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[Greggy1964]

What follows are details of the servo/sail winch I built from a defunct acoms servo.

This particular winch is used in my sailing canoe and controls jib, mainsail and mizzen on the three drums.

Each drum diameter is worked out depending on the length of sheet required to haul in.

I can't vouch for the internal layout of other makes of servo for this project as I have only tried it with acoms servos.

Here goes,

The dead guts of the servo were removed to make way for the M6 threaded screw/final drive shaft. This can be seen passing through the underside of the final gear bearing support in the centre of the photo.



The drive shaft passes through the final drive gear and is supported at the bottom of the servo by simply passing through a hole in it's base.

The final drive shaft is a screw fit through the top of a circular control horn and the centre of the final drive gear .

The final drive gear must be set up in such a way that is allowed to continuously revolve in either direction and any limit stop molded into it cut away.

A piece of copper wire bridges the slot in the top of the final drive shaft screw preventing it turning independently of the final drive gear and is fixed through the circular servo horn on either side and its ends turned over underneath the servo horn.



The winch drum is fixed to the circular servo horn by 4 screws from underneath.



On the final drive screw is a small traveller made in such a way so as it connot turn. This is achieved by shaping the right hand end in the photo so that it runs up and down the inside face of the servo case. At the left hand end can be seen the limit switch arm. When the motor is running, this turns the gears and thus the final drive shaft.

Depending on which way the motor is turning, the traveller if forced to travel up or down the thread on the final drive shaft. The switch arm on the traveller lives between the upper and lower contact circuits described below but is allowed to pass the centre contact.



The travel stop micro switch is made up of a sandwich of 1mm birch play shims with three contact plates. In the dead centre of the sandwich is a tin sheet contact plate that makes contact with both upper and lower contact plates of the sandwich. The middle contact (black wire) goes to the servo motor. The two outer contacts (yellow and red wires) are two separate circuits, one for winch out travel stop circuit and the other for winch in circuit.

When the travel stop arm comes into contact with either of the outer contact plates, it breaks that particular circuit with the middle contact plate thus cutting power to the motor. The motor stops, the travel arm stops as a result holding that side of the switch open.

Of course the other circuit plate is still in contact with the centre plate and thus the winch may travel back in the opposite direction.



The green wire from the other side of the motor and the yellow and red limit stop circuit wires pass out through the side of the servo winch and are connected to a simple switch board fixed to the top of the winch control servo.

The green motor wire is connected to both contacts at the front of the switch board and the yellow and red limit switch wires are connected to the left and right contacts at the back of the switch board respectively.

The wipe arms fixed to the winch control servo horn carry the positive and negative wires to the battery driving the winch motor and thus give us forward and reverse i.e. winch out and winch in for the sail sheets.

The winch servo is assembled as follows.

The final drive gear is fed through its hole in the upper part of the servo case, the circular servo horn is fixed onto the splines on the upper end of the final drive gear.

The final drive screw is screwed down through the top of the circular servo horn and through the centre of the final drive gear. Keep turning until the head of the screw is tight down to the top of the servo horn.

Now fit the copper wire preventer into the slot on the screw head and through two holes in the servo horn either side and bend over underneath.

The winch drum/drums can now be screwed to the top of the servo horn.

The upper part of the servo winch is assembled so that the final drive shaft screw passes through the bearing support for the final drive gear and into the lower half of the servo case.

The limit switch traveller is screwed onto the bottom of the final drive shaft and its arm carefully positioned between the upper and lower limit contacts of the travel stop micro switch which is bolted to the inside of the lower part of the servo case.

The servo horn is hand turned so that the limit arm draws the bottom of the servo case towards the main body when it comes into contact with the upper part of the limit stop switch plate. Keep turning until the lower part of the servo case closes with the main body and then stop turning!

Turning further will strain the limit travel stop arm preventing proper operation.

Beforehand we have calculated the number of revolutions the winch drum will make so that the traveller makes a full passage between the upper and lower limit switch contacts.

If we now turn the winch horn back half this number of turns, the limit stop arm carrier should end up half way between the upper and lower contacts of the limit stop micro switch.

The winch/servo screws holding the whole thing together can now be put in place.



Final drive screw ready to be fitted into place.



Veiw of top of winch drums.



Winch drum sheet fairlead assembly.

When all is in place and powered up, the winch will operate either way between the limit travel stops.

The transmitter stick controlling the winch is set up spring loaded to the centre.

When the stick on the transmitter is held at winch in, the winch will continue to haul in the sheet or sheets until the travel stop is reached and the sails are sheeted fully home.

The stick on the transmitter may now be set to allow the winch to haul out and if the stick is held in its current position the sails will be let out until its limit is reached and the winch will stop again.

Of course the sails may be set in any position between the two limit stops by allowing the transmitter stick to centralise cutting power to both out haul and in haul circuits.

The sails will remain at their current setting until the transmitter stick gives a command to haul in or out from the sails current positions.

Feel free to ask questions and I will be happy to help.

[Greggy1964]

Here is a sketch that hopefully will clear up details of the micro switch assembly



 

Note, to get more revolutions on winch drum/drums between travel stops, increase thickness of shims between centre contact plate and outer contact plates as space inside the servo case will allow.

The contact plates were cut from an old bean tin can and have to be long enough to allow the natural springiness of the tin to be used to advantage in the switch, of course if access to proper thin copper coated spring steel used in switches of this type is available for these items it should be used.

It is important that the upper and lower contact plates spring back remaking contact with the centre contact plate after the switch arm moves away for the circuits to work.

[Greggy1964]

Here is a direct link to the micro switch sketch as some areas are not too clear

http://i431.photobucket.com/albums/qq32/greggy1964/Servo%20sail%20winch%20conversion/Travelstopmicroswitchassembly.jpg

 

[Greggy1964]

At the risk of over simplification I have presented here how I control the sails via one sail winch on my sailing canoe using one channel of my radio control set up.

The winch controls jib, mainsail and mizzen on three stacked drums as described in an earlier post.

One winch can control any number of sails by simply adding another drum(s) to the stack. up to the maximum total sail area the winch is able to control.

The down side to this system is that all sails are controlled as a group with no individual sail setting possible   other than at the pond side via bowsie's on individual sail sheets.

The answer is to build separate servo winches for each sail.

I have devised a cunning plan to control multiple sail winches using one channel of my radio controls.

Hopefully the sketch below will make things clear.



Here is a direct link http://i431.photobucket.com/albums/qq32/greggy1964/SAilwinchcircuitlayout.jpg

The sketch demonstrates my intention to control an additional winch circuit (circuit 2 in the sketch) to that currently used in my sailing canoe.

Notches cut in the ratchet wheel on the back of the transmitter stick corresponding to the servo switch board positions gives me a positive feel for each chosen position but when the stick is released, it will spring back to the neutral setting thus cutting power to the circuit previously adjusted holding that sail at its current position.

When the transmitter stick is in neutral there is no power to any circuit.

It will be seen that as the stick is moved upwards to set winch 1 to out-haul, winch 2 will be briefly energised to out-haul as the transmitter stick passes its notch. The sail movement would be tiny and I don't see this as a problem at the moment.

However, a delay circuit placed on the battery side could be introduced whereby any sail circuit will only be energised after a 2 second (adjustable) delay at any transmitter stick position.

This setup will give me infinite sail settings, altering my ships performance, which to me is the fun of sailing such models and I plan to use this system on my Master Hand sailing trawler project http://www.modelboatmayhem.co.uk/forum/index.php?topic=19422.0

I plan to use both up/down movements of my 4 channel setup on my right and left transmitter sticks, each controlling two sail winches.

I am also currently dreaming up a further circuit for full up and down postions at the transmitter stick whereby fully up will be 'all sail winches set to outhaul' irrespective of their current positions and stick full down will be 'all sails set to in-haul'.

This will hopefully allow me to control my ship in the event of an imminent collision with another boat.

Master Hand will weigh in at around 60lbs and close hauled she will, I imagine have quite some momentum behind her.

In an emergency running close hauled for instance I can put the helm hard over and let all sails out, or when running down wind rudder hard over and haul all sails to the centre line.

The other reason for all this is that I can set my foresail and jib aback during tacking manovers thus giving additional umph in pushing the bows round, which will I hope negate the need for a massively oversized rudder on the model.

Yes I know this idea is a flagrant misuse if digital proportional control,   but I want to adjust multiple sails individually and to my mind my radio control is a means to an end, i.e. controlling my ship belting up and down the pond.

The multiple winch control idea is all pie in the sky idea at the moment but we will have to see.

Watch this space!

[Greggy1964]

Forgot to mention,  

The pot that used to live under the final gear was thrown out with the duff circuit board if this is not already obvious

The shaft of the pot used to go up inside the final gear and the thing was bolted to the underneath of the middle section of the servo body by two tiny screws.

The hole in the final gear is opened up very carefully and drilled right through to allow the final drive screw (on which the micro switch traveller runs) to pass right through from the top of the circular servo horn, down through the final gear and through a snug fit hole in the bottom of the servo case.

It is very important that the hole in the final drive gear is drilled centrally to avoid the gearbox binding.



Here is a shot of the gearbox and the underside of the final drive gear, not the travel stops molded into the case under the gear have been cut away to allow the gear to revolve in both directions continuously.

Start with a tiny drill gripped in a pair of mole grips and carefully hand turn the gear down on to the drill bit, all the while checking it is turning true.

Then go up one drill size and do the whole trick again, keep going up drill sizes until you get a hole size just smaller than the final drive screw thread.

This will then cut its own thread in the gear, use a screw with the first few threads filed away so that it acts like a thread cutting tap.

I'm not sure what the maximum sail area would be for this winch but it controlls all three sails on my sailing canoe with ease, though I doubt it would be strong enough for a one metre class job!