Postby Timothy Huff » August 28th, 2019, 7:49 pm
Hi all,
This is by way of an "AAR" to the posed questions. I eventually went with two SMC pneumatic double-acting pneumatic rams, with flow control valves (needle-valve restrictors) to slow the extension and retraction rates which would otherwise be more on/off than analogue. I intend to try and design and build a valve to give fine-tracking control for small movements of the servo, with a linear increase in movement of the rams as the servo moves from the neutral point. Such valves do exist commercially, however, they're all electrically controlled, large, heavy and 24 v! And it's an interesting problem.
The pneumatic rams are a little longer and thinner than they should be, so I've made some 3d-printed cladding pieces to make them more closely resemble the original rams. This has had the side-benefit of also making it impossible to mount the two rams at different positions.
On the subject of wiring, I was provided with a large number of different JST/XA connectors and pins, and after a false start, procured the correct crimping tool. I then spent an entire day practising crimping these on scraps of the same gauge of wire as the turret services, before attempting the wiring work. I would heartily recommend such practice as it is something of a "skill" I found.
All the JST connectors were trimmed of excrescent plastic, and were airbrushed black to make those that couldn't be concealed resemble the profusion of cosmetic transformers etc around the turrets.
Black heat-shrink tube was used to cover "modern" pvc insulated wiring, again to make it less visually striking, relative to the cosmetic wiring made from silk-covered wire hand-dyed to resemble wartime wiring.
So, thanks all of you who helped with suggestions, all were most valuable!
Regards,