Fletcher Gun Tubs and Mark 49 Director

[Rick E Davis]

Bob,

The fantail bulwark was similar but not the same. The fantail installation was more elongated with the Director further away from the twin 40-mm mount.

I actually was going to suggest "printing" the 40-mm rounds in place, at least one variant(?) of the tub. It certainly should provide more strength to the structure. Blending in the "backside" of the rounds to the bulwark wall should work in this scale. Some PE makers make PE clip holders for going around in "tubs". To be real honest, except in actual COMBAT, the ready-use rounds were covered by canvas. So, some 95% of the time at sea, they were covered.

You need to at least do something to indicate the center point where the twin 40-mm mount "Should be Located". Some kits have a hole (Trumpeter 1/350 scale), some have a pin for the twin 40-mm mount. May I suggest a foundation ring and a dimple that can be drilled out if not a small hole in the center. See the attached image. By the way, the small rectangular holes you see in this image were for the empty shell casings. There were bins below for them. Also, note that this "later" built FLETCHER at a different builder has wider spacing for the stiffeners which are also wider.

For the Tamiya 1/350 FLETCHER kit, some surgery will be required because that kit is an early war version with the elevated (one deck level higher) "tub" originally intended for the quad 1.1-in mount. So cutting off the extra structure and sitting this tub on it (covering the hole?) will be needed. It may be a good idea to make the bottom a little thicker anyway for that situation.

[aptivaboy]

How does this look? I made the 40mm clips, four to a clip, and angled them in a bit. Now, the little wires and frames that they were seated in just aren't printable in this scale, so I didn't even attempt them. The 40mm rounds are barely on the edge of what is printable, the smallest resolution at 0.3mm, which is how thin/thick the splinter shielding is, and that may need thickening.

Thoughts?

Many thanks,

Bob



PS. I like the idea of a mounting ring and hole, so I"ll add them. The ring will likely be less than 1/2 mm in heighth, so enough to see it but not enough to throw the Bofors sited atop it out of whack. I nominate Mr. Davis for Chief Designer. Seriously. You are the resident expert/bastion of common sense.

[aptivaboy]

Hi Matthew,

Sorry for not replying earlier. I tried on my crappy Iphone, but it didn't go through.

I can certainly rescale the tub for 1/700th, but I can't guarantee that the little details will print. The smaller you get, the less resolution the printers are capable of achieving. If nothing else, I could print up a basic tub without the internal details for you to order through Shapeways. If I forget, please remind me; I tend to be 1/350th focused, so feel free to shout out to me if doing so slips past my feeble mind. Seriously, I can be REALLY forgetful, at times.

Bob

[Rick E Davis]

Looks like too many ammo clips. Remove four columns of two clips each from each side closest to the director (total of eight clips on each side), should be about right. The crew climbed over the bulwark to get to the gun/director and needed room so they wouldn't be likely to be getting hung up on the clips with these removed. Are you going to try and put in the stiffeners? In this scale they are pretty small, so I wasn't sure.

Trying to find overhead photos of this area WITH the ammo in place is nearly impossible without canvas covers.

It would be nearly IMPOSSIBLE to mold this with conventional molding ... AND get the part OUT of the mold.

There will be a platform on the director base that the modeler will need to make (if not in the kit) for the Mk 51 director to mount to. The shape of the platform varied so much from FLETCHER groups during the war and whether there was a solid bulwark or railing or half and half around the Mk 51. If the Mk 49 director was installed, there was no platform.

Speaking of ... I wonder how much a Mk 49 director would cost to have made .... hmmmm.

[Rick E Davis]

Finding Tear Drop shaped tubs for 1/700 scale FLETCHERS is easier. They are NONE EXISTING on 1/350 Scale Plastic FLETCHER kits. Tamiya's 1/700 scale CUSHING has the more or less proper shaped Tear Drop Shaped Tubs in their kit already. The Trumpeter 1/700 THE SULLIVANS doesn't have the Tear Drop Shaped Tub ... they scaled down the 1/350 Scale kit.

[aptivaboy]

Is this better?



PS. I'd love to do the little frames and wires holding the clips in place, but I guarantee from past eperience that they're not printable in this scale. That may be something best left to photoetch.

Regarding the Mk 49 director, with plans and dimensions, I can probably CAD that up.

Okay, I'm done for the night. at the risk of sounding maudlin, between the gin and tonics and finding out that my Mom doesn't have cancer (EFFING YAY!), its been a very long and stressful day. CADding has in some ways, been a therapy to reduce the stress. Sorry for venting, but its been a long and hard past two weeks. The tub will have a base ring of about 0.4 mm in height, and a 0.5 to 1.0 mm mounting hole in the center. Does this sound about right?

Bob

[MatthewB]

BTW, there are services that do printing with resolutions down to .012mm.

They are, of source, more expensive, but the idea would be to make the tub in two parts (splinter shield, and base), and then make molds of the parts to cast in resin.

Most of the printing I have done has been in this resolution. It costs me about $250 to have a 1.3" figure made (such as a Roman Legionnaire, or Saxon Theng). But when they are wearing chainmail, which has details smaller than .1mm... I have little choice.

Also, Shapeways has a FUD/FED (Frosted Ultra/Extreme Detail) material that has a resolution down to .1mm.

It is only slightly more expensive. This part would probably run between $25 and $40 (I haven't used that material from Shapeways, I know it is more expensive, but there is just very little material in this tub).

Printing in that material would allow you to thin the walls of the tub, add the internal supports, and allow the 40mm clips to print (Looking at them, and doing a quick estimate... They are going to turn out as nothing more than wedge-shaped blobs on the sides of the tub at .3mm resolution).

And, most importantly, at .1mm resolution.... The part would be useable for 1/700.

MB

[throck3]

Bob,
Congratulations to you and your mother. I'm sure that is a huge relief. I'm glad that the CAD process is therapeutic to you as well. Thanks for all your work here.
Rick/throck3

[Rick E Davis]

Bob,

Congrats for your Mother's diagnosis. Worrying about a serious illness of a loved one is a drain.

As for whether modeler's would rather have Tubs with or without the ammo clips "molded" on is one I can't answer. I just think it would save time and add "bulk" for the printing. The PE versions of holders and ammo look like a lot of work to apply. (Not sure if a set is made for the FLETCHER class kits?) I understand about the stiffeners not being possible, I just asked to know.

I'll try to locate the dimensions on the Mk 49 in my notes. The Mk 49 director diameter should match the Director Pedestal diameter, that is what it was designed to fit. The base worked out to be good for the Mk 51 and the platform to sit atop the "base". Otherwise the Mk 49 has a pretty simple geometry. The "cockpit", which doesn't need to be detailed in this scale, would be the complicated part. One out of three FLETCHERS had one to three Mk 49 directors and there is not ONE aftermarket Mk 49 director available. The Mk 49 director always reminded me of a fairly common round trashcan with a push in lid.

[aptivaboy]

Thanks, Throck. I can't tell you how relieved/emotionally spent I am.

Matthew, the issue is one of hanging wires. Frosted extreme detail has a 0.1mm resolution, true, but not for hanging wires, like many of the supports and such. The minimum hanging wire requirement is 0.6mm in FED, so a lot of things like stanchions, posts, and internal support rails simply aren't printable. the 0.1 resolution works for surface details, like plating atop a flat surface or the chainmail you're referenced. Supports and such that hang out from the part's surface need to be thicker. That's what's slowed down the Hughes' deckhouse for so long - so many of the little details have had to be redone to suit Shapeways' printing requirements.

I also don't see people paying more than $10 tops for a simple gun tub, nor would I expect them to. I know I don't have a lot of money sitting around, so I'm more or less locked in to using Shapeways and their resolutions and not another printing service. I'm going to try to add some plates and supports for the clips down to 0.3mm width, but beyond that...

[MatthewB]

I know that Shapeways dictates a lot of what goes on in 3D aftermarket parts for models. It is just so much simpler to allow people to order a part that is printed on demand than to spend a little more to get a part printed with a form of SLA, which is then cast in resin or metal (I have a lot of contacts with companies who do white metal and resin, so that is the route I go, rather than offering a print-on-demand service).

Most people, though, do not have access to mold-making and casting services.

I expect them to upgrade their service next year to include newer print processes that have higher resolutions.

MB

[aptivaboy]

I hope so! A lot of designers also want to be able to specify the print orientation. I've gotten identical parts from them at different times which were printed in varying orientations on the print tray, and they look and sometimes feel totally different. The hanging wire issue could be alleviated at least partially by printing in a preferred orientation so that the wires and thin shells "hook up" certain ways when printed bottom to top, let's say. There would be support for them while still within the printing matrix and wouldn't break, allowing the hanging wire specs to be relaxed.

Shapeways is looking into it, but as to when that will happen there's no ETA.

Bob

[MatthewB]

I hope so! A lot of designers also want to be able to specify the print orientation. I've gotten identical parts from them at different times which were printed in varying orientations on the print tray, and they look and sometimes feel totally different. The hanging wire issue could be alleviated at least partially by printing in a preferred orientation so that the wires and thin shells "hook up" certain ways when printed bottom to top, let's say. There would be support for them while still within the printing matrix and wouldn't break, allowing the hanging wire specs to be relaxed.

Shapeways is looking into it, but as to when that will happen there's no ETA.

Bob

I know.

I have talked to many people who work for Shapeways, and they are incredibly arrogant in terms of thinking they have everything covered.

They overestimate the extents of their technology, and often are blind to many uses for which a bit of investment would see a spectacular return.

Of course, I am closest with the people who work with StrataSys, who are the people who take up the slack that shape ways leaves (they provide very high-quality, high-resolution, and advanced 3D printing), You can get vapor deposition printing from them, which has a resolution of �.001mm (It is used to provide prototype aerospace parts - I haven't ever needed it, yet).

But I regularly use their higher resolution �HDSL and FDP (the former is the .017mm resolution - I got the conversion wrong the first time. It is .017, not .012).

The latter has a roughly .1mm standard.

But since it is fused deposition (and you can specify any print direction), things like overhangs are not an issue. In fact, you can print anchor chains, and parts that are interlocking, but separated by at least .05mm with it.

Unfortunately, they do not have a web-site that allows others to buy your parts. But doing a quick estimate based upon the volume of material in a 1/350 40mm tub (with the walls thinned down, and the additional reinforcement sections added), the cost per part would only come to about $20 (I need to check my math again, and get a scale to weight what I think is a comparable part).

But StrataSys may eventually set up a competition to Shapeways. They have a larger infrastructure than does Shapeways, but they are absolutely overwhelmed with industry work, and thus it would be a vanity project at the moment to compete with Shapeways, which really is only maintained because of the novelty of the business.

Full disclosure: I have worked in the 3D prototyping industry for over 12 years (as an architectural designer and sculptor - I made decorative structural components for people's buildings and homes), as well as having worked for the gaming industry in a similar capacity around 25 years ago, and again about 5 years ago.... So I have been working with companies like StrataSys for a long while.... And we tend to view Shapeways as a bit of a joke. They provide a service that is really only useful to a handful of people. The rest of it is just "Hey! Mom! Look what I can do!"

[aptivaboy]

I have talked to many people who work for Shapeways, and they are incredibly arrogant in terms of thinking they have everything covered.

They overestimate the extents of their technology, and often are blind to many uses for which a bit of investment would see a spectacular return.

I tend to view Shapeways as a dinosaur in the middle of the Jurassic Period. Times are good, there�s plenty of food, and lots of room to grow. However, the asteroid is on the horizon, and that asteroid will come in two forms. The first is when another printing house starts up and seriously challenges Shapeways, stealing their market share, especially one that does what Shapeways doesn�t, like specifying print orientation. The second is the home printer; prices are coming down all of the time, to where the average home hobbyist and tinkerer will be able to afford one with exceptional printing resolution in the not too distant future, say five years.

Shapeways will either adapt like the birds and survive, or go extinct. Given their recent history, I sadly suspect it will the latter.

It would be great if a company like Stratysis would open up virtual shop fronts like Shapeways has done. That�s what will really create competition and an increase in customer service, printing speed, and all of those other things that create growth. There are folks who make a significant amount of their income selling goodies through Shapeways (I usually make $20-30 per month when times are good) who would like a competitor to emerge. Many feel that they�d sell more if Shapeways� search engine actually worked properly, if the storefronts were more accessible, and if products were printed better and shipped faster. Here�s hoping...

Bob

[aptivaboy]

Okay, I took a step back and redid the interior of the tub. I added the pipe rails/supports that were in some of the pictures. It looks as if the 40mm clips fit inside the rectangles formed by the vertical pipe supports. Here's a half of the tub cut away to better show what the interior now looks like. Thoughts? Before I go any further, I should probably add the little drains at deck level. Was there a fixed pattern or did they vary from ship to ship, as I suspect?

Bob

[Rick E Davis]

That looks better with the stiffeners in place.

It appears the holes/slots did vary depending on when the destroyer was built and maybe by builder. I think a light bulb went off as to the purpose of those short 1-ft bulwarks on the side of the deckhouse and the slots in the bulwark. This area was to be an overflow area for spent cartridges. The loaders could kick them out of the tub that way until they had time to get them down into the bins. The aft mount handled these spent rounds differently than the other 40-mm mount "tubs". The others had "short" bulwark rings under the mounts that controlled the spent rounds so they could only go down the holes in the deck and "not" be underfoot. No such rings for this mount, now I think I know how they handled the spent cartridges.

Here is what was sort of typical, at least early in the war. This view also shows the ammo clip brackets and stiffeners arrangement quite nicely. Wish I had spotted this photo earlier. I put in arrows where the holes/slots were on either side of the bulwark and where the visible drain holes through the deck can be seen. Plus the rim below the tub deck.

There were three slots/holes opening into that area with the short bulwarks on each side and then there were holes (I'm guessing four ... two on either side of the centerline stiffener due aft and one on either side as seen in this image ... aka about in the same location as the under construction destroyer) in the floor that drained out on the deck below. On that destroyer I showed earlier under construction, they seemed to cut these drain holes to drain out the side of the bulwark wall instead of the deck. I surveyed quite a few photos, and the external bulwark "wall" drains were not as common. I think using the arrange seen in the image above is the best one to use as being the most common. Can't cover EVERY variation.

A feature I didn't think of before. There was a ridge/support rim at the bottom of the tub that overhung the deckhouse below. This should be modeled on the "tub as well". Now it will be tricky to determine the exact location where this would attach/blend into the deckhouse below the mount/tub. This is where every kit is a "little" different in sizing/scale with tapers from being molded of the deckhouse parts proper. Take your best guess and let the modeler trim as required.

I have added a different view of the deckhouse/Gun Tub interface from the BIW Engr Drawings at the bottom. This was how BIW changed some things on later construction and it has a better view of the twin 40-mm foundation ring. Not much changed, except this is when the cut off the bulwark of the "Spray Shield" forward of the director base as being unnecessary. The two "rectangular" holes in the tub deck were for ammo scuttles to pass up more clips. I think this drawing makes some details clearer, particularly the foundation ring, hopefully it doesn't cause more confusion for you.

[MatthewB]

I am also seeing two different types of railings around the top of the deckhouse near the narrow end of the tub.

One set of railings looks to be welded steel tubing/pipe, while the other is the typical stanchion and chain.

MB

[aptivaboy]

It also looks like like there were three clips in each vertical row, not two as I had them earlier. I may have to resize the clips to make them all it.

Speaking of which, they keep disappearing when I convert the file to an STL for test uploading the Shapeways. ts like on the Sims when the whistles and associated assemblies kept vanishing on STL conversion. Argggggg...

[MatthewB]

It also looks like like there were three clips in each vertical row, not two as I had them earlier. I may have to resize the clips to make them all it.

Speaking of which, they keep disappearing when I convert the file to an STL for test uploading the Shapeways. ts like on the Sims when the whistles and associated assemblies kept vanishing on STL conversion. Argggggg...

You might need to select each item individually, and then do an "Export Selected as..." rather than a simple "Export file as..."

I had noticed this happening in earlier versions of Maya when I exported at .obj or .stl at times.

Another possible fix:

Save the file, and then re-open it, and then the first thing you do is "export file as stl" before doing anything else.

It seems to be an issue with the file not recognizing sub-components, or updating the object list.

MB

[Rick E Davis]

The "third" row of clip brackets aren't for another row of ammo clips. They are simply to hold the second row in place at the bottom. The top row is held in place by being tucked behind the second row. There isn't enough depth for adding another row at the bottom. Look at the attached close-up image, the bottom row is narrower than the two above it. I believe that the typical 40-mm shell was 17.6 (to 21) inches long as best I can tell (references provide different round lengths).

As for "surrounds" for the Mk 51 director. There were solid bulwarks, half bulwark and pipe/railings, and all railings/pipes. Some destroyers started out with solid bulwarks and then during refits had them replaced with railings (many times covered in canvas) to save weight. Too much trouble trying to track all of them. easier to pick a subject and then find photos of it for its "uniquenesses".