Making clevis connectors for steering system/autopilot

[Quandary]

I have now got a mobo. with mechanical steering; a Morse/ Teleflex/ Seastar D290 type cable connects to a stainless steel clevis pin fitted under the end of the steel tiller arm, very light with little friction. I am adding an new autopilot, basically a Raymarine EV100 kit controlling a Teleflex/ Octopus type remote drive pushing and pulling a second D290 cable running just above the first. To keep things simple I intend to replace the clevis bolt through the tiller arm with one long enough to extend above the arm to also take the autopilot cable. It seemed straightforward until I realised that all the suitable clevis pins I can find have bolts that are shouldered rather than sleeved, so it looks like I will have to make up a clevis body for above and below with a single sleeved stainless steel bolt running up through both, nuts to secure it either side of the tiller and at the end to secure it. I do not have the skill or the workshop do a decent job of cutting the clevis body in stainless steel so my first thought was to use a bit of solid aluminium bar slotted and drilled to take spacer sleeves of stainless steel tube, it looks like I might need to buy 2m. of bar but it is not that expensive. The idea would be to cut a slot in the end of a bit of 25mm. square bar, bore two holes at right angles to take the sleeves then cut to length and grind off the edges. Plenty of grease here so differential metal corrosion should not be an issue. Then I had another thought, I have plenty of Tufnol and it laminates well with epoxy adhesive, so I could make up some Tufnol bar and cut my clevis body from that, it will be easy to drill and sleeve and Tufnol would have the advantage of insulating the rudder from the autopilot (something that Jefa make a fuss about when marketing their systems) The tufnol clevis of say 25x25x 32mm laminated bar would not be as strong as metal but it will be acting in tension and compression with hopefully negligible bending so surely should do the job? Tufnol appeals because I am much more comfortable with wood than metal.
Any advice?

 

[yoda]

I think a picture and/or drawing would be helpful as it's difficult to understand just what you want to achieve.

Yoda

 

[rogerthebodger]

Its quite difficult to visualize your setup but the normal outboard push pull steering is like this

Now I would attach a push pull autopilot opposite the direction of the existing steering so the autopilot is pulling inline with the existing rod so as not to put any offset load on the existing push pull rod. attaching a standard clevis to the outboard tiller arm inline with the existing one.

Hope that helps

Another type of steering setup

 

[Quandary]

The drawing shows what exists (though on this inboard engined boat the cable is attached to a short flat steel tiller under the cockpit floor) I am adding a second cable from a remote autopilot drive, running through a similar tube mounted 50mm. above the existing. The existing manual steering cable is connected to a clevis pin below the tiller arm, I need to mount the clevis for the pilot above the tiller so I plan to replace the existing steel clevis pin with a bolt or stud about 80mm long extending above and below the tiller arm. I can not find clevis pins with a body of the necessary dimensions, they are all too small and are not bushed as the pivot pin is shouldered so would have to go straight over the threads on the bolt. So my plan is to take two small blocks of aluminium or tufnol, cut a slot and drill one end for the flattened cable end and drill another larger sleeved hole to go over the vertical bolt or stud. This would be more or less the same shape as a cast steel clevis body but larger to compensate for the sleeves on the pivot and for the weaker material. Since the geometry of the mounting tubes dictate that the centres of the two cables are separated by 55mm. the offset above and below the tiller centre is only about an inch, clevis pins are always applying an offset thrust (the existing is about 18mm. below) so I regard the effect of the additional offset as negligible. I could make a double ended clevis and bring the cable from the other direction but there are complications with positioning the motor drive and it would still be offset anyway. Any removable tiller pilot operates okay with an offset thrust so I am content that this would. The tiller is difficult to take out and too close to the cockpit floor above to drill a new hole but since the steering cable is already below and the pilot cable is supposed to be quickly removable if something goes wrong, above is the best place to attach it.

Sorry if my original question was not clear, I thought it was getting to long and was trying to be brief. Failed again?

 

[vyv_cox]

Tufnol is a remarkable product that we used extensively when I worked in research. It has about a quarter of the tensile strength of cast aluminium but this may well be sufficient for your application. If you have some I would certainly try it first and if it is found wanting move up to a stronger material.

Properties of Tufnol here http://www.tufnol.com/downloads/carp-brand-sheets.pdf and of aluminium on Wiki here https://en.wikipedia.org/wiki/Aluminium_alloy