.

Here's as it came off the machine looking at three views. I had removed some of the supports around the delicate details, but did not post-cure.

On the left corner there was some distortion. I don't know what cause it, but it's usually a support failure. I will have to evaluate whats going on in the slicer. The handles and steps all formed nicely.

Note the delamination of the base raft! That's also strange showing there was good adhesion to the build plate. Could be too much attraction to the FEP.

No distortion on the right side!

And the back. Strange things were going on in the back.

Some remarks about this...

I thought the drawing was finalized, but the latches on the right side cartridge chutes moved out of position. The center section bolt heads are not there. That too is a drawing error.

BTW: As predicted, I already broke those bottom two foot rungs. I will have to add them late in the build and maybe make them out of metal.

In the back, the right side latch dogs were not attached to the surface. Remember was I was saying about have to be sure their embedded in the drawing. Well... I guess these weren't. I was able to put them back using Bondic, but I'm not keeping this part for the model. It's going in the scrap box and will be used for parts if necessary.

And then there's these malformations. I'll have to explore this defect. Because it's actually more material, I can grind it off if I need this part.

I now have the powder handling doors in the printer. They'll be done about 11 p.m., but I'll get them tomorrow. If they come out as nicely as the QAWTs did, I'll be happy. If I can't get the curved wall to print effective, I can print the add-ons and build it out of styrene. There's always a way!

This is just plain lazy brilliant detail you are poutting into this one again.....Cheers Mark

Haven't printed the new doors yet. But I have been busy. I nailed down the turret curved back with all the doors, hinges, latches, foot rungs and bolt heads. I did it at least five times until I got it right. Each time I thought I had it all tied down, I'd put the STL version into the slicer and then would see something was wrong. Either some details were imbedded too deep or not deep enough, or they tilted in some way. The I saw that I didn't use enough segments on the curved surface and it looked terrible. Then when all that was done, I found that somehow the pieces was about 3 scale inches too narrow. So I to fix too. All told it took much of yesterday and today to get it right.

SketchUp does not actually draw curves. It draws a series of straight lines that approximate curves. For circles the default is 24 segments. That's quite clunky and in 1:48 would be very noticeable. To fix it you'd have to sand all the peaks down to curves, but all the details are part of the print and they would get in the way. For the tools that make curve parts, the default is 12 segments. When I'm doing a surface that I want to print almost a true curve I go minimum 48 and even better 96 segments. SU's computational engine works harder the more segments that curves have. For graphic display purposes, SU smoothes the curves, but the segments are actually there and when you export as an STL, there they are.

Here's an example:

The drums are R-L 24, 48 and 96 segments. With the curve smoothing they look like perfeect cylinders and if I were to print or render this, it would look great.

When I turn on "Show hidden surfaces" you see the segments, although the surface is still smooth.

But after STL conversion and loading into the 3D slicer, this is what the cylinders actually look like. In 1:48 that flats will be very noticeable. 

One of the most difficult aspects of drawing the back wall was putting the details onto a curved surface. SketchUp works on an X-Y-Z coordinate system with X being the red axis, green the Y axis and blue the vertical Z axis. It is always best for many reasons to orient your drawing with the these axes which facilitates moving things around. That works great on a rectangular object with 90 degree corners. With a curved surface like this wall, only one spot in each quarter turn aligns with the axes. I drew all the details off the model, ensured they were each printable solids and then embed them in the curved wall's surface. I actually push them into surface just a bit to ensure that the details don't form detached in space. I they have separate supports, which many will, they could completely form, but not part of the print. When the wall surface is not on axis, when you move the object in the x or y direction it moves in an angle. So if I wanted to put the part in a specific location, I had to zig-zag and creep up on it. It took a long time. 

Then about 3/4 the way through the exercise, I decided to copy and paste the completed wall to the master drawing. When I placed the wall against the rest of the gun house I drew previously. It didn't fit! Frankly I don't know when the size change. I say "changed" because the original curved wall was that gun house's back wall which I copied and then added the two scale inch depth. This image shows the first wall I drew superimposed over the corrected wall. This difference was unacceptable. The side walls have to intersect with the 0.040" thick side walls with no gaps.

Here's a vertical look at the wall over the main frame. Again, the wall has to key into the frame correctly. The new wall is on the frame and the incorrect one behind it. 

I couldn't just stretch the wall to fit. I had to start over. However, I was able to take all the details off as a group and preserve them. That sounds easier than it was since they were on slightly different distances from the center and lying on slightly different radii. Lots of trial and error. Notice I've thought ahead for a change. I included the mating flange that will connect to the straight side walls. There is angle brackets on the real turret that do the same thing.

Here's how the finished product will look. Notice also the curved angle bracket that secures the floor and back wall to the frame. This is not the fianl look for this part. I have to study the pictures and drawings more.

And the finished front.

And in a more rendered way.

Here's how the wall fits on the printer.

I'm using heavy supports on the wall itself and a lot of them. It's not that there's that much surface area, but it's a bit heavy and that weight starts to play a part in the support scheme. All the details are supported by fine supports. Notice how fine the facets are on the surface using 96 segments. Very light sanding will remove them entirely. In 1:48 you can include ALL the detail.

While the attached foot rung will print, I'm worried about thier longevity, especially the ones hanging down below the lower edge. I will surely break them off. I am printing them in bulk so I can replace them if necessary. I've included a 0.020" stub on them that will fit into a drilled hole. Each rung has to be supported separately. I can make many of these fairly fast.

We're heading back East on Tuesday. I may do some work tomorrow, but after that we'll be gone a week.

Based on information from Ryan and Jim Slade I completely redrew the magazine doors. There appears to be two types, both smaller than the standard QAWT that I drew eariler. They're the same width (26"), but significantly shorter at 45". They are also locked by individual dogs (8) and have the pass-through scuttles where the powder canisters are passed from the powder magazine into the projectile magazine where the dredger hoists are that take both (separately) up to the ready ammo handling room.

I'm going to print the door complete with all the levers attached. I believe it will work as long as I don't break them all in handling. I can always subsitute wire (I did this in the big turret). 

Here they are installed in the partitiion that separates these two spaces. There's still a ton of work and research I need to do on them to make this a viable model.

The larger doors have a 7" sill, whereas these have a 24" sill requiring the step to make them easier to negotiate.

Here's the opening side. The floor plan shows which direction the door swings. I now know that the black bump on the door's symbol is the scuttle in the middle of the door. There is also a line on some of the door symbols that shows the handwheel of the QWAT door. Then there are the rest without specific symbology which I have to figure out.

Here's how they're going to be mounted on the printer. I'll put them on tomorrow. Print time is less than two hours.

Trying to print the moving door hardware separately of the doors probably would answer the printing qustion; bnut not likely be successful overall.

(It would probably want a "casting block" that would want sanding away--that or a holding jig/fixture to install on the doors; or both.)

I've run into both problems while 3d printing--of both havign "too much detail" and "building up too much detail as separate parts."  There's likely a happy medium, but it will ellude a person at times.

The reprint looks good, but useless! The door I drew is not used in the magazines. Jim Slade and Ryan sent me photos and information about the magazine doors. They're not quick acting, but have individual dogs and they're much smaller. I will share and keep the full-size QAWT door since it's used a lot of places onboard ship.

It happened again!!!! I accidentally hit the little "X" in the tab on my Apple Safari browser and closed the very long post I was just about to finish. I lost the whole thing! I broke my own rule that I just created last week: Save the bloody thing periodically so you can replace it if I keep doing this.

Here we go again.

I was able to find FREE deck plans of the USS Missouri in 1950 configuration when it still had all the 5" gun mounts. I was able to load up the main, 2nd, splinter and 3rd decks into SketchUp and display them in full size... you read that right... in SU this file is a ship 887 full length measure. SU doesn't care. I also had profiles of the exterior and center line section. With these I was able to line them all up and finally understand just where everything is going to go. I was also able to size the Ready Ammo Handling Room that supports the turret, and the elusive powder and projectile magazines which do not lie directly under the guns.

The 2nd deck has no gun handling apparatus as does the splinter deck. The splinter deck is a shallow void space to catch any explosive debris before it gets to the delicate spaces below like boilers and magazines. I used the 16" barbettes to register the drawings since the lower decks have overall sizes that are slightly smaller than the main deck due to the ships lines. You can find those plans here: https://archive.org/details/bb63bogp1950/08%20-%20second%20deck.png

When overlaid in correct resgistry I am able to model in full size the paths of the curved powder and projectile hoist trunks. These trunks are designed like this deliberately to mitigate fire from spreading from the upper decks to the magazines.

And I was able to accurately scale the Ready Ammo Room both in area and height by matching to the full size floor plan.

I erred in my design by including a lip around the rooms roof. It is flat.

I also found very good data on the design of the Quick Acting Watertight Door (QWT). It took a while to search through hundreds of images until I hit on a sight that manufactured the style used by our Navy with great head on images on which I could draw the door. I also took screen shots from Ryan's USS New Jersey video "Doors". With these sources I was able to create a very respectable prototype.

Here are the three drawings I used:

Outside:

Inside:

And then the best... the door without the hardware where I could get good fixes on the positioning of the dog pivots.

This was a closeup from Ryan's vid. It shows nicely the roller dogs.

I drew the door in layers and 10X scaling. Sketchup has a trouble with working with curves especially when doing contours in FOLLOW ME. If the segments are too small, it leaves them out and makes holes, whereas when enlarged it fills them complelety. When you shrink the drawing back to original size, the filled areas stay put. I don't know why this is, but it is. To make those bulges, I produced external rounded rectagular shapes and internal ones and bonded them to the drawing on both sides ensuring that there was some material thickness between them. They're printing now, so I know if there was enough material to produce a viable part.

I then produced the frame as a component and finally overlayed the dogs and all their operating links. Some of the links were challenging since they have curves that enable them to clear the other parts.

And here's the finished product showing both sides. The real door has an extension lever on the wheels to give more torque. These would be too frail for printing and I'll attempt to add them with wire. I am attempting to print the doors as a single part. I will see how that works out. I also had to thicken everything. At scale thickness many of these peices would not be viable. The beauty of 1:48 is you can really lay on the detail and have a reasonable chance that it will show up.

As usual, I print multiples. I will probably need at least this many. I'm also contemplating printing the entire rear curved wall of the gun house including the hatchs and details. It might be the easiet way to go if it all fits. Otherwise, I'll print the curved corners with rabbets to seat the styrene walls. That will work to, but won't be as elegant.

Whew! That was a load of stuff. Now I'm goint to check on the print which just finished. Let y'all know how that worked out.

 The prints were marginally successful. All of the complex contours, cranks and arms printed well. The handwheels failed as predicted and the rollers on the ends of the bellcranks didn't form well. They were highlighted in pink, but it wasn't bright pink so I thought they might make it.

At first glance it looked pretty good.

Upon further inspection here's what I saw.

I'll print the handwheels off the model and add them after post-curing. I will also do something to support the roller ends and that should do it. 

Thanks Pavel. Maybe... I'm more partial to really big guns, but I'll think about it. Didn't Rye Fields do Abrams with the full interior?

Impressive, as always!

Recently I thought... There's actually one more turret you should do, and there are many people interested... I'm talking about the interior of the M60A1 tank turret. I tried to tackle one myself, but the design got too complicated for my computer plus I couldn't resolve some of the dimensional problems...

For now good luck with your twin turret, I'l be watching! Have a nice day!

Paweł

I spent almost an hour the other day writing the post with lots of images. Unfortunately, I let it sit too long before uploading and my computer reloaded the website "Because it takes too much memory" and the whole deal was lost. And now I have to do it again. I came up with a scheme to copy after writing so if anything happens, I just paste it and am good to go. This time I forgot to do that.

So here goes.

The reprinted ring gear was excellent, one slight area needing fixing. I fixed with Bondic. It fits the mounting ring on the frame well and the two can rotate. The real one has retaining clips that grip under the training gear and I'm going to duplicate so the turret will be positionable. I found that the Training Buffer interfered with the ribs on the stand, I surgically removed the offending material. I found another drawing of the buffer and it looks like the back is relieved for the same reason.

The mod: I also replaced the printed plungers with steel. One didn't form right and after replacing it, I did the other to match.

The gun mounts printed well. I always make more than I need and one set had a fatal defect. Didn't matter, I had three more and only need two. As printed off the machine.

Finished set: Not glued, just set in place.

Printed a gaggle of trunnion caps. I erred. I put two bolts on each side. There is only one... Not going to worry about it.

Here's the caps placed on the mount. Again... not glued. Can't do that until the guns are in place.

Here's the one that failed. And you can see why. That support failed. When the support fails it usually leads to a local or catastrophic failure depending on how strategic the support is.

I also printed successfully, three out of four Training Worm/pinion assemblies. Only need one. This one was also a support failure, but of the more catastrophic variety. It left the partially formed part stuck to the FEP film at the vat's bottom. The new version of Elegoo's FEP film is very forgiving. Stuck parts pop off with no damage to the film. I can run for months without having to replace the film ... a 20 minute job. Looks like something that didn't make it through the Star Trek transporter too well...

Here are the good ones. Even among these there are some that are better than others. Always make more than you need!

Here's the trial fit top view. Part has NOT YET been finish sanded and you can see by the support marks on the top.

And the bottom view showing the pinion meshed with the training gear.

That's all the parts that are drawn to the point of being able to print. There's a whole lot more going on in the design department. I finished the gun shield and elevating sector gear, but both have to wait until the gun proper is finished. There are some brackets that engage in the gun that can't be finalized until gun is done. I also started delineating the armor housing with the curved back plate. I'm going print the hatches with their hinging, but the curved wall will be 0.040" styrene. Technically, the armor on the this ship's secondary batteries are 2.5" which is 0.050" in scale. I may laminate 0.040 and 0.010 to make fifty. Laminating also helps maintain the curvature. I had to extrapolate the lateral position of the hatchways due to the curvature of the image. I then flattened the curved piece using SU's "UNWRAP & FLATTEN" facility. 

The gear teeth are finer on the prototype, but at 1:48, if they're too fine, you won't see them.

Here's some WIP shots of the rear panel. I'm not sure if the hatch is curved. It too a while to create the curve using a copy of the wall section to cut the inner and outer faces. If flat, that's much easier to do in styren. In addition to the crew hatch, there are four others for the cartridge discharge chutes.

Here's the wall flattened as a test.

There are angle bars that attach all of armor panels to shape the gun house. I'm going to 3d print these with fasteners. My shape isn't exactly right as I've ssen on some video footage. Don't know how anal I'm going to be about it. The fastener pattern's probably not right also other than it's a combination of rivets and bolts.

Here's the actual back do. I'll print the foot rungs too. Hatch looks flat. This is the lower discharge port. The six bolts to its left are those that are holding the housing to the longitudinal frame rail.

Now the gun. The geometry is a killer for me! I don't have any drawing of the parts separated, e.g., slide, housing, etc. I was very difficult for me to visualize just what parts move during recoil and what parts are fixed. When you watch videos of the guns firing, the recoil is so fast you can't stop it when recoiled. I suppost you could copy the video and do some frame-by-frame editing, but my bet is that it would highly blurred.

The real of the housing is curved in two directions... sort of part of sphere. I first had it curved only in the vertical direction, but realized it was wrong. To do compound curves in SU, I find it easiest to create a cutting too of the right shape and use it to shape the object. In this case, I created a segment of a sphere and placed it so it would remove the right amount of material.

After cutting I grafted the part to the rear of the gun frame and it actually worked out. Still have lot of details to include and am constantly checking that the object is still solid and printable. Last night started working on the rammer hydaulics. I used one of my drawings a as guide only to find it was completely wrong for the reservoir. Found others that were accurate. I spent almost 8 hours yesterday just doing drawings. And I have hours and hours more to go. Taking the day off to go see Openheimer.

After cleaning you can see the difference between the non-support, direct print one on the left and the one with the supports that raised it a bit off the build plate.

Besides that slight difference in the bore at the breach end, the rest of the print is perfect and not different between the two. They're getting post-cured now and only a very little cleanup will be required to create some beautiful guns. There are no layer lines and they ARE NOT warped that I can see. I'm quite pleased. I will not have to get machined barrels.

Once they're cured, I will take a diameter reading at the slide end and use that number to draw the bore in the slide, plus some clearance tolerance. I don't want a press fit. If I wanted to, I could make the guns able to recoil, but I probably won't. This will be enclosed in Plexiglass and never be touched to play with it.

Onward and upward! 

Guns just came off printer. I was correct. The resin didn't drain well from the one that was printed directly on the plate and the bore is narrower at the plate end due to "elephant footing". Elephant footing is the phenomenom created when the part widens at the first five base layers. These are generally exposed at 1 minute instead of 2.5 seconds. The long exposure is used to create the "raft" that holds the model to the build plate. You really want this layer fully hardened so it sticks well. When you put a part directly on the plate, that 1 minute exposuse/layer causes those five layers to widen also. They become wider because the long exposure leaks from the pixels that are to be illuminated to neighboring ones. 

The gun with the support's bores are parallel throughout the print. They're in the Ultrasonic cleaner now. I will take pictures as I clean them up. I just put the modified base on the printer. It will be done around 10 p.m. Nice thing about printing... I generally like to print overnight so it's working when I'm sleeping. Unlike string printing where you have to keep an eye on a clogged nozzle, with resin printing, when the part is right and mounted right, and the printer is lined out, it will work without any attention.

From my cursory inspection the guns show no imperfections and should look great.

It shouldn't be too hard to populate the gun mount in 1:48. I'm going to do a selective cutaway rather than transparent for reasons too numerous to mention. Suffice it to say, I'm not very good at transparent parts. There's always a blemish somewhere. 

I've started producing parts with varying success. My first part was the base ring printed flat on the build plate. For some reason, the training gear teeth started to form and then just stopped. A few layers were laid down nice and parallel, but then nothing. I also had some slight delamination. The delamination I could fix, but the gear teeth would be a bit trickier. I could print the gear separately flat on the plate and insert it. Meanwhile, I've set it up at an angle and will try again before going with the separate gear approach.

Next print was the main frame. Strangely, one set of supports failed causing one of the frame's lower extensions to fail. I changed the supports in the slicer and tried again. Here's attempt #1 compared to attempt #2 which was clearly worse. 

There's a silver lining. The arm extensions are mirror images of each other. By surgically removing the bad arm from #1, I was able to graft the good arm from #2. With some thick CA followed by Bondic UV resin, the graft is invisible and strong. The Bondic is the same chemistry as the UV printing resin and when applied to UV parts welds them. Only caveat is the UV curing light must be able to reach the Bondic so it can be used on blind glue joints. Otherwise, it's essential in your UV printing tool box. It cures in seconds!

Here's the removal of the bad arm.

Here's the part ready for the graft. I broke apart #2 to better expose the arm for amputation. I then trimmed the end properly in a miter box with razor saw so the end was square.

I used the CA to stabilize the part (with accelerator) and then used the Bondic to fill all the gaps.

And after sanding, the part, when painted will show no evidence of being "Frankensteined"... Just made a new verb.

Here are the remains of #2. It served well and saved me a bunch of resin. Resin is not cheap, about $40 a liter. I never throw away rejects and have used them many times to provide repair pieces. I'm creating two boxes... "good parts" and "bad parts". Often it's about 3:1 bad to good. 3D printing is an art with a scientific underpinning. I thought I had figured out the failure mode on #2, but the results were worse. The failure still started in the same region some something was going on there. Since I now have a good part, I'm not going to worry about it any longer.

Right now the guns are on the printer and will come off around 7:00 tonight. The fit of the frame ring into the base was very tight. I may have to chain that diameter on the recess a tad so it slips in. They were both created by the same circle so their diameters are exactly the same on the drawing. However, the printing process enlarges parts very slightly, so the holes gets smaller and the ring bigger by a few thousandths each. What was a slip fit is now a no-fit. It's the reverse with laser cutting. I you cut a window opening and the window frame with the same dimension. The opening grows bigger and the frame smaller since the laser cutting beam has some kerf width, just like any saw only much tinier.

I almost have the gun mounts ready for printing. I drew them over my profile drawing. My first attempt had the cross bracing in the front on the wrong end. I was able to fix it without too much difficulty.

The guns are printing successfully with both setups building straight down.

I redid the ring gear for printing and drew the training worm and pinion. I ended up making the gear with 14 teeth and a pitch radius of 8". It meshed well. Nothing is going to have to move and everything is printed as a solid obect.

Here are the finished drawings of the engine mounts. I saw that there were bolts holding them down so I added those and added bolts to the Trunnion Caps (being printed as a separate item so so the guns can be installed. The bosses jutting out from the side are where all the sighting gear is attached

I did have sufficient drawing to build the training worm and pinion with reasonable fidelity. The worm is driven by a drive shaft from the hydraulics. Manual drive is selected through a series of clutches, but still enters the worm via the same shaft. I'm probably going to use metal shafting for all of them... and there are a ton.

Front view:

And reverse view:

Here's how the training gearing is going on the printer. As usual, I never print just one. It cost about 20 cents worth of resin for each one and it doesn't add any printing time. If this was a filament additive machine, the more parts you have up on the machine the slower it is since it must draw each line like a plotter, versus the resin machines that expose an entire layer at once, like a laser printer. I group them close together to facilitate popping them off my flexible build plate.

Builder 2010

If I was printing this part in 1/35 instead of 1/48

Ah, I wondered about the scale change.

It occurs to me that, were a person to cast a clear gun house, but fill it with the full crew (and simplified "innards"), this would make Ryan more than passing happy, as he fields a lot of questions on just how many people are wanted in a gun mount.

This is likely a more reasonable task than the 16" mount, given the difference between WWII's 80-odd versus the 80's manning with around 60 (not that casting 60 figures would be a simple task)

This would be a simpler situation with a 5" mount.  It would also allow getting some use out of "test prints" too.

It's just a thought, if one inspired by Ryan's own words.