Hey guys, I’m back to work on my first footy and I need a good way to connect the tiller arm to the rudder shaft. What’s the usual practice here? I’ve got 1/8" brass rod and 5/32nd" brass tube for our rudder post and tube. Thanks,
Steven
Lately, I’ve been using a square-shaped aluminum shaft fitting, that I bond into my rudder shafts. The tiller has a molded square hole in it, to mate with the aluminum shaft top. A bolt from the top holds it in place, with a carbon spacer to adjust any play. Got the idea from how cranks bolt onto square bottom bracket axles, on a lot of bicycle designs.
Steven - There are a whole lot of posts about rudder linkage types on this forum. Try the search function in the banner at the top of the screen. Many topics like this have already been broached and debated extensively. Searching through the topics can take some time but will be well worth it and may answer some questions that you haven’t even come up with yet.
The short answer to your question is most every model sailboat uses some variation of the push/pull linkage like the one Nigel molds in carbon fiber above. The easiest way to set up this system if you don’t have Nigel’s expertise is to adapt the off-the-shelf linkage parts from r/c aircraft, available from most hobby shops that deal in r/c planes.
I did do a search but I guess I didn’t dig deep enough. What I’m thinking is that I will buy a die to thread the end of my 1/8" rudder shaft and trap the tiller arm between two nuts(w/lock washers).
Steven
Hi Steven - Try looking up the whipstaff steering thread. It has a pretty thorough discussion of the merits of different rudder linkage systems.
If you are going to try to fashion a rudder arm for a push/pull linkage from scratch I wouldn’t go about it in the way you describe. The nuts, even lock nuts, are bound to slip a bit just when you don’t need them to. That is just Murphy’s Law. They also may freeze up and make the rudder hard to remove if they are exposed to salt water (like at the WoodenBoat race). (I use a 3/32 stainless rod for my rudder shafts and brass tube. Everything gets a coat of teflon lube before sailing in salt or brackish water.)
Steven, it sounds like that you are not new to working with metal since you know what a die is. A simple non-slip method of making the rudder arm involves soldering, drilling and threading. You will need a vise or the means of improvising one (a drill press would be helpful too).
_Cut off a 3/16" long section of 3/16" or 1/4" diameter brass rod. Drill a hole to match your rudder shaft’s diameter from one cut side of this barrel to the other (this is where the vise comes in). The shaft hole doesn’t have to be perfectly on center, in fact I often drill it off center which will become clear later. Try to drill this hole as perpendicular to the cut sides a possible (where a drill press would be of help).
_A center punch is useful to locate the hole to start so the bit doesn’t wander around before grabbing.
_Once the shaft hole is drilled, a hole for a threaded bolt needs to be drilled perpendicular to the shaft hole. (I use a 4-40 tap to thread the bolt hole because it is a fairly rough thread, finer threads may strip when tightening down on the rudder shaft.) This is a fairly difficult hole to drill. To help with drilling into the curved surface of the rod section filing a flat and using a center punch to locate the hole will make the task much easier. This is where drilling the shaft hole off center helps by increasing the distance from the shaft hole to the filed flat, this in turn provides space for more threads in the bolt hole. Drill the bolt hole through to the shaft hole.
_ After drilling and treading the bolt hole the next step is to solder the rudder arm plate to the drilled and treaded barrel. I use silver solder for this which is probably overkill for Footies. Regular plumbers solder would probably do just fine. A butane torch (I use an old “Blazer” brand) is best for soldering. The arm should be cut out oversize as sometimes the pieces to be soldered may float about somewhat. Tin both the location on the arm plate and the barrel where the two are to be joined. Clean off any soot or debris so that the tinned areas can get the best bond. Try to orient the bolt hole in a direction that will facilitate easy access to the bolt, facing aft is usually a good bet for above deck linkages, facing forward for those below deck. Drill the shaft hole through the soldered on arm plate.
_The next step is to drill holes for the connecting rod to thread through. Try to match the hole spacing on the rudder servo horn that you are going to use.
_The simplest connecting rod is just a rod with two “L” bends in each end. The “L” bends are just one right angle bend in the rod followed by another right angle bend so that the extension beyond the bend is parallel to the main body of the connecting rod. The rod extension is threaded through a hole in the rudder arm so that the short perpendicular section of the bend rests in the hole. Threading the servo horn onto the connecting rod is done in the same way before the servo horn is attached to the rudder servo.
This is as short an explanation as I can give. Look around at some of the photos of the Footies on this forum and study the rudder linkages. If you come up with the better mousetrap please post your ideas so others may benefit.
Here’s the way I do it on my RG65 using a micro servo. The lines are added to the pic to make the shape clear. The slot is milled on a Unimat, but could be cut by hand if you’re careful. Either Lexan or ABS would work; I used 1/8" Lexan because I had a scrap the right size. Works well.
Cheers,
Earl
Nicely executed whipstaff Earl!
An easier alternative would be like what we use on powerboats. Just get a strip of brass sheet, say about 5x 18mm, and bend it to for an L. then drill a hole on each arm, screw one side to the rudder blade and the other accepts the rudder pushrod, with a z-bend on the end.
You might have some plastic or other material that would work. I keep a box of scrap plastic from radios, tape players, etc. for such things.