Wind vane self steering design

Meow!

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.

 

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

 

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?

 

something about if the wind is blowing in the right direction you can avoid being eaten

 

Phew !!

 

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

 

Old an broken angle grinders, small outboards??

 

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

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...

 

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

 

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

 

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

 

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

 

Why thanks Boston!

 

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

 

Well, I'm buzy designing an electronic/mechanical one, it sure is going to be easier than your mechanical one 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
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

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