How to Fit a Bowden cable

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I've just received the RC kit for Occre Ulises and there is a bowden cable supplied to connect the servo to the rudder assembly.

I'm used to fitting bowden cables and adjusters on mountain bikes but this time there are no adjusters.

Would welcome any advice on the best way to fit such a cable on a model board. (At the moment, I've easy access to all the rear bulkheads, etc. as I've delayed gluing the rear deck in place until I know how to solve this problem.

Many thanks.
 
My first thought is to install some bicycle type cable adjusters. Mount a proper sized M6/M8?- teenut on a bulkhead and thread in the adjuster and lock ring.
 
I've just received the RC kit for Occre Ulises and there is a bowden cable supplied to connect the servo to the rudder assembly.

I'm used to fitting bowden cables and adjusters on mountain bikes but this time there are no adjusters.

Would welcome any advice on the best way to fit such a cable on a model board. (At the moment, I've easy access to all the rear bulkheads, etc. as I've delayed gluing the rear deck in place until I know how to solve this problem.

Many thanks.
Please post some pictures of what you have and where it needs to go.
 
Hi Rob!

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Why not a rigid linkage rod?

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The rods are available with thread or connections for soldering. They can be bent around any obstacle and easily mounted.

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There are also screw-on rudder fittings with ball joint. A M2 thread is cut in the servo horn and the screw is screwed in.

Best regards
Thomas
 
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Please post some pictures of what you have and where
Here are some photos of my build with servo, rudder, cable, etc. loosely in place but all unconnected. There is a very good build log on SoS for Ulises that used bent wire but, on the log,it mentioed there was not enough rudder movement from the servo so was having to rethink.

Hope this helpsIMG_20220104_124458.jpgIMG_20220104_124547.jpgIMG_20220104_124622.jpgIMG_20220104_124707.jpg
 
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The housing tube is glued in place, I have always used epoxy. Roughen the outer tube with coarse sandpaper to aid adhesion. For your installation holes would need to be drilled in the beams for the tube. The tube NEEDS to be run so the end of the tube is at the same elevation as the arms on the servo and rudder. The cable will flex but you want to keep the amount of flex as minimal as possible. Keep the housing run as straight as possible to minimize friction.

I'm not familiar with those cable ends. It looks like they have clamps to hold the cable. If so this is where you adjust them. Be careful when you cut the cable not to fray the end. I like to wrap it tightly with tape then use a Dremel cutoff wheel. Make some practice cuts using different methods until you get good results.

Your setup is actually a good candidate for a Pull-Pull rudder setup. This would involve moving the servo so it is centered in the ship and installing cables on both arms. It works just like the name implies. Google "rc pull-pull rudder system" and you will get several YouTube videos as well as sources for this system. This system will give full throw and eliminate any slop that the push-pull cable you are working on has.

Hope this helps, ask if more questions.
Glenn
 
The housing tube is glued in place, I have always used epoxy. Roughen the outer tube with coarse sandpaper to aid adhesion. For your installation holes would need to be drilled in the beams for the tube. The tube NEEDS to be run so the end of the tube is at the same elevation as the arms on the servo and rudder. The cable will flex but you want to keep the amount of flex as minimal as possible. Keep the housing run as straight as possible to minimize friction.

I'm not familiar with those cable ends. It looks like they have clamps to hold the cable. If so this is where you adjust them. Be careful when you cut the cable not to fray the end. I like to wrap it tightly with tape then use a Dremel cutoff wheel. Make some practice cuts using different methods until you get good results.

Your setup is actually a good candidate for a Pull-Pull rudder setup. This would involve moving the servo so it is centered in the ship and installing cables on both arms. It works just like the name implies. Google "rc pull-pull rudder system" and you will get several YouTube videos as well as sources for this system. This system will give full throw and eliminate any slop that the push-pull cable you are working on has.

Hope this helps, ask if more questions.
Glenn
Thanks Glenn for the helpful reply:)

The arms of the servo and the rudder assemblies are the same height but unfortunately they are above the level of the decking. So I have to drop about 20mm to come below deck and clear the crossbeams (or 8-10mm if I was to drill through them). Those cable ends just make things worse as they are so long that when the rudder is hard over, the cable end will only by 3-5mm away from the end of the outer tube which is 8-10mm lower :(

Maybe there are fixed vertical connectors on the market that I could fit to the rudder to get the drop. I could then centre the servo as you suggest, install it upside down for a pull-pull system with pretty straight cable runs.

Is that feasible or is there a better or more practical solution?
 
Hi Rob!

Various options for extending or reducing the rudder path.

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No. 1 give the same rash between rudder and servo.
No. 2 gives a large deflection of the rudder.
No. 3 gives a small deflection of the rudder.

P1040654.JPG
To achive a very large deflection of the rudder (no. 2), servo arm extensions are available. Here on a steam locomotive.

Best regards
Thomas
 
Do the arms you have on the rudder now allow enough movement of the rudder? If so I think the rods @Thomas Marocke suggests above would be the way to go with what you have. Keep the angles of the bends as small as possible to minimize flex. Typical rod installations have one end threaded and the other is soldered. Try not to bend the threaded portion as it tends to break, or at least weakens the rod.

You can try the cable you have. Keep the entry/exit elevations even with the arms and minimize any bends. Experiment with the cable and housing, bending the housing and push/pull the cable by hand to feel the resistance bends create. The bends your installation requires may not be an issue.
 
Hi Rob!

A bowden cable has its justification on a bicycle. I consider it unsuitable for the Ulysees.

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Due to the curved movement of the control arms, the inner cable can slide poorly into the outer cable. The distance (A and B) between the inner wire and the guide tube should large enough so that the inner wire can be cleanly guided back and forth.

Imagine a outer tube around the control rod. Each time a different entry angle.

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Best regards
Thomas
 
@Thomas Marocke does bring up a great point, actually he has brought up several. On a bicycle the cable is actually in a pull-pull situation, lever pulls one way and a spring pulls it back when lever is released. The way you wish to use it as push-pull relies on the stiffness of the cable to push against the rudder. The cable is likely up to the task but is something to take into consideration when setting up the unsupported ends.

In one of Thomas' posts he talks about using the various holes in the arms. If you use the cable it would be helpful to determine which holes you will use. Best practice is full servo stroke equals full rudder movement. Once the holes to be used are determined point the housing end accordingly so the angles Thomas talks about in his next post are minimized.

Using a rod would be a much easier solution.
 
Thanks @Thomas Marocke and @GAStan for the helpful inputs. I might now be able to solve some of the problems in terms of fitting a bowden cable end to end but I'm pretty sure the rudder movement will still be compromised if only because the connector from the cable to the rudder will take up much of the horizontal space needed to get that full movement.

So I've contacted the dealer and asked if he can supply the necessary rods and couplings :)

Thanks again
 
It's my pleasure to pass on some of the help and knowledge I have gained from so many people in my life.

@RobFJ I encourage you to make a log of your build, it looks like a very nice boat you are building. I'm interested in how this linkage goes for you, please keep us informed.

Glenn
 
It's my pleasure to pass on some of the help and knowledge I have gained from so many people in my life.

@RobFJ I encourage you to make a log of your build, it looks like a very nice boat you are building. I'm interested in how this linkage goes for you, please keep us informed.

Glenn

After a few attempts, it looks as though I have worked out a solution to get a good rudder turn without any of the connections htting bulkheads, stern hatch cover or hull.

I've got the added bonus that the main push rod is completely straight and horizontal and the whole lot can all be assembled/disassembled/adjusted once all the decking and hatches are in place.

The two choc block connectors avoided any bend in the rod to get from servo arm to rudder arm (one was insufficient to get complete rigidity.

Photos are attached of everything in place but not secured.

Thanks again to everyone for the combined advice
 

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After a few attempts, it looks as though I have worked out a solution to get a good rudder turn without any of the connections htting bulkheads, stern hatch cover or hull.

I've got the added bonus that the main push rod is completely straight and horizontal and the whole lot can all be assembled/disassembled/adjusted once all the decking and hatches are in place.

The two choc block connectors avoided any bend in the rod to get from servo arm to rudder arm (one was insufficient to get complete rigidity.

Photos are attached of everything in place but not secured.

Thanks again to everyone for the combined advice
Hi. I am also working on the Ulises and am worried about the clearances using the bowden cable. Your solution looks great. Can you let me know where you bought the parts - rods, connectors, choc block? Thanks, Carl
 
Hi,

The rods and connectors came from howesmodels.co.uk


The chocbox came from a box of electrical odds and ends I had but its the metal connector inside the case that's the important bit

https://www.screwfix.com/p/debox-in-line-junction-box/8692h shows you what the product looked like at the start

When I come to do the final install I'll need to change the nuts that came with the rod connectors to self-lockers (or use loctite) otherwise the vibration will cause them all to come off.

Hope this helps.

Regards

Robin
 
I'd say the wire I used (that was recommended to me by the shop) had an ideal balance between rigidity and bendability. It just needed round nosed pliers and fingers to do the bends. (I cheated a bit as I used bonsai wire, which is much more bendable, to make a template with the lengths and bends in the correct positions. So I bent these SS ones first time :)
 
I'd say the wire I used (that was recommended to me by the shop) had an ideal balance between rigidity and bendability. It just needed round nosed pliers and fingers to do the bends. (I cheated a bit as I used bonsai wire, which is much more bendable, to make a template with the lengths and bends in the correct positions. So I bent these SS ones first time :)
Thanks...Very helpful. I'll be trying my luck! Cheers, Carl
 
Hi Rob. Me again. I am in the process of planking the hull. I know I have to waterproof it. I understand that I add a coat of epoxy resin to the inside, and also epoxy resin and fiberglass to the outside once I have sanded it and filled in the cracks. Do you have any tips or sources for help on how to properly prepare the hull? All I know is that I apply the fiberglass sheeting, then paint over it with epoxy resin??
 
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