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[Billyruffian]

I am fighting my way through the Cervia build and all was going swimmingly well until the weekend.

I though I had positioned everything correctly before the deck went on and all was working as it should.

Problem arose when I cut the deck out for access only to find that whilst I could access the servo horn I couldn't get to the mounting screws

It was also sitting right over the motor connector making that impossible to get to.

After a few hours last night, I did manage to get the servo out without cutting any further deck out.

Now I am stumped as to where to position it

If I move it over the motor, it will be above deck level but concealed by the superstructure which is OK but how do I get the conenctor rod below deck and then back above deck to connect to the rudder?

How many bends can you put in a 2mm connector rod and still have it work efficiently?

I have seen these thing called snakes but have no idea what they are used for - would they be OK for this application?

I am following - or trying to follow - the build in the masterclass and am trying to avoid cutting further deck away from the stern.

Any help would be fantastic and make an old man very happy 

[John W E]

Hello there my mate,

May I enquire of you, do you need to remove the servo?

When I originally built the Cervia, I knew I wouldn't have a great deal of access to the screws which secure the servo in place.  This is because, I work on the principle that if the rudder servo is located and fitted correctly, it should operate for years on end, with very little if any maintainance and be trouble free.  If the servo did misfunction or the linkages did come apart, the build is such that you could cut into the deck; to give you access to the locating screws and remove the servo.  You would then repair the said fault and then reglue the deck back over the servo & thus camouflaging the cut into the deck using ropes etc.

If the radio gear is to be used in another model, surely the price of a cheap servo warrants leaving the servo in place; and purchasing a new one to go into a new model?  As far as linkage rods are concerned between the servo and the rudder, the straighter they are, the more efficient the movement will be transferred between servo and rudder.  As a friend says - suit yourself 

As far as hinges are concerned, have a look at the Whaleback build, I built some hinges for the sickbay doors 

Good luck with your build - and let us see some pics 

aye
john e
bluebird

[Billyruffian]

Thanks John,

Unfortunately, I spent 2 hours last night fighting and cursing to get the servo out without cutting any deck.

So now I have the servo out and wondering where to put it - please be polite with your answer

I took it out because I had no access whatsoever to the motor connector or prop tube and without ready access to the servo mounting screws, I could't remove the servo either.

Now I have it out I am struggling to find where to locate it.

I was hoping not to have to cut any further deck away.

If you remember, I am not using a gearbox as you did but a direct coupling so I do need access.

I always value your opinion John and as soon as I get this servo back in somewhere I shall post some pics.

Cyril

[Colin Bishop]

Is it possible to mount the servo upside down so that the bottom sticks up into the superstructure but the actuator arm is below deck level?

Can you post a photo of the setup so we can get a better idea of the problem?

John is quite correct in saying that servos very rarely go wrong but it's the inaccessible ones that usually do.

Colin

[Shipmate60]

If it is below the deck, carefully measure where the screws are positionar and drill 4 holes big enough to get a screwdriver through.
You can fill the holes with silicone and paint over or place something as an escape hatch ove some of the screws.

Bob

[Billyruffian]

Thanks Colin,

That's given food for thought.

I assume there is no problem with the servo working upside down?

As for a pic - it is pretty much as the Cervia build in the Masterclass except I am not using a gearbox so my coupler was also hodden under the servo.

Perhaps I am being a bit too careful but as this is my first scratch build I would rather be able to get at all the bits that can go wrong as they probably will.

Cyril

[oldiron]

Would a mounting arrangement such as this help:
http://www.modelboatmayhem.co.uk/forum/index.php?topic=10387.100 (see the bottom of the page).
I screwed the bracket through from the top of the deck. As has already be suggested, the screws can be covered with deck cargo, tarps, ropes etc, but provide for easy removal without destroying anything and giving good access inside.

John

[Billyruffian]

Thanks John,

Another cracking alternative.

Where would we be without this forum?

Cyril

[Circlip]

Another one to think about Cyril is the closed loop system. With the aid of a few pulleys and strings, you could put the servo virtually anywhere.

  Regards  Ian.

[John W E]

hi there Cyril
I have done a little scribble for you, of a way in which you can mount the steering servo upside down, as Colin has suggested.
What you will have to do is to glue 2 blocks of wood on the inside of the combing to support a piece of plywood across the access opening at the back.
This piece of plywood would have the servo mounted on it upside down.    The plywood in turn would be secured to the 2 mounting blocks with screws so, if you required access to get to the motor coupling or prop shaft, you will be able to do so by removing the mounting screws.
I have already tried an upturned servo in the Cervia which I built, to give me some guidance of the space required and as long as the motor in your model is in roughly the same position as it is in the gearbox/motor in the Cervia build, you should have no problems.  There is also ample height as well in the engine room casing for the rear end of the servo.
aye
john e
bluebird
 

[Tug-Kenny RIP]

Don't forget, the servo will be rotating in reverse.

ken

[Billyruffian]

Brilliant John thankyou so much.  As usual you have gone the extra mile to help.

Kenny - thanks for that - I wouldn't have given that any thought prior to installation - phew

Cyril

[Colin Bishop]

Most radios have a servo reverse function these days so you shouldn't have to set up a diagonal linkage from servo to rudder.

Colin

[BarryM]

Nobody seems to have considered the snake or control cable that Billy himself mentioned. Keep the ends anchored and the curves gentle and it's a good way to mount the servo remote from the rudder and still get full movement.

As the Sage says "It works for me".

Barry M

[Billyruffian]

Thanks Barry - I'm glad that somebody has mentioned the "snake".  I have heard of them but have no idea in what circumstances and for what purpose they are used.

Are they - for want of a better description - flexible connecting rods?

If I understand correctly you could use snakes where the servo is a different height to the rudder  - as in my situation - and still  have full and accurate control of steering?

Cyril

[Colin Bishop]

"Snakes" are basically the same as bicycle brake cables with an inner braided wire in an outer sheath. As Barry says, the ends of the sheath do have do be securely fixed. I suspect there is a bit more "give" in them than a rigid linkage but if fitted correctly not enough to matter. The aircraft boys use them for control cables in model applications. My old 1:1 scale yacht used them to control the outboard from within the cockpit. It's a perfectly viable solution.

Now Billyruffian you have gone from not knowing what to do to having too many solutions to choose from. It's called the Mayhem effect! 

[Billyruffian]

Too much information is a dangerous thing Colin

As it happens for my solution on this model I am going your route and John's description of mounting the servo upside down but what a wealth of information this asylum - sorry forum gives 

Thanks all for the info.

Cyril

[Circlip]

Used to use snakes on toy A/C but unless the outer is well supported for its whole length you allways end up with "Slop" in the system, that's why we changed to closed loop. Very precise control, much more important in three dimentional media.

  Regards  Ian.

[BarryM]

Used to use snakes on toy A/C but unless the outer is well supported for its whole length you allways end up with "Slop" in the system, that's why we changed to closed loop. Very precise control, much more important in three dimentional media.

  Regards  Ian.

Fixed at both ends with maybe one/two points in between (depending on length) and it gives all the precision you need in marine craft.

Barry M