View Full Version : Wind vane self steering design


BillyDoc
12-13-2005, 04:06 PM
Gentlemen,

Being a dedicated lazy sort, I like to sail with wind vane self-steering. But I have not been happy with the available systems for many reasons and have always built my own. So far I have never been entirely happy with the result, although I think I have done better than a lot of commercial systems. Anyway, due to a recent severe case of cerebral flatulence, I am going to try it again and I would like your comments on my proposed system, presented below.

First let me mention a few things I don’t like about existing systems.

1. I don’t like any system that relies on electricity in any form whatsoever. Not that I have any thing against flowing electrons (I sometimes design circuitry for a living) but using electricity in a salty environment leaves entirely too many ways for things to fail. Besides, there are better ways.

2. Wind vane self-steering systems must be as frictionless as possible between the sensing vane and the actuating servo rudder. If it isn’t, then you can forget about sailing down wind with one. This means good rolling bearings of some sort . . . and these are usually susceptible to corrosion, thus a build up of friction and eventual failure. Friction is bad, and so is corrosion. BUT, non-corroding bearings that can stand up to sea water either do not perform well (plastic bearings) or are so expensive you have to sell too many body parts to pay for them to actually be able to sail (ceramic with ceramic races). If a “sealed” bearing is used, my experience has been that the seals or the outer races corrode (even with “stainless”, and the seals themselves add considerable friction.

3. Complex systems that are difficult to actually use or adjust interfere with my sailing. Did I mention that I’m lazy?

So I have dreamed up the following system, in which all the mechanical parts between the sensing wind vane and the actuating servo rudder are immersed in a light oil which is pressurized slightly with an elevated and vented oil reservoir. There remain only two oil seals in the mechanical path from wind vane to actuating rudder. All the bearings in between can be high quality steel “open frame” types, which have very low friction. Additional oil seals will be placed as needed in areas that are actuated by hand or by the action of the servo rudder. A little extra friction doesn’t matter much in these areas.

Please look now at the first figure, the wind vane head. This “head” is designed to be mounted on a post or the like on the stern, but could conceivably be mounted anywhere a good unobstructed wind direction signal can be found. Assume for now a vertical stern mount and that the angle of the wind vane relative to the boat has been fixed. We will get back to the business of changing that angle below. Assume further that the wind is coming from forward, which would be to the right in the figure, and that the boat has wandered off course to port.

So, a boat rotation to port would cause the wind to exert a pressure on the starboard side of the sensing vane, which would be attached to the wind vane mount shown. This wind pressure would cause the vane to rotate to port, and this rotation would be translated through the wind vane shaft (with suitable bearings and an oil seal), through a “Helicoil” linkage, to the green “differential” gear at the top of the head. This green gear would then rotate clockwise as you look vertically down on the head. The lower, light blue, differential gear can be regarded as fixed for now. Three pinion gears are affixed to a yoke (red) between the green and light blue differential gears with open-frame bearings within each pinion gear. So, there is a two to one mechanical advantage between the green differential gear and the red pinion yoke which will likewise be driven in the clockwise direction, looking down. This red pinion yoke is mechanically linked to the “signal shaft” which exits the bottom of the wind vane head through suitable bearings. No oil seals are needed here, as this part of the whole apparatus will be immersed in lightly pressurized oil.

Moving on to the second figure, we have a clockwise rotation on the signal shaft, looking downward, and this torsional signal represents an error from the boat drifting to port. We can use quite a few torsion shafts and bearings here, if we need to as there is little friction, and the “Helicoil” coupler is also very friction-free.

In the second figure the right side would be forward, and the servo rudder is mounted in an enclosed structure that can pivot about a horizontal axis. Suitable bearings and oil seals would be included, naturally, but are not shown here for clarity. The shaft connecting the green gear to the servo rudder would pass through this structure with (again) suitable bearings and the second oil seal in the wind vane to servo rudder mechanical path.

A clockwise rotation of the signal shaft, looking downward, results in a clockwise rotation of the grey gear, looking forward (to the right). This clockwise rotation of the grey gear will drive the green gear counter-clockwise, looking downward, thus causing the servo rudder to likewise rotate counter-clockwise, to port.

Assuming a flow of water past the servo rudder from right to left in the figure, the counter-clockwise rotation of the servo rudder will cause a force to be exerted against the starboard side of the servo rudder, thus causing it to pivot about the horizontal axis comprised of the grey gear and it’s drive shaft, and the enclosed structure, in a clockwise direction as viewed from aft. This rotation of the enclosed structure will result in two things: first, an attached rudder actuator can be used to drive the rudder appropriately, and second, since the grey gear is stationary (relatively speaking) the green gear rotating about it will tend to rotate the servo pendulum back to its original orientation relative to the flow of water. This gives us a proportional correction which is very important to a self steering system because it means that the force exerted can exactly match the steering requirement without a lot of hunting and overshooting. The direction of the servo rudder’s deflection is such that the servo rudder itself exerts a steering moment on the boat which is in the same direction (correcting to starboard) as the rudder it drives, so there is no energy lost by having both surfaces “fighting” each other.

Now about that mess of differential gears in the wind vane head.

As should be apparent, there are some real advantages to a torsional error signal, and this would be easy to implement if we always sailed on a fixed course relative to the wind. This might prove inconvenient, however, so if we are set on using a torsional error signal we must have some way to “decouple” the error signal when we rotate the wind vane head to a new relative course, and then re-couple it. Some sort of clutch could be used, but . . . did I mention that I’m lazy?

Looking back at the first figure, the wind vane head, imagine that the whole head is mounted in bearings with an oil seal and a worm-gear drive arranged so that it can be rotated about its vertical axis from wherever I want to mount my crank. Like in a center cockpit, for example.

If I rotate the entire head (and the wind vane is assumed to be fixed relative to the head, for now) then the green gear will rotate with the head and try to drive the pinion gears and the red yoke with it. On the other hand, if the light blue gear is rotated by the same amount in the opposite direction, the two rotations will cancel each other out at the pinion gears, and the red yoke will remain stationary, relative to the boat. This second rotation (of the light blue gear) is accomplished by affixing the purple yoke to the hull through the shaft shown in the figure. The grey gear, affixed to the head, will therefore drive the pinion gears associated with the purple yoke, thus rotating the light blue gear in the appropriate direction . . . in exact proportion to the original displacement but in the opposite direction, as required. The light blue gear just floats between the two sets of pinion gears and is attached to nothing.

The intent of this design is to build the whole thing into the hull as an integral part of the boat. I never go far from land without self steering, so . . . why not? Having a lot of it below decks also offers some protection, and it would be simple to plumb in that oil reservoir somewhere convenient and protected, like in a pilot house. Oh, the little red thing at the top right of the wind vane head is a bleed port so the air can be vented and the entire inside flooded with light oil. This means that the oil reservoir has to be higher than the bleed vent, obviously. The oil provides some damping as well as protection from salt water.

The design of the oil seal on the servo rudder is a little tricky, as this will not only be under water at least part of the time but must be able to withstand surges from pounding against the water’s surface. I have been thinking of incorporating a narrow gap between the servo rudder shaft and a larger volume chamber surrounding the shaft, with a baffle on the shaft to prevent a direct impact from the water against the seal. In this way a momentary surge from pounding would have to fill the chamber before it pressed very hard on the seal. This chamber should also be vented to atmosphere somewhere to facilitate draining.

So, there you have it. I hope you will work through the logic of the thing, and if you find any errors PLEASE let me know! I have more than a little difficulty wrapping my brain around this thing and can use all the help I can get. If something is not clear, just ask!

BillyDoc

http://breakthelink.org/windvane head.png

http://breakthelink.org/windvane servo rudder.png

FAST FRED
12-14-2005, 06:53 AM
Only question for me is how easil the penlum can be moved by the stern moving down the side of a wave.
On the Aires system the best part is how well the unit handles large following seas, The stern gets kicked a bit and the servo is instantly giving the helm the proper direction to get back on course.
No wait for the air flow to catch up.

Will your unit do that?

FAST FRED

BillyDoc
12-14-2005, 11:07 AM
Hi Fred,

I believe so. The Aries and the design above are set up so that the pendulum servo rudder exerts a force on the water in the same direction that the rudder itself does when activated. So, when sliding a bit sideways down a wave and exerting a force on the servo rudder directly (either the Aries or mine) the resultant correction is the same.

If I did this right (and there may be some doubt there) you should be able to "box up" both units so you couldn't see the internal workings and the action on the servo rudder resulting from a force on the wind vane would not be distinguishable between them . . . except for friction. The reason I have taken the approach I have is twofold: to reduce system friction (thus improving performance), and to protect the components from corrosion or direct damage. The Aries looks like a fine machine to me, actually, and I studied it carefully at one time. I couldn't afford it, though, so I built my own.

On another topic, I want to apologize to everyone for the pictures above, I couldn't get the "thumbnail" thing to work. They are in a .png format, too.

Bill

gonzo
12-14-2005, 01:20 PM
The main problem I see, is that if the coils are soft enough to create little friction or torsional force, they will also provide a sloppy movement. How do deal with that?

BillyDoc
12-14-2005, 06:45 PM
Good point Gonzo,

The thing could be made as drawn, with a couple of interleaved springs, but that would give a "soft" response in torque as you point out, and I want the linkage to be stiff in torque but still accommodate the required angular displacements.

When I first started thinking about this design I got on the web and googled on "flexible couplers" or some such, and came up with a longish coupler that looked like a stainless steel rod that had a bunch of interleaved slits cut in the side so it was flexible in a radial direction but stiff torsionally. I believe the thing would accommodate something like 30 degrees. It looked perfect for what I had in mind. Naturally, I can't seem to find it again. I thought the brand name was "Heli-coil" but apparently I am mistaken, their web page only seems to have thread inserts. I'll keep looking.

Any coupler is going to exert some force on the bearings holding them in place, but good hardened steel bearings do not change their rolling friction very much with the application of the small radial loads we are talking about here. Ceramic is even better, of course, but there is that cost thing.

And then there are always bevel gears, which may actually be best in this application.

The problem is, assuming the wind vane is tilted about 18 degrees from the horizontal (which will give it a proportionating behavior), then that leaves 72 degrees that the torque needs to be turned initially, then another 90 degrees or so below the vane head to drive the servo rudder. This is a lot of torque redirection, and the simplest way to do it with the least friction is not obvious to me. Should I use the helical couplers? Bellows type couplers? Universal joints? Any ideas along these lines will be greatly appreciated!

Bill

BillyDoc
12-15-2005, 11:43 AM
The coupler I originally found is here: http://www.heli-cal.com/Html/Products/ujoints.htm

Heli-cal, heli-coil . . . computers are so picky!

Anyway, Heli-CAL claims an angular displacement capability up to 90 degrees and:

No Backlash
No Moving parts
No Maintenance and lubrication requirements

So, two or three of them in the system. I would think, since there is no sliding or even rolling friction involved except for a few bearings, that they would be relatively friction free in the application shown above. Also, since each helical "beam" is thick radially, torque transmission should be fairly good. It shouldn't take much anyway, if the system is well balanced to start with.

Bill

gonzo
12-16-2005, 09:38 AM
They claim torque capability of up to 150 ft/lb. That should be enough for a vane steering.

BillyDoc
12-16-2005, 10:16 AM
Absolutely.

A detail not shown above is a friction connecting surface with a single pivotable bolt through it attaching the servo rudder to it's shaft. This serves two functions, if you hit something the joint will simply slip and alow the servo rudder to fold up, and you can use this joint to adjust the balance of the servo rudder. I plan to adjust the balance by getting underway with a friend and pivoting the servo rudder forward or aft at this joint until I can easily steer the boat back and forth by twisting (in this case) the signal shaft with my fingers . . . but a little less than neutral so it will return to center when I release the signal shaft. This capability means that the foil shape doesn't have to be perfect, although that would be nice, and simplifies the design.

And of course we do sometimes hit things at sea. I once split a partially submerged wooden crate completely into two parts with a Contessa 26. Tough boats, those Contessa's.

Bill

OldYachtie
02-02-2006, 08:44 PM
http://www.heli-cal.com/Html/Products/CoupGuid/PFSeries/index.htm is pretty cool. Think these things could give http://www.aquadrive.com/ a run for their money? The Aquadrive systems are verrry pricey--$3500 for a system for a commercial duty 85 hp diesel.

BillyDoc
05-02-2007, 06:36 PM
The images for my original post needed to be loaded from a web site that no longer exists (because I couldn't figure out how to load them here) and the post is so old I can't edit it . . . so here they are!

lazeyjack
05-02-2007, 07:02 PM
why do you need to move the nain rudder, would it not be best lock the main rudder, and use a secondary rudder long span small chord, or even a trim tab on that secondary rudder, you are surely making a chore trying shift the main rudder
I should intro you to my mate also PHd , who sailed Kate around the hORN from NZ to Uk
betcha you will be 90 and still designing beautiful objects for THAT boat:))

BillyDoc
05-03-2007, 08:55 AM
betcha you will be 90 and still designing beautiful objects for THAT boat:))

Damn, I hope so!

To answer your question, LazeyJack, a trim tab on the main rudder also works but the linkage to operate it is more complex and much more exposed to corrosion. Just locking the main rudder would also work, but not as efficiently as having the main rudder AND the servo rudder acting in the same direction, which this design attempts to do. Another advantage is that I intend to use hydraulics for the steering linkage, which means it is simple to switch (valve) the self-steering into and out of the steering loop when needed.

And to respond to the other question properly, the wife has given me three and a half years to get this baby in the water . . . or else! She hasn't told me what "or else" means though. She retires in three and a half so she probably plans on working on it then.

BillyDoc

BillyDoc
05-03-2007, 11:26 AM
Very good points Alan. Let me get this description in here before proceeding. I am quite excited by the ideas you have presented! And don't worry about corrosion, I plan to immerse the whole mechanism in oil. That way I can use open-frame bearings and I only have to deal with a very few oil seals.

The basic function.

The whole point of wind-vane self-steering gear is to steer the boat relative to the wind, so let's start there. Look at Figure one first (in post #10), and imagine an airfoil section mounted vertically on the blue wind vane mount at the top of the figure. The wind would be blowing from right to left across this wind vane, and as long as the vane is perfectly aligned with this wind it will remain vertical. No error signal is generated in this case (we'll get to the “error signal” below) and the boat will stay happily on course because we previously rotated the whole structure shown in Figure one on it's vertical axis to align the wind vane with the wind while at the same time maintaining the desired course by hand.

But alas, things never remain static and we are bound to eventually drift off course relative to our wind unless we make corrections. Assume we drift a bit to the left of our desired course (counter-clockwise, looking down on the boat). Now the wind is no longer aligned head-on with the wind-vane, but is applying pressure on the side nearest us. The wind-vane mount is pivoted on the wind-vane shaft, which is mostly horizontal, so the wind-vane will be pushed away and cause the wind-vane shaft to also rotate. Note that I said “mostly” horizontal. Actually the wind-vane shaft is inclined 18 degrees from true horizontal, and this gives the wind-vane an important property: it's angle relative to the wind changes as it is rotated in such a way to again bring it into alignment with the wind. In other words, the magnitude of the rotation of the wind-vane is proportional to the magnitude of the wind direction error. This is a very desirable property to have in a wind-vane and is often implemented (look at an Aries, for example).

The wind-vane is also counterbalanced with the purple weight to a point where in a still room it will just barely remain upright.

The gears shown in Figure one serve one primary purpose only: they allow the entire wind-vane “head” to be rotated on it's vertical axis to set a course relative to the wind. But before delving into that particular mind-twister, let's just assume a fixed relationship on the course setting and skip all the gears for now. To do that, just picture the torque from the wind-vane shaft being transmitted through the green spring-looking heli-cal device straight through the mess of gears directly to the red “Signal shaft.”

Now look at Figure two. The red “Signal shaft” passes torque through a second heli-cal device to a gray bevel gear which is driving a green bevel gear which is rigidly attached to the shaft of a servo rudder through suitable bearings and seals. The gray bevel gear is free to rotate within a bearing mounted in the blue structure, and the blue structure is free to rotate on an axis coincident with the gray bevel gear. In Figure two the right side of the figure points to the bow of the boat, so water will be flowing from right to left across the servo rudder. As long as the servo rudder is oriented directly into the water flow, it will remain vertical. If the red signal shaft rotates, however, thus rotating the gray bevel gear and subsequently the green bevel gear and servo rudder, the servo rudder will pivot either toward or away from the observer looking at the Figure. In the example above we had a course error to the left relative to the wind which caused the wind-vane to pivot away from the observer, which will cause the green bevel gear to rotate clockwise-looking-down, which will cause the red signal shaft to also rotate clockwise-looking-down, which will cause the gray bevel gear of Figure two to rotate clockwise-looking-forward, which will cause the green bevel gear of Figure two to rotate counter-clockwise-looking down, which will also cause the servo rudder to rotate counter-clockwise-looking down, which will cause the servo rudder to rotate clockwise-looking-forward on it's horizontal pivot . . . thus steering the boat to the right and applying power to the rudder actuator to steer the boat to the right thus correcting the original error. (Phew!) Note that as the servo rudder pivots on it's horizontal axis it also rotates the green bevel gear relative to the gray driving bevel gear (Figure two) in such a way to cancel the original error rotation. This cancellation effect as the servo rudder rotates on it's horizontal axis produces a proportional response at the servo rudder that is also highly desirable.

Course setting.

A simple way to set the desired course could be to put some sort of clutch in the signal shaft and simply decouple this clutch to rotate the wind-vane on a vertical axis. But I tend to get rather lazy when at sea, what with the sea-sickness and all, and I just don't want to be climbing aft and trying to set the wind-vane, then back to the center-cockpit to adjust the course with the wheel, then back aft to try again . . . and so forth. So, I was looking for a way to keep the arrangement described above but be able to just arbitrarily adjust the course using a worm gear on the entire wind-vane head assembly. I envision a small crank in the cockpit for this, with a long torque tube to a worm drive on the self-steerer. I did something similar on another boat I had and it was most convenient!

It should be obvious, however, that simply rotating the wind-vane head will really screw up the relationship between the wind-vane and the signal shaft if something isn't done about it. What we need here is a way to be able to rotate that head but at the same time cancel out the effect of that head rotation on the signal shaft. Which is the whole point of the mess of gears shown in Figure one. Here's how it works.

First let me explain what you are looking at in Figure one. There are two “differential” gear sets, the top one comprised of a green bevel and a teal bevel, with a red three-way yoke in between that has three gray bevel gears attached by bearings. The red yoke is directly attached to the signal shaft, so when the green bevel rotates, say, 180 degrees, and the teal bevel is stationary, then the signal shaft will rotate exactly half that distance, or 90 degrees, in the same direction. All the functioning of the self-steering apparatus is the same as described above, except that the magnitude of the rotation on the signal shaft is half what it was.

We want to preserve the relationship between the wind-vane and the servo rudder and also be able to rotate the wind-vane head on a vertical axis. This means that we have to cancel out the effect of the rotation of the wind-vane in some manner. We do this with the second “differential” gear set comprised of the teal bevel gear and the gray bevel gear with the purple three-way yoke in between that has three gray bevel gears attached by bearings. The teal “double bevel gear” is not attached to anything except the six small gray yoke bevel gears. The purple yoke is fixed relative to the hull of the boat, and the bottom gray bevel gear is fixed relative to the wind-vane head.

Now when we rotate the wind-vane head on it's vertical axis, the gray bevel gear drives the three gray bevel gears on the purple yoke (fixed to the boat) thus driving the teal double-bevel gear by the same number of degrees in the opposite direction! The green bevel gear is also effectively attached to the wind-vane head and it also drives the gears of it's red yoke, thus driving the “teal double bevel gear” in the opposite direction by the same number of degrees exactly as the lower differential gear set has done. Thus the two yokes stay stationary in their positions if the wind-vane and servo rudder remain stationary relative to their respective attachments, yet the wind-vane head is rotated as desired and the function described above for the wind-vane to effect steering has not changed at all.

I apologize for the length of this post, but I have a good excuse: just figuring out the above relationships completely broke an otherwise good brain!

BillyDoc

lazeyjack
05-03-2007, 04:20 PM
And to respond to the other question properly, the wife has given me three and a half years to get this baby in the water . . . or else! She hasn't told me what "or else" means though. She retires in three and a half so she probably plans on working on it then.

BillyDoc[/QUOTE]
well given there is abt 3500 hrs in the metalwork for a good man, and 2000 for the woodwork, and in your case a billion for gee jaws gismos, that three and a half years is looking a bit , um, then of course there the lectrics, plumbing, sewage electronics
and if you a re going to fill fair and paint 1000 hrs , gee I,m getting tire thinking abt it mate
but you can do, if you knuckle down buckle down as Rodger Miller sings
yes its possible, its the fairing that the killer GOOD LUCK BON CHANCE!!
Oh my first build in 78, I tried getting a link down the hollow rudder stock onto a trim tab,
by half way thru, I,ll sail over in my simple chine boat and give you a hand, by then Maybe they will let me back into USA:)

BillyDoc
05-03-2007, 06:00 PM
I need to know the maximum degree difference. How many degrees total could the angle deviate between the vane and the rudder?

I'm sorry Alan, but I don't know what you mean by this. Are you talking about the wind-vane and the servo rudder? If so, are you asking how much "slop" is acceptable between the rotation of the wind-vane shaft and the rotation of the servo rudder shaft? As little as possible! Any "slop" will be a potential source of vibration, although I will balance the servo rudder so that it will be pivoting slightly ahead of it's center of lift and will add weight internally forward of that to prevent just this sort of "flutter."

BillyDoc
05-04-2007, 10:38 AM
Yes, you are quite right. Sorry I misunderstood your question yesterday.

The wind-vane will never be aligned straight forward except to stow it in a storm, and will always be operable in a range from about 30 degrees left of dead ahead around to about 30 degrees right, so 300 degrees in total. Perhaps a little more given weirdness in apparent wind angle. The design I show has a full 360 degrees, which is handy when tacking because you don't need to crank the thing all the way around the back side to re-set it . . but this is just a convenience not a necessity.

BillyDoc

BillyDoc
05-05-2007, 11:34 AM
Thanks Alan,

I will definitely keep this approach in mind as I get nearer to actually implementing my self-steerer.

BillyDoc

alan white
05-05-2007, 07:28 PM
Inertia is no good in a reciprocating device. Even without any friction, inertia has too much memory. Inertia, the flywheel effect, resists accelleration and decelleration, which is why iron flywheels absorb the unequal impulses of cylinders firing, and why pistons are light aluminum.
In attempting to eliminate friction, one has to take into account the friction that is generated by a rudder hesitating in returning to a neutral position, until the boat figures out what the rudder is doing and turns a bit, only to present more of its sails to the wind, or to put the wind behind the sails, either of which cause the vane to find out how to correct the situation that occurred five seconds ago, but no longer exists.
Nor are ball and roller bearings exempt from becoming involved in inertial memory. Any reciprocating control device will work better with light, strong levers and links, and plain bearings.
It's not so much an approach as it is an acceptence of simple geometric laws. An "approach" would imply that what is being approached is the same thing.

Alan

BillyDoc
05-06-2007, 10:23 AM
That's weird! Alan, your post that was between what is now #16 and #17 has disappeared. Did you delete it?

BillyDoc

alan white
05-06-2007, 11:15 AM
Yes, I deleted all of my posts. Your last comment indicated that your level of interest had peaked, as you found no reason to discuss the mechanism I'd drawn.
This is fine, but you had asked for assistance, which required a rather tedious communication process, which is also fine and always to be expected.
Wading through that, I finally understood (or thought I did) what it was you were trying to achieve. I recognized at that point that the bevel gear cluster(as far as I understood its purpose) wasn't necessary to achieve change in ratio or remote indexing. I could get infinite ratios, reversing, remote indexing, motor drive capability, low cost, home buildability, reliability, and a few other benefits using only a few simple and cheap parts.
This drawing I showed represents what came of many hours of concentrated effort. Without constructive feedback, its value to anyone but me was questionable. It might be analyzed and shot down if necessary, but what I got was a kind of a "Thanks, I'll keep your idea on file."
That was strange to me. I didn't feel comfortable at that point leaving my comments and drawing up. I don't like things half-finished.
You asked for help with it, I apparently misunderstood what you meant by that, and if I am missing something here, let me know.

Regards, Alan

BillyDoc
05-06-2007, 02:12 PM
Alan, I am very sorry if I offended you in any way, or made you feel uncomfortable. The truth is, I got swamped with things I had to attend to and recognized that I didn't have the time to continue this discussion with the attention it deserved. I also recognized that you had come up with another way of achieving part of what I was trying to do, but not all of it, and I could see that we would both be spending way too much time getting that sorted out, so, as you say, I guess my interest had indeed "peaked."

You did help me a great deal, and I am grateful! I don't need a "V" drive at this time, but if I ever do I will certainly be implementing your design, which I think is elegant. And the "L" drive you showed us is nice too, and I may very well use that to replace the bevel gears driving the servo-rudder in my own design.

BillyDoc

alan white
05-06-2007, 08:29 PM
No problem, Bill. I wasn't offended at all. I never did discuss with you what the rest of the goal was, which made my own work seem incomplete. I pulled the picture because it appeared to be unimportant to anyone but me and it being only a partial design, apparently uncompletable for lack of interest or time on your part. I'm not paranoid about having ideas stolen or anything like that. I get into a project 100% and this was a good project to work with, and it would have been very productive to have produced a finished design for anyone who wished to build it.
I've designed mechanisms since I was a kid, and my approach is obviously not the same as others use.
Mechanical design approaches a mystical level for me. There is a point one reaches, when one has spent enough time absorbed in contemplation over thousands of designs, that not even paper is needed. I have spent, for example, several hours staring at a piece of paper without moving and drawn the entire thing out in one shot. Some complex designs live entirely in my head, and have never been drawn even once.
I work with wood for a living, on boats when I can. I don't particularly like working so hard to make a living. It is generally repetitious and physically exhausting at times. When I get an opportunity to do what I really love, design work, I see the project as a work of art, a true definition of geometric integrity.
I wanted to know what it was you wanted to achieve. How to do it was what I had offered. I went back this morning to read again your request to eliminate gears and come up with a solution to your windvane idea.
What you said, I took seriously. No whimsical idea, but a clean and elegant mechanism that made for a basis for continuing on to the complete design.
I've done it a lot of times in the past. No prototype has ever failed to achieve its objective, nor have any one-offs I've built ever required changes or improvements, even after years of hard use.

Alan

alan white
05-06-2007, 08:55 PM
Just because you like elegant designs, Bill, here's a sailboat winch that has five ratios and no gears. It also has only three basic parts, all rolling contact, and near 100% efficiency. Here shown with the drum on.

alan white
05-06-2007, 10:40 PM
Then I'll re-post the drawing, Rayk. I apologize for not considering others who might be interested. Here it is, as it stands, along with the right angle drive.

Alan

sigurd
05-23-2007, 10:25 AM
Hi Alan, your second pic in the last post, what is the rotary cable for, motor drive?

And how does the winch work?

-
Maybe a hydraulic piston each on the vane and the rudder could work?
I like them, they seem reliable, and gearing, reversing and offsetting doesn't seem so complicated. Plus the drivetrain is so easy to hide away if it is long.
I prefer ropes and pulleys though, cheaper, lighter and easier to fix.

sigurd
05-23-2007, 10:42 AM
and here is a 4speed winch. :P

alan white
05-23-2007, 12:38 PM
Hi Alan, your second pic in the last post, what is the rotary cable for, motor drive?

And how does the winch work?

-
Maybe a hydraulic piston each on the vane and the rudder could work?
I like them, they seem reliable, and gearing, reversing and offsetting doesn't seem so complicated. Plus the drivetrain is so easy to hide away if it is long.
I prefer ropes and pulleys though, cheaper, lighter and easier to fix.

Hi Sigurd,

The rotary cable goes to the cockpit, to rotate the vane. A motor would be mounted on the unit itself. Handcrank would have no place to go, as shown, if both remote crank and motor are hooked up, so in such a case, I would put the motor inside the boat along the run of the rotary cable.

Regarding the winch, I suppose I don't care to patent it any more. It's impossible to get a patent cheaply these days. The system has broken down and corporations hardly care to even look at a design that isn't already patented. Then you patent it yourself, and when it's stolen, you'd better be a millionaire to fight the case.
This may not have copied well. Sorry about the neck pain. I have to learn to rotate pictures.
Now, the design...

alan white
05-23-2007, 12:56 PM
A better picture... The drawing is diagramatic, or rather an instructive mental desktop model. the actual design is very compact and harder to visualize.

alan white
05-23-2007, 01:20 PM
Hi Alan, your second pic in the last post, what is the rotary cable for, motor drive?

And how does the winch work?

-
Maybe a hydraulic piston each on the vane and the rudder could work?
I like them, they seem reliable, and gearing, reversing and offsetting doesn't seem so complicated. Plus the drivetrain is so easy to hide away if it is long.
I prefer ropes and pulleys though, cheaper, lighter and easier to fix.

I wanted to be able to rotate 360 to save back-winding. That's winding as in clock-winding.
Ropes are simpler and better, I agree. They won't work with this design as the rotating control orients with the rudder position, so the cable housing bends as the rudder turns. There are ways, of course. the nice thing about the cable is that it can pierce the deck/aft cabin and be out of the way. Ropes along the deck are one more thing to trip over or catch other ropes.
All that said, I like ropes for their visibility and simplicity, which means reliability and ultimate safety. For that reason, I would have a quick-disconnect to the cable in case of failure.

sigurd
06-07-2007, 09:29 PM
Alan,
Nice winch. the E, R and F and G is one piece? I'm not sure I see the function of the grooved "gate" part.

BillyDoc,
could you explain what part of your requirement Alan's sketch doesn't fulfill? Then maybe it would be easier for me to understand why you made yours the way you did.

alan white
06-07-2007, 09:52 PM
E, F, and G are all the same solid piece. R is a slot the handle slides back and forth in. The multi-cam rotates to align a new cam with the roller. However, the cam can only rotate when the handle is in the round part of the gate, and that requires pushing against a spring, so that normal ratcheting would not allow shifting--- it has to be a conscious push away from the operator.
The four cam faces each are generated shapes. Therefore, action is absolutely linear, and each cam makes the inner ratchet toothed face of the drum move an exact whole number of teeth clockwise.
For instance, in low gear, maybe four clicks are heard as the drum turns. In second gear, 6, third gear 9, etc.. I have worked out many gear number sets, similar to how bicycle ratios are numbered.
There are "advancing pawls" and "holding pawls". The drawing doesn't show the holding pawls. I believe there would be six holding pawls (three sets of two), and the way they are arranged, they are phased, so that advancing to a new holding pawl requires only a third of a tooth pitch rotation. So whereas there might be 100 teeth, for example, on the inside of the outer winch drum, the drum can be advanced one three-hundredth of a full rotation.
So now, looking at the gate R, see how there is one position only where one could spin to a new cam. The actual gate is not anything like the one shown. It is actually simpler and smaller, and inside. In fact, the cam ends when the handle is pushed away from the operator, and because the roller is sprung against the cam faces, it self aligns EXCEPT when the cam begins its rise. There, the flat face of the cam is no longer against the roller, but instead, a rounded groove is, and so the multi-cam can rotate even though it is sprung against the roller.

Alan

sigurd
06-08-2007, 12:01 AM
oh-- but there are 2 r's - that is what confused me. I noticed only the one you did not mention above.

otherwise the drawing is clear and your explanation seems clear too.

alan white
06-08-2007, 12:26 AM
The left R is the gate. The right R is the rounded groove that allows the cam to rotate. Sorry, Sigurd. I should have fixed that.
The biggest challenge to this design was the logistics--- fitting it all in. The later drawings could be built from. All necessary to fit everything into a 3 1/2" drum with a 7" base.
Harken's winch engineer said, after examining the design, that he felt the cams would pick up material between the cam face and the roller.
I disagreed that this was an issue. Both cam (forged and ground 17 ph ss) and the roller 310 ss (softer) would contact each other in the same way any roller bearings would under similar pressures. The advantage to my design was I could get five speeds by using the same number of rolling high pressure surfaces as a common geared single speed winch.
Vertical axis roller bearing for drum, two roller bearings for the handle pivot, plain bearing (bronze) for the rotation of the multi-cam, one for the roller, and the cam/roller contact. The entire unit could be completely disassembled with a single allen wrench. Half of the inside space was empty, and in that space, a plasic snap-closing container would store extra pawls, grease, oil, and spare hex wrench. The handle that is used to ratchet the winch has a simple rotatable lock that allows the handle to be removed. The handle has a hex wrench on the end of it, formerly hidden. It then looks like a screwdriver with a hex end. That is the tool that disassembles and reassembles the whole thing, every part. That means repairing the winch or servicing it at sea is very easy. The handle also has clear numbers one through four to tell at a glance what gear you are in, and which direction to twist the handle to get the next gear.
Because no gears are used, the winch should be at least 98% efficient in every gear (and even better using the direct drive top handle, which is the fast gear, and which uses a regular winch handle.
Such a winch would also allow the pull to be a lot lower, and as has been my experience, turning top handle winches requires unweildy positions that twist the wrist. The side handle Murray winch from NZ is loved by anyone that has used them, I hear. You sit down and pull naturally instead of raising your arms too high pulling a vertical handle.

sigurd
06-08-2007, 01:53 AM
wow so you really finished the design.
I have only used the simplest 2-speeds so I don't really know what the state of the art is.
One drawback of the regular top cranks is they are slow to wind onto - problem when tacking the jib. You either remove the crank, wind the rope, etc, or wind with the crank on. If you prepare with three or four turns before the tack then you'll get englishmen when pulling in fast.

So, maybe there could be a high gear on the low handle on one model? I think only huge boats need 4-5speeds anyway. Maybe not as quick to pull back and forth as a top handle is to rotate though - dunno.

Doesn't seem very likely/common with junk on the roller/cams, and not a showstopper if it comes.

I eyed an old sachs 3speed bicycle hub gear for a kite reel. IIRC I got something like 4:1, 2:1, and some ratio close to unity - by locking the sprocket and cranking the axle. Ditched it for the endless rope reel.

Edit: if you have time some time, please develop a better bicycle gear. the flimsy derailer **** is annoying. wears out fast/unreliable/cannot be shifted under load. maybe cogbelt with variable size sprocket or something. they can fit inside each other or segments can slide radially? 14speed hubgear exist but nobody use for some reason. They are a tad heavy and expensive.

alan white
06-09-2007, 12:33 AM
The spinshift winch is five speeds because it is possible to do so with only slight modification of a single speed of the same design.
Having 4 ratios with the bottom handle is great for mixed crews--- women, kids, etc.. The shifting is so easy and natural, you know what gear you're in from a number on the handle as it faces you. The ratio spread can be large.
I think the fastest ratio I designed for the bottom handle is a 10:1 or so, whereas a 10" handle on top (direct drive) with a 3 1/2" drum is 5.7:1.
The swing of the side handle is, I think, about 70 degrees. It's always there too, not lying on the cockpit sole or worse, missing. The line is wrapped and tailed and there is no fitting of a handle while doing this. The fast retreive top socket would only be used in light air with someone else tailing. Otherwise, the same ratio as the top handle would yield could be made available with the bottom handle. Drum diameter can be increased too.
To get an entirely new set of ratios, only the cam need be changed. And in terms of super mechanical advantage, it's easy to get a ratio of 60:1, about 9 times direct drive, on a sheet winch sized for a 100 sq ft headsail. Finger tip control.

sigurd
04-13-2009, 06:14 AM
here it is, the bicycle gear. nuvinci (http://www.youtube.com/watch?v=3YtIpBexW_M&feature=channel)

Otherwise I think reciprocating motion is easier to make variable transmission, for instance one of the locomotive valve gears, the baker for instance. Hoekens linkage (http://gtrebaol.free.fr/doc/flash/four_bar/doc/) can make a constant velocity in a straight line for more than 50% of the input rotation cycle. So the driving bar would be an eccentric on the crank shaft, then from point p would the motion be geared by a valve gear, then to a rope, onto a freewheel on the rearwheel. Two of these mechanisms would be needed ofcourse. I have tried to make a constant velocity + quick return linkage, using only rope, would be neater. not very good so far. Any way, the point would be to make bike transmission lighter and more reliable.

Boston
04-13-2009, 09:57 PM
Billy can you post a exploded view of the bits and pieces of your wind vain steering
along with maybe a perspective drawing of the thing assembled
I might like to try to build one myself if you dont mind me hijacking the design

BillyDoc
04-14-2009, 10:39 AM
Hi Boston,

I'd be honored if you "hijack" the design! There is a more detailed description of it here: http://poiesisresearch.com/Wind%20Vane.php and a description of the boat it was designed for here: http://poiesisresearch.com/Lieserl.php The boat design is a bit dated now, as I've been through several more iterations on the design but with the economy tanking have been looking to buy instead . . . and not finding . . . so I may yet build and will probably die of old age before finishing it!

Let me know if there is anything there that isn't clear and I'll do what I can to sort it out. I might still have the original Rhino file somewhere as well, but I'm not at all sure of that.

BillyDoc

Boston
04-14-2009, 10:51 AM
thanks
I like the mechanical systems over the electric ones any day

Ild like to incorporate in is some aesthetic way into the design Im working on

nice site by the way
thanks
B

BillyDoc
04-14-2009, 11:24 AM
You're welcome!

I just re-read the site for the first time in a couple of years and found I had forgotten to mention that all mechanical parts (bearings, gears, etc) can and should be immersed in oil to prevent corrosion. I just fixed this rather important detail.

And I'm definitely with you on the mechanical systems, certainly for self-steering. Electrical is nice, but way too subject to problems for my taste.

I once sailed over a week steadily on course out in the Atlantic without ever touching my earlier version home-brew self-steerer. Then one morning I got up, took a look around, and it was a nice sunshiny morning so I ducked back below and made myself a cup of tea. (I was single-handing.) Got the tea brewed and went up on deck to enjoy the sunrise, which I did for about 30 minutes before it dawned on me (pun intended) that the sun had just come up in the West.

Now, I'm certainly not the best of celestial navigators. I can do a noon sight with a sextant, and in fact that was how I was navigating at the time as GPS wasn't available yet. But, I certainly did know that the sun does not usually come up in the West!

After pondering this anomaly and sipping on my tea it did finally occur to me to check the course . . . and sure enough the wind had come about 180 degrees during the night and that old reliable fireball in the sky was arising in the East after all. That was a relief, I can tell you! I like consistency in sun behavior. It's reassuring. And the self-steerer did exactly what it's supposed to do. In fact, it never failed me in many years going to sea. But I did have trouble with deterioration of plastic parts (delrin) and seals over stainless steel bearings. Thus the present design.

BillyDoc

Boston
04-14-2009, 01:53 PM
if your wondering what Ive got planned for it go to

http://www.boatdesign.net/forums/propulsion/these-turbine-alternaters-easy-make-26738-new-post.html

BillyDoc
04-14-2009, 02:14 PM
I only see one mast . . . it's a sloop, right?

Nice boat!

Boston
04-14-2009, 02:58 PM
actually its a wind vein self steering brothel

BillyDoc
04-15-2009, 01:18 PM
Excellent! I wouldn't want to be stuck at the tiller with THAT kind of action going on. Don't forget the "not under control" lights (two red lights, one above the other in the cockpit)!

Actually, I live in a cat house now. The Madam is named Annie, and the place is known far and wide as "Annie's Cat House."

Only six cats now. We had a couple of deaths.

Boston
04-15-2009, 02:51 PM
my condolences

we have two
and the you know where wants me to help in the cat house because they need people badly
I can still work over with the swimming things
but Im ok with the big cats as I have tons of experience with them anyway and know how to handle myself round em

roar

B

BillyDoc
04-15-2009, 04:37 PM
This guy was big. I approached quietly and got a picture of him sleeping, but my SLR camera woke him up (Olympus Pen with 150 mm lens). The noise from the second picture (this one) made him jump up and roar at me.

I can take a hint. I didn't try for the "roaring" picture. I apologized and left. Without delay. Usually sleeping big cats with obvious big round bellies indicating recent meals can't be bothered to yell at pesky neighbors. He must have had indigestion.

Christians will do that . . . he may have tried one for lunch.

Boston
04-15-2009, 04:46 PM
thing that surprises most people about where I am now is that if you put an animal in a cage they tend to get very territorial even if they are not normally so
even the friendliest of species can get aggressive when only given a limited space

in the wild or at the park I have gotten away with situations I would never get away with elsewhere

nice pict though
ever seen what one can do to a side of beef with a camera

BillyDoc
04-15-2009, 05:35 PM
You're right, nobody likes a cage. The big boy in the picture was in the Kalahari. Lots of room.

Wild lions are not particularly dangerous, actually. They would much rather eat an antelope or zebra than a nasty, stinky human. And up on the Masai steppes the lions have learned that it is downright unsafe to mess with humans.

I used to worry a lot more about this gal. Note the condition of the stomach. I tried very hard to avoid hungry cats, so all my pictures show them with big bellies. This one lived about three miles from me, just outside of Gaborone, the capitol of Botswana. My horse didn't much care for her either, and used to let me know if she was about. On the other hand, I never did know her to ever actually bother anyone, and she was in the area for at least two years.

I got the shot after about a two hundred yard sneak. Same camera. I could see she wasn't in any particularly "anxious" mood, and she didn't even move when the camera made it's cha-clunk. For all I know someone stuffed her and left her in the tree for photo-ops.

Ah, to be young and really stupid again! Oh, oh! What was this thread about anyway?

Boston
04-15-2009, 06:40 PM
something about if the wind is blowing in the right direction you can avoid being eaten

Fanie
04-16-2009, 01:08 AM
Wild lions are not particularly dangerous, actually.
Phew !!

BillyDoc
04-16-2009, 11:43 AM
Oh, yeah! Now I remember, wind vane steering was the subject. One thing I haven't sorted out with the design I made is where to get those differential gears without spending way too much. Something with the "big" gears about 2.5" in diameter would be good. A differential for a lawn mower, maybe? Any ideas?

BillyDoc

TeddyDiver
04-16-2009, 12:02 PM
where to get those differential gears without spending way too much.
Old an broken angle grinders, small outboards??

Fanie
04-16-2009, 01:21 PM
Hi Billydoc,

Mechanical stuff is sometimes a challenge to make. There are co's that specialize in gears, they shouldn't be too expensive. Standard gears can often be available off the shelf. For corrosion you either have to look at stainless or plastic. Stainless is expensive bottom line, but it is good and durable. Plastics on the other hand have a reputation to perrish, but if you look at some of the new engineering plastics, they are very easy to work with, much more durable and wear resistant than the old stuff. They also doesn't rust surprise surprise :D

One need only to consider the forces to know what materials one can use. Personally I favour the plastics. They are lightweight as well and those used for linear bearings are referred to a 100 000 km travel range before adjustments needs done only. The thing to watch with plastics is their water absorbtion and colour.

I don't know what skills and tools you have, but it may be possible to have a bracket laser cut and bent, the bracket so that bearings for the sprocket shafts line up in place. Maybe a bracket that one can adjust the sprockets towards one another to adjust play out.

Making the enclosed housing could be expensive, a casting that has to be milled, especially in small quantities usually goes at around an arm and a leg.

Besides, sealed bearings that are self lubricating or rather are pre lubricated are easy to get and not expensive. One usually have two different hardness materials working on each other to extend life expectancy. I always try to make something with forever in mind...

Boston
04-16-2009, 02:25 PM
looks like you could salvage one out of a old differential for just about nothing
size to be determined by whether or not it is a big vehicle or a small one
but that thing reminds me of the gears in a differential and a little machining later and you could have that thing build in no time

thats why I asked if I could go for it
it looks like a salvage build most of the way

cheers
B

BillyDoc
04-16-2009, 02:52 PM
Thanks Teddy,

I have an angle grinder, but it isn't broke so I guess it's time to take it apart and re-do the lube. If the gears are appropriate I can look into "spares."

Hi Fanie,

Good advice there! But I do have a pretty well fit-out shop here, with a CNC mill, lathe, TIG welder and so on. The wind-vane design has all the bearings and gears submerged in oil to prevent corrosion, just so I can use steel and open bearings for the internal works (steel being usually the cheapest). Open bearings in light oil also have very low friction.

I've looked into just buying the gears from commercial suppliers . . . and the prices have been pretty outlandish! Which is why I'm looking for a cheaper source. Something that is made in large quantities that I might find junked and tear apart or buy "repair" parts for. I did find a complete differential unit for $49 US, but it looked like the gears would be too big ( https://www.surpluscenter.com/item.asp?UID=2009041613270437&item=13-1032&catname= ). Maybe not. I'm tempted to buy one just to see.

I've tried sealed bearings for a wind vane before, with little luck. These were very expensive stainless steel bearings press-fit into a stainless steel frame. The frame was type 316, but the bearing cases were probably some sort of hard 400 series type. Anyway, there seemed to be enough galvanic difference between them to cause corrosion, and the seals deteriorated badly in sunlight. So I had to replace them every couple of years, which was expensive, and slather them with grease every few weeks to try and preserve them! The greasing was messy and a lot of bother too. And replacing was an insult! Like you, I like to build once, and have it last forever.

This experience was one of the main drivers for the present design. I'll do the outer stuff out of aluminum for the most part, with some stainless steel (316), with all shafts penetrating using oil-seals and shading "washers" that just barely clear the shaft, yet have drainage. I can get oil seals with stainless steel metal parts, but preventing galvanic corrosion between that and an aluminum housing will be a challenge, I think. I haven't found any oil-seals with plastic housings, but this would be perfect! Unless they were graphite-filled, which would be worse than the stainless steel.

Thank you very much for taking the time to provide such a thoughtful answer!

BillyDoc

Boston
04-16-2009, 03:01 PM
Billy
your efforts to work in convergent technologies is perfect
anything already on the shelf can be had cheep cheep cheep
try and go with the most popular devises to salvage components from
the seal at the back of some kind of transmission will be your most durable oil seal for oil so pick one that is extremely popular and has been round for eons
the gears from small common transmission and the seals should mean that the shaft size is not a problem and so simple rod stock can be modified to make the right length shaft
there is nothing in the design that looks like it cant be salvaged except for a few bits and pieces
its a dam economical design mate
well done

B

BillyDoc
04-16-2009, 03:13 PM
Hi Boston,

Salvage stuff it is, for a lot of it. But differential gears from an auto are way too big for this job. The forces involved are pretty light with normal operation, but you do need to design it to be strong enough to resist being pooped, which WILL happen, and that is a lot of force! This is why I'm thinking about lawn mowers. Hardened steel gears with enough strength to drive a riding lawn mower should work nicely.

And to work in light air going down wind, the mechanism has to be as frictionless as possible. As in, you should be able to go up to the wind vane in still air and just gently blow it over with about the force needed to blow a smoke ring. (I'm guessing on that one, I never could do the smoke ring trick.)

If you look at the design, the primary sources of friction in the error signal path are the two oil seals at the vane and at the servo rudder shaft. The bearings are all open type roller or ball, so little friction there. The oil will provide some damping, but little actual friction if it's something like WD-40 (which is actually what I had in mind).

My previous self-steerer was a joy to use even directly down wind in light air. A reach is easy, because you have a lot of air going over the vane. But directly downwind the boat's velocity is subtracted from the wind's . . . making it much more of a challenge.

BillyDoc

BillyDoc
04-16-2009, 03:15 PM
Why thanks Boston!

Boston
04-16-2009, 03:19 PM
hmmmmm
have you looked into roller bearings
there are lots of em and they are cheep
oh
idea
ok
this is not so easy to build
how about a vein on magnetic bearings with a optical sensor to guide the system
would be dam sensitive and could run on minimal electrics based on solar or wind generators
hows that for a whole different idea

forget it
I like your better

hows that for a shot from the hip

Fanie
04-16-2009, 03:21 PM
Thank you very much for taking the time to provide such a thoughtful answer!
Well, I'm buzy designing an electronic/mechanical one, it sure is going to be easier than your mechanical one :D Well, ok that said the problem is usually the controller which in my case is something I do. For the gearing I have already obtained the cutters and has made a part here and there to test. Also, some new electronic components are available with superior specs, like the pot (variable resistor) you use on the wind vein is now available in a 5 to 50 million operations unit... the old ones was like 100k. I intend an inboard unit with a cable steer, similar to what outboards push pull steerings use.

Why don't you make the gears yourself ? If you have the tooling it is going to cost you the minimum, just the material. If the forces on the materials does not really require extreme power then plastics like high or super high density polyethylene would be perfect and are very high wear resistant. You can also have a look at ertalite and ertasetel, very hard and strong and high wear resistance, cut easily and beautifully when machined.

If you machine them yourself you can just as well make some extra for spares or even a spare unit.

You are going to have to use black, this is important, the white have UV problems, the black lives forever and this is nothing to do with racism :D
Polyethylene absorbs almost zero water. When some plastics absorb water they expand a certain amount depending on the plastic type and they lose strength... nylon rope when wet can lose up to 40 % strength, while PE remains consistent, same with the parts.

If your forces allow, and you use plastics then you could save a lot of weight. Although a heavy monstrosity could always double as a spare anchor :D

What forces do you expect on the parts ? I'm going on about plastics...

BillyDoc
04-16-2009, 04:13 PM
Hi Fannie,

Cutting my own gears is my fall-back plan . . . but the design and cutting of gears of all sorts is not at all a trivial issue! If you do it right, that is. There are some mighty fancy machines for doing it right, and I'd much rather salvage what I need from something common, if I can.

The maximum force I need to design to is from a pooping wave hitting the vane directly from the side with a few tons of sea water. Lucky me, I've actually had this happen. At the time I had the vane tied in an upright position and it wasn't harmed. The idiot on the tiller (me) got himself ground into the cockpit sole after an altercation with the engine controls though, which hurt for the next ten years or so.

So you play with controllers? Are you using one with built-in A/D converters? If so, I'd ditch the pot and go with a bi-cell photodiode with a LED shining on the intersection. Mount the LED off axis just enough so that the light from it exactly bisects the split in the bi-cell when the vane is vertical, but biases the photodiode cells one way or the other as the vane rotates. The two outputs from the bi-cell will thus react inversely to one another, that is as the resistance of one increases, the other will decrease. The magnitude of the difference between cells is then an analog to the vane rotation magnitude, and whichever one is going up gives the direction. The advantage to this approach is that everything can be behind glass and protected. And no additional moving parts are required. No moving parts means infinite lifetime, too.

BillyDoc

Fanie
04-16-2009, 05:31 PM
You don't need a fancy machine, just the right cutter for the pitch. Attached a small HDPE rack I've cut for another machine I'm designing. I've cut the rack for the steering also but has a courser pitch. Have the cutters for the sprockets also. For the small rack I've made an attachment for the small milling machine. Guess what it was ;) For the gears you need a vertical deviding head.

Cutting these gears are no black art, I have a nice pdf if you're interested I'll e-mail it to you. send a mail to fanie at faze .co .za I'll attach the file and post back.

The processors we use have a 10 bit resolution, that is 1024 steps full range.
I assume you refer to a motor doing the movement ? I'm not sure what this bi-axial led is that you refer to, but I know what you have in mind, but a pot is really easy to use. As I mentioned, you get some very nice stuff nowadays.

The way mine will work is you'd set the direction to wind for ie optimal speed using a manual steer control pot. Once you're pointing where you are happy with it, you flip a toggle switch and the controller keeps the direction wrt where the wind vein is set to. You get compass chips, if I can source some of them then you can have the steering unit warn you when you veer off course say be 10 degrees. This will prevent you from sailing in circles or go off course when the wind changes.

I seem to have read somewhere about someone who sailed all night to end up where he started the previous day... and something about the sun come up in the west ?

R i i i i i g h t :D Anyway, the compass unit would prevent that the sun come up in the wrong place providing you don't pass through any of the poles.

Boston
04-16-2009, 08:04 PM
Cogswell Cogs is about to be in business
or will it be Spacely Sprockets

BillyDoc
04-17-2009, 10:07 AM
I seem to have read somewhere about someone who sailed all night to end up where he started the previous day... and something about the sun come up in the west ?




Hi Fanie,

I read that too. What an idiot! He should have had a fluxgate compass and an alarm set. If he had a brain, that is.

Nice pictures! I just sent you an email for the .pdf and I'm looking forward to seeing it. I've actually cut plain gears like you show before, and drive belt sprockets (cogged belt) as well, but I fear that the angled pinion gears for a differential will be quite a bit more challenging as the teeth expand as the radius gets larger on the taper. My mill is actually a four-axis model with the fourth axis being a rotary table, so it's conceivable that I could get the programming codes together to do the cutting . . . but it sounds like a real nasty problem to me this morning! Maybe after I get my coffee inside it will look easier.

I think you are going to have a very nice self-steering machine there when you get finished. The bi-cell photodiode I was referring to is basically two photodiodes manufactured on the same chip with a very fine divide between them. You can also get them as "quad" photodiodes (four sensitive areas). They are used to measure miss-alignments and usually to drive a servo feedback loop of some sort. I've attached a data sheet for one below.

BillyDoc

Fanie
04-17-2009, 10:16 AM
I'll have a look at those diodes.

Your file has been sent, let me know if you received it ok.

I bought a 2nd hand Hermle 810 machine I'm renovating currently (f heavy :(), it is mostly extremely dirty, the oil is like mud. It has a verical and horizontal spindle, this machine will cut the gears, the smaller CNC machine will do the racks.

The gear cutting is going to be easy. You can calculate all the info (see pdf), devide the radius by the teeth, then when you cut, undercut and see when the gears fit. Once you have the final settings it's a matter of repetition. As far as I can remember the gear slot depth is given. I use the metrics only (Mod 1, Mod 2....) which is much easier than the inches thing you guys do.

Boston
04-17-2009, 11:00 AM
I built a machine shop for a friend of mine from Ball Aerospace
everything is cc
he has a machine specifically for cutting gears that I would think would interest you guys if your going to be making a living slicing out bits and pieces

I could ask him what it is and who makes it if you like

things pretty slick
he spends a few programming locates the block on the table and clicks a button
stands back with a grin

guy was the head machinist down there for years
Im sure he would be willing to discuss what tool would work best for production work of the components your considering

best
B

BillyDoc
04-17-2009, 12:37 PM
Hey Fanie,

I got the file and it is a wealth of information. Thanks!

Then I went to the section on bevel gears (page T61) and started reading . . . and it's way worse than I thought! I'm going to order one of those units from Surplus Center right now. I REALLY don't want to go through all of that to make my own gears. I guess it's why, as Boston points out above, there are special machines to do it.

BillyDoc

BillyDoc
04-17-2009, 12:43 PM
Hi Boston,

Sometimes I have to leave my CNC machine on for days at a time working on some part. Like you say, I position the material on the bed, press "Cycle Start" and the thing starts downloading instructions from a computer in another building and executing them. It's just working away, I'm grinning and watching, and when it comes time to leave I go to the door and start to turn out the light . . . and pause and remind myself that I'm not really turning the lights out on a poor guy slaving away over a hot milling machine . . . but it sure seems like that sometimes. It's weird!

I love this machine! It makes so many things possible that I couldn't begin to do by hand.

BillyDoc

Boston
04-17-2009, 01:30 PM
sometimes seeing various robots work I have to wonder if its not all true
that sentience in the machine world is inevitable

ok
back on topic

Fanny if you can cut gears and not even blink my hats off to you
I know it takes a fare bit of talent to get that accomplished and there are more than a few machinists who never learn how to do it
course there are carpenters who cant build a set of stares either
but cheers to you
its a knack

best
B

Fanie
04-17-2009, 05:59 PM
I'm sure you guys are missing something ! I'm not even a mechanical (kind of) guy :D

If I remember I'll make a short video so you can see when a gear is cut. You're going to kick yourself :D

Boston
04-17-2009, 06:41 PM
no its the eliptical gears that are the hard part ( worm gears )
even bevel gears are kinda a pain with two sets for each group of passes if I remember it
there is a set up on the table that the gear spins on as you cut it
although I think Denis showed me that all you do it set once turn through each cut on an beveled gear then change the angle and cut the taper on the teeth
I think
its been a long time but there is a table attachment used for sprockets and bevel gears
Denis ( guy with the machine shop ) got sick of setting it up and tearing it down all the time so he got a dedicated gear cutter

I just help out in the shop every once in a while and no very little about the machines
although I can bludgeon something out on the three axis mill if I take my time
cutting gears is a pain cause of all the set up
seems like of all the guys in the shop Denis is the only one who knows how to program a gear
so I think it still takes talent to be proficient at those more difficult gears
and my hats still off to you

Im sure given enough time any fool with the right cutting head could cut a bar gear or simple cog
but all the cone gears in that wind vein thing look like they would be best salvaged cheep rather than spend all that time
specially for a one off

I take it you guys didnt like my idea of a optical sensing vein with more of a fly by wire system rigged to it

Fanie
04-18-2009, 01:09 PM
When you cut a gear, all you have to do is figure the first slot to cut out. Once you have that done you advance the deviding head the required degrees and repeat the same slot to cut, advance the deviding head and so on.

BillyDoc
04-19-2009, 11:13 AM
When you cut a gear, all you have to do is figure the first slot to cut out. Once you have that done you advance the deviding head the required degrees and repeat the same slot to cut, advance the deviding head and so on.


You're absolutely right Fanie, no problem. And in the case of Bevel Gears you can keep it simple by going with the straight cuts, forgetting about helical or offset approaches. I've extracted and posted the table of formulas for the setup from the excellent document you sent me below for those interested.

BillyDoc

Fanie
04-19-2009, 11:47 AM
Those formulas makes my eyes water :D Forget about that.

Just get the right cutter for the pitch of the gear you want to cut. In the US they are cheap to buy. One cut and one gear tooth emerge. The cutter's profile is made so that the gear shape comes out right.

The cutter cuts a streight slot through the material. Then you advance the required degrees and cut the next slot. Once you've cut all the slots you have a gear. Drill the hole the shaft fits into using a parallel drill and you're in business.

BillyDoc
04-19-2009, 02:25 PM
It's do-able Fanie, but still not within my definition of "easy." The problem is that the teeth do not have parallel faces, but taper from one end to the other.

Here's a step-by-step explanation here: http://www.sherline.com/tip27.htm

And reading this, I'd still prefer to salvage them! But if I can't, well, I guess I'll just have to get to work.

BillyDoc

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