Hi chaps.
I havn't posted lately as I've been busy on the CAD side of things, finalising the drawings for the rear-turret cupola and supporting structure. This is primarily 3d printed members of 4mm square profile, clad with two or more shaped 0.45mm thick brass pieces and bolted through, to provide extra strength whilst not adding appreciable weight. The drawings for all the brass pieces will be made into .dxf files, then sent to Hodder and Grainge for acid-etching to the required shapes. Similarly the main front superstructure with the two slots for the guns and baffles, is likewise stiffened with sheet brass, as this will eventually take the strongest loads.
The design of the rear-turret cupola is finalised, and the doors improved to be closer-fitting, incorporating double articulating hinges to allow each door to move directly aftward before opening; and an working latch mechanism concealed largely within the 4mm thickness of the RH door. A further modification has been to add two concealed screws which can be operated to screw the doors shut, whilst allowing eventual access to the FPV cameras and the turret mechanism. Now similar work begins on the front-turret doors and aft section of the cupola, again to improve fit. As I started work on the rear-turret cupola before Christmas, this promises to be a long process, although I now know what's required, and it should be a bit quicker to draw-up the required parts.
In the meantime, I've now built the 2nd fixed-ring, with 72 x 3.1mm ID individual bearing-pockets for 3mm bearings on the upper surface, 72 fixing screws and the capping strip for same, and 24 6.2mm ID pockets and 6mm bearings on the lower surface, with a thicker capping strip and the peripheral brass inserts for the circumferential metal strap which will connect the fixed-ring to the airframe.
One of our number has most generously, and unexpectedly, offered to fabricate the two "turret-tubs" for which I'm very grateful indeed! I'd best check he's okay with being named, but my thanks anyway!
I'm still waiting for the final parts to be made for the rams, which connect the reduction gearbox of the motor to the lead-screw, so can't test that yet. So at the moment, there's quite a lot of useful progress, just not much visible! I attach some pictures. The nest of rear-turret parts, the nest of hydraulic lines for both turrets, and a close-up shot of a new wrinkle:
In preparing the drawings of the hydraulic lines, it became obvious that some needed to adjust for the changing geometry as the guns elevated and depressed. So I've made them solid, and 3d printed, and added a series of cut-outs to each so that the progressive bending required can be by these gaps closing. As the 3d-printed solid cable is going to have black heat-shrink tape over it, and the profile of the cut-out area also remains circular, I'm hopeful this will allow the cable to bend as required, where required, but still be controllably stiff where that's needed too. Bit of a punt, which'll be nice it works as planned.
To economise on printing costs, all straight lengths of hydraulic lines will be tubular brass, mostly 1/16th", glued to lugs on the ends of 3d printed parts, which had added to the time to draw, but made nesting them rather easier. Going to be a bit of a puzzle to reconstitute though!
New no films for a bit, but that's where I'm at currently...
- Nest of parts for rear-turret doors. Note the large orange and brass coloured parts of the base of the cupola split as required to "fit the nest".
- nest1.jpg (58.08 KiB) Viewed 12314 times
- Nest of parts for both turrets hydraulic lines. Incomplete, as voids will be filled with small parts and fixings from turret cupola.
- nest2.jpg (84.35 KiB) Viewed 12314 times
- detail of bendable lines and (orange) escape-route for ram-wiring. The aim has been to have no visible servos or linkages not present on the full-size turret in shot from the FPV camera.
- nest3.jpg (75.59 KiB) Viewed 12314 times