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[destroyer42]

Hi Model boaters,
Has anyone any experience in using servos to turn a battleships guns?
How is it done?

Destroyer42

[6705russell]

Hi,

This is the set up on my Majestic class, the servo sits underneath and under the turret are two pegs whih drop on to the servo.

Russ

[Tug-Kenny RIP]

 

I do hope I'm not steering the topic, but does anyone think this is a good idea for turning a Crane ?

Please contribute as it will save a lot of gears and pulley's if acceptable

Cheer...Ken


 

[Bluebird v2]

hi there all

The method I am going to try and describe is the method I used to rotate HMS AJAX's guns - it involved 1 'good' servo and 3 'naff' servos

First of all, on the good servo, you have a choice of leaving the servo as it is, with regard to the movement, which is roughly about 20 degrees from the centre line.

Or, increasing the movement electronically, which is dealt with somewhere else on this Forum in depth and that is the method I used.

Secondly, on the good servo, you must solder two wires onto the motor terminals on the pc board inside the servo.   These two wires form the basis of the power supply to the other 3 servos.   

Servos 2,3 and 4 need the physical stops removed from the gearing.  Also, the electronics need to be disabled inside the servo.  Two wires are then soldered onto each servo motor in turn.

These are now connected up in parallel with the two wires coming from servo 1.    Any movement that servo 1 does, the motors in servos 2,3 and 4 will mimic.

Now, dont forget, the aft guns will rotate (or should rotate) in an opposite direction.

So....looking down on the model, for the guns to give a broadside on the port, the two forward guns will rotate anti-clockwise.

The two stern guns will rotate clockwise.

I hope this is as clear as mud for you.

Ive included a scribble.....to try and explain.

Also, I do know there are other methods using chain drive separate motors and electronic switches.  Ive read this article somewhere in a book.  But, for the life of me I cant find the book tonight  :)

To answer TugBoatKenny's problem, have you ever thought of using a sail winch servo, which has a greater rotation than a standard servo.  I know its an expensive alternative, but, they are stronger than a standard servo.

Aye
John E
Bluebird 

[6705russell]

Ken,

A servo will turn a crane but only about 30 degrees i think, when i did my Norderney i attached a gearwheel on top of the servo and a gearwheel on the bottom of the cranes main mast so they were touching this way it turned about 260 degrees, i think the gears were abot 60 teeth?

Russ

[Admhawk]

There are many ways to do this. One is to connect a linkage to several turrets(like a rudder), so that they can all be turned by one servo at the same time, another is to pop off the servo arm and go straight into the turret bottom with a shaft. If you put a cam under the barrels and a small bar/roller attached to the barrels riding on the cam, you can have the barrels elevate as they turn. If you buy a small cap gun with the round cap cartridges, it can be modified to make popping sounds as the servo pulls the trigger and if you're really creative, and fit the gun into the turret with the gun barrel feeding into the turret barrel, you can have sparks and a puff of smoke!!!

There's no right way, only limited by your imagination!  :)

[Colin Bishop]

Saw this by Alex MacFadyen at today's ME Exhibition. Intended to go in a model of Jean Bart/Richelieu.

[J.beazley]

Colin have you any details or know the scale of the turret set-up in the pic???

Could be just what i need for my Richelieu

Jay

[dreadnought72]

Hi Destroyer42,

I want rotating turrets in my HMS Dreadnought - and at first I thought this could be achieved mechanically. After a pile of thought, I came up with this method (requires the Flash player on your browser - right click if you want to zoom in. Drag the yellow arrow to the desired bearing, then hit the red "acquire" button.)

It's all rotating discs and commutators...and while it could work well for forward or aftward facing turrets, it doesn't work for both. It would take some arm-waving to explain, but at some point, for fore-and-aft turrets, a disc has to rotate 360 degrees in order to cross a "dead zone". It would work well for a one-off crane or catapult, however.

So, wanting five turrets to move, I decided to go down the microprocessor route (Basic Stamps are the price of a couple of good servos) - and this is a model of the result. Drag the bearing indicator (that'd be one stick on the tx, reflecting 0-90-180-270-360 degrees) then hit the acquire button (an extreme movement of another stick.)

The programming running the Flash is nearly identical to the programming needed in the microprocessor. Just a few lines of code, whose output would be sent to servos set up for each turret and able to provide the full range of motion. Basically:

If a turret can point to a selected bearing, then it will train to it when the acquire button is pressed.
If a turret can't point to a selected bearing, then pressing the acquire button will train it to its parked position.
If the turrets are training or parking and another bearing is selected, they'll park or train to the new bearing as appropriate.
A separate park button (other end of the acquire stick) will restore the turrets to their starting position.

Fancy stuff I'm still toying with: there are solid-state gyros available for model helicopter use, and I suspect it would be possible to use one of these to set absolute bearings and hold this angle accurately enough - for a few minutes at least. If so, then the acquire button would set this bearing and the turrets could be made to hold this angle irrespective of the heading of the ship (simulating tracking a distant target as course changes are made).

Andy

[Colin Bishop]

Colin have you any details or know the scale of the turret set-up in the pic???

Could be just what i need for my Richelieu

Jay, Alex usually builds to 1:96 scale which would make the model around 9 feet long. The turret unit shown is pretty heavy and has been engineered as a one off scratch built unit by Alex. I think the guns are made to fire too. Not something you can buy off the shelf.

Colin

[Ghost in the shell]

kenny, whether it be a crane or a warship turret, the principle is the same, a servo mounted in the deck, however, on a standard servo you are restricted to about 90 degrees across the entire arc of travel, rotating a crane will require 2 servos for a basic set up, and one of the servos will have to be hacked to give constant rotation

one servo will push on a linkage at the base of the crane to give the jib-up/down action, the rod going up the centre of the shaft, pushing the boom up from inside.  the hacked servo could be used to rotate the crane. 

My Yamato also has rotating guns, the front two have their servo working a cam arrangement, the stern gun has its servo hard wired to the underside of the turret.  barrels are fixed.  (besides I not got enough channels free!)

if its for your villestroom, ask Farradays cage how he did his. 

[Tug-Kenny RIP]

Cheers Ghost

yes. It's for the Vliestroom. I had a packet of gears ready, but have not designed anything yet. I like the idea of a servo as I might have the room, and besides, it's a handy little box complete.   


Cheers...Ken


 

[Ghost in the shell]

terry has stripped the guts out of a camcorder for his