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Aileron and flap servo arms in moulded wings.


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isoaritfirst

The point  is, that they shouldn’t need taking out. The OP’s question although answered by others does have a deeper problem, that is highlighted by their requirement to remove servos for correction of installation problems. 
It is completely possible to calculate/ guesstimate or even mock up installations so that once installed there is no reason to remove or adjust. 
LDS installations are non adjustable. Fitting rods and clevises are no different. 
When I do an install of this type I solder the clevises to the rod at both ends. I use a rough guide of 7/10 servo arm to horn ratio and take great care in ensuring all horn positions / lengths are equal. 
To the OP I would suggest that they spend some time researching or just considering what they are trying to achieve. 

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Andy_B

And when you buy a model second hand and put a new rx tx combo on it you dont have a chance to install as you want , and as we know not all centres are born equal .

 

😇

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isoaritfirst

Clearly their are occasions when servos need to be removed, and breaking them out isn’t  usually that difficult. 
But worrying about, 90 degree screwdrivers etc is worrying about a problem that, with care you should not have. 

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oipigface
23 minutes ago, isoaritfirst said:

To the OP I would suggest that they spend some time researching or just considering what they are trying to achieve.

Mike,

     This seems an unnecessarily harsh judgment on the new recruit who started this thread. He was sitting there with a servo that he had not yet fitted into the wing, and it suddenly occurred to him that if he were to glue it in with the standard retaining screw in the output shaft, he might have difficulty getting it out again. He had, in fact, come across an issue that has exercised many builders over the years, and has been the source of much ingenuity. 

    He knew what he was trying to achieve, and he thought he was ‘researching’ by asking contributors to this forum. I can’t see why he should be berated for that. As far as I know there is no readily available printed or online source that discusses these matters. They are still under active development, so even if they were such a discussion it would be out of date. There  is a lot of experience, though, and many solutions have been proposed. A lot of that experience can be tapped by a question here.  
 

  Sorry has nothing to be sorry for.

 

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oipigface

“It is completely possible to calculate/ guesstimate or even mock up installations so that once installed there is no reason to remove or adjust.”

Really? Have you never stripped a gear, broken a servo arm, or had a servo fail?

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isoaritfirst

Of course I have John,  but Op is asking about ways to remove servo arm for adjustment. 
My answer is that you should not need adjustment, if you take care and consider the installation geometry. 
Correct geometry/ ratios will also help protect servo from damage. 
But in the event of a servo failure etc, unclip the clevises and pull the servo out.


 

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isoaritfirst
9 hours ago, isoaritfirst said:

Clearly their are occasions when servos need to be removed, and breaking them out isn’t  usually that difficult. 
But worrying about, 90 degree screwdrivers etc is worrying about a problem that, with care you should not have. 

This was mean't as advice not criticism, as were the earlier comments that the problem that he is having can be negated by a considered approach.

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satinet

it is fairly easy to estimate how much travel you are going to end up with. Assuming the horns are not installed at crazy angles in the wing, the travel on the servo will be proportionate to the horn length ratio. I.e if the servo horn is 10mm and the aileron horn is 20mm you will get basically half as much rotate on the aileron as you do on the servo. As nearly all servos have the same rotation, this isn't problem (in the region of 100-110 degrees total).

Some of the LDS stuff that comes with pre-installed horns in the wing isn't done perfectly and you do end up with unequal travels. I find the best way to tackle this is to use curves on the radio.

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isoaritfirst


Link to article that I penned a few years back. Less relevant these days as few models use pushrods and clevises. 
unfortunately pictures have got from the thread.  
The techniques written were from my own experiences and spending time considering what was important and how to achieve it.  

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Scram

Home made from a bit of alloy and ground off bit.

IMG_3839.thumb.JPG.2589aa3b65107afd6101bf350379b70a.JPG

IMG_3840.thumb.JPG.abde7c1a9fa84436c57c94814ffa6e8c.JPG

Drill an undersize hole and drive the bit in, then cut off the excess

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Big Si

something worth trying as we as in Heli flyers use them a lot on the tail so make sure we don't have any ATV on the servo for the Gyro set up

would need to be cut down a bit but good thing is it can be flipped over to make a left and right hand one with out any problems

never had one come loose not even in a good crash and I spanked a 700 big time so have tried  lol

CNC Adjustable Metal Servo Arm For Futaba Kst T-Rex Tarot RC 500 550 600 700  item number:  191729711367

I am sure if you look they make them for other brands of servos

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BigT

I have another method which is a combo of some above. Heat shrink tube round the servo body  or masking tape works just as well. Glue the Servo in place using UHU Por like a co tact adhesive. I E apply a thin coat to each surface, push the two surfaces together and pull apart, wait approx 10 mins for the glue to go off and then push surfaces together. If you need to remove the Servo the glue can be dissolved by the application of lighter fluid with a small paint brush or cotton bud. Lighter fluid does not damage the foam or the carbon fibre.  I have used this method of disassembly on Depron, EPP, Stryro, balsa and lite ply.  Before committing to the model, test it out on a scrap piece of fibreglass or foam. 

To gain access to the horn screws I also use the Pete Beadle method of a slot to allow access to the screw head. 

On the subject of adjustable linkages: on smaller models with servos <10g I find the adjustable clevis too large. I make up 2 rods with Z bends at one end that go through the Servo horn and surface control horn.  Then get hold of a strip of  small 3 amp choc box connectors. Strip off the nylon outer, this leaves a metal tube with 2 screws. Now cut this in half and you have 2 pieces ( or could be used as one piece) . Simply use this to connect the rods. Once the correct length have been set the rods can be soldered or glued. Personally I don’t bother but I do use loctite on the screws. I have used this method for many years on all sizes of models, on rods and cables. 

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BigT
On 27/02/2020 at 20:05, Big Si said:

something worth trying as we as in Heli flyers use them a lot on the tail so make sure we don't have any ATV on the servo for the Gyro set up

would need to be cut down a bit but good thing is it can be flipped over to make a left and right hand one with out any problems

never had one come loose not even in a good crash and I spanked a 700 big time so have tried  lol

CNC Adjustable Metal Servo Arm For Futaba Kst T-Rex Tarot RC 500 550 600 700  item number:  191729711367

I am sure if you look they make them for other brands of servos

 

I used those type of arms on a Delta head autogyro that had 48 inch blades and weighed 14 kg. They are strong. 

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  • 2 weeks later...
sorry

Big belated thanks to everyone who replied.

All useful and interesting comments.  Some really good ideas.

I will be using servo trays and bodging a screwdriver.

I think it is really odd that a servo manufacturer  designs and makes servos for thin winged moulded planes and doesn't think about how people will change the servo arms after the servo is installed. All they needed to do was supply a screw like the picture.

I have written to some servo manufacturers but have had no reply as yet.

thanks again everyone

Robert

screw.jpg

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pete beadle

Hi sorry

I've never received feedback from any Eastern European manufacturer, good luck with yours!

Personally, I think most of them simply refer you to the (expensive) servo fitting kit(s) they make:yes:

A lot of people are having their models fitted out for them by the manufacturer now, again, expensive but it at least takes out all the head-scratching involved in fitting the servos......good luck too them, I can't afford the basic 'plane let alone all the extras like fitting-out, serves me right for being a pensioner!:(

Regards

Pete

BARCS1702 

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Phil.Taylor

Modelfixings probably have suitable hex head bolts for you.

http://www.modelfixings.co.uk/fixings.htm

Hopefully, after you have succesfuly installed the servos & linkages (after several dry-runs) - you will then find out that you never need to move/change the servo horns anyway.

Only times Ive had to was when buying used planes where previous owners Txs had different centres & throws. Oh, and old Voltz servos with broken horns in used planes - but they are special...

Phil.

 

 

 

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isoaritfirst

Many years ago all servos had mounting lugs that ran across the width of the servo. 
mounting these into wings was tricky and the easiest way was to simply glue the servo in. 
Most wing servos now are available with lugs that run along the height of the servo, making screwing then down to a fixed point very easy.

Removal is equally as easy. 
A couple of hardwood or ply bearers glued into the wings, or a piece of shaped ply is all you need. 
You  can of course buy servo frames. Some will allow the servo to simply be clipped in and out of place. 
So I would argue that servo manufactures have addressed the issue. There should be no need with a modern servo to have to remove a servo arm with the servo in place. 

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oipigface

I agree with Mike. In fact, even servos with   ‘traditional’  lugs can be mounted with screws into a servomount. The Baudis system which I mentioned in my post on 23rd Feb does this with pieces of plywood slotted into notches cut into the lugs. 

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