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[GrayWanderer]

Hi,


I am currently building the Sir Kay Minesweeper (my first military vessel) and would like to enhance the model somewhat.  In particular I would like to motorise the 12 pound anti-aircraft gun.  I would want it to oscillate through perhaps 180 or 120 degrees.  I have noted motors with gearboxes to slow rotation but nothing that oscillates.  I vaguely remember reading about using servos for such a duty but a simple servo would not meet the duty.  Also I have read comments about servos stripping gears, burning out etc.


It seems to me that with the number of model military ships available this requirement must have been solved many times over.


I would be grateful for any guidance on the best techniques to implement this feature.


Many thanks.

[C-3PO]

Hi - do you want the movement to be controlled in any way from the RC  handset or just a standalone system?


Regards
C-3PO

[JimG]

If you just want the gun to oscillate mount it on top of a servo and use a servo tester as the control. These generally have the option of manual movement or a slow or fast oscillation.
Jim

[GrayWanderer]

At this point I think my ambition is limited and I would go for a stand alone system. 

[DaveM]

I'm not sure exactly what you're looking for, but I'm also not sure that you are either! Have a shufti at this gizmo when you've time. I've handled an earlier version and it's brilliant. http://www.forge-electronics.co.uk/index.php/boats/servo-controller
DaveM

[malcolmfrary]

At this point I think my ambition is limited and I would go for a stand alone system.

Swinging the gun mount using a servo is not a problem.  Cheaply, most servo testers have a "swing" function that causes the servo to repeatedly travel from one extreme to the other. It will swing as long as power is available.
However, a permanently swinging gun might not look as good as imagined after the first couple of minutes, so Daves suggestion of controlling the gun on a spare channel sounds good.
On a "Sir Kay", which is known to be a but tender, I would be careful adding extra weight above the waterline.

[Akira]

Another way to skin the cat: Many of the new computer radios allow the servo slewing speed and the end limits of servo travel to be set in/on the transmitter. This can save buying servo stretchers like the one previously mentioned. there are, as well, quite rugged servo capable of 300 degrees of travel, out of the box. The combination fills most needs relative to animating weapons ect.All that said, if using a radio that does not incorporate said capabilities, servo extenders and servo slows, as we call them over here, fill the requirements perfectly.

[C-3PO]

Pololu Maestro USB servo controllers

https://www.pololu.com/category/102/maestro-usb-servo-controllers

A very flexible way to control servos. Come in a few different capacities. You can program a servo movement sequence, servo speed and more - then simply store it in the onboard memory and it will replicate the movements each time power is applied in standalone mode.

The setup is achieved through a simple program that you run on your computer and then save the details to the Maestro board.

Example Maestro board



Software



Video - https://youtu.be/AqToEWmTVXA

Or you could do pretty much the same flying solo with an Arduini Nano clone £3.00

C-3PO

[GrayWanderer]

Many and belated thanks for all the advice.  I think the comment about not knowing what I want was very true.  I had not really thought through how artificial the gun continually swinging would look.  I have decided to up my ambitions and add a servo.


Again many thanks for the advice it was all very useful.

[Southern Sailor]

Perhaps an ignorant question, but can the Polulu and the Forge Electronics units control say 4 servos at the same time? Thus, one channel controls 4 gun turrets elevation and one the slew movements. Brian

[Akira]

https://www.servocity.com/servos/gobilda-servos-8 

These servos will swing 180+ degrees right out of the box. Capable of 300 degrees, they will need a servo stretcher hooked up, though.I am using them on my Fletcher destroyer, coupled directly to the turrets( see the couplers available on the web site) and I adjust their end limits with my radio. I have 270 degree rotation on my turrets.