Nice mechanics. A similar logic is used to raise the sail on racing sailboats, but there is no leading groove on the drum. The simple multi-layer wrapping gives the friction, which prevents it from slipping, even in a wet environment.
What is the advantage og this system. Over just wrapping the rope around the drum multiple times? Of couse cutting a spiral groove would be more difficult, but other than that?
I really enjoyed this. I'm planning a wide, tall gate (8' x 8' x 1" or 2.4m x 2.4m x 25mm plywood) with an unusual hinge system I could adapt this for opening it. A slightly remote crank handle and concealed drive would be a nice novelty, or exposed clusters of cogs and chain for an industrial feel.
Sir this is a thing I have put a lot of thingking in. What I have in mind before I build such a thing (driving machines directly from windpower with a VAWT, so mechanically) is a flywheel. A flywheel might stabilize the driving shaft and it can be spun at a higher speed aswell. Directly connected to the turbine it is kept going by windpower and it keeps a steady rotation of the turbine. Although with a VAWT such as the one you build there is little need for it, since it is its own flywheel by mass. But a rotating mass at a higher speed can also store energy, thats the whole purpose of a flywheel ofcourse. WHat i personally have in mind aswell is a set weights that are spinning on the upright axis and are flung out by the rotationspeed. When that speed is suddenly reduced by any load the wieghts fall back in and from that the rotationspeed is increased because of the rotating weights is closer to their axis. A governor does a similar thing. Hope this is of your advantage
Good idea. You could also wrap the cable/chord around the drum multiple times like a sail boat winch. That'll increase the friction sufficiently. Then you dont need the pulleys at all. The drum could be a scaled down version of the table you are working on with the in-feed at the top, wraps running the length of the drum, and the out-feed at the bottom. Two such drums could be positioned at right angles. They could also be of different diameter to get the gear ratio you want. Just a thought.
This is the way, the pullies are nothing more than additional unneeded friction that actually lessens the potential overall grip of the cable or cord. just make the pullies in a similar manner to a screw thread. a helical drive pully is the best description I can think of for what I am envisioning.
Pretty neat, I like it. Always thought there was something elegant about light weight cable drives like this. I'll bet you could replace all the pulleys with another grooved spool on each side. Although you could also run the cord in a groove around the edge of the turbine rotor, that'd probably have plenty of traction being so large already. If you did want to try homemade gears though, I'd consider an arrangement of radial and axial peg gears. Easier to hand build than toothed gears. Easier to fix if something goes wrong, too. Maybe you could even put pegs somewhere towards the outer edge of the turbine rotor if you needed more speed and less torque. Even seen some contraptions that play with combinations of pegs and cords in various ways; lots to consider. Thank you as always for sharing your experiments!
Thanks for the interest; I've been trying out different ways to get the power off the turbine, including cord drives, gears, and even a friction drive.
Several lathes in the machine shop where I went to school were originally driven by a single overhead shaft and 3" or 4" flat belts around relatively small pulleys. Around WWII they were converted to individual three phase electric motor drive. The wide belts used for those kinds of applications can transfer an amazing amount of torque, even when under relatively low tension on smooth steel or iron rollers. It was also quite common to use belts to transfer power at right angles with nothing but air in-between the two shafts. That does require a relatively long distance between the two shafts relative to the belt width to allow for enough twist without significantly stretching the outer edges, but it's hard to beat it for simplicity and reliability.
Great prototype/proof of concept. Those old late 19th century traction engines used very long leather belts, some even changed axis with device being powered.
Impressive design. I'm curious of what you got to lock the turbine or mill in place to service it incase the rope breaks or something needs worked on. As well as how to adjust the rope.
Right now on the turbine I have some crude friction brakes on the outer circumference to stop and hold it. The drive train for that is still in the works.
The capstan equation[1] or belt friction equation, also known as Euler-Eytelwein formula[2] (after Leonhard Euler and Johann Albert Eytelwein),[3] relates the hold-force to the load-force if a flexible line is wound around a cylinder (a bollard, a winch or a capstan).
@@doubleMinnovations of course you would only get about half the force of a regular capstan because you are only touching half the cylinder with the rope, but you could use a pulley and a weight hanging on the rope as a tensioner in order to stand in for the rope "pulling force" variable.
Instead of a grooved drum and 5 small pulleys, you could use a drum with a convex or saddle shape to hold multiple wraps directly. No tiny pulleys needed, and no risk of the individual grooves creating wear on the rope. 4-5 wraps is sufficient for almost any rope to grip the drum.
The rope moving across the drum will create a twist that creates wear on the rope. It would be OK for occasional use but a machine that's going to run hundreds of hours per month is going to need something a bit more reliable.
Nice idea ! You could use a worm gear drive. Put worm gear in center of wind turbine axials . than just a gear for output. giver 90 deg change and change size of great for ratios of speed.
Awesome build! Is there a tensioner somewhere? Or, how did you space everything to pull the paracord into tension and keep it under tension while screwing the pieces together?
I left one board that 5 little pulleys are attached to loose. After I connected the ends of the paracord, I pulled the assembly of pulleys and board tight, then put screws in the board to hold it.
there's no need for the little pulleys at all. just wrap the rope directly around the shafts. choose the number of wraps so that the wrapped section of one shaft is the same length as the diameter of the other shaft and then you can get your right angle drive with just the rope and shafts. it's called a capstan and was a very very common machine in pre-industrial times.
I did think of that, but the problem was getting the rope wraps to slide to the other end of the cylinder with ease. If it's gripping the cylinder good, it takes a lot of energy to get it to slide to the other end of the cylinder where it leaves. The multiple little pulley idea, doesn't take much energy to gradually travel the rope wraps down the cylinder. Thanks for the comment! It's food for the thinking.
I am afraid that with all those pulleys you will be fighting high losses. It might not matter much though. If the energy is free and the system is easy to make and maintain.
A dozen bearings. Each bearing cost you 1~2% of losses. And we are not talking about all the rope friction. That’s a lot of losses to transmit power at 90deg. I wouldn’t be surprised if that units is 60% efficient. FYI The efficiency of a helical bevel gear unit can be up to 98% What you can do to improve the efficiency would be to wrap the rope around the drive drum 5x and exit and go directly to the driven drum and wrap around 5x then go back to the drive drum without going thru 8 idler pulleys.
Great basic concept, but it needs a critical refinement: the rope needs to wrap fully from drum to drum on every turn, and use the pulleys to manage / redirect the rope through the twists / deflections between the drums. Further, this system could easily use chain-link style V-belt instead of rope for greatly improved durability and force capacity. Critical core concept: Imagine a simple single V-belt drive at 1 to 1 ratio, running at 50% of its maximum gripping friction capacity. The belt engages each pulley for 180 degrees. On the driven pulley, the belt exits at full tension at 180 degrees, and enters at slack tension at 0 degrees, because you can't push a belt (or rope). Now somewhere back from the full tension exit point at 180, there has been been enough total friction to transfer the force, and that means the belt is slack from that point for the remainder of the arc back to the 0 degree point where the belt enters. At exactly maximum capacity, the belt would be gripping for the full 180 degrees, and beyond that would slip across all 180. Finally, I assume that the grip friction gets concentrated towards the 90 degree point where the tension is pulling the belt into the V instead of along the V. Now here's the rub: ALL ropes / belts have some stretch. The harder you pull, the more they stretch. That means the belt stretches between the slack point and the 180 point where it's at full tension. But the hard pulley surface DOES NOT stretch. That means that for every length of belt actually engaged in friction doing work, the stretch MAY cause a rubbing slipping creep between the belt and pulley along that working length. That means belt wear, power lost to friction / heat, and a tiny loss of transmitted rotation below the ideal 1:1 ratio we assumed from equal pulleys. The only way to avoid that stretch induced slipping across the working friction zone, is to keep the total stretch small enough that the elasticity within the rubber belt material can take up the difference without the rubber surface actually sliding across the pulley. Even still, you will be flexing rubber and thus heating and slowly wearing the rubber inside the belt. Outcome: Even if a single belt would have been far more than strong enough in tensile strength to handle the total pulling force required, you might need to use multiple belts instead, simply to reduce the stretch on each belt, by dividing the tension across multiple belts. I assume we would see overloaded drive belts and even pulleys wear out very rapidly from stretch induced slippage. But as soon as enough belts are used to avoid that slippage, we should see belt and pulley wear reduced to a negligible normal minimum. I fear that this problem will be far more challenging to avoid in rope driven systems, because rope typically stretches at least 1% under load, even for extremely low stretch ropes. And if any load bearing fibers contact the friction working surfaces, they will inevitably be exposed to stretch-slippage rubbing. This could be mitigated using a rope that carries the tension load in its core, with a lower tension jacket that allows enough flexibility to absorb the 1% of stretch internally without having the jacket actually slide on the drums. Even better, a high quality steel wire core rope would easily reduce the stretch far below what any textile rope could achieve. What you got right and why: -- Not trying to use multi-turn wraps on the main drums. Because that causes a screw winding effect that creates friction and wear to overcome in a continuous turning system of this type. -- Using a single continuous loop instead of multiple separate loops. Because that can help balance tension through the entire system (but not the way you wound it). -- Using intermediate pulleys to guide the drive rope into straight alignment with the main drums, to eliminate the screw-winding action. What you got wrong and why: -- Because you can't push a rope, it means that 100% of the drive force is transmitted entirely where the very first turn of the driving drum PULLS the rope from the very last turn of the driven drum. That puts extreme tension on a single rope crossing, which means high stress on the rope. -- If the friction of one or two wraps on each drum is enough to resist the workload, then all the earlier / later wraps will actually be running slack, just causing wasted friction and extra wear with all the little pulleys and flexing of the rope for nothing. Critical revision and why: -- By winding the rope in full wraps between the drums, you divide the tension evenly across the wraps, thus also dividing the stretch slippage factor by the number of wraps, just like a multiple V-belt system would work. -- By using the small pulleys to deflect the ropes between drums, you only have at most about 90 degrees of deflection total, less than 45 degrees on each pulley. Instead of almost 180 degrees at each pulley in your current setup. And because of the smaller deflection angle, you reduce the force on the pulleys about half or less. -- Bonus: the defection pulleys could be mounted close to the drums, allowing far more than 180 degree of engagement arc on the drums. I can imagine 270 to 300 degrees being easy to achieve. The biggest challenge is working out the weird angles needed to mount all the pulleys at in order to keep them all deflecting the ropes perpendicular to the tension, and I am assuming it would be open pulley wheels with bearings, then mounted to rigid shafts / studs on some weird frame. Sounds like a job for CAD.
Wow! Sounds like you really thought this out. -will be beneficial to the readers of the comments. It's basically taking the diagram I showed in the first part of this video, and doing it multiple times, and getting the little pulleys directing each individual rope oriented correctly. My current thoughts for use on my turbine is to have 2-3 wraps around the vertical shaft with a large drum, and driving a smaller cylinder at a horizontal position. With about a 5 to 1 gear ratio. So the smaller cylinder is going to need more wraps to get a good grip. Lots to consider...
You could use an old car axle, you could even chop it down smaller. This is really cool, I might try to make one.
A rear end car differential would work if you have one. Thanks!
It gives two outputs as well but you may need to weld some gears together
Nice mechanics. A similar logic is used to raise the sail on racing sailboats, but there is no leading groove on the drum. The simple multi-layer wrapping gives the friction, which prevents it from slipping, even in a wet environment.
What is the advantage og this system. Over just wrapping the rope around the drum multiple times? Of couse cutting a spiral groove would be more difficult, but other than that?
I really enjoyed this.
I'm planning a wide, tall gate (8' x 8' x 1" or 2.4m x 2.4m x 25mm plywood) with an unusual hinge system I could adapt this for opening it.
A slightly remote crank handle and concealed drive would be a nice novelty, or exposed clusters of cogs and chain for an industrial feel.
Sir this is a thing I have put a lot of thingking in. What I have in mind before I build such a thing (driving machines directly from windpower with a VAWT, so mechanically) is a flywheel. A flywheel might stabilize the driving shaft and it can be spun at a higher speed aswell. Directly connected to the turbine it is kept going by windpower and it keeps a steady rotation of the turbine. Although with a VAWT such as the one you build there is little need for it, since it is its own flywheel by mass. But a rotating mass at a higher speed can also store energy, thats the whole purpose of a flywheel ofcourse. WHat i personally have in mind aswell is a set weights that are spinning on the upright axis and are flung out by the rotationspeed. When that speed is suddenly reduced by any load the wieghts fall back in and from that the rotationspeed is increased because of the rotating weights is closer to their axis. A governor does a similar thing. Hope this is of your advantage
What an enchanting sound!
I wish you lived in Alberta, I would come help you build.
So amazing! GOOD WORK!
Appreciate the interest!
It reminds me of a fire mandrill.
I suspect that performance may be better with a belt made of something other than paracord though.
Good idea. You could also wrap the cable/chord around the drum multiple times like a sail boat winch. That'll increase the friction sufficiently. Then you dont need the pulleys at all. The drum could be a scaled down version of the table you are working on with the in-feed at the top, wraps running the length of the drum, and the out-feed at the bottom. Two such drums could be positioned at right angles. They could also be of different diameter to get the gear ratio you want. Just a thought.
This is the way, the pullies are nothing more than additional unneeded friction that actually lessens the potential overall grip of the cable or cord. just make the pullies in a similar manner to a screw thread. a helical drive pully is the best description I can think of for what I am envisioning.
Pretty neat, I like it. Always thought there was something elegant about light weight cable drives like this. I'll bet you could replace all the pulleys with another grooved spool on each side. Although you could also run the cord in a groove around the edge of the turbine rotor, that'd probably have plenty of traction being so large already. If you did want to try homemade gears though, I'd consider an arrangement of radial and axial peg gears. Easier to hand build than toothed gears. Easier to fix if something goes wrong, too. Maybe you could even put pegs somewhere towards the outer edge of the turbine rotor if you needed more speed and less torque. Even seen some contraptions that play with combinations of pegs and cords in various ways; lots to consider. Thank you as always for sharing your experiments!
Thanks for the interest; I've been trying out different ways to get the power off the turbine, including cord drives, gears, and even a friction drive.
Several lathes in the machine shop where I went to school were originally driven by a single overhead shaft and 3" or 4" flat belts around relatively small pulleys. Around WWII they were converted to individual three phase electric motor drive. The wide belts used for those kinds of applications can transfer an amazing amount of torque, even when under relatively low tension on smooth steel or iron rollers. It was also quite common to use belts to transfer power at right angles with nothing but air in-between the two shafts. That does require a relatively long distance between the two shafts relative to the belt width to allow for enough twist without significantly stretching the outer edges, but it's hard to beat it for simplicity and reliability.
Thanks for sharing!
Great prototype/proof of concept. Those old late 19th century traction engines used very long leather belts, some even changed axis with device being powered.
At the old pioneer shows around here, they still use them for sawmills, grinders, and threshing machines. Thanks
Impressive design. I'm curious of what you got to lock the turbine or mill in place to service it incase the rope breaks or something needs worked on. As well as how to adjust the rope.
Right now on the turbine I have some crude friction brakes on the outer circumference to stop and hold it. The drive train for that is still in the works.
The capstan equation[1] or belt friction equation, also known as Euler-Eytelwein formula[2] (after Leonhard Euler and Johann Albert Eytelwein),[3] relates the hold-force to the load-force if a flexible line is wound around a cylinder (a bollard, a winch or a capstan).
Thanks for the info!
@@doubleMinnovations of course you would only get about half the force of a regular capstan because you are only touching half the cylinder with the rope, but you could use a pulley and a weight hanging on the rope as a tensioner in order to stand in for the rope "pulling force" variable.
Instead of a grooved drum and 5 small pulleys, you could use a drum with a convex or saddle shape to hold multiple wraps directly. No tiny pulleys needed, and no risk of the individual grooves creating wear on the rope. 4-5 wraps is sufficient for almost any rope to grip the drum.
The rope moving across the drum will create a twist that creates wear on the rope.
It would be OK for occasional use but a machine that's going to run hundreds of hours per month is going to need something a bit more reliable.
In the steam traction engine days they used belt drives to do the whole thing
Nice idea ! You could use a worm gear drive. Put worm gear in center of wind turbine axials . than just a gear for output. giver 90 deg change and change size of great for ratios of speed.
Yes, there's another idea. Thanks!
Awesome build! Is there a tensioner somewhere? Or, how did you space everything to pull the paracord into tension and keep it under tension while screwing the pieces together?
I left one board that 5 little pulleys are attached to loose. After I connected the ends of the paracord, I pulled the assembly of pulleys and board tight, then put screws in the board to hold it.
Great job on this project :D
Appreciate the interest, thanks!
Excellent
Thank you so much 😀
there's no need for the little pulleys at all. just wrap the rope directly around the shafts. choose the number of wraps so that the wrapped section of one shaft is the same length as the diameter of the other shaft and then you can get your right angle drive with just the rope and shafts. it's called a capstan and was a very very common machine in pre-industrial times.
I did think of that, but the problem was getting the rope wraps to slide to the other end of the cylinder with ease. If it's gripping the cylinder good, it takes a lot of energy to get it to slide to the other end of the cylinder where it leaves. The multiple little pulley idea, doesn't take much energy to gradually travel the rope wraps down the cylinder.
Thanks for the comment! It's food for the thinking.
Is the advantage of this machine just that it is simple?
Yes. A primitive inexpensive do-it-yourself way.
@@doubleMinnovations thank you
I am afraid that with all those pulleys you will be fighting high losses. It might not matter much though. If the energy is free and the system is easy to make and maintain.
I'd probably use a rear differential/axle unit from an old car.
Yep. I'm trying to use what I have available and inexpensive. Thanks for commenting!
A dozen bearings.
Each bearing cost you 1~2% of losses.
And we are not talking about all the rope friction.
That’s a lot of losses to transmit power at 90deg.
I wouldn’t be surprised if that units is 60% efficient.
FYI
The efficiency of a helical bevel gear unit can be up to 98%
What you can do to improve the efficiency would be to wrap the rope around the drive drum 5x and exit and go directly to the driven drum and wrap around 5x then go back to the drive drum without going thru 8 idler pulleys.
Great basic concept, but it needs a critical refinement: the rope needs to wrap fully from drum to drum on every turn, and use the pulleys to manage / redirect the rope through the twists / deflections between the drums. Further, this system could easily use chain-link style V-belt instead of rope for greatly improved durability and force capacity.
Critical core concept: Imagine a simple single V-belt drive at 1 to 1 ratio, running at 50% of its maximum gripping friction capacity. The belt engages each pulley for 180 degrees. On the driven pulley, the belt exits at full tension at 180 degrees, and enters at slack tension at 0 degrees, because you can't push a belt (or rope). Now somewhere back from the full tension exit point at 180, there has been been enough total friction to transfer the force, and that means the belt is slack from that point for the remainder of the arc back to the 0 degree point where the belt enters. At exactly maximum capacity, the belt would be gripping for the full 180 degrees, and beyond that would slip across all 180. Finally, I assume that the grip friction gets concentrated towards the 90 degree point where the tension is pulling the belt into the V instead of along the V.
Now here's the rub: ALL ropes / belts have some stretch. The harder you pull, the more they stretch. That means the belt stretches between the slack point and the 180 point where it's at full tension. But the hard pulley surface DOES NOT stretch. That means that for every length of belt actually engaged in friction doing work, the stretch MAY cause a rubbing slipping creep between the belt and pulley along that working length. That means belt wear, power lost to friction / heat, and a tiny loss of transmitted rotation below the ideal 1:1 ratio we assumed from equal pulleys.
The only way to avoid that stretch induced slipping across the working friction zone, is to keep the total stretch small enough that the elasticity within the rubber belt material can take up the difference without the rubber surface actually sliding across the pulley. Even still, you will be flexing rubber and thus heating and slowly wearing the rubber inside the belt.
Outcome: Even if a single belt would have been far more than strong enough in tensile strength to handle the total pulling force required, you might need to use multiple belts instead, simply to reduce the stretch on each belt, by dividing the tension across multiple belts. I assume we would see overloaded drive belts and even pulleys wear out very rapidly from stretch induced slippage. But as soon as enough belts are used to avoid that slippage, we should see belt and pulley wear reduced to a negligible normal minimum.
I fear that this problem will be far more challenging to avoid in rope driven systems, because rope typically stretches at least 1% under load, even for extremely low stretch ropes. And if any load bearing fibers contact the friction working surfaces, they will inevitably be exposed to stretch-slippage rubbing. This could be mitigated using a rope that carries the tension load in its core, with a lower tension jacket that allows enough flexibility to absorb the 1% of stretch internally without having the jacket actually slide on the drums. Even better, a high quality steel wire core rope would easily reduce the stretch far below what any textile rope could achieve.
What you got right and why:
-- Not trying to use multi-turn wraps on the main drums. Because that causes a screw winding effect that creates friction and wear to overcome in a continuous turning system of this type.
-- Using a single continuous loop instead of multiple separate loops. Because that can help balance tension through the entire system (but not the way you wound it).
-- Using intermediate pulleys to guide the drive rope into straight alignment with the main drums, to eliminate the screw-winding action.
What you got wrong and why:
-- Because you can't push a rope, it means that 100% of the drive force is transmitted entirely where the very first turn of the driving drum PULLS the rope from the very last turn of the driven drum. That puts extreme tension on a single rope crossing, which means high stress on the rope.
-- If the friction of one or two wraps on each drum is enough to resist the workload, then all the earlier / later wraps will actually be running slack, just causing wasted friction and extra wear with all the little pulleys and flexing of the rope for nothing.
Critical revision and why:
-- By winding the rope in full wraps between the drums, you divide the tension evenly across the wraps, thus also dividing the stretch slippage factor by the number of wraps, just like a multiple V-belt system would work.
-- By using the small pulleys to deflect the ropes between drums, you only have at most about 90 degrees of deflection total, less than 45 degrees on each pulley. Instead of almost 180 degrees at each pulley in your current setup. And because of the smaller deflection angle, you reduce the force on the pulleys about half or less.
-- Bonus: the defection pulleys could be mounted close to the drums, allowing far more than 180 degree of engagement arc on the drums. I can imagine 270 to 300 degrees being easy to achieve. The biggest challenge is working out the weird angles needed to mount all the pulleys at in order to keep them all deflecting the ropes perpendicular to the tension, and I am assuming it would be open pulley wheels with bearings, then mounted to rigid shafts / studs on some weird frame. Sounds like a job for CAD.
Wow! Sounds like you really thought this out. -will be beneficial to the readers of the comments. It's basically taking the diagram I showed in the first part of this video, and doing it multiple times, and getting the little pulleys directing each individual rope oriented correctly.
My current thoughts for use on my turbine is to have 2-3 wraps around the vertical shaft with a large drum, and driving a smaller cylinder at a horizontal position. With about a 5 to 1 gear ratio. So the smaller cylinder is going to need more wraps to get a good grip. Lots to consider...
@@doubleMinnovations It was an interesting system, I couldn't help but try to puzzle through the logic of it. Cheers :)