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Octuple pompoms, part III

March 18, 2012 / efoeth

Continuing from part II.

Because I though it would be fun, I purchased drawings of the quadrupple guns along with the Mk V and MKVIs of the octuple pompoms to make small models to be distributed by any manufacturer. If you have seen the barrels of Master from Poland, you know you are dealing with a manufacturer who’s really committed to accuracy. I asked them if I could trade a few custom barrels for the etch design and a few parts. They said yes! However, having accurate custom made barrels as tiny as a 1:350 40mm gun is great but now my models couldn’t be so awkward that only I can handle them; other people have to be able to make them as well. So, I decided to make a series of prototype guns. One set of three guns is for my own model and will be a set of no-comprise all-singing-all-dancing models. One set of three different guns will be made for Master for casting. One set of two guns will be made as a demonstration showing that all parts—etched or cast—will actually fit. I made a series of parts and the best parts were selected for casting, the worst part was for the test-fit model and the rest are for my models.

Here’s a production drawing that was sent to Master. The cooling (heating) sleeves around the guns are placed eccentrically but not on the models. A small rod will be placed inside the gun cradle master so that all guns will fit nicely. The bottom drawing shows a version of the gun with additional sleeves (Remote powered versions). Perhaps some drilling is required for the cast parts. Note that both short and long barrels are designed for the inner and outer guns.

The gun cradle started as one main part with a smaller detailed part glued to its inside. The MASTER model will be a monoblock.

The gun cradle block was drilled through using the drill press. I had to first position the drill and to then take a picture using the macrosetting of the camera to see if the drill was set properly! Perhaps I should buy a visor or magnifying lens?

Small detail parts were added to the roof of the gun cradle. I use Tamiya tape to position the part and use a 0,1mm brass wire to apply a drop of glue. The gun cradle of the quadrupple gun is seen at right.

All MASTER gun cradle parts are now complete. The parts are fitted with disks or rods to help aligning them in the main etched parts.

There are two pieces of equipment at the front of the model; an electric motor and the hydraulic pump. Here’s the production drawing for the electric motors. With these small parts, you really have to plan ahead and such CAD drawings are of great help to me.

Here are the models of the electric motors situated front left on the model. They are a combination of lathed parts and rings made with the punch & die set (I make all rings on the lathe now, the punch & die is not accurate enough). The brass wire is 0.1 mm thick.

The pump for the hydraulics is on the other side. This part is much more complex than the drive motor. A lot of pipes run from this gear to various points around the weapon. It appears to be an iron cast housing of complex shape. I made an approximation for this part. The final part isn’t really as accurate as the drawing might suggest. This part was so time consuming to make that I decided to make one and cast the rest. Among other small parts I decided to cast are two hydraulic units behind the ammo trays, bolted to the side of the main gun frame.

This is an overview of all the parts. The top left part of the image shows the hydraulic pump and drive motor situation at the front of the gun. The image top right shows the elevation drive with one of the hydraulic pumps below it, also shown bottom left. The bottom right image shows the rear of the guns protruding from the rear of the main gun housing.

These are the test-fits of the demo models. The parts are assembled a bit wobbly… I was so preoccupied with detailing the modes that I forgot that HMS Hood carried one Mk VI. The main etched part for the gun cradle is now a Mk V but the rest of the parts are not. Complaint forms can be downloaded at the IPMS main website. Anyway, the fit is fine but some parts were very difficult to align. Many of these errors were ironed out for the second design. These etched parts arrived last week.

The new design works much better. It’s made from brass so I could finally solder all parts; no glue so far. I have no experience with soldering but you learn a lot in a day. One ammo tray took hours, disassembling itself when re-adding heat; the second one was produced quite quickly. Still, these are very tricky models to make but the results should be well worth the trouble!

Custom Photoetch Set Part IV

March 9, 2012 / efoeth

In an attempt to further delay the inevitable—that my model might actually reach completion—I designed a new photoetch set. Every time I make a new set I have to change the order of programs for making the masks. I still start in Autocad for its accuracy and ease of us (I find so). However, after having spent many a fine evening with Autocad, pdf-printers and graphical programs, I found myself unable to export the file to a good quality PDF. Circles remain jagged, even when setting the Autocad view setting the maximum, setting the print quality to highest and printing to A0 size. I’ve decided that Autocad is terminally lousy at plotting. Exporting the file (DXF, DWG, all versions Autocad can export) won’t work; the cause is the bad hatch definition in Autocad that other programs as Adobe Illustrator and CorelDraw (latest versions, demo) just won’t accept. I remembered with the previous etch I could directly copy the design to clipboard and insert it into Illustrator. But now I have Windows 7 that runs out of memory while attempting this copying, even though I inserted the full 8 Gbs that my aging PC can handle to avoid exactly that problem. Anyway, away with the hatches and fillings. Reading the lines in Illustrator and filling in all parts, AGAIN, worked.

Here’s the design. I’d love to show you the etched fret. However, the etcher (etchworks) decided that wrapping the etch in crudely shaped cardboard—taped shut leaving all the movement a delicate etch needs to destroy itself while roaming its lush and spacious surroundings—is all the protection you need in the mail. Many parts are now loose, damaged and one or two missing (I did design the lines hold the parts to the fret too thin though). Fortunately I needed only half an A5 and nearly all parts are already etched twice in the fret. If this were a set of railing this would have been a complete failure. Of course, one could ask the etcher to re-etch the design, if this weren’t the second etch already. The first attempt had both top and bottom layers merged on the top of the etch removing all detail and folding lines. The quality of this etch is really good though. I have a few parts designed much smaller than recommended—such as the 0.05mm bars of the sights for the pompoms—and they look wonderful.

The etch itself doesn’t really contain anything new. I removed some design errors from the pompoms and added parts that I wasn’t happy with in the other set. Flag lockers, a few ladders, some parts for the 4″ guns that proved unfoldable (yes, I tried). I also added a selection of rings (always useful), scuppers (overscale, no doubt) and some pulleys, mainly for the funnels. I have a set of custom-made barrels on order from Master in Poland to finish these small pompoms.

Camouflage of HMSs Queen Elizabeth, Valiant, Renown, 1944

February 13, 2012 / efoeth

I was watching the Imperial War Museum’s DVD “The Royal Navy at War; British Pacific & East Indies Fleets”. The British fleet was accompanied by the USS Saratoga in 1944 from which some color footage was shot. HMS Queen Elizabeth, HMS Valiant, and HMS Renown are depicted in their well-known Admiralty Standard Camouflage Scheme A—G45 warm light grey overall and a B20 medium blue panel on the hull—and I noticed that the main turrets and non-vertical surfaces of the secondary armament are in the same tone of blue. You’ll notice that these turrets appear darker on black & white footage as well, unlike the camouflage of other cruisers and battleships in the same scheme.

HMS Queen Elizabeth.

HMS Valiant. Note that HMS Valiant main mast is a pole mast and that HMS Queen Elizabeth has a tripod mast.

HMS Renown

Making rings with the lathe

December 17, 2011 / efoeth

I posted a small tip on making rings with the Punch & Die set earlier. I now use my lathe.

I use stock styrene rod from Plastruct. I drill in the rod with the correct inner diameter and use the lathe to remove enough material for the correct outer diameter (example in the image shows this in reverse). Instead of using a parting tool, I reinsert the drill and use a knife to cut the ring from the rod; the drill with catch the ring. You can make a series of rings quite quickly and collect them on the drill. Using the knife can result in some variation of the ring thickness, but the number of rejects is a lot smaller than with the punch & die set and I can now make rings of all sizes. You do need to be careful using the knife while the lathe is rotating; this is why I position the knife as in the image—cutting with and not against the direction of rotation—so that the tip of the knife can’t be hit by the jaws of the chuck and catapult into my eye.