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Old Jul 27, 2013, 11:28 PM
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FightingSteel1's Avatar
Missouri, USA
Joined Jan 2008
150 Posts
Question
Looking for servo/button animation ideas

I'm close to completing getting turning gun turrets on my model. I currently have each turret attached to a geared motor, which are wired to DPDT switches that control left or right rotation.

My idea was to use a servo (one servo channel for bow turrets, one for stern) that would push or pull the DPDT toggle switch, and therefore rotate the turrets. The issue with that, is the toggles are spring loaded momentary on-off-on, and require so much force to push or pull that the it's a very rough mechanism and not reliable without eventually breaking something. The switch kind of "pushes back" at the servo arm.

I'm looking for ideas on how to easily mechanically press a button, or flip a switch or whatever to turn the motors off and on, forward and reverse. Everything else is there and working, I just need a way to run the motors by radio.
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Old Jul 27, 2013, 11:51 PM
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MILLERTIME's Avatar
USA, CA, Fresno
Joined Apr 2004
7,177 Posts
I use a DPDT toggle switch with no problems. Maybe you can use momentary switches.
Here is a picture of some that I have made up.
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Old Jul 28, 2013, 12:34 AM
KC8WPF
CG Bob's Avatar
Euclid, Ohio, United States
Joined Sep 2004
3,677 Posts
You could try an electronic switch unit.

Use the KISS principle and remove the switches and motors, connect the servos by pushrod to the turrets. On my CGC TAMAROA model, I have the fire monitor and 3'/50 connected to a single servo, and they both pivot left or right together. I have the servo connected to a rotary (airplane flap) switch on my transmitter.
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Old Jul 28, 2013, 01:03 AM
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FightingSteel1's Avatar
Missouri, USA
Joined Jan 2008
150 Posts
Quote:
Originally Posted by CG Bob View Post
You could try an electronic switch unit.

Use the KISS principle and remove the switches and motors, connect the servos by pushrod to the turrets. On my CGC TAMAROA model, I have the fire monitor and 3'/50 connected to a single servo, and they both pivot left or right together. I have the servo connected to a rotary (airplane flap) switch on my transmitter.
Honestly, my design has been a pain. I'm liking your idea of just using the servos themselves to run the turrets. I could use a servo slow or something to get a more realistic speed of rotation.

I'm just trying to figure out how I can run two turrets with one servo, and where I would mount said servo. How far does your gun rotate on your design? I would need something like 270 degrees of rotation to make the guns realistic, and I don't know how that much would factor in with the pushrod part of the design.
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Old Jul 28, 2013, 04:56 AM
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Blackpool, Lancs
Joined Feb 2006
2,681 Posts
A cam on the servo working a pair of microswitches would do the job. Use Millertimes circuit. Operate one switch, the turret moves until you tell it to stop, operate the other, it moves the other way.
Co-ordinating more than one turret without mechanically coupling them is more of a problem, especially getting everything facing fore and aft afterwards reliably. Servos directly coupled (one per turret) and something like Actions Servomorph unit would work well. http://www.action-electronics.co.uk/pdfs/P96.pdf To get 270 would need some gearing or having the turrets being driven via a pulley arrangement much like the tuning dial on an old time steam radio.
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Old Jul 28, 2013, 08:50 AM
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patmat2350's Avatar
Motor City
Joined Dec 2004
12,061 Posts
Servo activated switches-- SO 1960's!

For slow smooth motion, your gearmotors are likely the best, but they can be activated with e-switches and DPDT relays... there are other commercial solutions out there, tho I only recall the defunct MCD units right now.

Direct servo action: You need a gear-up somewhere to obtain 180 range of motion... CG Bob appears to do it with servo arm lengths. In my Lindy Fletcher, I used one servo to activate all 5 turrets. A long pushrod and gears at each turret did the job.
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Old Jul 28, 2013, 03:05 PM
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boater_dave's Avatar
Wisconsin
Joined Jun 2007
1,829 Posts
What about using a simple pulley setup of different sizes and monofilament line to the turrets. One servo for the bow set, one for the stern set. The pulleys can be easily made from laminating three pieces of plastic card stock, with a smaller circle inside for the line to ride on. Remember, they aren't spinning fast or requiring too much power. To figure the sizes, you need to compare the servo rotation to the desired turret rotation, and how big (or small) you can fit under the deck. Plus, the line can be routed through screw eyes (fairleads) if you need to bend around corners or get creative in routing the line.

Dave
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Old Jul 28, 2013, 09:42 PM
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CG Bob's Avatar
Euclid, Ohio, United States
Joined Sep 2004
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I only have about 60 degrees of travel, and I'm happy with that on my model. If you go the pulley or chain/sprocket route, the drive pulley on the servo needs to be 4.5 times larger than the driven pulley on the turret; 270 divided by 60 (normal servo throw) = 4.5.
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Old Jul 28, 2013, 10:42 PM
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CaptDH's Avatar
United States, CA, Avalon
Joined Oct 2002
603 Posts
Get one of these with continuous rotation. Speed is varied so you don't have that jerky movement associated with regular servos and up gearing which looks very unrealistic. A whopping $17

http://www.servocity.com/html/hsr-14...s_rotatio.html

D
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Old Jul 29, 2013, 03:44 AM
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FightingSteel1's Avatar
Missouri, USA
Joined Jan 2008
150 Posts
Thanks for the ideas everyone. I'm going to go with one servo per set of two turrets; I have a couple of servo slows on order to give them a more "scale" rotation speed.

I think I can mount the servos and mechanism to the underside of the deck. The only thing is that I was planning on using silicone to hold down the entire deck and just having access hatches. I'm fine with having the whole deck removable, I just need to figure out an easy way to hold it down.
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