Name of Fastener

[AKacres]

I need to get some plate connectors/fasteners but I don't know what they're officially called, so I can't find them online or in a store.
What I'm trying to do is connect plastic paddles onto a plywood wheel to make a waterwheel. So I'm looking for a connector that faces one way to fasten to the plywood (maybe with two screws or bolts) and then sort of twists to fasten on to the paddles. I don't even know how to describe this clearly.
Can anybody help? Thanks!

[farmrbrown]

How about this?

http://www.lowes.com/pd_21993-166-RT...7C1&facetInfo=

It's a rafter tie, maybe what you're looking for, maybe not.

[DEKE01]

have you considered that plywood is going to deteriorate rapidly when in contact with water?

[huisjen]

Maybe this:

Simpson Strong-tie Angle.

[1shotwade]

Originally Posted by farmrbrown

How about this?

http://www.lowes.com/pd_21993-166-RT...7C1&facetInfo=

It's a rafter tie, maybe what you're looking for, maybe not.

I clicked on your link and it came up to the Madison,Indiana store. Is that my computer is are you so close that the link was for that location?
Wade

Originally Posted by huisjen

Maybe this:

Simpson Strong-tie Angle.

If this is what you want I think we just call them "L" brackets!

Wade

[wy_white_wolf]

Huricane clip for rafters/trusses might work

http://www.dhcsupplies.com/store/p/2...icane-Tie.html

[Harry Chickpea]

I can easily visualize what the O.P. wants. Imagine the aluminum U bracket used on commercial toilet partitions.

Now imagine two of those, welded together, bottom to bottom, but with one of them rotated 90 degrees.

I can't recall ever seeing something like that in reality, and I think that there would be some major stress points that would begin to tear with use, especially if there were uneven lateral forces on the paddle.

The real answer to the conundrum is to use TWO marine plywood disks and a proper axle. As mentioned before by another poster, this is likely to have a limited lifespan due to material choices, but even the big guy built with that restriction.

[AKacres]

Thanks, the hurricane clip for trusses is what I had in mind, only smaller. Maybe I can cut them to size with a hacksaw. This is a tiny wheel.
The wheel will only be in the water for two months out of each year, so limited lifespan is ok. I'm going for small and cheaply and easily replaceable/improveable. My big worry is that the wheel will be too heavy for the water flow (which is sluggggish) to turn. That's why the tiny size and why I'm using only one disc rather than two- to save weight. The plywood disc is a base for coils of a spiral pump, so there will be several pounds of water weight in the coils for the creek to move in addition to the wheel structure itself.
If the creek will turn this thing effectively, I'll build something stouter and larger.
Thanks everyone for your help. Harry Chickpea, your concluding statement brought a smile.

[Harry Chickpea]

If you are attempting a spiral pump, you will need a fair amount of torque. Looks like you will be figuring out gearing as well.

[AKacres]

Gearing? I don't think it needs gearing. That would be for creating a different rotary or lateral speed for another application, right? From what I've read, for a spiral pump one puts a rotating joiner set-up in the axle and the water flows from the coils into that. Sounds like that's the most complicated part- putting the axle together. But there isn't any reason for gearing that I can see. Maybe I'm missing something though.
Torque...so far, I'm figuring the weight of the whole thing, with water in it, at over 20 lbs. I don't have the numbers in front of me so I don't remember the exact weight. I plan to put it on a floating or suspended platform with a vee underneath to speed up the water flow in front of the wheel. Depending on weather, the speed of the creek in midsummer is less than 1ft/sec; it averages about 3.5 feet deep and 7 ft wide- of course it will be a good bit faster, deeper, and wider in spring and the vee will speed it up too. The material I've been reading says that as long as the wheel will turn at all it will pump water; low speeds are actually preferable. There are so many variables with spiral pumps (water speed, number of spirals, size of wheel, diameter of coiled pipe, etc) and nobody seems to have done enough experimenting yet to really know a concrete formula for volume, head, etc. requirements. If this wheel will turn in the creek it will give me increased pressure from a pipe at creek level, which is the most basic thing I want from it, to run a set of venturi pumps in the creek. I think it will have a good bit of head but woefully insufficient volume. If it surprises me and turns quickly and easily, I'll shoot for a bigger one that will provide better volume and maybe be able to skip the venturi pumps.
I've looked for a way to figure out on paper how much weight a given amount of flow will move, but never found anything so I'm just going to build it and see if it works. Math is not my strong point.
I really appreciate the input and discussion!

[ronbre]

yup they are in the home depot, generally at the end of the aisle with all the other hangers and fasteners..sold by the piece

[Harry Chickpea]

To figure how many watts of power you need, just use an online calculator.
http://www.ajdesigner.com/phppump/pu...r.php#ajscroll

A gallon of water is about .15 cu ft., so if you have a continuous lift of water that equals a flow of one gallon per minute, and the height of the lift is 12 feet, you will need about 2.5 watts of power PLUS the amount needed to overcome pump and pipe friction. My GUESS is you will need twice the 2.5 watts at a minimum.

"I plan to put it on a floating or suspended platform with a vee underneath to speed up the water flow in front of the wheel."

You'll be wasting your time on that. Bernoulli's Equation and the conservation of energy rule out any gains. It is a common error, and is often used in windmill scams to impress those who don't think it through.

The easiest way to explain it is using a common funnel. Plug the end of a funnel and set it vertically on a stand. Pour water into it. The weight of the water creates a pressure at the bottom. If you weigh the entire funnel full of water, it will seem like a lot of weight. However... if you place a sensor or scale at the bottom of the opening of the funnel ONLY MEASURING THE WEIGHT OF THE WATER the weight of the water is ONLY the column of water directly over the sensor plate. The water that is off to the sides is being supported by the sides of the funnel, making the funnel appear heavier than it is.

If you overfill the funnel, the water will overflow the sides of it rather than stack up and create more pressure.

Bernoulli figured out that when water was rushing through the bottom of a funnel or restriction in a pipe, there was a relation between the speed of the flow and the pressure at that point. To obey the laws of conservation of energy, a fast moving stream of water has to DROP in pressure. That means that your vee shape will do nothing to help and possibly introduce energy robbing cross currents.

http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

The closest that we get around Bernoulli while still obeying the laws is in a ram pump. In a ram pump, the water is allowed to build velocity and then stopped short to generate a peak pressure higher than otherwise possible. Because the flow is interrupted, the overall same amount of energy is taken over a complete cycle. (High peak energy, rest, rest, rest, start flow, let flow get faster, stop flow to make high peak energy, repeat ad infinitum)

Bernoulli allows other neat things as well. The change in speed and pressure are a key part in air conditioning systems, and the way carburetors work.

[AKacres]

But then why does water flow more quickly in a narrow part of a creek than at a wider part? My hope with the vee is only water speed increase, not actual pressure increase, in front of the wheel. The spiral pump is supposed to provide the increased water pressure with compressed air in the spiral.
Water mechanics are fascinating and amazing but the terms are incredibly confusing to me. I know that technically it is the pressure of the water against the paddles that turns the wheel. The creek as a whole has a lot of water (a lot being defined as several thousand more gallons than I need for my end purpose of pasture irrigation) moving very slowly in it, and the weight of that water is, I think, a more powerful factor than its speed. If however I can increase its speed by narrowing the area much of that weight must move through, surely that would maximize my harvest of the creek's potential energy for turning the wheel.
That said, I have thought that depending on the width of the creek at my site and the size of the vee under my platform, I may just be speeding up the water on either side of the vee.
Maybe it would be better to put extremely wide paddles on the wheel to catch as much of the creek's natural flow (ie not funneled with a vee) as possible. But then there are weight and drag issues...
Again, thank you so much for the discussion. I don't mean to be argumentative, just trying to understand.

[Harry Chickpea]

You are correct that wider paddles would give a better result.

I understand struggling with the concepts. They are easier to understand if you know the math or how to do vector analysis, but that isn't really needed if you can use your mind to visualize.

Here is a fun way of examining it. Your creek flows because water is going from a higher level to a lower level. The energy it uses to do this comes from gravity. Say that 50 gallons of water drops one foot in height over a length of twenty feet in one minute.

Now for a mind trick to help understand: We know that a shallow pond of water 20 feet long doesn't have any energy, so we know the change in elevation is what is powering the stream. If we ISOLATE 50 gallons of water in a barrel, and allow that barrel to act as a counterweight on a balance beam with the barrel 1 foot above the ground, and we know that each gallon weighs 8 lbs, then we have a potential energy source of 400 (8lbs*50gal) foot-pounds of energy.

Given those parameters, there is no way we can EVER get more than 400 ft-lbs of energy per minute out of the stream or the barrel setup. If you roll the barrel of water down an incline with a vertical drop of one foot or you drop it straight down one foot you will STILL only have 400 ft-lbs of energy.

But you say "The barrel can get rolling REALLY fast if I roll it down a 20 ft long incline of one foot height. Isn't there more energy?" The answer is "No. You have only converted most of that energy into forward momentum. If you stop the barrel at the bottom of the incline, it will push at you sideways strongly, but will not be able to crush your toes, like it could if you dropped it one foot onto your foot."

Now for the key to all this. Notice that I said foot-pounds. Foot is a measure of vertical distance, and pounds is a measure of weight. We can also get 400 ft-lbs of energy by taking ONE pound of water 400 feet up and dropping it in a small container. (Eliminating air resistance of course) Ft-lbs is a measure of energy. As long as there is at least some part of a vertical foot, and some part of a pound IN COMBINATION, there is energy. Hence, the flat pond has no difference in vertical elevation and no energy. Hence, go up thousands of feet in the air and drop nothing, and there is no energy.

The characteristics of the energy shift depending on the combination you use. Our 50 gal drum one foot in the air is like an elephant, heavy and slow. Our one pound of water 400 feet in the air is like a diving hawk, light in weight but with lots of speed.

Walk back to the stream now, and you will see where the stream narrows it speeds up. The distance across the stream is less, so therefore the AMOUNT of water in that cross section of stream is less, but it goes faster. The stream widens, and the amount of water in a cross section increases, but the flow slows down a lot. Over a one foot drop of a slow section, and a one foot drop of a fast section, the SAME amount of energy is expressed. In one case it is a lumbering elephant, in the other a lightweight hawk.

"But then there are weight and drag issues..."

Weight (actually mass) is not a real issue in a properly balanced rotational device like a water wheel except at startup, when momentum comes into play.

[AKacres]

Aaaagggghhh! Vector Analysis!!???
I think I understand your illustration. Energy in the stream is constant and cannot be increased, just harnessed differently.
The stream is frozen solid right now, but will hopefully be out in a few weeks.
I had forgotten about momentum as a factor. It will be really interesting to see how (if) this thing works.

[Harry Chickpea]

LOL! Don't be afraid of terms. VA is super simple once you lose the fear factor.

You are doing real experiential learning. It can be the best learning that there is. In some ways, I envy your doing, looking, and coming to an understanding that goes beyond words.

Please keep us informed.